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Discussion Starter #1
Hey guy's

I've been BPU for several years now doing HPDE/track days/time attack.
I will be building the head. GSC S1 or S2 cams, springs, retainers, seals.

My 94 JDM Supra is in need of a reliable, track worthy single turbo capable of 650whp on pump 94 octane

My goals are:
- Reliability
- Keeping heat down to a minimum
- Full boost by 4000rpm
- 650ish Whp on pump 94 octane

Which turbo? T3 or T4? What A/R ? Why?

Cast or tubular exhaust manifold?? Why?
 

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I have 6266JB T4 a/r81 with tubular mani , 264 has on 94 I'm making 642whp 22psi
full boost at 4500ish , but gained on top end rpm up to 7200rpm
with the same turbo but cast mani, stock cams was 530whp 22psi full boost at 4000ish top rpm 6000ish the torque is the same at 520ish
the car felt more snappy on cast mani ,
I don't have problems with heat but I haven't time attack , I just did for fun 2 times
 

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Discussion Starter #3
Hey Mark,

Thanks for your input, those are numbers I am after. I take it your using 94 Octane only?
Why did you switch to a cast manifold?
What do you mean you gained on top end rpm up to 7200rpm
with the same turbo but cast mani?
Are you saying the cast manifold will hold power and torque further up the rpm range?

Thanks!




QUOTE=markk;13879699]I have 6266JB T4 a/r81 with tubular mani , 264 has on 94 I'm making 642whp 22psi
full boost at 4500ish , but gained on top end rpm up to 7200rpm
with the same turbo but cast mani, stock cams was 530whp 22psi full boost at 4000ish top rpm 6000ish the torque is the same at 520ish
the car felt more snappy on cast mani ,
I don't have problems with heat but I haven't time attack , I just did for fun 2 times[/QUOTE]
 

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iSketch Master!
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I believe you are reading his post all wrong. He gained on top end when he switched from cast manifold, and stock cams. His power band moved to the right, while losing some low end grunt with the switch. If you are looking for a track setup I don't understand the want for 650 on pump. That should be a 650-700 goal on higher octane fuel for the track IMO. I don't believe T3 setups have any business on our cars. Pick a turbo first, then you can get assistance on your exhaust side. There are so many turbos that fit that power goal, but again, you gotta set a preferred goal/budget first. If you have all the money go for a billet precision/BoostLab, or EFR turbo. If you are going for a reliable setup that doesn't break the bank, any Borg Warner turbo will fit the bill. 366 or smaller if going that route for me. Cast mani's will come with some restrictions up top, so that choice is kind of yours. Are you OK with sacrificing some performance in the upper RPM ranges for added low end flexibility. Once you are on the track you shouldn't be terribly worried about gaining a few hundred RPM on the bottom end, when you will have your foot in it most of the time.

Alex
 

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I run 9-12 hpde events yearly with good success on Borg Warner S300 60mm turbo. Makes 600+wheel on 93 and VVTi, RPS tubular manifold - you got yourself a potent responsive roadcoarse setup that takes the abuse. I will admit, I did have the turbine housing egg-shape from the excessive and prolonged heat of these events. My downpipe also egg shaped (deformed). I had to replace the housing.

Those few hundred RPM on the bottom make a world of a difference on corner exit on specific corners/tracks. Most of the tracks I've been, 600wheel is plenty since you don't usually have enough straightline to use it to full potential. I still get lapped by Miatas...

I don't think time-attack is as abusive as 20-25min hard HPDE events going 10/10ths, you may be fine otherwise.
 

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handy with the steel
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From what I've read, a turbo that can safely make 650 on 94 will be ill suited for track use. By "safely" I mean under 20psi, and to make those kinds of numbers with that little boost you're looking at a 70+mm compressor...powerband won't start until ~4800. You need low-mid range grunt coming out of corners far more than you need a screaming top end, so something like a 6266 or a GTX 3582R would be my suggestion, and if you really think you're too slow on the straights then add a water/meth injection kit and turn up the boost/timing.
 

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Reading is one thing: I'm giving you first hand experience :) Can't beat that!

I am making a tick over 600wheel at 21psi on a 60mm - can be done! Full boost under 4000rpm with VVTi 4th gear. I can go more but it's already too much to handle for me.
 

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handy with the steel
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So, not 650 whp and not below 20psi?? :p Also from your build thread, the dyno graph indicated the 600whp pull was made with methanol injection?

Regardless that sounds like a bad ass setup, especially in something light like a Z4. I bet that thing is a absolute weapon! Maybe you were ahead of the curve on the MKV...

I'm hoping to get mid 500's on 93 out of my single conversion, but I'm not sure if the log manifold will allow. If not, I know where to look to uncork it.
 

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I would stir the boat with Twin G25-660 garret turbos, I can advise you on what exactly you would need to do the twin setup if you like
 

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First, what rev range and boost are you planning.

Based on my calcs, at 8000 rpm a 3L will need over 18psi to make 650hp at the crank. I doubt 18psi is a reliable road course number. Did you plan on buzzing the engine to 8k on each shift?

For road course work you are look for a broad powerband...power coming off the corners is more important than at the end of the straight. Typically, for max performance you want a pretty violent major intensity which is hard on valves and springs. I'd write/call GSC if their R2 would be appropriate in this application. It is nearly the same ADV duration as the S2 with more lift and it gets the valve off the seat faster. Their conical valves springs should be ideal for this application. That said, on pump gas and 7000rpm, the S1 may be the better choice

The choke like of most turbo compressors (all turbo compressors?) slopes up to the right. That means at lower pressure ratios there is less flow for a given size turbo. The problem is the bigger turbos have more inertia and should therefore have more lag.

My guess is the BW EFR 8474 might be a good option. TiAl turbine keeps inertia down. Revised for 2019. Is available with an internal wastegate which simplifies the exhaust, has a built-in recirculating BOV again simplifing things. It even comes with a 3-port boost solenoid that mounts on the compressor cover. In the Garret lineup the turbo would be a GTX3582R or GTX3584RS. The 3576 isn't going to get to 650, or will be right at the choke line. The G25-660 is a nice turbo...Garrett's compressor map is similar to or better than the EFR 7163 which is a bigger turbo. But they won't generate those numbers.

If you drop the expected power to 600hp at the crank, the G25-660 is an option. It is also available with an IWG. Because of its small wheel sizes, it would be a G2767, it probably has the same or less inertia than the EFR 7163, much less than the 8474.

Full-Race has a divided T4 IWG manifold with smaller diameter tubes. A tube header with merge collector will always be bettter than a cast manifold, IF it is correctly designed for you app. A tube header designed for 30psi drag racing is not going to be ideal for road racing

Now a sense of reality. You are not doing racing or time trials in a close competitive class where the money is spent to be competitive. You aren't running BFG R1 S or Hoosier A7s, replacing them when they drop in lap times. Those aren't Penske or Ohlins TTX shocks. The car doesn't have a full cage. This is fun time on a race track which you mainly do for fun. Keeping the car where it will be reliable and you will get seat time is far more important than chasing mechanical gremlins. Cars at the bleeding edge have gremlins and just a lot more maintenance as parts are more stressed.

Have you considered leaving the car alone and working on data acquisition? You could record internal and external tire temps across the tread. Torque on each axle. And just the more mundane g-forces, speeds, yaw, pitch, and roll, wheel displacement, etc. That would let you work on your driving and tuning. Remember a 2JZ-GTE Supra has never been a significant road racing car.

My 2¢.

 

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From the land down under
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Great reply, David.

Lots of valid points there, and lots of food for thought.

I also agree with the tactic of leaving the power alone, within reason of course, and just focusing on the driving. Once you simply cannot improve your lap times at the same tracks, with all of the same variables being equal, then its time to turn the wick up some :)
 

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Great reply, David.

Lots of valid points there, and lots of food for thought.

I also agree with the tactic of leaving the power alone, within reason of course, and just focusing on the driving. Once you simply cannot improve your lap times at the same tracks, with all of the same variables being equal, then its time to turn the wick up some :)
Or you could buy an actual race car. If the car ahead of you burst a water hose and covered the track with anti-freeze, what would happen? In real racing, anti-freeze isn't allowed because it is very slippery and hard to clean up. A 90mph encounter with a guard rail or tire wall could easily leave a Supra chassis twisted beyond reasonable repair, not even counting difficult to obtain 25-year-old repair parts.

A tube frame or carbon chassis race car is a straightforward repair at that point. 18 years ago I was in a 70mph t-bone...I was in the accident before the yellow flag came out. The radiator was wrapped around the engine. The left front brake rotor was cracked in half. I pushed the steering wheel inside out (although I was fully belted) and my neck stretched enough that the helmet hit the forward hoop of the roll cage. The car, a tube frame, plastic body super late model stock car (3000lb, 500hp, 13" wide tires), was repaired and back on the track in less than 3 weeks for under $5000. In a Spec Miata it would have needed a new chassis. Similarly, a Supra would have been turned into a parts car.
 

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First, what rev range and boost are you planning.

Based on my calcs, at 8000 rpm a 3L will need over 18psi to make 650hp at the crank. I doubt 18psi is a reliable road course number. Did you plan on buzzing the engine to 8k on each shift?
18psi reliable? Really? How about 24-28psi? I have close to 20,000 track miles with 24 low and 28 high...

To the OP, have you searched this forum? Over the years there has been a lot of discussion and posts by those that have racked up a lot of track time.
 

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18psi reliable? Really? How about 24-28psi? I have close to 20,000 track miles with 24 low and 28 high...

To the OP, have you searched this forum? Over the years there has been a lot of discussion and posts by those that have racked up a lot of track time.
If you have 28psi on 93 octane you should write a paper on it. Lots more boost is possible with E85, C85+, methanol injection, straight methanol, etc. Not the case here. There are lots of folks here running mid-30s or higher on E85.

And on a road course, what is the point of having F1, IndyCar, NASCAR levels of power? Certainly don't have their traction, downforce, safety equipment, competition, or budget. Fresh BFG R1 S or Hoosier A7 tires are probably worth more in lap times than 300hp on say...Hankook RS4s or Azenis RT615K+. Forgetting adhesion, tires that are communicative, responsive, and forgiving near their limits would probably add more by letting the driver explore those limits.
 

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Discussion Starter #15
Thank you for the info so far guys, I have been using R compound tires, and yes they did shave 6~seconds off my times. I am just looking to know if I can achieve 650whp with 6466 DBB precision turbo, spa manifold, built head on 94 octane without stressing the turbo beyond its threshold. E98, 85 are not readily available in my area.

Jay
 

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The 6466 has an 87mm compressor wheel and 74mm turbine. The 6266 has the same ODs on the wheels, but the inducer on the compressor is smaller. They rate one at 900hp, the other at 800hp but don't provide compressor maps. Other brands that those sizes who do publish maps would handle 650hp at 16psi or so. You can call Precision or one of their dealers to discuss. Their number is: 855.996.7832

However, the question is probably how fast are you going to rev the engine? At 3.0L those numbers may happen at the crank at 8200+rpm. At the wheels? Is your engine built to handle 8200-8500rpm in terms of connecting rods, pistons, pins, oil pump, and oil pan for high-g road racing?

What tracks are you running? Have you estimated what the horsepower will change in lap times? You are talking about more power than GT3, GT4, or DTM.
 

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A single GTX3576r Gen2 just put down 800whp at 43psi on a K20 motor, check out Garrets Instagram page
 

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A single GTX3576r Gen2 just put down 800whp at 43psi on a K20 motor, check out Garrets Instagram page
Is this related to the price of tea in China? A totally different problem. Op is running 93 octane with much lower pressure. The trick is to get a turbo that will deliver the required airflow at the low pressure ratio. Those numbers aren't unusual for a K20/K24, however the 4:1 pressure ratio would be off the charts for that turbo...so I doubt it.

Thank you for the info so far guys, I have been using R compound tires, and yes they did shave 6~seconds off my times. I am just looking to know if I can achieve 650whp with 6466 DBB precision turbo, spa manifold, built head on 94 octane without stressing the turbo beyond its threshold. E98, 85 are not readily available in my area.

Jay
Which tires in which sizes? Are you lowered? Do you lift or severely lighten your inside wheels, especially your inside rear? What differential are you using? S2000s, which are lighter with a lower center of gravity, usually have to switch to a Salsbury diff (usually OS Giken) when the tires get very sticky (e.g. Hoosier A7s)
 

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Actual track experience here; although in an IS300.

Things to keep in mind, for every HP you make of power, you're dumping a HP into the cooling system. You're going to tax the oil temps and radiator at 500+whp. There's a reason GM struggles even w/ OEM resources to make the new Vette's and Camaro survive on track.

I've tracked my IS w/ the stock twins turned up, a Precision 6766, and now a BW EFR8374. Stock twins were OK, definitely left wanting for more. And hey, it's a 2J, so why not.

6766 was run at 27psi for single lap fliers at a T/A event. Made it 4 sessions before locking up. Notes, the torque onset was brutal and a handful. Yes, it was wicked fun, but terrible to keep in check and honestly not the fastest thing. I could have fun faster laps on a smaller turbo. But yes, shaft bent, compressor ate itself. Precision makes a good street turbo. But they're not water cooled. Go around the pits at a road course event and count the number of Precision turbos you see. Sure, they're great drag race turbos, but you just wont see them on a road course as often.

So that's why I'm on the BW. I stepped "down" to a 8374 (BW sizing is different). Torque onset isn't quite as aggressive, but it wasn't a huge difference versus the 6766. Honestly, if it my car was strictly for track use, I'd try the next size down. I'm making right at 600whp on E85. Should make more but I'm ECU limited currently.
 

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Actual track experience here; although in an IS300.

Things to keep in mind, for every HP you make of power, you're dumping a HP into the cooling system. You're going to tax the oil temps and radiator at 500+whp. There's a reason GM struggles even w/ OEM resources to make the new Vette's and Camaro survive on track.

I've tracked my IS w/ the stock twins turned up, a Precision 6766, and now a BW EFR8374. Stock twins were OK, definitely left wanting for more. And hey, it's a 2J, so why not.

6766 was run at 27psi for single lap fliers at a T/A event. Made it 4 sessions before locking up. Notes, the torque onset was brutal and a handful. Yes, it was wicked fun, but terrible to keep in check and honestly not the fastest thing. I could have fun faster laps on a smaller turbo. But yes, shaft bent, compressor ate itself. Precision makes a good street turbo. But they're not water cooled. Go around the pits at a road course event and count the number of Precision turbos you see. Sure, they're great drag race turbos, but you just wont see them on a road course as often.

So that's why I'm on the BW. I stepped "down" to a 8374 (BW sizing is different). Torque onset isn't quite as aggressive, but it wasn't a huge difference versus the 6766. Honestly, if it my car was strictly for track use, I'd try the next size down. I'm making right at 600whp on E85. Should make more but I'm ECU limited currently.
Great post.

6766 is an 88/74, only a little bigger than the 8374 in wheel size. I'm wondering what other parameters were different.

One EFR sizing issue is the holes. In many ways the 8374 (now 8474) is one step up from the 7163 small frame turbo, since the other models (7064 and 7670) don't really move the choke line for at least pump gas applications.

The 8474 is new for 2019. It will be interesting to see if BW updates the rest of the EFR product line and if Garrett flushes out the G-series between the G25-660 and G42-1200 Compact.
 
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