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Supra FAQ page 6
How much power
will my car make at BPU™?
It varies from car-to-car, and the conditions as well as tuning. Most BPU™-only Supra
Twin Turbos, dyno between 370 and 410 horsepower at the rear wheels. This is usually achieved with moderate temperatures,
a reset ECU (to erase anything bad the ECU may have learned), and often a little bit of high-octane un-leaded race fuel. On
the street, power will be reduced, especially in poor weather, but at least 90 percent of the power should be retained.
What
kind of 1/4 mile ETs and trap speeds should I run at BPU™-only?
It varies WIDELY depending on driver skill. As
well as track conditions, elevation above sea level, ambient temperatures, humidity, and pre-race preparation. But most fall
between 12.3 to 12.9 ets with 112 to 119mph trap speeds on street tires. Times can drop well into the 11s with drag radials,
a good driver, and good conditions, as well as proper pre-race preparation.
What is a BPU™'d Supra TT's top
speed?
Speeds in the mid-high 180mph range should be achievable. Once the speed-limiter is disabled, by pulling the
"TRAC" fuse of course.
Will the life of my Engine and Drivetrain be adversely affected with the BPU™ mods?
Yes, but not by a significant amount. If the car is maintained properly, and the car is treated with some respect for
the components, you should maintain much of the power train’s life. Which considering the fact that the Supra is by
far one of the most reliable and durable sports cars, it will last longer than most well maintained STOCK sports cars. The
only Drivetrain components that will see a significantly shortened life will be the stock clutch. It will more than likely
not last much longer than 8-10k miles once at BPU™. This especially holds true if the car is making repeated high speed
runs using 5th and 6th gear at wide open throttle. If your stock clutch has high mileage on it, or is already starting to
slip, you will need to plan on a new high-performance clutch. Also the stock turbos will be subject to a somewhat shortened
life span (how short will depend on how you drive and maintain the car, as well as how much boost you will run)
What's
the reliability of a 600hp Supra Turbo?
Chassis, electrical, and suspension components should see little effect on
reliability on street driven Supras. The stock 2JZ-GTE engine should hold up pretty well to this power level. Just how long
depends on maintenance, and how hard you drive it, and how often. But typically Supras can go for years at this power level.
The transmission reliability will depend on whether it's an Automatic or Manual. A stock automatic will not hold this much
power, a built transmission will be required, and it's reliability will depend on it's design and construction. The 6spd Manual
should hold up just fine, as well as the rear differential and axles.
The only real reliability concerns at these low
power levels would surround the actual modifications you perform. Excluding installation short-comings, the components utilized,
even very high quality ones, may fall short of factory component reliability, as the built in compromises that exist in everything,
would lean more towards the side of ultimate performance, than of ultimate reliability (Keep in mind we are talking about
a Toyota here, whose reliabilty standards are exceptionally high) This may include fuel system components, turbo components,
and especialy electronic wizardry. Basically a set-up that is either VERY well concieved, or utilizes OE components as much
as possible, without over burdening them, would posses *near* stock reliability. And tuning of the components, and component
selection, and matching, would play a HUGE role in this.
What are the power limits of the various factory components
(Differential, Transmission, Motor, etc.)?
There have really not been enough failures to really pin point a limit
for the various power-train components. The motor could fail at factory power levels if it was running dangerously lean. But
when well tuned, the motors internals (Pistons, Rods, Crank, Head Gasket etc) are reliable to 700rwhp. But of course at these
power levels, if the engine is not set-up and tuned properly, it is literally a bomb waiting to go off, however this would
be just as true with a built motor. Some owners have pushed their stock internals to the limit and have well exceeded 800rwhp,
and even approached 900rwhp. I still don’t understand how such an over built motor made it past the bean counters at
Toyota Corporate.
The 6-speed Getrag is ridiculously strong for an OE transmission. Its limit’s will be affected
greatly by driving technique, such as launching, and whether or not power shifting is used. Even driven hard, the Getrag should
hold up reasonably well with 700RWHP. If you treat it with some respect, it should be able to handle around 800RWHP or more,
although great care and respect will need to be practiced at those levels.
Differential, axle, CV Joint, and drive
shaft failures are a VERY rare occurrence. So I don't have much info on their failure limits. On street tires, it would be
almost impossible to break any of these components at ANY power level. The tires would spin before they would put the driveline
under that kind of strain. The tires act sort of like a circuit breaker. If you run drag slicks, this does not hold true of
course, yet they have proven themselves to be 10 and even 9 second capable.
Will drivability, interior noise levels,
and low-end power be adversely affected with the BPU™ mods?
Drivability is not adversely affected. Interior
noise level depends on the exhaust system you choose. Some will make it far louder; some will actually make it quieter. But
most are just a little bit louder than stock. But the added dBs are also combined with a MUCH sweeter exhaust note, so it's
definitely worth it. And the interior of the Supra is pretty quiet anyway, so on the highway, it will be VERY livable. As
far as low-end power goes, the down-pipe will greatly decrease Turbo Lag. So low-end power and response is much improved over
stock.
Will emissions be adversely affected by the BPU™ mods?
As long as a high-flow cat is used,
emissions should not be effected, and you should still pass visual inspection. If you run without catalytic converters, you
are doing so at your own risk, and you would not pass visual or emissions testing.
Will fuel mileage be adversely
affected by the BPU™ mods?
If driven calmly, as in light throttle, mileage should not be significantly affected.
Mileage will greatly decrease during however, if you drive “vigorously”, more power equals more burned fuel I
am afraid.
Should I install an "Intake" (Open Element Filter)?
This is a bit of a yes and no answer. The
stock filter assembly is a flow restriction, and an open element intake would increase potential flow. However, it will also
draw in more heated engine compartment air, which can hurt performance. My advice is to either modify the stock filter box,
or install a cool air induction box, like the Max Air. An added bonus of the open element filters, is that they allow you
to easily hear the primary turbo and by-pass valve.
What about the stock intercooler?
The stock intercooler
does a decent job up till about 17psi on the stock turbos, after that you would probably notice a significant gain, especially
in warmer temperatures, with a nice front mount intercooler. However, keep in mind it will block some of the airflow to the
radiator, as well as decreasing response slightly.
Should I replace the factory rubber Intercooler hoses with aftermarket
metal hoses?
It wouldn't hurt. But it won’t help a lot either. At the most you may slightly increase throttle
response, but at least it will look nicer.
What about the fuel system, are the stock injectors and fuel pump large
enough for BPU™?
Yes, the stock fuel system is very safe and reliable to 450RWHP, although I would recommend
a fuel pulsation damper bypass. Anything over that, and I would highly recommend having the car dyno’d, and using a
wide-band O2 sensor (not a cheap A/F gauge connected to the stock O2) to check the fuel ratio at your high boost setting.
11.5:1 would be a safe fuel ratio.
What are the stock injectors rated at?
540cc/min
Would the
Supra benefit from a fuel controller?
BPU™'d Supras run a little on the rich side as far as fuel ratios go.
This hurts power. What it does do is provide a safety margin that makes engine damage through detonation unlikely. If you
get a fuel controller, and tune it properly (on a dyno, with an accurate EGT gauge, and a high band O2 (The Stock O2 sensors
are not accurate), then you should be able to gain a noticeable amount of power. One of the most popular electronic fuel controllers
is the A’PEXi S-AFC. The Fields SFC is good too.
What should I use to increase my boost level, an Electronic
Boost Controller, or a Manual BC?
Using an EBC is the safest way to raise boost, it will prevent spiking and over-boosting.
But it really comes down to your budget. If you can afford an EBC, get one. If you can't, go with a MBC. And always keep an
eye on that boost gauge. And whatever you are using to control boost, remember to not get carried away, I don't recommend
going regularly over 18psi.
What is the best Electronic Boost Controller?
There really is no BEST. Although
the A’PEXi AVC-R is a nice unit, it provides much more control over boost than other EBCs, but it is also more complex
to install, and tune. The new Blitz unit is also nice. Most of the large manufacturers make decent units. Just avoid fuzzy-logic
equipped models if you still have the sequential stock turbos, they will become "confused" by the unnatural behavior of the
sequential system.
When installing my EBC, do I connect it to both of the Turbo's Wastegates?
The Primary
Turbo is the only one with a wastegate. When in full twin turbo mode, the boost of both Turbos is regulated by the primary
turbo's wastegate. So, only connect it to the Primary's.
Some people say I need to replace my ECU with a reprogrammed
one, instead of just using a boost controller. Do I?
Reprogrammed ECUs for the Supra TT are VERY $$$. They are in the
$1200 range. And they have not been proven to provide a significant increase in performance or safety on BPU™ level
cars. Their merit shows itself on cars with upgraded Turbo(s). Just be sure you buy your ECU, or have it reprogrammed by a
reputable shop that knows what they are doing. And have it tailored to your particular car (Driving habits, and Mods). And
I would also recommend taking a look at the AEM Programmable system.
What is a safe boost level to run at BPU™?
The general consensus is 17-18psi. Some people have taken it higher, but I don't recommend it if you don’t have
the money for a turbo replacement/upgrade.
Which Down-Pipe is recommended?
The RMM (or Rod Millen Motorsports)
Cat-less Downpipe is the most commonly used. However many other brands exist. Some down-pipes, such as the Random Technology
DP, feature an emissions legal high-flow catalytic converter.
Will a high-flow cat hurt performance?
It
will have some effect on power output, but not a lot. Its exact effect on HP is not clear, but it probably costs a few hp
at the most, maybe 5-15hp at BPU™ power levels.
What is a Down-Pipe?
It is the section of the exhaust
system that connects the outlet of the Turbocharger's Turbine section to the "Cat-Back" exhaust system. The Downpipe is also
where the two catalytic converters are located, as well as the O2 sensor (or sensors in OBD-II cars).
I have an
OBD2 car. Can I still install a Down-Pipe?
Yes. But unless the DP has a Catalyst and a second location for an O2 sensor,
you will trip your check engine light, unless you get one of those O2 “black boxes”.
Which Exhausts
are the loudest?
The Tanabe Racing Medallion, and HKS Hiper Titanium seem to be the two loudest systems.
Which
Exhausts are the quietest?
The Tanabe Hyper Medallion, the discontinued Tanabe G-Power Medallion and the GReddy (SP)
Street Performance seem to be the quietest. At anything less than full throttle, they are no louder than stock. But at full
throttle they seem to “wake up” a bit.
What are some recommended exhaust systems?
It depends
on your personal preferences. Below I will break down some of my recommendations based on certain combinations of preferences.
Subtle
Styling / Very Low Cost:
-Random Technology (75mm, full stainless steel)
Subtle Styling / Low Sound Level / Moderate
Cost:
-GReddy Street Performance (80mm)
-Tanabe Super Hyper Medallion (80mm, full stainless steel, 50-state legal)
Subtle
Styling / Moderate Sound Level / Moderate Cost:
-ATR (75mm, full stainless steel)
Tasteful Styling / Low-Moderate
Sound Level / Low Cost:
-HKS Dragger II (85mm)
Tasteful Styling / Low-Moderate Sound Level / Moderate Cost:
-GReddy
Power Extreme (80-94mm)
-HKS Super Dragger (95mm)
Tasteful Appearance / Moderate Sound Level / High Cost / Super
Light:
-Veilside Tear Drop Titanium (90mm, full titanium)
Tasteful-Wild Styling / Low Sound Level / Moderate Cost:
-TRD
2nd gen.
Wild Styling / Moderate Sound Level / Low Cost:
-A’PEXi N1
-HKS Hiper (75mm)
Wild Styling
/ Moderate Sound Level / Moderate Cost:
-A’PEXi GT Spec (95mm, full stainless steel)
-Blitz NUR Spec (80mm, full
stainless steel)
-HKS Hiper Carbon/Titanium (75mm, CF wrapped muffler, titanium tip)
Wild Styling / High Sound Level
/ Moderate Cost:
-Tanabe Racing Medallion (80mm, 50 state legal)
Wild Styling / High Sound Level / High Cost / High
Flow:
-HKS Hiper Titanium (104mm, titanium muffler)
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