| 1993-'98 Supra Twin Turbo FAQ's |
|
| This FAQ is based on the one
at MKIV.com,
the best source for Supra info online. The original
FAQ is very informative, but there were some things I noticed that could used touched up.
I will add to some of the FAQ's, and create new
ones as well. Text with a dark background is original
text from the MKIV FAQ that I haven't rewritten
yet. You will notice that much of this new FAQ will
be VERY different from the one at MKIV as I touch
it up. |
1.
my tt is currently stock, but i want to improve
its performance. what should i do?
the
twin turbo (tt) responds very well to the following
list of basic performance upgrades (bpu). these
four upgrades are proven to have a high degree of
reproducibility from caar to car:
- Cat-back
exhaust system - this all of the exhaust piping
coming from the downpipe, and includes the muffler
and tip. some brands have a 'silencer' (which
is basically a 1-chamber muffler) sitting about
half way back. most of the major brand name
exhausts are fine, and there are many styles
and sounds out there.
- Downpipe
- this pipe connects the turbo collector piping (which
is a 2 into 1 pipe coming from the turbos' turbine
housings) to the cat-back exhaust system. It contains
2 catalytic convertors from the factory which are VERY restrictive.
Downpipes are available with or without high-flow
catalytic convertors; preferrably without the
'cats' for max hp and spool.
- Boost
controller - either a manual bleeder, ball-and-spring,
or eletronic version will work. You do not
electronic boost controllers w/ fuzzy logic
(e.g.. profec a and hks evc) with sequential
turbos. Most people run either a GReddy PRofec
B (my favorite, has hi/low boost buttons) or
HKS EVC-EZ.
- Fuel
cut controller - GReddy BCC (boost cut contoller
- same thing) tuned to 4.3V is the BEST mod to prevent fuel cut at 14.7psi of boost. HKS's FCD is basically the same
thing as the FFCD (free fuel cut defenser),
which is simply capping off the hose coming
from the turbo pressure sensor...however this
is not recommeded because it TOTALLY blocks
off the signal from the turbo pressure sensor
which affects other engine functions as well.
with
the bpu installed, you can expect to obtain approximately
375-425 rear wheel horsepower (rwhp). you gotta
love the supra tt!!
you will also want to install a boost gauge to monitor
how much boost you are running. obviously running
more boost is going to decrease the life of your
turbos more than low boost, so you will want to
watch this. the #2 turbo quickly comes online from
a slow spin to peak boost (starting around 3800rpm's,)
which can eventually lead to the shaft between the
turbine and compressor wheel becoming warped and
cause the turbo not to boost, make a howling sound
(aka death whine), and spit out oil. some people's
turbos don't last long at all at higher than stock
boost levels, but most seem to take the increased
boost just fine. most people think the best trade
off is no more than 18 psi on a daily basis, although
some have had success and longevity with higher
boost. a conservative number would be to run 15
psi low boost with occasional runs to 17 psi if
you get an ebc that is easily adjustable on the
fly. i have heard of people hitting 29psi max boost
on the stock twins with the hose from the vsv to
the actuator pulled...i hit 28psi twice on a long
straight away in my first 6-speed (with the t-bleeder
still on) one night when I lived at sea level with
air temps around 25 degrees; sideways thru 3rd gear
is pretty insane for stock turbos :) the heavily
boosted #2 turbo died several days later. even with
a supra, you gotta be willing to pay to play...
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2.
how much will bpu cost me?
around
~$2k if you go for the electronic boost controller
instead of using a manual boost controller or a
bleeder valve. not bad, huh? try to get that kind
of serious hp for the money in any other performance
ride!!
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3.
i have a '96-'98 mkiv with the obdii computer. can
i still do bpu?
yes,
they work just fine with the obdii computer. however,
when you install the dp you will get the 'check
engine' light continuously because you are disconnecting
the second oxygen sensor from the catalytic converter. however,
that second sensor has no effect on performance. click
here for how to clear the 'check engine' light. a
dp with high flow cat will accommodate the obdii
o2 sensors and will not alert the mil. alternatively,
you can purchase an
o2 simulator that will trick the computer into
thinking the catalytic converter is still there.
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4.
what is the free fuel cut defenser (ffcd)?
*read
why the greddy bcc is better then the ffcd mod
here
& here.
The free
fcd is basically a low-buck way to bypass the
computer's fuel cut control. this is critical to
maximizing your hp output when your boost levels
go over say, 14-15 lbs of boost. here's how you
do it within 5 minutes and for less than a dollar!! this
modification requires no soldering or tapping into
the harness and is reversible within minutes. please
be aware though that with this mod, you have no
fuel cut. you need to ensure you don't boost too
high! to install the "free" fcd, completely remove
the 4-inch vacuum line that connects the pressure
sensor switch to the "y" connector. (you'll find
the pressure sensor switch on the passenger side
of the intake air manifold on the throttle body
towards the top. the correct sensor is marked "sensor
turbo pressure" in green.) notice that the vacuum
line is attached to the bottom of the sensor switch. leave
the wire connector attached. cap the bottom of the
switch with a 1/8-inch cap. cap off where the 4-inch
hose connected at the "y" with another 1/8-inch
cap. (note: when you slip the cap onto the sensor
turbo pressure, you must make sure not to trap too
much air in the cap. one tt owner had some difficulties
because the sensor thought it "saw" high boost all
the time. just a warning.)
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5. i didn't do the bcc, and now
my check engine light has come on. what can i do?
you need to reset your ecu. see
the faq entry on that topic for details
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6. since i'm upgrading, should
i replace the air intake as well?
dyno results show that mkiv supras with the bpu
and no intake system dyno about the same as those
with either a k&n or a hks super mega flow (the
gain is minimal). higher horsepower cars will benefit
more from the installation of an air intake system. if
you must upgrade, the max air airbox with intake
has been given high praise by several list members. one
upside for some if you get a cone filter upgrade
is you will hear a lot of new noises from your engine
if you like that sort of thing.
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| apu
- advanced performance upgrade |
1. what about the stock fuel
system in the tt? does it need to be upgraded as
well?
the stock 2jzgte twin turbo fuel system is a remarkably
good system straight from the factory. the in-tank
pump, fuel filter, fuel pulsation damper, injectors,
and boost dependent fuel pressure regulator are
all capable of high fuel flow. toyota did its homework
here, as the tt's fuel pump and injectors both max-out
at about the same fuel flow.
fuel
pump:
the stock pump is a denso unit, capable of supporting
up to 450 rear-wheel horsepower (rwhp) reliably. push
it up to 500 rwhp, and you start gambling. go past
500 rwhp, and you are flirting with disaster! the
pump is controlled by the fuel pump electronic control
unit (ecu) located under the plastic panel just
behind the rear driver-side shock tower. the ecu
controls the pump at two different speeds based
on engine load. at low engine loads, the pump is
operating at reduced capacity due to reduced voltage
from the ecu. once you floor it, however, the fuel
pump operates at full capacity. also, the fuel pump
ecu is equipped with a fuel pump system diagnostic
function.
fuel
filter, lines and the "mysterious" fuel pressure
pulsation damper:
the stock fuel lines are a decent size compared
to other cars. there is no need to go to larger
lines unless you plan on making over 500 rwhp, at
which time you will need to rework the whole system
anyway. the stock fuel filter is as good as any
after-market unit. the fuel pressure pulsation damper
is really no mystery. it is simply designed to minimize
the "water hammer" effect in the fuel caused by
the fuel pump's mechanical action and the opening
and closing of the injectors. the damper acts to
absorb these pressure waves in an attempt to extend
fuel pump and injector life. the necessity of this
device, however, is questionable. people have reliably
run up to 500 rwhp on the stock fuel system after
removing this restriction and making sure the rest
of the system is in top shape.
fuel
rail and injectors:
the stock fuel rail and injectors are quality units,
capable of supporting the same HP as the stock fuel
pump. the injectors are rated at 540 cc/min at 41.2
psi of fuel pressure (~550 cc/min at 43.5 psi),
and are a two-hole, side-feed, low resistance design. these
injectors enable the hot injector to be cooled by
its fuel supply, increasing both hot starting and
drivability. push your power past 475 rwhp, however,
and your exhaust gas temperatures (egts) may climb
due to a leaning-out condition. those pushing the
limits of the stock system will need to keep a close
eye on this. it would be a good idea to have your
injector cleaned and balanced if you plan on pushing
500 rwhp on the stock system.
fuel
pressure regulator and fuel tank:
the fuel pressure regulator is a boost-dependent
style. the regulator controls fuel pressure at around
36 PSI above manifold pressure. so as boost pressure
rises, so does fuel pressure. this ensures a nice
consistent differential pressure across the injector
tip which optimizes spray pattern. the fuel pressure
regulator directs all of the excess fuel through
the return lines on back to the fuel tank. the fuel
tank contains both a main fuel tank and a subtank. this
subtank (along with an internal baffle-type design
feature called the "jet pump system") prevents fuel
sloshing, and assists the fuel return flow in providing
an uninterrupted supply of fuel during high-speed
turns and low fuel level conditions, as fuel shifts
from one side of the fuel tank to the other.
fuel
system options:
most people who upgrade their fuel systems are using
either the paxton "signature" series, paxton "kamikaze",
or walbro high pressure fuel pump, depending on
hp goals. couple one of these pumps with a paxton
or earl's fuel filter,-8 or -10 (an size) stainless
braided lines and fittings (earl's, aeroquip), 720-cc
injectors (hks, greddy, rc engineering), and adjustable
fuel pressure regulator (aeroquip, paxton, sx),
and you end up with a monster fuel system capable
of supporting up to 700 rwhp!
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4.
which single/twin turbo kits fits my supra best? their
potential?
take
a look at steve v's turbo
page for great information on a lot (if not all)
of the different turbos out there that can be used
on the 2jz.
RPS
Kits:
TS04:
Most common housings for this turbo are 0.58 and
0.70, it makes about 450 rwhp in the former and
500 rwhp in the latter, spools slightly slower than
stock, and can commonly be used on the stock fuel
system. This is a good turbo if you have an automatic,
and can be daily driven.
T61: Somewhat bigger than the TS04, this
turbo can make 550-600 rwhp. It requires an upgraded
fuel system. This doesn't lag too much, a T61 car
lags a bit more than stock, but is streetable, if
not particularly responsive, could be used for road
racing, not sure if I would recommend this turbo
for a daily driver.
T66: Capable of making 600-675 rwhp, the
T66 is a bigger turbo yet, this is probably as big
a turbo as I would recommend for the street, it
makes full boost right around 4250 rpm on most cars,
a significant amount of lag, but not horrendous...
(full boost being 1.5-1.6 bar) This is a very common
turbo, and a nice setup for drag racing with some
street driving.
T70: Slightly bigger than the T66, the
T70 is probably not a streetable turbo. Lag is a
couple hundred rpm more than the T66, power output
ranges from 650-750 rwhp... perhaps a bit more with
headwork... This is a nice turbo for drag racing.
T72+: These turbos are only good for drag
cars for the most part, lag is far more than smaller
turbos, power outputs are from 750-1000 rwhp.
Twin turbo kit: Using T25/28 ball bearing
turbos, this kit will make slightly more than 500
rwhp, while spooling faster than the TS04 0.70...
very good choice for a street car that needs more
power than BPU.
HKS:
GT2540: These twin turbos are used on the
UPRD supra, and used in single form on quite a few
different cars. Nice turbos, not enormous lag,
maybe slightly more lag than their brethren the
2835s, but they spool a little faster too...I'm
told that car makes power in the 900 rwhp range
on turbo alone, but this could be just a rumor.
GT2835: Probably the most common twin turbos
used on supras, this kit is large, and the turbos
have a fair amount of lag, they make full boost
in the 5000 rpm range, perhaps a bit higher. Very
nice top end on this system, and I've seen power
output in the 700-800 rwhp range fairly consistently
with the right fuel support.
T04R: A fairly large single turbo, this
comes with a pretty big exhaust A/R stock, 0.96...
I would have thought it would be laggy, but my experience
with it shows otherwise... it spools a touch faster
than a T66, but has a bit more power output capability...
it has made power in the 675-750 rwhp range, and
is becoming fairly popular because of this.
T51R: This is HKS's biggest single turbo
that is commonly sold, although it isn't THAT much
bigger than the T04R. Probably in between the T66
and T70 in size, the T04R makes full boost in the
5k range, and none has really been able to realize
its full power potential... I wouldn't be surprised
at seeing 800+ rwhp from a T51R under the right
circumstances... very strong turbo but I wouldn't
use it on a street car personally.
Greddy:
T67: The T67 isn't used on supras very
often, its a TD07-25g turbo, more commonly used
on MR2s... its capable of right around 600 rwhp,
and spools similarly to a T66, so most people choose
to go with either the T66 or T61. Again, on the
upper limit of streetability.
T78: This is one of the more common turbos
used on supras... it makes full boost somewhat past
5000 rpm, but has the potential to make 750+ rwhp...
nice turbo, very good top end once it gets spooled...
lots of drag cars use it, and its fairly inexpensive
now.
T88: Somewhat bigger than the T78, the
T88 has close to 1000 rwhp capability, although
I would imagine it makes full boost close to 6000
rpm, so a built motor is almost a certainty with
this turbo... not too expensive but its not too
usable on most supras so...
Blitz:
Single: The blitz single turbo uses a
K27 turbo and is capable of right around 600-650
rwhp... spools somewhat faster than a T66, and the
kit is well made, but you need to modify it to work
on the US spec supra, pain in the ass to do.
Twins: Supposedly capable of right around
700 rwhp with about as much lag as the single, haven't
really heard too much about it to corroborate this,
but I wouldn't doubt it... kind of expensive, and
this needs heavy modification to work on a US spec
supra.
Others:
TPC: This turbo supposedly has 625-750
rwhp capability with faster spool up than a T66...
don't know enough about it to really say, but the
dyno charts seem to show full boost at right around
4500-5000 rpm, which isn't TOO bad for a turbo with
its power capabilities... not enough people use
it to really say.
Fastrax: Fastrax makes all sorts of custom
turbos... my experience with them is that they make
somewhat more power and spool somewhat faster than
the turbos they were built off of... Fastrax has
allot of experience in the drag racing scene, and
they make high quality products. My Fastrax turbo
supposedly has 750-800 rwhp capability while spooling
slightly faster than a T66... it certainly spools
faster than a T66 in my experience, we'll have to
see how much it puts down on the dyno.
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to start
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5.
what exactly is a/r of a turbo?
a/r
stands for area / radius on the turbine side of
a turbo. area being the area of the turbine inlet
and radius being the distance from the center of
the turbine shaft to the center of the turbine inlet.
this picture explains it perfectly. changing this
property affects the spool-up and overall flow of
a turbo. lower a/r generally reduces spool-up and
maximum flow of a turbo.
|
| engine |
general
description
the 2jz-Gte is a high performance 3.0 liter, inline
6 cylinder engine. it features dual overhead camshafts
(dohc), 4 valves per cylinder, twin sequential water-jacketed
turbochargers with a common charge air cooler (air
to air intercooler). it is a "square" configuration
with equal bore and stroke dimensions. it is also
designed as a non-interference type engine and both
camshafts are driven from a common toothed drive
belt.
its mate, the 2jz-ge, or naturally aspirated (na)
version of the engine, shares the same block casting,
but is fitted with higher compression pistons. the
two head castings are similar as they both must
fit on a common block, but are cast and machined
differently to suit the design requirements of the
two models. the real differences between the two
engines are found in the ancillary systems such
as fuel, ignition, intake/exhaust, cooling, and
of course the turbochargers and their control system.
where similarities or commonality exists between
the gte and the ge engine, they will be mentioned,
otherwise the descriptions below are for the gte
engine.
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1.
what is the difference between an i-6 engine and
a v-6?
the
i-6 Supra engine has all six cylinders "inline". the
camry's and other models in the toyota lineup use
a six-cylinder engine with its cylinders arranged
in a "v" like an american v-8. the supra engine
is a superior design for smoothness, high performance
potential, and ease of modification. sadly, toyota
has decided to phase out their i-6 engines in favor
of the v-6, for economic and space reasons.
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2.
what is meant by "...designed as a non-interference
engine"?
by
definition, if the design of the paths of the valves
and piston causes them to intersect at any point,
regardless of the timing, the engine is an interference
engine. in practical terms this means that if the
camshaft drive system (timing belt) breaks in an
interference engine, and several valves are left
open or partially open, chances are there will be
damaged valves, pistons, and perhaps other components. in
a non-interference engine, if the timing belt breaks,
the engine will simply stop running, but there will
be no damage to it. some honda and dsm engine designs
are the interference type.
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3.
i sometimes hear slight detonation when boosting.
if this is consistent with any type of readily available
fuel, you are probably running too much boost.
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4.
what causes knocking, pinging, detonation, and pre-ignition?
detonation and pre-ignition are about the same thing,
they just happen at different times in the compression
cycle. pre-ignition is either caused by hot spots
that pre-ignite the fuel before the spark plug goes
off or the actual compression of the air/fuel igniting
the mix. remember, when you compress a gas, you
heat it up. that's why too much boost can cause
extra high cylinder temperatures and subsequent
pre-ignition. a lot of people call this detonation,
but it isn't. you can feel pre-ignition, it will
feel like rough power. detonation occurs after the
spark. if the air/fuel ratio is too lean, you don't
get a nice progression of the flame front from the
spark plug towards the bottom of the cylinder. the
burn will be uneven, and you will develop many different
flame fronts going in many different directions. as
these flame fronts collide, they make noise and
you hear the knocking and pinging. more importantly,
the oxygen is going to react with something. better
it react with gas than metal. both of these will
lead to high EGTs. now hesitation can be caused
by both lean and rich conditions. usually by too
rich conditions. you basically flood out the spark
and it doesn't light off the air/fuel mixture. this
will lead to black smoke out the tail pipe and low
EGTs. if you run too lean to get a hesitation, you
will be way past the point that your EGTs should
be sky high. another thing to check is make sure
all injectors are firing. you should be able to
do this at idle by putting a screwdriver on the
injector and the other end butted up against your
ear. or, you can sometimes feel them by putting
the tip of your finger nail on the injector and
pushing a little hard. the vibration is carried
through the bone and you feel it.
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specifications
bore
& stroke of the engine are both 86mm (3.39") giving
a true displacement of 2997cm3 (183in3). The turbocharged
(gte) engine has a compression ratio of 8.5:1, while
the na (ge) engine is raised to 10.0:1 using different
pistons and head configuration. the engine is internally
balanced, has a firing order of 1-5-3-6-2-4, and
produces a maximum horsepower of 320 (sae net) @
5600 rpm, with 315 ft-lbf peak torque @ 4000 rpm.
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1.
i want to have the motor bored & stroked like my
chevy. what's available?
interesting
idea, but there are no big bore kits available,
nor can the engine be bored any significant amount. there
are only two stroker kits (jun and crower), and
these cost in excess of $5000 and only increase
the displacement by approximately 10%. this is very
expensive horsepower...
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features
the engine has an advanced dis type cop (coil on
plug) ignition
system which is crank and camshaft triggered. no
external ignition timing adjustments are available
or necessary. all timing adjustment is made electronically
by the engine management system (ems) according
to internal 3d ignition maps. two knock sensors
are provided and timing is retarded by the EMS when
knock is sensed.
fuel delivery is by a sfi
system with both pulse rate and fuel pressure
adjusted according to load demand by the engine
management system.
intake air is measured before the turbochargers
by a hot-wire type, mass
airflow (maf) meter. this measurement is then
compensated for temperature & barometric pressure
(altitude) in the engine management system.
all systems are controlled by an integrated engine
management system consisting of a main engine
control module (ecm) and several peripheral
electronic control units (ecu) for the ancillary
systems.
all aforementioned systems are described/discussed
in more detail in later sections of this faq.
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1.
what spark plugs should i use?
stock vehicles respond very nicely to factory toyota
plugs, gapped to toyota specs. of .043". if you
have a tt or single-turbo Supra and run higher than
stock boost, or if you notice a high-rpm miss, you
may want to consider reducing your plug gaps until
the miss goes away. there is still debate about
whether to switch to another plug at bpu levels,
but single-turbo supras will probably benefit from
a plug one heat range cooler than stock. many bpu
owners have switched to plugs one heat range cooler
than stock also such as NGK 3330, 1095, 6097, and
1283. these four are described below.
to begin with...stock plugs on the supra are the
NGK BKR6EP-11, which is defined as:
BKR6EP-11: B = thread diameter of 14mm, K = construction
type: hex size 5/8" w/ ISO projection tip, R = resistor
type plug, 6 = heat range #6, E = 19mm (3/4") thread
reach, P = platinum-type plug, -11 = x/10 - 1.1mm
pre-gap (0.044")
now keeping that in mind, (in what the car calls
for, and specs it requires) now lets compare the
BCPR7ES(-11) 1095/3330 and the BKR7E(-11) 1283/6097 plugs:
(1095) BCPR7ES-11: B = thread diameter of 14mm,
CP = hex size 5/8" w/ projected insulator (which
is out-of-spec), R = resistor, 7 = heat range #7, ES
= standard 3/4" thread reach w/ 2.5mm diameter center
electrode (which is prone to misfires), -11 = x/10
- 1.1mm pre-gap (0.044")
3330 is simply the BCPR7ES w/out the 1.1mm pregap
(therefore gapped at 0.0315")
(1283) BKR7E-11: B = thread diameter of 14mm, K
= construction type: hex size 5/8" w/ ISO projection
tip, R = resistor type plug, 7 = heat range #7,
E (stand-alone digit) = v-grooved center electrode
w/ 1.5mm diameter electrode.
6097 is also the BKR7E w/out the 1.1mm pregap (0.0315")
the 1283/6097 (BKRxE) plugs are pretty much the
same specs as stock, but one heat range Colder,
as well as non-platinum in a copper-core form. the
center electrode, as compared to the 1095/3330 is
also 1mm smaller in diameter as well as have a v-groove. the
smaller the diameter of the center electrode, the
better the spark flow. (less chances of misfire) think
of the spark traveling through the center electrode
as a water traveling through a small/steady stream,
as opposed to some wide stream w/ wild rapids and uncontrollable
tides. the v-groove also furthermore helps the spark
by directing the sparks toward the edges of the
electrode, closer to the a/f mixture for the best
ignition possible.
if you ever have the chance, try laying down a oem-spec
plug... along side with the 1095/3330, and you'll
notice the physical difference. although they "may"
work, it is not the correct plug for the car. the
BKR-construction plugs are the way to go on the
supras (and not the BCP-construction plugs, which
are designed more towards Hondas which require a
longer insulator), and brian weaver at ngk tech
will also agree with me.
the main reason people on this list use 1095's (and
also 3330's) is that they are more readily available
to the public. many napas, and even pep boys stock
them and can also get a hold of them if necessary. the
1283 and 6097's on the other hand, wont even show
up on many stores' ngk parts list! the only means
of obtaining these plugs would be through NGK directly,
or by calling their main distributor (monarch) at:
888-800-9629 (outside california) or 909-672-8501
(within california).
now that you've read all about those plugs, you
might also want to try denso iridiums. they are
pretty expensive, though. but they are also a platinum
tipped plug and won't need changing every 3k-6k
miles. they seem to work well for many in both bpu
and higher hp applications.
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2.
i'm using stock plugs, and my car isn't running
quite right.
one of the reasons that stock plugs sometimes do
not respond well to the added cylinder temperatures
created under higher boost conditions is the fact
that the plugs were designed to run with longer
spark plug noses and longer ground strap. a longer
ground strap dissipates heat slower and therefore
can contribute to detonation. typically the missing
that many experience on higher boost is not because
of the heat range of the plug, but because the gap
is too wide. it should be noted that denso and ngk
plugs such as those supplied with oem cars are designed
to operate with a specific gap width (or length),
and not smaller gaps. you may need to reduce the
gap on your stock plugs or switch to a colder plug. see
question 1 above
for a list of ngk plugs people have had success
with.
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3.
i want to replace the spark plugs on my supra tt.
what are the steps?
- buy
6 new spark plugs from toyota (toyota part number
# 90919-01178) or by choosing from section 1
above. also buy 2 crankcase hoses, toyota part
number 12263-46010 & 12264-46010 (if needed)
- with
allen wrench (5mm) remove top cover of engine,10
screws.
- remove
the two crankcase vent hoses that run between
the valve covers.
- using
small screwdriver, release the wiring harness
clips.
- unbolt
the ignition coils (coil packs). there is a
10mm bolt on each side. there are 3 coil packs.
- disconnect
wiring from the coil packs. two connectors per
pack.
- lift
out coil pack.
- use
deep well 5/8th socket to remove plugs.
- gap
(if needed) and install the new plugs (torque
it to 13 ft/lbs). stock plug gap is .043 or
1.1mm, for bpu try stock gap or a lower setting
like .035 if your engine is missing.
- install
coil packs... make sure you have a good seal
on the plug.
- connect
wiring and re-clip wiring harness(2) to clip. make
sure each harness routes *below* the crankcase
vent.
- install
crankcase hoses that you bought (or previous
ones if they are not cracked).
- re-install
cover.
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4.
how can i read my sparkplugs?
this is covered in the tech section. click
here to go directly there.
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5.
the engine misses at high boost.
try re-gapping original plugs or new plugs at .026"-.035". start
high and work your way down until it stops missing.
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6.
how do i check the engine trouble codes?
for cars with obd1 (93.5 - 95)
turn the ignition switch on. connect a wire between
te1 and e1 in the diagnostic
connector. supras have two diagnostic ports. one
inside the car under the dash (driver side), and
one under
the hood. if everything is okay the light will
flash on and off steadily. if there is a problem
it will flash in a sequence that will decipher to
a number that relates to a specific fault. for more
information about reading these codes click
here.
for cars with odb2 (96 - 98)
use an obd2 scanner to read the code. the connector
is located under the dash by the left knee of the
driver.
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cylinder
head & valvetrain
the cylinder head is a single casting of aluminum
alloy with two camshaft/valve covers and a central
coil/plug cover. combustion chambers are pentroof
design with valves angled at 45 degrees away from
each other. the spark plugs are mounted near the
centers of the chambers.
both intake and exhaust valves are made of tempered
steel with nitrided stems and valve faces which
have been bonded with cobalt alloy for good wear. the
valves run in replaceable guide bushings and have
replaceable stem seals. single valve springs are
employed which are held in place by split keepers
and steel retainers, steel spring seats are also
provided. valve lash adjustment is by "bucket and
shim" type lifters fitted between the valve stems
and camshafts. the intake valves are 33.5mm (1.32")
in diameter and are lifted 8.25mm (0.325") by their
camshaft. exhaust valves are 29.0mm (1.14") in diameter
and are lifted 8.40mm (0.331") by their camshaft.
the intake camshaft is fitted with special timing
lobes for the dis ignition and sfi systems. the
intake camshaft opens the valves 3 degrees btdc
and closes them 50 degrees abdc. the exhaust camshaft
opens its valves 52 degrees bbdc and closes them
4 degrees atdc. each camshaft is held in place by
seven heat-treated, unbushed bearing caps.
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1.
what does dis
mean? is it an abbreviation for distributor?
dis is an acronym for "direct ignition system" and
generally means a distributorless, crank triggered
ignition.
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2.
how about sfi?
sequential fuel injection. some electronic fuel
injection systems called mfi cut corners by injecting
into multiple cylinders (3 groups of 2 cylinders)
simultaneously - the mkiii supra used such a system. the
mkiv supra on the other hand, "can" control fuel
into each cylinder individually.
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3.
how can i do a cylinder leak-down (clt) test?
- basically,
a cylinder leak-down test consists of pressurizing
a cylinder with shop air and listening for leaks. fashion
an adapter from an old sparkplug so you can
hook up an air hose from your air compressor. rotate
the engine until the cylinder to be tested is
at tdc compression. be sure to get it exactly
on tdc. next slowly turn up the air pressure
regulator on your air compressor or slowly open
the supply valve to pressurize the cylinder. go
slow because the engine may try to spin - keep
hands and tools clear of belts, etc. once the
cylinder is fully pressurized listen for air
leaks. do not confuse a "seashell" sound for
a leak. air leaks will be very distinct sound
and you may even feel a rush of air. open the
throttle and put your ear next to the intake
opening. a rush of air indicates a leaking intake
valve (bent valve? misadjusted or sticking?). next
put your ear to the tailpipe opening, air rushing
out means a leaking exhaust valve (bent, misadjusted,
sticking, or burnt?). listen at the oil filler
cap. you will hear a slight hiss of air. this
is normal 'blow-by' leakage. how much is normal? well,
many clt tools have a flow meter to measure
how much air is coming by the piston rings and
out thru the oil filler cap. usually less than
15%. you probably don't have an air flow meter
to hook in-line with your air hose, so instead
try to remember what each cylinder sounded like
and compare them to one another. engines with
good compression and good rings will sound even,
slightly louder than a 'seashell' and you will
not feel any air rush. lastly, take the radiator
cap off and look for bubbles. bubbles indicate
a blown head gasket or maybe a cracked cylinder
head. doing a clt along with a compression test
will tell you a lot about an engine's condition.
-
a number
of people have asked "What is a LEAK DOWN
test?" and "Can I do it myself?". first, let
me explain the concept. we already use a compression
test to determine an engines condition. The
problem with this test is that there are too
many variables. it can only be used to check
engine condition by comparing cylinders to
each other or a past norm. variables such
as cam profile, engine cranking speed etc,
will affect the readings.
a leak down
tester uses air from a compressor and measures
the rate at which it leaks through the engine. this
is done with the engine not running and the
beauty of this is that toy can find the source
of the leakage by listening for the escaped
air. internal leakage is found by air bubbles
in the cooling system. tools need are a leak
down tester and an air compressor. the tester
is available from Milton at about $60.00. compressor
should be at least 2hp and deliver 90psi.
procedure:
remove spark plugs. set engine to tdc #1. calibrate
test gauge per the instructions. Lock engine
so it can not turn. connect hose to spark
plug hole. connect pressurized gauge to hose
connection. read leakage. if looking for coolant
leaks and nothing obvious shows up, bypass
gauge and connect shop air direct to cylinder. open
radiator cap before this. if coolant sprays
out, you have a head problem. do same test
on rest of cylinders. remember to set tdc
of each piston for compression stroke. this
test is also great for air cooled head leaks
and valve problems. note that all engines
will have some leakage past the rings. i always
do full pressure test when i suspect a problem. make
sure engine is secured with full pressure
test. it will spin violently. with gauge connected,
you can rock crankshaft to see if leakage
changes. if so, this is a sign that the ring
lands are wearing, new engines will also do
this until the rings are seated.
i know these
instructions are kind of flaky, but I hope
this gives some insight as to this type of
test. if having a mechanic work on your vehicle,
he should be familiar with the leak down test. i
would be concerned if he isn't. this is a
basic troubleshooting tool that all fleets
use. especially on diesels.
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block
the cylinder block is a single iron casting without
lined cylinders. it has seven massive main journals
with two bolt main caps. accessory bosses have been
cast into the block to allow direct mounting of
the alternator, starter, A/C compressor, and other
accessories. with only minor machining differences,
both the GE and GTE engines share a common block
casting.
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1.
i thought the supra was a
high performance engine. why doesn't it have four
bolt mains like a camaro?
first reason is that the main journals in the 2jz
engine are absolutely massive. they are some of
the biggest mains you'll ever see in an automotive
engine, so block flex is not an issue as it is with
domestic blocks. second reason is that the 2jz crankshaft
is already a precision balanced component with twelve
counterweights. as such, it does not require extra
restraint or externally balancers. third reason
is that with the inline configuration of this engine
there are seven main journals taking the load, not
just five as there are with domestic v-8 engines. in
summary, the box stock lower end of the 2jz engine
is nearly indestructible and is capable of delivering
well over 900 horsepower reliably to the rest of
the powertrain. it was "designed" as a high performance
engine, not modified to be one.
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pistons
& rods
pistons are an aluminum alloy and have two compression
rings and one oil control ring. the first compression
ring and the oil control ring lands have been
nitrided for durability. the second compression
ring has been chrome plated and the piston skirt
has been resin coated to reduce cylinder abrasion. an
oil gallery has been cast into the piston and
as oil from the oil jets is sprayed onto the underside
of the crown, oil circulates within this gallery
and cools the piston.
the same forged connecting rods are used in both
the ge and gte engines, employing press fit pins
with retainers on the small ends and replaceable
rod bearings on the crank end. oil jets are provided
on the large end for directing oil onto the underside
of the piston crown for better cooling.
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1.
are aftermarket forged
pistons and rods a good idea?
the sellers of these components think they're
an excellent idea! in reality, the stock supra
pistons are as advanced a design as any aftermarket
piston, and the rods are already forged. the stock
reciprocating assembly "can" hang together just
fine up to 8000-8500 rpm (although we're rev limited
to 6900-7200) and can produce insane power levels. however,
to be fair to the aftermarket, there are some
weight savings and strength increases to be gained
with aftermarket rods and pistons, but these become
advantageous only when the engine is being prepped
as a full race engine.
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crankshaft
& torsional damper
the forged steel crankshaft incorporates twelve
counterweights and seven main journals; the main
and rod journals are induction hardened. replaceable
aluminum alloy main bearings are used.
a dual mode torsional damper is fitted to the
front of the crankshaft. this is NOT an external
balancer, as the crankshaft is fully balanced,
rather it dampens both the axial twisting couples
produced by the firing pulses, and the radial
bending moment from the accessory drive belt.
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1.
can I pull the harmonic balancer
off, replace it with an underdrive pulley and pick
up 10-15 horsepower?
first, it's not a "harmonic balancer". it's a torsional
damper. second, it is NOT a good idea to replace
it with a solid underdrive pulley.
torsional analysis of a reciprocating engine is
an extremely complex, computerised study and design
of a system to smoothly and safely transfer 20,000
explosions per minute into useable torque without
destroying the engine or drivetrain. oh, and do
it for the life of the car. without exception, every
reciprocating engine, pump, or compressor can benefit
from torsional damping, but getting it right is
an extremely complex process, and the consequences
of getting it wrong are broken crankshafts and/or
ruined drivetrain components. so in summary, this
is NOT a good area to try to pick up cheap horsepower
on the supra unless you are prepping a full race
engine and plan to rebuild the engine and drivetrain
on a semi-regular basis.
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lubrication
system
the engine lubrication system consists of a wet
sump, pressurized system with a crankshaft driven
gear type pump, spin-on oil filter, and a water
jacketed lube oil cooler which is built into the
oil filter adaptor housing. the engine oil pan is
actually two pans, an upper and lower unit, neither
of which can be easily removed without either lifting
the engine from its mounts, or removing it entirely
from the car. there are dual oil supply galleries
in the engine which supply the cylinder head, crankshaft,
piston oil jets, and the turbochargers with pressurized
oil. pressure relief valves are fitted to the oil
pump, filter and oil cooler. if oil pressure at
the discharge of the pump is too high, its pressure
relief will open and relieve pressure back to the
suction side of the pump. if either the oil filter
or the oil cooler become plugged, their pressure
relief valves will open and allow oil to bypass
around them. in this way, the system is both protected
against overly high pressure, and oil flow is always
assured to the main gallery.
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1.
which type/brand of oil
and filter should i use for the mkiv tt engine?
turbocharged car owners generally favor pure synthetic
or synthetic blend oils over dino oils. synthetics'
shear and anticoking properties at high temperatures
are ideal for protecting turbocharged engines. any
synthetic of the proper weight will do. don't
get hung up on brand names. if your tt has a new
engine or fresh short block, allow 5,000 miles
for break-in with dinosaur (mineral) oil before
changing over to synthetic oil. the "dino oil"
helps seat rings, seals, etc. generally stick
with toyota's specification of 10w-30. however
in cold climates, a change to 5w-30 may be warranted
during the winter. be aware if you have a high
mileage supra and switch to synthetic, your oil
consumption will probably increase. despite synthetics'
other very desirable qualities, some supra owners
have found that certain brands of synthetic are
not as friendly to valve stem seals as dino oil,
and may actually accelerate wear in this area!
toyota make an excellent stock filter for the
supra, and an even larger capacity filter is available
with the same construction for the land cruiser
or lexus, and these are good upgrades for the
supra - the toyota p/n for these is 90915-20004.
In the aftermarket, Amsoil make a very good filter,
as do k&n. stay away from the bargain store brands
that are on sale for only two or three dollars. this
is not a good area to save money.
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2.
how often should i change
my oil?
the critical question that has no hard & fast answer. it
just depends.... how often is the car driven, and
"how" is it driven? is the engine modified, is the
car raced, etc. the best answer is "somewhere" between
2500 miles and 10000 miles per oil change. 2500
miles if the car is raced, and/or does lots of stop
& go driving or quick trips to the grocery store,
or if you operate the engine in a very hot or dusty
climate. if, however, you clock a hundred miles
of driving each day at freeway speeds, and the engine
is running at normal operating temperatures and
NOT at peak output for several hours, extended oil
changes are certainly possible with synthetic oil
AND regular oil analysis. in summary, frequent oil
changes are sometimes seen as a waste of good oil,
but they're a good insurance policy for you and
your engine if you don't have an established oil
analysis program and don't know exactly what's going
on with your oil.
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3.
is it difficult
to change the oil? how long should it take?
it isn't difficult, but the first time you do
it, set aside a couple of hours to complete the
task and be prepared to get messy. after you have
done it once or twice, it should only take about
20 minutes and you'll have figured out how to
do it with less mess. while you have the car up
on stands, it's a good opportunity to check over
the entire undercarriage and check the torque
on the suspension mounting points both front and
rear.
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4.
what specification and oil
weight should i use?
the list members have personal preferences. for
fastest turbo spooling and maximum horsepower, stay
with the recommended 10w-30. heavier oils can be
used, but they will make the engine warm up slower,
run hotter, and lose more horsepower to fluid friction. in
very cold climates, a switch to the same oil in
a lighter range, such as 5w-30 will improve starting
in the winter.
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5.
aren't all engine oils basically
the same?
no! conventional and synthetic oils are as different
as day and night in performance. you can't beat
any pure synthetic with a conventional (mineral)
or conventional/synthetic blended oil. the pure
synthetic wins, hands down, in any performance comparison
except price.
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6.
how can i know if my oil
is not performing?
the old mechanics' practice is to wipe the inside
of the oil filler cap with a clean rag. if there
is a visible brown deposit on the metal surface,
they'll say it's time for an oil change. this isn't
really a valid test, but no one has ever ruined
an engine with too frequent oil changes, where the
opposite is certainly true! the best way to know
about your oil's performance is to establish a regular
oil analysis program, which involves taking samples
of the oil periodically to an oil analysis lab,
and they'll tell you exactly how the oil is performing.
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7.
how important is it for my
turbos/engine to use the right oil?
superheated oil exiting the turbo bearings sometimes
looks like a chocolate mousse. this is why the turbos
have a water jacket to help cool them. a turbocharger
puts extreme stress on oil, and the oil is the only
thing in your engine separating metal-to-metal disaster. again,
bargain basement or generic brand oil is not a wise
idea.
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8.
when to switch to synthetic? what
kind?
you can switch to synthetic as soon as break-in
of the engine is complete. ordinarily this will
be somewhere between 2,000 and 4,000 miles. if you
have taken the engine to maximum load (top speed
for more than 15 seconds), regardless of mileage,
break in is complete. list members have varying
experience with mobil 1, sastrol syntec, redline,
and amsoil. they are all very good, some have advantages
over the others in terms of availability, price,
and small performance differences.
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9.
what is the best way to change
the oil on my mkiv?
to change the oil, first get the engine to normal
operating temperature by going for at least a 20-30
minute drive. when you get home, put the car up
on ramps or stands, make sure it's in park or in
gear, and the emergency brake is set, open the hood,
remove the oil fill cap, and then get underneath
and remove the drain plug. it goes without saying
that you should anticipate which way the oil is
going to pour out and have your drain pan positioned
and NOT have your hands, arms or face anywhere near! after
the hot oil has drained out, replace the seal washer
on the drain plug with a new one and tighten it
snugly, but be careful not to overtighten. although
the lower pan is steel, it's also thin. now to remove
the filter, for the '93-'95 models, if you're removing
the filter from underneath, it's sometimes necessary
to remove the suspension strut that attaches to
the lower a-arm, and the plate that is mounted just
above it. if you're a contortionist and have small
arms and hands and the proper tools, it's "just"
possible to remove the filter from above. next,
put some kind of catch towel up underneath the oil
filter to catch the oil that is going to spill when
you first start to remove the filter. then, using
a filter wrench that fits over the end of the filter,
remove the old oil filter. if you have some time
to spare, it's usually better to let the engine
cool for a half hour or so before you do this to
avoid burning your arm with hot engine oil. wipe
the filter mounting surface and block sealing surfaces
with an oily rag, and spin it on and tighten snugly
by hand. now, fill the crankcase with 5 u.s. quarts
of oil. start the engine and watch the check lights
to make sure you have oil pressure, then check for
leaks around the filter. if everything is ok, then
check your oil level and adjust it to indicate at
least halfway between the f and l marks on the dipstick.
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10.
a "quickie lube" place changed
my oil and wanted to put in an additive. they said
my engine would get 30% better gas mileage and make
at least 20% more power.
oil additives are the "snake oil remedies" of the
automotive world. many additives are available with
very extravagant claims. there are numerous reputable
articles available on additive performance, and
they are all negative. in short, it is not recommended
to add anything to your oil; as competitive as motor
oil sales are, if a worthwhile additive were developed
and became available, the major oil companies would
be scrambling to include it in their products.
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11.
where can i learn more about
oil?
there are many technical articles on oil available
on the web, see the mkiv tech references for some
of the better ones.
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12.
why does my oil look dirty
when i check my oil level?
all automotive motor oil contains detergent and
dispersant additives which will hold oil degradation
and by-products of fuel combustion in suspension. in
short, a dirty oil is doing its job. the oil is
designed this way to prevent these contaminants
from depositing on engine surfaces where they can
cause piston rings to stick and plug oil pump screens. the
oil works in conjunction with the filter to remove
these contaminants
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13.
my front crank seal blew out. why?
neither the root problem nor the solution is known.
(the crank seal blows on some cars with stock rev
limiters.) but one possible cause/solution that
has been theorized and tried is that at higher than
stock rev limits, the stock oil pump cannot relieve
enough pressure as it spins faster. as a result,
oil pressure rises too much and blows out the seal.
modification to the stock oil pump is required to
ensure that it won’t happen again.
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cooling
system
the engine uses a sealed and pressurized, forced
circulation cooling system, consisting of a belt
driven pump, radiator and a cooling fan which is
fluid coupled to the pump. coolant temperature is
controlled at the inlet side of the pump by an integral
wax element thermostat. the thermostat modulates
coolant flow between a bypass line and coolant coming
from the bottom tank of the radiator. when the engine
is cold, the thermostat blocks the passage from
the bottom tank and coolant circulates in a loop
through the engine and bypass line only; it does
not circulate through the radiator. as the engine
warms up and reaches the thermostat temperature,
the thermostat opens and allows coolant from the
radiator bottom tank to mix with hotter coolant
from the bypass line. by modulating between these
two lines, the thermostat controls the temperature
of the coolant going into the engine. once inside
the block, the coolant flow splits and part circulates
through the block and the rest goes into the cylinder
head and ancillary systems. coolant return from
the block splits again and goes into both the heater
system, the oil cooler, and thereafter back to the
pump suction. coolant return from the cylinder head
splits and goes to both the throttle body and the
turbochargers, and from there it returns to the
pump suction.
while the actual flow rates of the pump are not
known, adequate flow is provided at all RPMs and
normal loads to limit temperature rise out of the
engine to an ideal 10-12 degrees F under normal
conditions. the stock radiator is adequate for casual
driving at stock power output, but at higher engine
outputs and/or extended high speed racing in warmer
climates, the stock radiator cannot cope with the
increased load and should be upgraded.
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1.
how do i know if my coolant
needs changing?
use a voltmeter, and attach the ground lead to the
battery negative or the engine. then put the positive
lead in the coolant at the radiator cap. it should
measure less than 0.500 vdc, and ideally should
be 0.100 vdc. more than 0.500 vdc is very bad and
the coolant should be changed immediately.
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2.
which coolant should i use?
toyota's red coolant is best, in a mix that is proper
for your climate. "green" coolant usually has silicate
additives which were formerly promoted as helping
cooling efficiency. this is not so, and these additives
will reduce cooling efficiency in our engine, and
in extreme cases may plug small coolant passages.
only use toyota's red, or other reputable ethylene
glycol coolant "without" silicates or other additives.
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3.
what's the proper mix of coolant and water?
some owners in very mild climates use as little
as 15% coolant to 85% distilled water with a bottle
of redline's water wetter to help reduce cylinder
head temperatures and provide water pump seal lubrication.
water-wetter is highly recommended. it has helped
produce measurable increases in gas mileage with
reformulated gasoline. reduction of cylinder head
temps allows more ignition advance before onset
of knock, and more ignition advance is conducive
to better fuel economy.
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4.
why distilled water?
tap water contains varying amounts of minerals and
ions, as well as chlorine and sometimes heavy metals.
also the pH of tap water may vary from acidic to
very base. the minerals in the water will deposit
themselves in the cooling passages of the engine
and radiator, and eventually build up and reduce
the efficiency of the system. worse than this however,
the minerals and ions may react chemically and electrically
with the aluminum and copper components in the cooling
system, and set up an electrochemical process known
as bimetallic corrosion which will actually accelerate
the failure of these components. this process can
be detected with the voltmeter test described above,
and if a voltage higher than 0.500 VDC is detected,
a very damaging bimetallic corrosion process is
at work eating away your cooling system! distilled
and deionized water contains no minerals, heavy
metals or chlorine, and has a neutral pH, so it
is the best fluid for your system.
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5.
why is such a low concentration
of coolant recommended? i always thought that a
50/50 mix of coolant and water was the best protection
for my cooling system.
maybe it's the best protection if you want to store
or drive your supra safely at -40 degrees fahrenheit,
but it's not the best mix to help your cooling system
get rid of the engine's heat. first, understand
that water is absolutely the best heat transfer
fluid commonly available - bar none. all other heat
transfer fluids can "carry" only fractions of the
heat that pure water can. the effectiveness of a
fluid's ability to "carry" heat is called its "specific
heat capacity". for example pure water has a specific
heat capacity of 1.0 and pure glycol (coolant) has
a specific heat of 0.6. mix them in equal proportions
(50/50 mix) and you have a fluid that will perform
only about 80% as well as pure water in carrying
heat away from the engine to the radiator. a 15/85
mix will perform 94% as well as pure water, or to
put it another way, about 14% better than the 50/50
mix.
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6.
doh, i didn't
sign up for a course in heat transfer. just tell
me the right proportion of coolant and water to
put in my system.
okay, here's just the facts: run the "least" amount
of coolant you can in your system that will provide
freeze and boil over protection "for your climate",
throw in a bottle of Redline water wetter too,
and fill the system the rest of the way with "pure
distilled" water. here's a table that's pretty
accurate so you can pick which proportion will
work best for your climate. all figures are in
degrees fahrenheit.
% Coolant
Freeze
Boil
20% 16
253
33% 0
256
50%
-34 265
70%
-90 277
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7.
what's the best way to flush
& clean the cooling system?
people have had very good luck with the prestone
flushing system and there is a tech article about
it. you can find it here.
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8.
my car seems to run very
hot in the TX or AZ summer and gets terrible gas
mileage. should i try a lower temperature thermostat?
several members in the warm, humid climates have
reported good success switching to the trd 165 degree
thermostat.
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9.
i think i'll take the thermostat
out altogether. won't this help cool the engine
even more?
no! this will cause the car to warm up erratically,
the coolant, and oil temperatures in the engine
to vary considerably, and both of these will cause
accelerated wear of components such as rings and
bearings.
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10.
what about electric fans,
do they help?
again, the sellers of these fans claim improved
performance, however other users think the performance
is less than the stock fan system. if they help
at all, it appears to be marginal, and then only
at idle or low speed cruising.
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11.
how 'bout that cool looking
trd radiator cap. will that make it cool better,
and the car go faster?
actually it might! that radiator cap allows the
cooling system to run at a higher pressure, so in
theory you could run less coolant and more water
without having to worry about boil over. more water
means better cooling and more cooling means less
timing retardation. also, higher pressures cause
smaller bubbles to form in the system thereby causing
better heat transfer. so yes you might even go a
little faster with that radiator cap! the caveat
is that a cooling system running at higher pressure
is going to cause more of a strain on the water
pump seals, hoses, and radiator.
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12.
i live in denver, and in
the summertime when i park my car and turn off the
engine, i hear gurgling noises. once i even saw
steaming coolant coming out of the radiator into
the overflow tank. what's wrong?
several things working here. first, water boils
at a lower temperature at higher altitudes. second,
our engine and cooling system tends to "heat soak" for a few minutes after shutting off. that is to
say the engine is still very hot internally, but
since the cooling system is no longer working with
the car off, the temperature continues to rise in
the system. also, with the engine shutoff, and the
water pump no longer circulating the water, there
is no pressure in the system. so more heat getting
dumped into it, plus less pressure, plus higher
altitude will all contribute to coolant boil over.
back to start
|
13.
my car overheats since i
installed (pick one or more):
1) a fmic
2) oil cooler
3) electric fans
4) started road racing
5) went bpu+++
what's wrong?
this is really an apu topic, but it's a good lead-in
to help explain and understand the cooling system.
fmic's and oil coolers that are mounted in front
of the radiator degrade the performance of the cooling
system. instead of the radiator getting air at ambient
temperature, it's getting it at ambient plus perhaps
30-50 degrees. another way of looking at it, all
that heat that the fmic and/or oil cooler are getting
rid of, is being picked right back up by the cooling
system.
a very important point to understand is that automotive
engines are only about 30-35% thermally efficient,
which means only a third of the fuel you burn will
make useful horsepower, while one third is wasted
and gets turned into heat in the cooling system,
and the last third is wasted and goes into the exhaust
system as heat there also. following onto this point,
something that is nearly always overlooked with
horsepower raising mods is that for each horsepower
gain at the rear wheels, there is at least the same,
if not a greater horsepower loss into both the cooling
and exhaust systems. so, after you've turned the
supra from a docile little 300rwhp sports car into
an 800rwhp monster, but you've done nothing to the
stock cooling system, it's no wonder the car overheats
whenever you go for a longer drive than just to
the grocery store. you've more than doubled the
engine output, without doing anything to help the
cooling system!
last point, there is a big misconception that since
the supra's rated output is 320 BHP, the cooling
system is rated to cool the engine OK at 320 bhp.
this is not so at all - and not by a long shot!
why? well the engine in normal use very rarely sees
maximum output, and then only for very short durations.
so the toyota engineers (and every other brand of
automotive engineers) figured out how much "average"
horsepower the car needs to make under normal operating
conditions, added some reserve and then used that
figure to size the cooling system and radiator.
we'll be shocked to know that this "average" horsepower
figure is probably on the order of only 30-50% of
the maximum engine output. gm/ford & chrysler engineers
used to be notorious for getting this figure wrong
and building cars with undersized cooling systems
that overheated on a regular basis. so this is why
you can take your 600rwhp supra out on a straight
flat highway and it's probably happy at 60-70mph,
where the engine is only making 100rwhp or so to
maintain 65mph, but you can't take it road racing
without it overheating. to validate this point,
you only need to look at the size of the radiators
on the large 18 wheelers. these truck engines actually
produce less horsepower than a stock supra, but
it takes nearly all that horsepower on a continuous
basis to keep a big rig going 60-70mph. so their
cooling systems must be rated for their maximum
horsepower on a continuous basis. because of this,
their radiators are typically at least 600-800in2
in frontal area, while ours on the supra is only
about a third of that.
so what's the solution?
a bigger radiator and/or more/better air flow across
it. with a fmic, this is a tough situation, but
some road racing list members have come up with
innovative
solutions for ducting air to the radiator separately
from the fmic.
back to start
|
intake
system
the ge and gte engines share a common air intake
system consisting of a high capacity, disposable
type panel filter mounted in an air box, with a
cool air intake snorkel oriented to the front of
the car. the commonality between the ge and gte
intake systems ends at the outlet of the air box. For the gte engine, following the air box, air is
then metered by a hot wire mass air flow (maf) sensor,
then goes to the twin sequential turbocharger system
inlet. it is then compressed and thereby heated,
and the charge air then goes to an air to air intercooler
mounted in the lower front of the car on the passenger
side. cooled charge air from the intercooler then
is piped to the throttle body, and twin chamber
intake plenum, until finally, air flow divides at
the intake manifold and goes to the six inlet ports
of the head.
the and their ,
, and are all described in greater
detail in other sections of this faq.
before leaving the intake system, it is useful to
note several features of the throttle body. it's
equipped with two butterflies; one is a "sub-throttle"
butterfly and it is upstream of the "main" butterfly.
although it looks like a choke for cold starting,
the sub-throttle butterfly is usually referred to
as the "TRAC" butterfly as it is used by this system
as a torque limiter when it senses wheel slippage.
both butterflies are equipped with position feedback
sensors.
back to start
|
1.
what can I do to improve
the performance of the intake air system?
lots of things, if you have deep pockets! check
out the and sections of this faq for
the expensive stuff that can make big differences
at higher engine outputs. one cheap mod that works
very well and will give you good return for your
dollar, is the "drop-in" k&n replacement air filter.
just take the stock toyota air filter out, and "drop-in"
the k&n replacement. it's a less restrictive design
than the stock unit, and over time as it gets dirty,
it "loads up" less than the stock filter. plus,
it's cleanable and reusable so it costs less to
maintain. one very important point with the k&n,
and other filters similar to it - these are oil-coated
filters and it is very important to not overcoat
the filter media. why? just downstream of the filter
in our supra is the hot wire mass air flow sensor
- if oil from an overcoated air filter finds its
way onto this sensor, and fouls it, it will start
producing erroneous readings and the car will not
run well at all. cleaning this sensor is a very
dodgy process, and replacing it is expensive. bottom
line, be very careful with oil impregnated filters
and do not overcoat them.
back to start
|
exhaust
system
the exhaust system on the 2jz-gte engine consists
of a pair of cast steel exhaust manifolds, each
serving three cylinders, and a crossover stainless
steel balance pipe with bellows which allows for
expansion/contraction of the system without warping
or cracking. each manifold (three cylinders) feeds
one turbocharger. the and their
are discussed in detail in a later section of this
faq.
from the single outlet of the turbochargers, the
exhaust goes to a downpipe equipped with another
bellows for expansion/contraction, and two inline
catalytic converters. the cats are monolithic construction,
three way type with metallic substrate. from the
rear most cat, the exhaust splits into two pipes,
then recombines at the muffler which is located
at the very rear of the car. the entire system is
made of stainless steel.
for closed loop control of the air-fuel ratio, and
fault sensing of the catalytic converters, the exhaust
system is equipped with two lambda sensors. one
mounted ahead of the first catalytic converter,
the other o2 sensor is just after the 2nd cat. only
the 1st o2 sensor provides feedback to the ECU for
closed loop fuel trim. apparently the 2nd sensor
is used for fault detection of the cats.
back to start
|
1.
i "accidentally" ran some
(pick one):
1. leaded gasoline
2. octane booster
3. mysterious fuel additive from a "quickie lube"
place through my car thinking it would make it go
faster. now it runs terrible and my gas mileage
is terrible.
chances are your plugs are fouled which is an easy
fix, but more importantly, you may have "poisoned" your lambda (O2) sensors. a single tank of leaded
gas is a confirmed O2 sensor kill, and all the other
junk that is sold to boost octane, etc. is suspected
to shorten their lifetime. these things cost around
$115 each from our discounted parts sources and
should be replaced any time you have these symptoms.
actually, you only need to replace the upper O2
sensor (the one at the top of the downpipe, as it
is the one which is used to trim the fuel calculation
in the ECU) Be sure to
after replacing
the O2 sensor(s) as this will clear the former fuel
trim calculations, and you should be good to go.
back to start
|
2.
my supra emits smoke when i start up. what does
the smoke indicate?
if the cloud is relatively blue or blue/black, it
may indicate oil being burned along with the fuel. this
may be caused by either worn piston rings, worn
valve stem seals (very common on older supras -
and fixable),
or an oil viscosity that is too low. if the cloud
is black, it indicates excess fuel being burned. if
the cloud is white, it may simply be the moisture
in the cold engine and exhaust system being burned
off. if there's a lot of white smoke and it continues
for a long time, you may have an internal coolant
leak. (*note, mobil 1 synthetic oil burns greyish-white)
back to start
|
3.
my car is (insert modification level here), do i
need an egr blockoff plate?
yes! emissions problems aside, every mkiv should
have one. it is possible for the egr valve to leak,
causing low compression in cylinders 5 and 6. this
is a common thing to go wrong, but a very simple
thing to fix.
back to start |
| turbo
system |
1.
how does the ssts (sequential twin-turbo setup)
work?
first off, the is no #2 wastegate. there is only
one wastegate and it comes off the #1 turbo because
that turbo is always on line, therefore you always
have a wastegate. there are 4 sets of vsv's, actuators,
and control valves for the sequential turbo system. each
vsv is simply a solenoid that is either 100% open
or closed, allowing manifold pressure to pressurize
the different actuators that open/close the four
different valves.
wastegate:
when the manifold reaches 11#'s of boost, the ecu
sends a signal to the wastegate vsv, that allows
manifold pressure to build in the wastegate actuator
which opens the wastegate.
exhaust
gas bypass valve (ebv):
somewhere around 3500 rpm, the ecu sends a signal
to the exhaust gas bypass valve vsv, which allows
manifold pressure to build in the exhaust gas bypass
valve actuator which opens the bypass valve. this
is a small opening inside the #2 turbine housing
which allows some exhaust gas to go through the
turbine of the #2 turbo which makes it start spinning,
and dumps the exhaust gas out the exhaust piping
coming off of #1 turbo. since it is a small amount
of exhaust gas, it pre-spools the turbo and does
not get it up to full operating speeds. this will
smooth out the transition from 1 to 2 turbos. This
valve is similar to a wastegate in design, but is
located after the turbine wheel instead of in front
of the turbine wheel like a wastegate would be. this
is not a wastegate!
exhaust
gas control valve (egcv):
this valve is located in the exhaust piping downstream
of the #2 turbo. when this valve is closed, all
exhaust gas must go through the #1 turbine wheel
to get out through the rest of the exhaust system. at
around 4000 rpm, the ecu sends a signal to the exhaust
gas control valve vsv, which allows manifold pressure
to build in the exhaust gas control valve actuator
which opens the control valve. this allows exhaust
gas to go through #2 turbo and out the exhaust system
which brings the #2 turbo up to full operating speed.
intake
air control valve (iacv):
this valve is located in the intake tract coming
off of #2 turbo. it is closed below 4000 rpm so
that boost pressure coming off of #1 turbo cannot
backup through the #2 turbo and back out the air
cleaner/suction of #1 turbo. there is also a 1 way
reed valve within the same housing of the intake
air control valve. as the #2 turbo starts to pre-spin
at 3500 rpm, it will build some boost. if it builds
enough boost, it will open the 1 way reed valve
to allow this boost into the intake tract to join
with the discharge boost pressure coming off of
#1 turbo. at somewhere over 4000 rpm, the ECU sends
a signal to the intake air control valve vsv, which
allows manifold pressure to build in the intake
air control valve actuator which opens the control
valve. this allows the full boost pressure coming
off #2 turbo to join in with that coming from #1
turbo and you are now fully on line. Usually, the
exhaust gas control valve will open first, which
gets the #2 turbo spinning at full rate so that
it is building good boost before the intake air
control valve opens, allowing this boost to join
in with that coming off #1 turbo. if the intake
air control valve opens before the exhaust gas control
valve, the boost pressure coming off #1 turbo will
go backwards through #2 turbo, spinning it backwards
if there isn't sufficient exhaust energy to keep
it spinning forward. when the exhaust gas control
valve opens, and the #2 turbo has to reverse the
direction of the spin. this is a tremendous strain
on the turbo shaft and bearings. if the sequential
operation is not a well orchestrated symphony of
motion, it is easy to see how the #2 can be prone
to failure. for an alternate explanation including
diagrams, see the new
car features section. the appropriate pages
are 91-95.
back to start
|
2.
what does a vsv do?
vsv is short for vacuum switching valve. it is just
an electronic solenoid, which either opens or closes
100% when energized. this will allow the vsv to
either pass boost pressure through it from the actuators
(like the wastegate actuator) or block it off.
back to start
|
3.
will a front mount intercooler (fmic) help my bpu
car?
probably. the stock intercooler is very good, and
keeps charge intake temps near ambient during normal
“sprints.” during longer periods, such as road racing
or high speed pulls, the intercooler will become
heat soaked and intake temps can go to 150F or higher,
depending on ambient conditions. cooling wise, a
fmic will probably only help during extended runs
or high boost. a fmic will flow better than the
stock unit, so it will probably make at least a
little more power.
the effect of a front mount is most dramatic when
the stock intercooler is in bad condition. the stock
unit does not take well to any sort of bug or rock,
as the fins bend and break easily. by comparison,
my spearco laughs at the largest of dragonflies.
another issue is oil. Over time, oil thrown out
by the pvc system and turbo seals will condense
in the intercooler and coat the bottom of it. not
only does this reduce intercooler efficiency, but
the oil mist is blown into the engine while boosting.
oil lowers octane and promotes detonation. i’ve
seen 1.5 to 3 degrees more timing advance with an
intercooler in good condition compared to an oil-filled
one with bent fins. to clean the stock intercooler,
use gasoline to get the oil off, and remember to
put a breather filter on the PVC hose to the intake,
or oil will just get all over it again.
back
to start
|
4.
i don’t want to put a big fmic in front of my radiator,
can i get an upgraded sidemount?
the only smic i know of is the greddy, which was
tested by reg reimer to flow worse than stock. it
also has less internal and external fins than stock.
back
to start
|
5.
how about upgraded ic piping?
only anecdotal evidence so far, but it doesn't seem
to hurt anything, and it looks trick. might improve
boost response because the hard ic pipes won't balloon
out with higher boost.
back to start
|
6.
my ic hoses pop off under high boost. what should
I do?
go to napa
and order a spring-loaded-t-bolt hose clamp for
their cars. the constant tension provided on these
units will never allow the hose to pop off again. i
have the 3.5 nominal clamp from napa and it was
a little too small for the tb, but with a flat blade
screw driver and tapping it with a hammer I was
able to get it over....get the next size up from
nominal in my opinion.
back to start
|
7.
my car won’t boost very high. it stumbles and lets
out black smoke while accelerating. what is wrong?
i have the stock mass air sensor (maf).
regardless of how bad it looks, it’s a simple thing
to fix. air metered by the maf is leaking out somewhere,
causing the computer to dump more fuel than is necessary
to move the car.
first thing is to check all the hoses and intercooler
pipes. make sure each connection is tight, and follow
the hose diagram on the underside of your hood to
make sure all the smaller hoses are attached correctly.
if everything appears to be in good order, you need
to do an intake leak test.
the primary method of doing an intake leak test
is to remove the intercooler hoses to the throttle
body and the turbo outlet pipe. plug both ends,
pressurize the system and listen for leaks. it helps
to splash soapy water on the pipes to spot the leaks.
some people perform intake leak tests by plugging
the intake and capping off the pcv hose from the
exhaust cam cover. if you do it this way, do not
be alarmed if a lot of pressure is mysteriously
disapearing. some pressure can escape due to valve
overlap, especially with aftermarket cam gear(s).
if you suspect this is happening, try turning the
motor over a little bit and see if it stops.
if the stock hose clamps just don’t seem to be working
well enough, get t-bolt clamps. you can order them
from www.mcmaster.com or buy them from napa (they
are listed as heavy duty hose clamps).
stock ic's need 10 clamps (9) 2.75 inch, (1) 3.25
inch
fmic's need more then 10 usually. (1 or 2) 3.25
inch and the rest are all 2.75 inch.
back to start
|
8.
my second turbo doesn’t kick in immediately after
i downshift. what is wrong?
its probably the pressure tank. Check to make sure
the 1/8” hoses leading to the iacv and egcv have
pressure in them. if not, your pressure tank is
probably bad.
back to start
|
9.
my boost is acting strangely, and i do not have
a boost leak. what could be wrong?
do you really not have a boost leak? an intake leak
test is the only way to be sure.
if not, the first thing to check is the hoses. see
the hose layout diagram on the underside of your
hood? make sure all the hoses listed there are connected
properly. the main culprits are the smaller 1/8" hoses that attach to the intake air control valve
and the exhaust gas control valve. some are hard
to get to, just remove whatever you need to check
them all.
if all the hoses are in good shape, then the next
thing to check is the solenoid valves (vsv's) themselves.
the vsv for the intake air control valve (iacv)
is located near the firewall on the left side of
the motor. it's connected to a 1/8" vacuum hose
which attaches to a hockey puck looking thing (the
iacv actuator). when the vsv is not powered,
it should not allow air to pass through it. the
side attached to the metal mesh of pipes should
be blocked, and the side attached to the actuator
should vent to the atmosphere.
the vsv for the exhaust gas control valve (egcv)
should perform exactly the same, but it is harder
to get to. it is located directly behind the wastegate
vsv, with one 1/8" hose going straight up and another
going straight back.
if the vsv's check out ok, the next thing to check
is the pressure tank. the 1/8" lines leading to
each vsv should be pressurized at all times by the
pressure tank. if these lines aren't pressurized
when you remove them, its likely the pressure tank
is bad.
if the pressure tank is ok, next try testing the
actuators themselves. apply air pressure to each
actuator (the hockey puck looking things attached
to the vsv's, 10 psi should do it) and ensure that
they are not leaking and correctly actuate their
respective valves. for the iacv, this can be easily
seen. the egcv is harder to see, but it can easily
be heard if you have an aftermarket exhaust (the
exhaust note will get deeper and louder). if the
actuator arm on the egcv breaks, the exhaust will
rattle excessively (note that some rattle is normal
with aftermarket exhausts) and the car will not
boost well at low rpms.
some people perform the
temporary ttc mod to troubleshoot boost problems.
if the problem is the iacv vsv, egcv vsv or the
pressure tank, the temporary ttc mod will fix the
problem.
note that any malfunction of these parts is suspected
to lead to sudden second turbo failure, also known
as the death whine. if your car produces exactly
zero boost when the second turbo is supposed to
kick in, has an excessive amount of oil in the intercooler
pipes, and makes a
sound like this, then you second turbo is probably
blown, sorry.
for more information on the supra's sequential turbocharger
system, see pages 88 to 95 of the ncf.
back to start
|
10.
how do i to trouble shoot the sequential system?
as you can see from the discussion in number 1 above,
the operation of the sequential system is complicated
and requires all it s components to be functioning
properly. failure of a component will cause the
disrupt the proper sequential operation of the turbos
and can lead to failure of one or both of the turbochargers.
if any of these valves aren't working properly,
you'll have low boost problems:
1. bov (boost will get bled back to intake)
2. ebv (loss of exhaust energy)
3. egcv (loss of exhaust energy)
4. wg (loss of exhaust energy)
now if the egcv, or ebv aren't working properly,
you should have strange transition problems, as
well as low boost on the low end.
if the problem is the wg, you should suffer low
boost consistently, whether it's only #1 or 1+2.
one way to sort his out is to put the car into true
twin conversion (ttc) as a diagnostic tool. (ttc
instructions) if your boost problem goes away
with ttc it has to be one of the vsv or actuators
that is malfunctioning. ( as an aside many list
members feel that ttc is safer for your turbos because
by eliminating the sequential operation eliminates
the chance that the turbo will boost against a closed
valve and twist the shaft).
the actuators can be checked in the car. all you
need to do is hook up a pressure source (i use a
60cc veterinary syringe) and pressurize the actuator,
then watch to see if it leaks down. it's pretty
simple. don't go over 20 psi with this as you'll
blow an actuator diaphragm or overextend an arm.
the vsv's are the same. hook up pressure to see
if they leak. then apply a ground to the wire going
to the ecm to actuate the vsv and see if it opens.
of course they are not all normally closed, so you
may need to check flow just the opposite.
if it's on the compressor side, it could be your
bov passing at low boost. these are easy to check
and just need a source of vacuum. there is the suck
and blow test… suck on the smaller tubing while
a friend blows down the larger tubing. if he can
blow through with out resistance it is normal. if
he cannot blow through while you are not sucking
that is normal operation.
another possible source of the problem is a vacuum
leak. the newest of the supras are 4 years old as
this is written (jul. 02) the oldest is 9 years
old. the various rubber control lines get brittle
and leak. the leaks may not be obvious to a superficial
look. i suggest replacing them with silicon vacuum
hose which has the additional benefit of looking
great. short of that if you suspect that is the
problem pull the individual hoses to inspect them
.
back to start
|
| transmission
& differential |
1. which transmission is better, the 6-speed
or the auto? can either of them handle the additional
horsepower?
both transmissions work well, and both can handle
400+hp without a problem. over 400 and you will
need to start thinking about getting a built auto. the
6-speed will likely handle pretty much anything
you can throw at it.
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|
2. what fluid should i use in my tt 6-speed? how
about in the differential?
we recommend only the stock v160 oil for the 6-speed. it
works great. pricey, but not compared to the thousands
for a new transmission. do not use redline synthetic
d4 atf for the transmission. click
here to read why. other brands you may use at
your own risk. the redline synthetic 75w90 (not
the 75w90ns) in the differential works well.
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|
3. my 6-speed transmission makes a rattling
sound at low speeds – should i worry?
all supra 6-speeds seem to make that sound, which
has been likened to shaking a bunch of ball bearings
around in a coffee can. it is not a cause for alarm
- all the 6-speeds make the sound. it is the flywheel
damping springs rattling, not the design of the
transmission dogs. if your transmission shifts smoothly
and doesn't pop out of gear, don't worry about it.
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|
4.
how do i check the torsen differential oil?
there are two plugs on the differential, one is
the drain plug and the other is the fill/check plug. the
check plug is on the right side just above the drain
plug. the hole is a 10 mm hex (allen type). just
remove the fill plug to check. if you have a 6 speed
and you stick your finger in the hole you will feel
the "oil slinger" before you feel the oil. make
sure to check the oil level on a leveled surface! according
to redline, you don't need friction modifier for
torsen to work, but friction modifier will reduce
operating temperature and extend service life of
gears.
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|
5.
should i get a lightweight flywheel?
only if you don’t mind the noise. every mkiv with
a lightweight flywheel will exhibit transmission
rattle with the clutch out. this is noisiest on
hot days where the tranny is warm and the a/c is
on. it's only noticeable when engine braking, idling
and accelerating at low rpms. make no mistake, it
can get VERY loud.
expect to gain about 15 rear-wheel horsepower on
a dynojet.
back to start
|
| brakes |
1. what minimal brake upgrades will i need for
road race tracks?
the most popular choice seems to be hawk blues for
the pads and the stock rotors. they stop great,
but they will also eat your rotors very quickly.
for a more rotor friendly pad that can handle the
heat and has almost as good performance, try the
carbotech xp/panther plus pads. stay away from cross-drilled
rotors. they crack easily if you take them on a
road course. motul makes the best brake fluid but
is expensive. a less expensive alternative that
is almost as good is ford heavy duty truck fluid. last
but not least is valvoline synthetic. it is pretty
good, inexpensive, readily available and if you
change your fluid before track events anyway, it
works just as well as the others. stock pads and
rotors would be minimal requirement.
back to start
|
2. i
want to remove my rear brake disc but it will not
come off, what should i
do?
there are two threaded holes on the disc, screw
in an 8x1.25 into both holes and keep screwing them
in till the disc comes off. make sure you have the
emergency brake off!
back to start
|
| suspension |
1. what
is a good street alignment?
front: camber
-1.0 , caster
+5.0 , toe
0.00
rear: camber
-1.5, toe
in 1.0mm
the front and rear toe
are critical to tire wear. even small deviations
from spec may cause unusual wear patterns or excessive
wear.
back to start
|
2. what
is the stock alignment?
front: camber
-0.5 degrees +/- 0.75, caster
+3.5 +/- 0.75 degrees, toe
0.00 +/- 0.080" (2 mm)
rear: camber
-1.50 +/- 0.75, toe
0.120" (3mm) toe in +/- 0.080" (2mm)
back to start
|
| wheels
and tires |
1. what kind of tires are the best for sport
driving? how about for drag racing?
the generally accepted best street tire for dry
track road racing are bfgoodrich g-force t/a kd's.
the generally accepted best street tire for wet
track road racing (and very good dry) are bridgestone
potenza s-03 pole position's.
back to start
|
2. i'm thinking about getting aftermarket wheels. how
much do the stock wheels weigh?
a set of 93-97 polished rims were as follows:
fronts: 24.75lbs
rears: 26.55lbs
the 98 polished rims are a bit lighter without the
ridges in the centers
fronts: 23.6lbs
rears: 25.4lbs
these are exact weights taken from a mailing center,
not a home scale.
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|
3.
what are the
names of the wheel parts?
check
out this illustration.
back to start
|
4.
what is offset?
check out this illustration.
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|
5.
what is the size and offset of the stock wheels?
17" x 8" (50mm offset)
for the fronts
17" x 9.5" (50mm offset) for the rears
back to start
|
| n2o
- nitrous oxide |
1. i
run nitrous. what plug should I run?
depends. but you'll probably have a maximum gap
of .030".
back to start
|
| electrical |
1. my airbag light has come on after i opened
the dashboard. how do i turn it off?
click here
for the fix.
back to start
|
2. i
want to improve the stock stereo. what
works?
the supra's stock stereo is actually pretty good,
so be prepared to spend a bit of money to improve
it.
front speakers:
the most common modification was replacing the stock
front speakers. several listers have found that
the MB Quart 6.5" separates (qm218.03cX) can be
installed in the door, replacing the stock 4" midrange
speaker there. one lister used 6.5" Boston Acoustics
speakers. either way, you will need to fabricate
a new mounting plate to replace the stock enclosure,
but this is not difficult. readers who used separates
up front generally mounted the tweeters in the door
above the stock mids rather than attempting to extract
the stock tweeters from their perch.
back
speakers:
in the back, the stock speakers are often replaced
with premium 6.5" coaxials, such as the mb quart
qm160.03kX or boston acoustics, either of which
would bolt right in.
subwoofer:
the rear subwoofer is a 5x7" oval, and listers wanting
a bit more boom have added 8" or 10" subwoofers
– sometimes 2,3 or 4 – either removing the spare
tire, or building a custom enclosure to the left
of the spare. two readers mentioned that a 10" sub
can be mounted directly into the fold-down portion
of the rear seat, in a custom enclosure facing backward. listers
have used cerwin vega or mtx subwoofers to good
effect.
amps:
precision power is the most commonly-used brand,
with some listers favoring rockford fosgate or mtx. small
amps (under 11" x 8" x 2.5") will fit under the
passenger seat. larger ones can be installed in
the trunk. one lister used a ppi a606.5 mounted
just behind the rear seat. some listers used an
amp only for the subwoofer, finding the stock amp
sufficient for the main speakers. this avoids the
need to run rcas from the head unit, as you can
just use a good speaker-to-rca converter attached
to the stock subwoofer speaker leads.
head
units: the
stock head unit is a double-din (ddin) size. several
manufacturers make ddin units which bolt right into
the stock location – many of these are expensive,
however, and some listers have installed a normal
din unit with a plate to fill in the extra gap. ane
lister going the din route used an alpine 7832,
and is quite happy with it. readers who bought disk
changers mounted them in the glove box or in the
trunk.
back to start
|
3. i
have the 7-speaker system in my mkiv, and i
want to upgrade the speakers. what
fits?
the subwoofer is a 5x7". the rear seat speakers
fit an oversized 6 1/2". the doors are 4". and the
dash tweeters are small (around 1"). you can modify
the door speaker enclosures to fit some 6 1/2" speakers. list
members have had good luck with mb quart speakers,
using 218.03cX separates up front and qm 160.03
kx coaxials in the rear. rather than replacing the
5x7" stock sub, some listers remove the spare tire
and put sub boxes in its space.
back to start
|
4. how do i clear the "check engine" light?
you need to reset your ecu. see
the faq entry on the topic for details.
back to start
|
5. how do i reset my ecu?
unplug the negative battery cable for 1 minute to
clear the ecu's settings, then re-connect it and
drive around for a few hours. this will clear the
"check engine" light, and your ecu will relearn
your car's mixture settings, allowing you to pass
smog if you've just reinstalled your cats. alternatively,
pull the cover off the fuse box located near the
battery. use the fuse pulling tweezers supplied
inside fuse box and remove the two green 30a fuses
for efi 1&2. after a minute put them back in and
the ecu will be reset.
back to start
|
6. is
it possible to swap out 93-96 headlights with the
new 97-98 headlights?
it is possible, but the 97-98 do not have the marker
lamps in them, other than that they will bolt right
in and plug in, if you can do without the clear
parking lights then go for it. you can also install
the 97-98 marker/turn signal lights on a 93-96.
it will take some re-wiring, though.
back to start
|
7. i
want to use a turbo timer, but it seems to interfere
with the factory alarm.
when you shut off the car, the doors unlock, just
as the doors lock when you start the car - but this
works only if you set the alarm with the keyless
remote. with turbo timer, you take the key out but
the doors do not unlock. get out, shut the door. hit
button on key remote and lights will flash twice
(flashes only once if you have not turned timer
on). hit button again and it flashes once and sets
alarm. when the timer shuts off, the doors lock
again (you hear it) and alarm stays armed, lights
shut off, and antenna goes down if it was up. when
you return to your car, hit the keyless remote and
lights flash only once causing no unlocking, then
hit it again to disarm and unlock. when I first
got mine I turned my car off and on in every conceivable
way and set alarm numerous times and then tested
it each time until I was certain of when it armed
and when it locked, etc.
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|
8.
i
want to install an aftermarket alarm/keyless entry
system and i
can't find the wiring color code for a 93-94' tt?
| name |
color |
polarity |
location |
| 12v |
[
wht / red ] |
+ |
ignition
harness |
| starter |
[
blk / wht
] |
+ |
" |
| ignition |
[
blk / yel] |
+ |
" |
| ignition
#2 |
[
blk / org
] |
+ |
" |
| accessory |
[
pnk / blu ] |
+ |
" |
| lock
(arm) |
[
grn / yel
] |
- |
passenger
kick panel |
| unlock
(disarm) |
[
wht ] |
- |
" |
| park
lamp |
[
grn ] |
+ |
driver
kick panel *1 |
| park
lamp |
[
grn ] |
- |
steering
column |
| door
pin |
[
red / blk
] |
- |
driver
kick panel |
| trunk |
goes
off with the door trigger |
| hood
pin |
[
purple / red
] |
- |
@theft
e.c.u. *2 |
| tach
wire |
[
blk ] (no turbo)
[ blk / wht
] (turbo) |
- |
at
igniter in engine compartment by driver side
strut tower |
| brake
sw |
[
grn / wht
] |
+ |
plug
in left kick panel |
| horn
trigger |
[
blu / red ] |
- |
steering
column |
| window[up----down]driver
side |
[
red / wht
---- grn
/ yel ] |
|
** |
| window
[up----down] pass. side |
[
red / blu ----
grn / wht
] |
|
** |
*1=bottom
of fuse box in white plug
*2=theft e.c.u. and door lock e.c.u. are built
together in one module. the module is located
high in the passenger kick panel.
**window wires are in the driver side door.
wires must be run into the door. |
back to start
|
| body |
1. i
want to keep my supra looking its best. what wax
/ polish should i use?
zaino bros.
back to start
|
2. at freeway speeds, my hood vibrates up and
down. is there a problem with it opening at higher
speeds?
that may be because the drive
side hood latch is not engaged when the hood
is shut. try placing the flat of your palm near
the driver side hood corner (the lower corner made
by the head lamp and front bumper) and push down
firmly but gently. if you hear a click, that's the
previously unlocked hood latch engaging and locking. to
fix, hand-tighten the two rubber bumpers under the
hood, click here for a
picture. now there's no chance of the hood popping
open at high speeds.
back to start
|
3. i
get a chirping sound from my door. what
can i
do?
i had enough of my door chirping when closing it
and driving with the window half way open. so i
decided to do some exploratory surgery – take the
door off. well, the inside panel. it is easy with
the exception of removing the screw cover from the
cup of the door handle. there are 8 screws to remove
and 4 plastic "pop-outs". (look like the plastic
thermometers which are stuck in turkey's, only black) all
of these are pretty apparent with the exception
of the screw inside the cup of the door handle and
the screw inside the cup of the door lever. after
you remove the obvious holding the door lever cup
in, there is another screw inside that. make note
that to remove the first door handle screw, you
must first remove the plastic covering. i would
not recommend using a screwdriver unless it is bent
in the shape of an L. use the bottom of the L to
pry up the plastic covering. it doesn't come off
easy (on mine at least). after you have all the
screws removed reach under and remove the wiring
harness for the windows/locks/speakers. then lift
the inside door cover up. immediately you will see
the culprit. Metal on metal. the fix: simply place
grease on all exposed areas, both the door and the
interior panel. i used a teflon grease, but i doubt
it matters. there are three primary hooks which
you need to ensure you get enough on. that's it. total
time @45min. 20 minutes was spent trying to figure
out how to remove the screw covering inside the
door handle cup. i hope this helps any of you who
are irritated by the door chirp.
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|
4. does anyone sell a car cover specifically
for the mkiv supra that would fit over the wing?
try to get a mkiv Supra cover from the Toyota dealer
or one of these links:
www.covercraft.com
| www.calcarcover.com
| www.performanceproducts.com
back to start
|
5.
my headlights
are fogged up inside. what can i do?
you
can either replace them or clean/polish them. click
here to see how to clean them.
back
to start
|
6.
there is a rattle coming from the hatch area. what
is it?
your supra probably suffers from the notorious "hatch
rattle".
-click
here for the fix.
back
to start
|
7. can i get an advice on the
care and up keeping of my supra?
-click here.
back to start
|
| drag
racing |
1. what
are the basics of drag racing?
click here
for drag racing basics.
back to start
|
2. what's the best way to launch my tt for
a drag race?
with either transmission type, you should deflate
the rear tires to 25 psi or less.
auto: powerbrake the car up to about 2000 to 2200
rpm, and when the rear tires begin to spin slowly
floor it and get off the brakes.
manual: there are two techniques. one is hard on
tires, the other hard on the clutch. the first technique
is to floor it in first, then sidestep the clutch
at 4,000rpm and let the rear wheels spin long enough
to get the second turbo online. the second technique
is to rev to 4,500rpm and slip the clutch, keeping
the rear wheels from spinning through clutch modulation.
with an auto and drag radials: (the following advice
from an experienced drag racer)
first thing to do is to do a good burn out. 5 seconds
minimum, but anything over 10 is unnecessary. also
don't do it "in" the water. back into the water
and then roll about 2 feet forward and do your burn
out there. as there will be some water there when
you are about done with the burnout, let go of the
brakes and burn out of the hole. this will ensure
the tires are dry. as far as tire pressure, take
the tires down to about 20 psi and work your way
down from there if you spin them too much. like
go to 19 then 18 if, I repeat if needed! the higher
the psi the less rolling resistance the better the
mph. when you are ready to stage you'll just want
to then pull the parking brake up and powerbrake
with the brakes as well as high as you can take
the rpm's (so power brake with the regular brakes
and parking brakes, this is not recommended with
street tires as you'll definitely get too much boost
of the line and smoke the tires too much out of
the hole). when the light's green floor it and let
go of the parking brake and regular brakes at once! (this
sounds harder than it is.) also make sure to have
the car in 1st and shift through the gears manually. shift
right at redline, but remember that in 1st the car
is revving so hard that you may have to shift a
few hundred rpm's before redline so you don't hit
the rev limiter.
back to start
|
3. what
is a good autocross alignment?
for a baseline, a good autocross alignment for the
Supra is:
front: camber: -1.8 (degrees), caster +4.0 (degrees),
toe 1/8" total toe out
rear: camber: -1.8 (degrees), 1/16" total toe in
for a street/track compromise, modify the above
specs by reducing the front toe-out to 1/16" or
even 0. if you run with toe-out you'll get better
turn-in but you'll wear your tires more quickly. the
other settings should be okay for the street. different
tires brands and compounds may require different
alignment specs to maximize grip. for example Hoosier
racing radials require more negative camber than
other tires. for the supra, that might mean -2.0
degrees or more. the recommended autocross alignment
will decrease the life of your tires! if you want
a compromise alignment, try lance's
numbers or modify the autocross alignment by
changing front and rear toe to 0 (or just a smidge,
1/32" out per side, of toe in the front).
back to start
|
| general
faq |
1. i
can't understand many of the posts - they all contain
acronyms i've
never seen before. help!
for a partial list of the acronyms used on the list
click here. after you've
read the list for a week or two, you'll pick up
on the lingo and no longer have difficulty understanding
the posts.
back to start
|
2.
what's
the equation which relates crank horsepower to speed
at the end of the 1/4 mile?
hp = (ts/234)^3 * w, where w = the weight
of the car with you in it, and ts = trap speed in
1/4 mile.
back to start
|
3.
i'm going to
store my supra for some time. how should i prepare
it?
fuel system: fill the fuel tank and add stabilizer
in appropriate ratio. run engine for a few minutes
to ensure stabilized fuel has made it through the
entire system.
engine: change the oil & filter and run the
engine up to temperature. then put two table spoons
of marvel mystery or similar fine lubricant into
each cylinder, and crank the engine a few revolutions
(don't start) to coat the cylinder walls and other
metal in the upper cylinder with a film of oil.
cooling system: measure the supra coolant
mix, if necessary flush the system and add a new
coolant 50/50 mixture.
electrical system: disconnect the battery
cables, put battery on smart charger.
tires: raise the supra on four jacks to save
the tires from getting misshapen.
body: apply two coats of a carnauba-base
wax to the Supra body.
exhaust:
plug the exhaust end with a shield to prevent anything
from entering the motor like humidity or little
animals.
back
to start
|
4. there's no cup holder. where do i put my
drink?
many listers have had good luck removing the ashtray
and putting their drink in the resulting hole.
other suggestions include stuffing 1l bottles between
the seat and center console back by the seatbelt
latch. also the following link shows a good photo
of an aftermarket cup holder: click
here
back to start
|
5. what is the difference between
the export mkiv supra and japanese mkiv supra?
click here
for the difference. also here
is another useful link.
back to start
|
6. what
is horsepower?
measuring maximum engine power, horsepower is the
amount of energy required to raise 33,000 pounds
one foot in one minute (or 550 pound-feet per second). it
is calculated by multiplying the engine's measured
torque by rpm and dividing by 5,252.
back to start
|
7. where can i get the repair manuals for my
mkiv supra?
you can get them straight from toyota. toyota offers
5 repair manuals (vol. i engine, vol. ii chassis/body,
electrical systems, automatic transmission- a340e,
collision repair). to buy these manuals you will
need to call Toyota at 1-800-622-2033 between 7
a.m. and 4:30 p.m. pacific standard time. click
here for a list of the repair manuals prices.
back to start
|
8. where can i get discounts on stock supra
parts?
you can get them form jay
marks toyota. here is part of jay marks toyota
response to our letter:
the discount for sogi/sonic also includes the mkiv
owners as well. the parts discount is 10-40%...depending
on the part. the average discount offered is 25%. thank
you for asking. if you have any questions or need
my help...please call anytime."
jay marks toyota, houston, texas, 1-800-327-2087,
713-943-8930 fax parts@toyotaworld.com
back to start
|
9.
i
see some list members have white gauges. where
can i
get those?
www.nrauto.com
| www.rodmillen.com
back to start
|
10. what is the right way to dyno the supra
tt?
before dynoing, it is advisable to let the car rest
for at least 1 hour with ice on the engine and the
intercooler piping. also reset
the ecu*, pull the trac fuse (or unplug the
trac ecu), and use high-octane fuel if possible. if
you have a stock filter, remove it, and try to dyno
on a cool day. the rpm sensor for the dyno will
need to connect to a timing wire. if you do not
connect this sensor, you will not be able to get
a torque reading. the closest wire is located on
the driver's side of the engine compartment in a
small, black box. click
here for a diagram. once the car is strapped
on, spray the intercooler with ice water/alcohol
mixture throughout the entire run if possible. leave
the ice on the engine and intercooler piping as
well. if the shop has a fan, direct it towards the
intercooler. the reason we take these additional
cooling steps is to approximate "real world" conditions. the
temperature of the intercooler has great bearing
on the horsepower the Supra will produce. by taking
these extra steps we are simulating the cooling
effects of high velocity, cool air, flowing across
the intercooler that would be present in normal
driving conditions. once the car is situated on
the rollers properly, slowly run the engine through
the first 3 gears with out bringing the 2nd turbo
online. in 4th gear bring the car slowly to 2000
RPMs and then hammer it to redline! in an automatic
you want to disable o/d, bring the car to 2000RPMs
in 3rd gear, and floor it to redline.
*some members have reported that resetting their
ecu's has also caused their electronic boost controllers
to lose their stored boost setting. this is most
common with the apexi avc-r.
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|
11. what are the production numbers for the
mkiv supra?
1.
click here.
2. the following production numbers* are for the
tt and na:
| year |
number
produced |
| 1993.5
|
2,887
|
| 1994
|
3,405
|
| 1995
|
2,266
|
| 1996
|
852
|
| 1997
|
1,379
|
| 1998 |
1,232
|
| total
|
12,021
|
*sport
compact car magazine, "farewell to the supra".
back to start
|
12. i
need help with my toyota
warranty, what should i do to make the process go
smoothly?
to get warranty:
- remove
all aftermarket parts
- reset
ecu by pulling efi fuse(s)
- change
plugs back to factory nd's gapped at the factory
specification (at least two have been denied
warranty on plugs alone).
- if
you have race fuel or additive in tank, drain
tank or if car is drivable, run remainder out
and refill with 92+ octane fuel (at least one
individual was denied warranty for funny gas)
- act
like a total dummy when getting warranty coverage. for
example: tranny: i woke up, got in the car and
noticed that i could not shift from 2nd to 3rd
gear as if something was stuck, then have a
blank look on your face. engine: sure i was
running the car kinda hard (5000 rpm) it is
a sports car right? when i shut it off after
waiting a few minutes for the oil to cool as
manual says, it sounded kinda funny, so I took
it right to you guys.
also,
click here for advice
from two of our members, after one of them had trouble
with his supra.
back to start
|
13. how much does the supra weigh? and what's
the weight distribution?
| Coupe |
Sport
Roof |
|
5 Speed Automatic |
|
Kg |
Pounds |
Kg |
Pounds |
| Front |
758 |
1671 |
767 |
1691 |
| Rear |
701 |
1545 |
710 |
1565 |
| Total |
1459 |
3217 |
1477 |
3256 |
|
|
|
|
|
| Weight |
Front |
Rear |
Front |
Rear |
| Distribution |
52% |
48% |
52% |
48% |
|
|
| 5
Speed Automatic |
| Kg |
Pounds |
Kg |
Pounds |
| 771 |
1700 |
780 |
1720 |
| 714 |
1574 |
723 |
1594 |
| 1485 |
3274 |
1503 |
3314 |
|
|
|
|
| Front |
Rear |
Front |
Rear |
| 52% |
48% |
52% |
48% |
|
|
| Turbo
Coupe |
Turbo
Sport Roof |
|
6 Speed Automatic |
|
Kg |
Pounds |
Kg |
Pounds |
| Front |
841 |
1854 |
855 |
1885 |
| Rear |
708 |
1561 |
712 |
1570 |
| Total |
1549 |
3415 |
1567 |
3455 |
|
|
|
|
|
| Weight |
Front |
Rear |
Front |
Rear |
| Distribution |
54% |
46% |
55% |
45% |
|
|
| 6
Speed Automatic |
| Kg |
Pounds |
Kg |
Pounds |
| 855 |
1885 |
855 |
1885 |
| 721 |
1590 |
726 |
1601 |
| 1576 |
3474 |
1581 |
3486 |
|
|
|
|
| Front |
Rear |
Front |
Rear |
| 54% |
46% |
54% |
46% |
|
|
back
to start
|
14.
i understand some
years only came with automatics. which ones?
for turbo models, '96 was available only with an
automatic transmission. all the rest were available
with manuals.
back to start
|
15.
is any year supra more desirable than others?
not really. 93-95 are more desirable to some because
their obd1 ecus are more friendly to ecu upgrades.
96-98 obd2 ecus can be quite useful in logging obd2
engine parameters and more useful error codes although
they generate errors if the cats are removed unless
an o2 sensor simulator circuit is installed. other
than that, there are only minor differences between
the model years.
|
16.
how hard is it to convert an auto supra to a 6 speed?
pretty hard. most agree that it's much easier to
just start with a 6 speed, but if you just can't
find one and have to have a manual, there is a long
list of expensive parts you will need. cost will
range from about $5000 to $10,000 for parts depending
on if you buy all new or try to find used. then
add labor...
|
17.
are there any common problems to look out for when
shopping for a supra?
not really. just do the standard checks. look for
collision damage. make sure you do a compression
test on the engine. does the car feel strong? there
aren't really any major problem areas. this is a
toyota after all...
|
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content copyright © 2002 MKIV.COM |
|
