How to obtain at most 300 Wheel Horse Power

allfans26

New Member
Sep 11, 2015
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0
Lawrenceville, Georgia
Hey everyone!

I'm a novice when it comes to modifying my supra.
I know the good basics of some mechanical parts but obviously still a lot more to learn. I'm wondering what I need or have to do in order to gain at MOST 300 WHP. The Supra stock is around 232 BHP @ 5600RPM & 254 ft.-lbs. of torque @ 3600RPM from what I've read. I'm interested to increase that HP. I want to find parts and accessories that are not financially dependent to install or purchase. So far, the only modification which I've done to the car is added a K&N Air Filter (Not an Intake or cold air intake; had to take screw off 3000 pipe and what-not...). I cannot say if this small modification to make the engine "breathe better" has paid off due to the small amount of HP that I could have gained or loss.

History of the Car:
I have a 1990 Supra Turbo Automatic stock (besides some replacement parts that got old as time passed such as the brake-master, water pump, and air filter). This car is a one owner car and still. It was bought the year it came out from the showroom floor. Has been garage kept for most of it's life. Paint still in fantastic conditions in the exception of a few rock and paint chips damaging the front part of the car. Black paint (Black Ruby Pearl 206). As of 2015, it will gain at least 1,000 extra miles to the engine due to it being my temporarily only daily driver. The head-gasket was never blown or damaged. A little over 86,700 miles driven. Engine: 7M-GTE.

Goals to be accomplished to achieve at MOST 300 WHP:
So this is what I was thinking to achieve this amount of power. I want an elaborated information on information about the parts I need, how those parts work, and how the parts should perform. For example, if I need to install a boost gauge and a 3" down pipe with a non-restrictive exhaust then I needed to change the ECU or something like that so the boost can exceed the 12 PSI fuel-cut off limit or something like that. An example of the effects of the car after some form of upgrade/modification that could limit the car's ability like the ECU thing I was talking about should be included. Here's an example of what I understand but don't necessairly know how to do...: "Install a 3" downpipe to the turbo exhaust." Well, I know what a 3" downpipe and a exhaust's purpose is but what do those two have in common and why is it necessary? I know the 3" inch down pipe increase more flow out of the car to be less restrive. Doesn't the stock car come with a turbo exhaust since it's equipped with a turbo? Stuff like that would be great to be included because it's hard to find a person or a community that elaborates on details and information that associate materials together. My experiecne with other mechanics or mechanical engineers are limited at the moment and this supramania community seems like a good candidate for information!

Again, I'm just asking for some information and help by emphasizing the importance of elaboration, a plethora of examples, before/after, and long/short term performance and ability. So an example would be re-torquing the head gaskets on the 7M-GTE engine. My response would be "well what do I have to do to re-torque it? How do I approach it? Where can I get one? Is there one that's the best or most reliable that everyone is using? What is the retorque value?? Questions like that should be included within your responses.

Please take your time writing, I'm not in any rush to do mods. I'm just gathering information from a community and as that information is being shared, other people can have access to it as well. This is not just for my benefit but for others as well!

Completely Different Note:
And on a completely different note, does anyone know where I can purchase a full sized European License plate that's black, blank, and glossy? I've tried the custom European license plates through Google searching but I don't want to pay $40 for just a black and blank license plate... thanks in advance for this one!

Thanks,
Branden
 
Last edited:

Nick M

Black Rifles Matter
Sep 9, 2005
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You don't need to change the ECU or anything like that. Yes, open the exhaust from the downpipe back. Leave the main cat in place. If you get a downpipe with an integrated elbow, then you do not need a separate high flow turbo elbow.

First is a turbo exhaust. This is the HKS Turbo Exhaust 75mm, which is about 3 inches in diameter. The muffler is straight through giving maximum flow.

HKS exhaust.jpg

This is the stock exhaust.

Stock exhaust.JPG

This is a high flow elbow in place of a downpipe with integrated elbow.

P1050818.JPG

You will need larger injectors and a way around overboost fuel cut. The 1UZFE airflow meter is the same kind of meter as your airflow meter, only larger. It matches up with 550cc injectors. Save yourself the hassle and get the replica meter housing from SupraSport. The final thing (aside from the ability to hold the power) is a boost controller. A manual will get it done at a low cost. Electronic ones are more, by quite a bit.

My 1991 automatic sport roof at 3640 curb weight and 3910 with myself and half a tank of fuel ran 98mph in the 1/4 with those mods at 13 psi.
 

IndigoMKII

New Member
May 9, 2011
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Madison, Virginia
Well, a good thing is if you've got a good starting vehicle that's healthy, the 300 bhp isn't a big deal at all.

Stock turbo at roughly 13 PSI will get you to where you want to be
You'll want an AFPR and remove the stock FPR, j tube, an adjustable fuel pressure regulator will let you play with the vF a little to keep things more under control
Turbo-back exhaust that's at least 3"
Apexi air filter
550cc injectors, evo injectors and mazda rx7 injectors do work but you'll need to solder in new ev1 clips
Not necessary but I suggest replacing the 20+ year old fuel pump with at least a walbro 255

Also, if you're not interested in changing the boost often, you can use around 5-6mm of spacer under the wastegate on the ct to raise the boost.


Here's an older 'path' if you're interested in reading. http://www.supraforums.com/forum/showthread.php?152334-Newbie-s-guide-to-Modifying-your-MK3-turbo
 

BrandonW

New Member
Jun 25, 2007
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N.J.

black89t

boost'en down 101
Oct 27, 2007
951
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36
humboldt, ca
for a stock turbo bpu 7m car i like the following mods....

intake
turbo back exhaust
boost controller plus 2 washer behind wastegate to help boost fade
afpr
wideband
then back the screw out on the afm housing or take it out completely which will allow you to run 12psi without boost cut. you need the wide band and afpr to keep the a/f ratio in the 11's for max power. i had my car like that for a while and it would do high 13's at low 100mph trap speed. think 13.7 was my fastest and that was with no drag radials just street tires. makes the car waaaaaaay more fun compared to stock. :biglaugh:
 

suprarx7nut

YotaMD.com author
Nov 10, 2006
3,811
1
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Arizona
www.supramania.com
OP: Welcome! Sounds like you've got a good clean slate. I'm biased, but I think you should start reading at the link below, as well as some of the stickied threads here on SM. It sounds like some of your questions or concerns may be addressed by the stuff I've written. It'll at least cover some of the basics.

http://yotamd.com/toyota/mk3_supra/index.html

Regarding your power goals: I think the responses so far are making this more complicated than it needs to be.

All you need for 300bhp is exhaust, boost controller and maybe intake. If you're talking whp, then the advice above here is probably what you need. In the car world you have two kinds of people: "car guys" who don't wrench on their own cars who speak in terms of engine horsepower (or bhp/brake horsepower). Then you have tuners (like most folks on here and other car forums) who generally speak in terms of wheel horsepower. Brake horsepower is easy to measure for the manufacturers so they always quote that number. Brake horsepower is misleading though, because it doesn't represent what you actually feel in the car. An AWD car will lose more power before it gets to the wheels because it needs to spin more components - an extra driveshaft, transfer case/center diff, front diff, front halfshafts, and finally wheels. Wheel horsepower is easy to measure in an assembled vehicle and is what really matters. My point of saying all this is that you should specify which you're talking about. Whp is likely 10-20% LESS than bhp for any given RWD vehicle.

Article here: https://www.carthrottle.com/post/the-difference-between-bhp-and-whp-explained/

232 factory bhp up to 300 bhp is easy on the 7M. Factory whp was probably somewhere around 185-195. Bumping whp to 300 (by my estimation) puts you right on the verge of fuel cut and gets more complicated.

My car is likely right around 300 whp (probably just below) and I haven't touched the fuel system or ECU. I should really get it dyno'd sometime soon so I know if I'm completely talking out my ass, haha.
 

supraguy@aol

Well-Known Member
Dec 30, 2005
4,232
37
48
Atlanta
Allfans26-
Did I already ask you what part of GA you're in?
I'm in Lawrenceville. If you're nearby, you can come by and I can look over your motor, and help out if you would want.
 

allfans26

New Member
Sep 11, 2015
26
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Lawrenceville, Georgia
supraguy@aol;2060049 said:
Allfans26-
Did I already ask you what part of GA you're in?
I'm in Lawrenceville. If you're nearby, you can come by and I can look over your motor, and help out if you would want.

Sorry, I don't recall just because I had to keep track of a few forum posts. But yeah, I'm in Lawrenceville GA and I live in the general vicinity of Sugarloaf Mills if that sounds familiar to you. :)
 
Last edited:

Nick M

Black Rifles Matter
Sep 9, 2005
8,873
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48
U.S.
www.ebay.com
IndigoMKII;2060020 said:
You'll want an AFPR and remove the stock FPR, j tube, an adjustable fuel pressure regulator will let you play with the vF a little to keep things more under control

This isn't true, and don't suggest it if you don't actually know.
 

supraguy@aol

Well-Known Member
Dec 30, 2005
4,232
37
48
Atlanta
allfans26;2060051 said:
Sorry, I don't recall just because I had to keep track of a few forum posts. But yeah, I'm in Lawrenceville GA and I live in the general vicinity of Sugarloaf Mills if that sounds familiar to you. :)

Yeah, sure do.
I'm at Sugarloaf and Lawrenceville hwy, maybe 4 miles from there.
Message me if you need any advice/help. I'm free the next 2 days.
 

allfans26

New Member
Sep 11, 2015
26
0
0
Lawrenceville, Georgia
suprarx7nut;2060037 said:
OP: Welcome! Sounds like you've got a good clean slate. I'm biased, but I think you should start reading at the link below, as well as some of the stickied threads here on SM. It sounds like some of your questions or concerns may be addressed by the stuff I've written. It'll at least cover some of the basics.

http://yotamd.com/toyota/mk3_supra/index.html

Regarding your power goals: I think the responses so far are making this more complicated than it needs to be.

All you need for 300bhp is exhaust, boost controller and maybe intake. If you're talking whp, then the advice above here is probably what you need. In the car world you have two kinds of people: "car guys" who don't wrench on their own cars who speak in terms of engine horsepower (or bhp/brake horsepower). Then you have tuners (like most folks on here and other car forums) who generally speak in terms of wheel horsepower. Brake horsepower is easy to measure for the manufacturers so they always quote that number. Brake horsepower is misleading though, because it doesn't represent what you actually feel in the car. An AWD car will lose more power before it gets to the wheels because it needs to spin more components - an extra driveshaft, transfer case/center diff, front diff, front halfshafts, and finally wheels. Wheel horsepower is easy to measure in an assembled vehicle and is what really matters. My point of saying all this is that you should specify which you're talking about. Whp is likely 10-20% LESS than bhp for any given RWD vehicle.

Article here: https://www.carthrottle.com/post/the-difference-between-bhp-and-whp-explained/

232 factory bhp up to 300 bhp is easy on the 7M. Factory whp was probably somewhere around 185-195. Bumping whp to 300 (by my estimation) puts you right on the verge of fuel cut and gets more complicated.

My car is likely right around 300 whp (probably just below) and I haven't touched the fuel system or ECU. I should really get it dyno'd sometime soon so I know if I'm completely talking out my ass, haha.
Sorry about the ambiguity between my "horsepower" terminology. I forgot about the 15-20% power loss and I'm definitely talking about the 300 WHP. This is around my goal or a little less since I don't need to exceed it, just be around that WHP. Say, 285-295ish is adequate if I had to see the results on a dyno.
So, if I were to bump up from factory to 300 WHP, what should I do to just get to the limit of the engine's ability to do that without messing around with the ECU and having to re-flash it and what not.

Let me clear that up if that didn't make sense, haha.

So, in order to reach a good limit of 300 WHP, I understand that I have to replace intake and exhaust, but is that it? Should that be enough to power through up to 300 WHP and on the verge of ECU cut off point while still maintaining a good throttle response and other points that I didn't have a chance to get to?
 

allfans26

New Member
Sep 11, 2015
26
0
0
Lawrenceville, Georgia
Nick M;2060014 said:
You don't need to change the ECU or anything like that. Yes, open the exhaust from the downpipe back. Leave the main cat in place. If you get a downpipe with an integrated elbow, then you do not need a separate high flow turbo elbow.

First is a turbo exhaust. This is the HKS Turbo Exhaust 75mm, which is about 3 inches in diameter. The muffler is straight through giving maximum flow.

View attachment 77125

This is the stock exhaust.

View attachment 77126

This is a high flow elbow in place of a downpipe with integrated elbow.

View attachment 77127

You will need larger injectors and a way around overboost fuel cut. The 1UZFE airflow meter is the same kind of meter as your airflow meter, only larger. It matches up with 550cc injectors. Save yourself the hassle and get the replica meter housing from SupraSport. The final thing (aside from the ability to hold the power) is a boost controller. A manual will get it done at a low cost. Electronic ones are more, by quite a bit.

My 1991 automatic sport roof at 3640 curb weight and 3910 with myself and half a tank of fuel ran 98mph in the 1/4 with those mods at 13 psi.

Where can I find the 75MM Exhaust? It seems like it's a hard find based off a few research from different exhaust selling websites.
 
Oct 11, 2005
3,815
13
38
Thousand Oaks, CA
You need the exhaust and downpipe/elbow, plus some means to increase/control the boost. An electronic boost controller (Blitz, Apexi, etc.) is best because you can easily adjust to keep below fuel cut as you drive, but mechanical solutions also work. The intake in my opinion is less critical at 300RWHP. I never noticed much improvement adding a Cartech intercooler and larger piping, but you will need to replace your bypass valve with at least a Bosch 110 or equivalent. The stock BPV is usually toast ( see if you can blow through yours off the car), since you will be running 10-11 psi you will need to upgrade it.

Your stock auto will likely be your limiting factor after all this. The 1-2 shift is so slow the clutches will not last long at 300RWHP. Also, the stock head gasket is going to be a potential weak point. Plan on replacing it with a metal MLS soon. Make sure your cooling system is in good shape as well, you are adding nearly 50% more load to it than stock.
 

suprarx7nut

YotaMD.com author
Nov 10, 2006
3,811
1
38
Arizona
www.supramania.com
allfans26;2060084 said:
Where can I find the 75MM Exhaust? It seems like it's a hard find based off a few research from different exhaust selling websites.

The HKS 75mm exhaust is not real common. I'm not sure HKS makes it anymore. Raptor Racing made one similar, that is on my car. Stealthy looking twin tip muffler like stock, but just a tad larger tips connected to 3" (75mm) piping. If you want the real HKS version that may be difficult. Similar results can be had without the HKS brand name.

allfans26;2060076 said:
Sorry about the ambiguity between my "horsepower" terminology. I forgot about the 15-20% power loss and I'm definitely talking about the 300 WHP. This is around my goal or a little less since I don't need to exceed it, just be around that WHP. Say, 285-295ish is adequate if I had to see the results on a dyno.
So, if I were to bump up from factory to 300 WHP, what should I do to just get to the limit of the engine's ability to do that without messing around with the ECU and having to re-flash it and what not.

Let me clear that up if that didn't make sense, haha.

So, in order to reach a good limit of 300 WHP, I understand that I have to replace intake and exhaust, but is that it? Should that be enough to power through up to 300 WHP and on the verge of ECU cut off point while still maintaining a good throttle response and other points that I didn't have a chance to get to?

Gotcha. Sounds like you're after something very similar to my setup. I'd aim for a little under 300. Past that you'll need to make a big leap into modifications. Short of 300 whp is the mk3 Supra's sweet spot, IMO (at least with a 7M).

Quick summary of what I've got that you may need:

-Divorced or Bellmouth Downpipe
-3" cat back, including muffler
-High flow catalytic converter (I'm not sure you need one at all for emissions in GA, but I think it's worthwhile for the sound - without a cat you'll get more rasp)
-Boost Controller (Electronic or mechanical) I'd recommend electronic. I have a Greddy ProFec B Spec 2 and love it. The settings seem cryptic at first, but you just spend a little time programming it and then leave it alone for good after that. High setting, Low setting and Off. Real easy. Power on demand, pretty cool.

Since you're wondering how stuff works or what it does, you should look into the boost controllers. It's a nifty device. I could explain it all here, but take a look at this link where I wrote it out and provided a few pics: http://yotamd.com/toyota/mk3_supra/turbo.html

You should find this forum to be a wealth of knowledge if you're friendly and receptive to feedback.
 

allfans26

New Member
Sep 11, 2015
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Lawrenceville, Georgia
Nick M;2060093 said:
The HKS 75mm exhaust is not real common. I'm not sure HKS makes it anymore. Raptor Racing made one similar, that is on my car. Stealthy looking twin tip muffler like stock, but just a tad larger tips connected to 3" (75mm) piping. If you want the real HKS version that may be difficult. Similar results can be had without the HKS brand name.

I think this is suffice. What's your opinion on this exhaust kit? It's a 75mm, twin tip single muffler exhaust. Part #: LET-T16

http://www.driftmotion.com/LET-T16-p/dm1585.htm
 
Oct 11, 2005
3,815
13
38
Thousand Oaks, CA
A couple of us have the LET-T16s. It is a quiet free flowing exhaust that adds noticeable power over stock. Only downside is its steel, so it won't hold up if you drive in cold winters. I've had mine 5 years but I live in Cali.
 

allfans26

New Member
Sep 11, 2015
26
0
0
Lawrenceville, Georgia
3p141592654;2062276 said:
A couple of us have the LET-T16s. It is a quiet free flowing exhaust that adds noticeable power over stock. Only downside is its steel, so it won't hold up if you drive in cold winters. I've had mine 5 years but I live in Cali.
So would you say that this is fine? I mean I would drive in the winter just because it's a daily driver in Georgia but hopefully it gets warmed up by just sitting there... Anyways, in your opinion, would you think this is a suitable exhaust? I personally don't like the loud sounds that most exhaust/mufflers emit when there is a high flow or 3". I'm looking for one that has the stock appearance, won't create that loud exhaust noise when you're just moving at 2-3k rpm at 30-45 mph lol.

I mean I'm open for other suggestions as well :)