The path to 500rwhp???

[yannis-supras]

I would like to have some experts suggestions/guidlines on this one. My goal is the 500rwhp benchmark for my 7mgte'd mkii.
The purpose of the car (at least for now) is street use and hardly any kind of racing. So the most important think to me is a balance between driveability and reliability. I know this can only be done the expensive way and even though I'm far from loaded I'm commited to get there with slow steps.
A twin turbo set up has always been very appealing to me. Less stress on two smaller turbos, lower boost levels thus lower stress on engine internals, minimal lag (I hate lag - regardless of the rush you get in full boost I find it very annoying and hard to drive the car in twisty roads like the ones we have over here in Greece). These are few of the pros I can think of right now.
My engine's status right now:
- freshly reconditioned block
- HKS mhg
- ARP studs
- Apexi AVCR
- HKS ssq dump valve
- hybrid Garrett turbo (I think t3.5, don't know exact spec since it came with the jdm engine and knowledge in turbos is quite rare over here - too many specialist/technicians that don't actually have a clue)
- upgraded very large oil cooler

From what I've gathered from all the reading I've done in the forums the last three years or so I believe I will need:
- AEM standalone (or maybe maf/maft/ASFC?)
- custom exhaust manifold
- pair of Garrett GT28R (60 Comp Wheel, 62 Trim - Ball Bearing)
- 620-660cc injectors
- walbro fuel pump/s
- fuel pres. regulator
- front intake manifold with larger throttle body(larger t/b not really
necessary but nice to have )
- front mount intercooler
- 48-50mm external wastegate
- maybe engine internals??? from what I've read so far opinions are
divided in how necessary forged pistons or even steel rods are for this
kind of power. I know they provide peace of mind but are they actually
necessary for a twin turbo low boost setup.(hopefully less than 15psi will
be necessary - correct me if I'm wrong)

What else de you think I'm missing here ???

On the other hand any suggestions for a single turbo setup that would spool fast and isn't gonna be a surge "bitch" are also welcome. I'm aware that many many supra owners have achieved 500rwhp with such setups but I'm not quite sure how compromised they are with lag/lack of response.

Before anybody start shouting about chassis mods for such a powrfull car let me tell you, I'm also aware of how imparative a big brake set up and a well tuned suspension are (yes tires as well )

But this is a different topic that I've short of planned already.
- 6 pot calipers up front with 330-340mm discs (or shall I say rotors )
and 4 pot with 280-300mm at the back.
- Trutrac on it's way
- 5 stud hubs from bacchhhyyy in australia
- front Leda custom coilovers, rear custom leda struts with custom height
adjustable spring perches
-Tech Toy Tunning front adjustable camber plates
- custom adjustable front sway bar, addco rear sway bar
-front, rear strut braces
The thing I haven't figure out yet is the rear suspension mod for camber reduction due to lack of posts about the "how to" so if anybody could help on this one that would be much appreciated.

Sorry about the long post but I wanted to be as specific as possible.

 

[yannis-supras]

Come on folks, anyone at all??? Doesn't anybody have an opinion on this one?
I really need the elders/more knowledgable to chime in here

 

[GrimJack]

There are a few basics to clear out of the way first.

Your theory on twins vs single is, to the best of my knowledge, incorrect. No matter how you get the air and fuel into the engine, it still takes the same amount of air and fuel to get 500 hp - so the stress on the engine and turbo(s) will be the same in any case. Same goes for lag - unless you are willing to take on building a sequential setup with twins, which is generally viewed as needlessly complex and a pain in the rump to deal with.

550cc injectors are sufficient for 500 rwhp.

Have you read Will Neely's article on http://7mpower.com? I'd start there, if you haven't.

 

[yannis-supras]

Unforunatelly 7mpower has been hi-jacked the last couple of days so it's off access. So wouldn't in theory a smaller turbo that would produce about 250-280hp spool up faster than a bigger one that'll produce 500hp? And if that is correct , multiplied by two would result in the twin setup of my dreams?

 

[supradan22]

I havent really seen a Twin turbo setup on a 7M. Would anyone have pictures of it?

 

[GrimJack]

Crap, not again. Hold on... I copied it for just this type of emergency...

Many have wondered what the limits of the MKIII supra are. After years of playing with it and tearing a few down and doing research I decided to write a summary of things I encountered. What you read is my thoughts and in no way written in stone. The 7mgte engine is a tough motor that can deliver if prepared for duty. What I will discuss is the path I took to making a reliable high horsepower MKIII.


CRITICAL ELEMENTS

Always use a reputable shop.
This is often misunderstood. My suggestion is to use a shop that specializes in the motor you have. In this case the 7mgte engine. American shops often don’t realize the tight tolerances that the Japanese engines have. So they slack on the little but big details. Look around the shop build a friend ship with the guys there and you might find yourself getting little things done for free. Trust me you’ll need little favors.


THE BUILDUP

The 400rwhp motor
The stock motor can take 400rwhp pretty easy but the age of the motor might be the problem. Don’t try to run 400rwhp on a stock motor with 200,000 miles on it. You’re just asking for trouble. However with the right mods and a fresh build up you can run the power all day long. That’s assuming you tune it to that and don’t try that seat of the pants stuff.

The 500rwhp motor
When you approach the 500rwhp mark you must and I repeat must go inside the engine. Pistons (.40) and rings are the tools to make 500rwhp reliable on this power level. Have the shop use a torque plate and get those cylinders perfectly straight while boring it. The head needs no modifications and of course the turbo will need to be upgraded. A nice balance job will be in order also if you want to feel great about it.

The 600rwhp motor
Things break here if you don’t be careful. I suggest getting forged rods and pistons. The valves and springs would also benefit from a Ferrea valve train enhancement. That means 1mm oversize valves, dual springs, titanium retainer clips and locks. At this point you need to balance it without a doubt. 2mm head gasket is a good idea also as it will lower your compression a bit. Also bearings don’t like this level. Get the Clevite 77 and do yourself a favor. Like all the rest you will need a supporting cast of parts more on that later.

The 700rwhp motor
With this step everything you have on the following stages plus the right turbo. Here is what I suggest at this level. Beef up the transmission or at least freshen it up. Go with a RPS stage 3 or any carbon carbon clutch. At this level you will need a lot of supporting power makers. Also note there is no mention of cams. Stock is fine! I searched all over and the stockers did the job. Spend your money elsewhere


SUPPORTING CAST

The lightweights
There are a few things that don’t make power but they definitely help when you intend to run serious numbers. Lightweight pulleys except crank pulley, electric fans, lightweight drive shaft, and lightweight flywheel. By doing these little things you free up a lot of power that is loss. The port and polish job.

The fuel system
My rule of thumb is always have more fuel then you need. This always good except when you are breaking the newly built motor up. A great fuel system will always have a adjustable fuel pressure regulator and strong pumps. My favorites like most are the walbros. Two if you decide to make 550rwhp plus. I have always used the 255lph pumps. They flow for days and are proven. With the lines you have a choice of 6an dual feeds or a single 8an feed line. Either will work fine. Don’t skip on this mod you’ll pay if you do. As for fuel injectors 550 are good to 500rwhp or so. After that shoot for the 720cc style injectors or larger.

The Electronics
You can go two routes here. The Lexus afm route or the VPC route. I choose the Vpc route because I like a crispy idle and the vpc frees up the intake with a adjustment spots.
The Lexus afm route can make power but prepared you learn how to tune. Eric Varah actually made 622rwhp all through a Lexus Afm and tuning. So power can be made this way but you will need to tune a little more with the Safc and fuel cut issues. On the other hand the vpc doesn’t have the fuel cut issue. For adjustments I chose the Safc for that, as the HKS GCC doesn’t have the tune ability that the Safc does.

The Intercooler
All I can say is get a Greddy three row for a MKIV or get a custom one made from spearco. At the 500rwhp mark I think the cooling effect of the Spearco kit for our cars is reaching it limits. Better to efficient then not efficient enough.

Turbo kits
My favorite part is the kit. I own the SP kit and the HKS cast kit. They both flow great but the SP kits blow everyone else away. Looks good flows good delivers. Little expensive if you’re not up to it but well worth the cash if you get it. Don’t skip on this mod. Depending on the power you want the MKIII responds great to smaller turbo’s but it really wakes up when you reach for the t61. Not the 60-1 but the T-61. People for some reason confuse the two. This turbo will flow 550 plus rwhp in a MKIII all day long.

Now for the guy really wanting to reach out and deliver a blow the t-66, sp67, bl67 and larger will work fine. Only thing is you start losing the great spool for the street and become a lag monster. I personally would not go past a t-72 for the street and that’s to big. For the Dyno queen the sky is the limits so go for the sp74 and all those track turbo’s. Avoid the t70 series and t64 series turbo’s they have surge problems. Although I hear now they have been cured with anti surge housing. Bottom line my feeling are that the t61 and t66, sp67, bl67 etc are the best bang for the street. They deliver 600rwhp and are again proven.

The Bottom Line
SPEED cost money! How fast do you want to go? Leaving things out almost always results in failure. Trust me I’ve seen it millions of time. Guys uses an old oil pump then develops rod knock. Guy runs 20 psi on a motor with 200,000 miles then ask what happened. Common sense plays a lot. This is one expensive game and there WILL be failures. Ask any big name out there things break. How you handle it is up to you but don’t expect the car to deliver if you don’t use good judgment. With that said build the car up the right way the first time if you don’t have the cash just save. Hard to do but worth it in the end.

 

[yannis-supras]

Yea I was aware of that one. Its articles and related threads like that I've been reading that provided me all the info for the list I wrote on my original post. Nothing about a twin turbo setup though...

 

[GrimJack]

The small turbo will spool quickly, yes. However, add a second turbo to that, and they will both only spool half as fast.

Turbos are always a compromise between fast spool with low power potential, or slow spool with high power potential.

The key is to find a turbo - or a pair, if you wish - that just meets your power requirements, but only barely. Then you'll have the fastest spool available - well, without tricks like spooling the turbo with nitrous, or the anti-lag feature on some standalone computers.

Unforunatelly 7mpower has been hi-jacked the last couple of days so it's off access. So wouldn't in theory a smaller turbo that would produce about 250-280hp spool up faster than a bigger one that'll produce 500hp? And if that is correct , multiplied by two would result in the twin setup of my dreams?

 

[yannis-supras]

I havent really seen a Twin turbo setup on a 7M. Would anyone have pictures of it?

There's a few pictures. #2 is definately my favourite one :bowdown:

http://www.supramania.com/forums/attachment.php?attachmentid=1126&stc=1

http://www.supramania.com/forums/attachment.php?attachmentid=1127&stc=1

http://www.supramania.com/forums/attachment.php?attachmentid=1128&stc=1

http://www.supramania.com/forums/attachment.php?attachmentid=1130&stc=1

 

[bgrieger]

actually, yannis-supras is correct on the theory of twins. The 2 smaller turbos require less than half the energy to get moving. The fact that the mass of the wheels is closer to the axis of rotation results in a lower polar moment of inertia. There is no more power to be gained, in fact, the absolute peak is a little lower, but faster spool is a reality. Now, that said, were talking a few percent here or there...as an idea, a full dual ball bearing single should be about as fast as twin journal bearings that flow the same as the single, and twin ball bearing may come in 1-200 RPM earlier still.

Now the downsides:

They drop speed faster than singles when there's no power (same as lightened flywheels). Take your foot off longer than needed to quickly shift, and they have to accelerate more again.
Complexity and price are the big downsides. To balance the budget versus street performance, I'd suggest a ball bearing single is the way to go. That said, my twin kit is still under construction, but that's more for my own satisfaction than pure performance.

 

[MRSUPRA]

To make 500rwhp, you will have to deal with some extra lag whether you go single or twins. As mentioned, properly sized twins will spool slightly faster than a single, but not much. Now what you really need to ask your self is, do I want to make 500rwhp at 18 psi on pump gas or 24+psi on race gas. The smaller, quicker spooling turbo will need to be run at higher boost to make that kind of power, where as a large laggier turbo could possibly do it on pump gas at lower boost.

You won't need a front facing intake manifold
You will be fine with 550cc injectors and LExus AFM
One Walbro will be enough.
A 38mm wastegate should be big enough.
I reccomend using a proven (full) SP turbo with a good aftermarket cast manifold.
Twins are just too complex.

 

[yannis-supras]

Now the downsides:

They drop speed faster than singles when there's no power (same as lightened flywheels). Take your foot off longer than needed to quickly shift, and they have to accelerate more again.

Yea that short of makes sense. But isn't the "less lag theory" coming in to effect on this one too? I mean they should spool faster than what a single that would drop pressure, right?

 

[bgrieger]

The single won't drop as much in the first place, and the twins come up faster after falling off.

In all seriousness, flip a coin...Singles theoretically should be more efficient for drag racing as peak efficiency is higher, and the turbos don't fall off as much during shifts. At the end of the day, in the real world, between shift performance is going to be measured in 10-20RPM differences (not noticable), but would depend more on the driver and shift speed than the equipment. Which is better? You'd likely never be able to tell the difference...

Pressure requirements to get to a power point depend on turbo choice. Most people mistakenly think twins mean too small, or more pressure required to do the same job. Perhaps because the 1j and 2j crowd swap them for singles that flow more at lower pressures than the stockers...think of the CT26: after turning up the boost, larger turbos flow more than it can at lower pressures too...all about choice.

In summary, flow and pressure requirements for power are dependent on turbo sizing. Size a pair right and you will find no appreciable differences in setup from twins to singles.

 

[yannis-supras]

In summary, flow and pressure requirements for power are dependent on turbo sizing. Size a pair right and you will find no appreciable differences in setup from twins to singles.

Hmm...you sound a bit disappointed man, is your project still in progress or you've finished it yet?

In all seriousness, flip a coin...Singles theoretically should be more efficient for drag racing as peak efficiency is higher, and the turbos don't fall off as much during shifts. At the end of the day, in the real world, between shift performance is going to be measured in 10-20RPM differences (not noticable), but would depend more on the driver and shift speed than the equipment. Which is better? You'd likely never be able to tell the difference...

Well my intentions are far from drag racing. I want a set up that would suit the car in twisty roads and bends. Something that wouldn't lag on the apex of a bend or burst high pressure for that matter. Good response in low rpm.
What kind of setup would you suggest for that.
I mean if I can have a single setup that can start boosting at 2400-2800rpm(or even lower ;-)) and hold power upto 5800-6000rpm and actually is linear and responsive I would like you (or anyone that would know of it) to point it out. In fairness though I wouldn't wanna spent over $2000 for a turbo.

 

[MRSUPRA]

I already tryed to explain this to you. To get 500rwhp you will have certain amount of lag no matter what turbo you choose. There are no majic turbos. Twins are going to cost you way over $2000 when all the plumbing, manifold, turbos are complete. If you go single you will need a T4 size turbo to make 500rwhp. Company's like SP and PHR will take a T4 turbo and port and optimize it for the most power and best response. Thats why all the big name surpas go to company's like these, because they are proven turbos that have dyno graghs to show there power and response. A PHR GT60, or an SP58GT for example would be perfect for you.

 

[bgrieger]

Nope. Not disappointed. The project continues. If I could stop working, I'd have the time to get on it...actually, without a job there wouldn't be the money...oh well.

2400-2800 full boost and 500HP? not likely going to happen. When I speak of quick spool through twins, by 3000 you'd be nearing 18-20PSI, but I haven't seen a map before that could support as fast as you wanted and still run to redline.

Singles - GT35R, the SP58. Low 3000RPM-3500RPM for 18PSI or so (ive driven both...very fun). The GT is very low 3000RPM.

 

[yannis-supras]

I already tryed to explain this to you. To get 500rwhp you will have certain amount of lag no matter what turbo you choose. There are no majic turbos. Twins are going to cost you way over $2000 when all the plumbing, manifold, turbos are complete. If you go single you will need a T4 size turbo to make 500rwhp. Company's like SP and PHR will take a T4 turbo and port and optimize it for the most power and best response. Thats why all the big name surpas go to company's like these, because they are proven turbos that have dyno graghs to show there power and response. A PHR GT60, or an SP58GT for example would be perfect for you.

Ok so since I can't really read a turbo map or understand a lot from a dyno graph, you do suggest that either of these turbos would perform closely to what I wish? Do you happen to know their spool up times and when they reach peak performance?
And aren't these a bit on the expensive side. I mean I'm willing to spend up to $3000 for a nice twin setup including piping but not more than $2000 for a single one.

 

[yannis-supras]

Singles - GT35R, the SP58. Low 3000RPM-3500RPM for 18PSI or so (ive driven both...very fun). The GT is very low 3000RPM.

So you reckon the GT35R is quite responsive? Is it the one going for about $1300-1500? They say this is dual ball bearing.

 

[GrimJack]

Couple more things to throw into the pot for consideration.

500 hp on twisty roads is a LOT. Especially on our chassis.

Also, you have mentioned a standalone ECU - which could increase your rev limit. A 4500 - 7500 range on a high output turbo with the standalone gives you the same operating range as a 3500 - 6500 range on a lower output turbo without a standalone and a stock rev limit.

 

[yannis-supras]

500 hp on twisty roads is a LOT. Especially on our chassis.

GrimJack I'll just make things more clear of what I want. After talking with other mkii over400hp owners I think that a 350hp(400hp tops) setup will be more suitable for what I want. I'd like to keep the option of been able to run 500hp at will, not constant and especially not at twisty roads!!!

Also, you have mentioned a standalone ECU

The standalone was mentioned on the "are these necessary?" list, I don't have one.

A 4500 - 7500 range on a high output turbo with the standalone gives you the same operating range as a 3500 - 6500 range on a lower output turbo without a standalone and a stock rev limit.

It's not as much about operating range-eventhough still important- as it is about lower rev spooling and response so given the choice I'd go for 3500 and even 3000rpm starting point of power range.