Turbo Selection

[Lextreme II]

I am currently running Garrett GT40 Right now with Precision .68 Housing. I am not sure how it would perform with my new engine, but i have been thinking about downgrading the turbo from GT40 to GT35R with .70 A/R.

Here is the link: http://lextreme.com/GT.html

GT40 is rated at 750 and GT35R is rated at 680 bhp. What do u think for the 4.0 liters?

 

[jtjerry]

why you want do that?
for faster spool up?
when your gt40 kick in?
Jerry

 

[Jon_Boy]

by the way, lextreme, you are my friggin idol man. i love your sight and am soooooo glad i found it. now onto your question.


how much boost are you planning on running??? i'm sure you know this very important to know when chosing a suitable turbocharger. but i'm assuming that you're gonna run around 12-18 psi (somewhere in that area) and from what i can see on the compressor maps i found (atpturbo.com, excellent sight) a gt40 is right in its sweet spot around those boost levels on these engines. it looks like a 35/40 is alittle too small. but if you're looking more for violent response, by all means, try the 35/40. as a general rule, it seems like optium efficiency with a garrett gt series turbo reaches peak efficiencyat about 175 hp/liter (as is testament to the 700 hp gt40 being peak on your 4.0L engine, and using 2 gt28rs turbos at 700 hp total hit peak right around there too) and obviously, if you're going to run more boost than that, you might think of looking into an even bigger snail. you know what you're doin though, and i have 100% faith that you'll make it work and make if fast!!!

 

[Lextreme II]

Honestly i really would like to run somewhere around 18-20 psi, but my computer only able to handle 16 psi.

 

[vn1uz]

why dont you spend the cash on a aftermarket computer instead that way you dont have worry about it not running past 16psi
a cost of a gt35 here would be the same as a wolf3d microtech both australian but you guys would have to have something over there you could use

 

[Jon_Boy]

lex, the only problem i would see with running 18-20 psi is fuel. at that boost and 9.0-1 cr you're gonna need some serious octane. i dont' know whats available where you are, but here in ND (don't laugh) the best we can get is 92. even here, at that, you'd be looking at running 92 and octane booster with EVERY tank of gas to stay out of detonation. i'm sure you could do it with a cr of 8.0-1, but then your motor would be alittle sluggish while off boost.

and i agree with vn1uz about the stand alone ems. but if thats not something you want to do, there should be some way around it. what have you found is limiting you to 16 psi?? is it the maf??? if so, maybe a 2jzgte maf would help. supra guys get rid of them ASAP and i don't know what the flow limit is on one, but if its on an engine rated to create 320 hp, i would say it probably flows better than the maf for the 1uz.

and if this is something you're aware of, please don't be offended that i told you. in forums, i've found its most helpful if you take nothing for granted and cover all the bases. sometimes it offends people, but thats just a chance i take i guess

 

[Lextreme II]

None taken and thanks for the inputs...

 

[Orion ZyGarian]

what have you found is limiting you to 16 psi?? is it the maf??? if so, maybe a 2jzgte maf would help. supra guys get rid of them ASAP and i don't know what the flow limit is on one, but if its on an engine rated to create 320 hp, i would say it probably flows better than the maf for the 1uz.

Actually, us MkIII Supra guys upgrade with the Lexus MAF because it flows much better than stock. Also, I dont think the 2JZ-GTE uses a MAF setup...I believe it uses MAP instead, as does the 1JZ.

 

[Cobolt]

lex, the only problem i would see with running 18-20 psi is fuel. at that boost and 9.0-1 cr you're gonna need some serious octane. i dont' know whats available where you are, but here in ND (don't laugh) the best we can get is 92. even here, at that, you'd be looking at running 92 and octane booster with EVERY tank of gas to stay out of detonation. i'm sure you could do it with a cr of 8.0-1, but then your motor would be alittle sluggish while off boost.

and i agree with vn1uz about the stand alone ems. but if thats not something you want to do, there should be some way around it. what have you found is limiting you to 16 psi?? is it the maf??? if so, maybe a 2jzgte maf would help. supra guys get rid of them ASAP and i don't know what the flow limit is on one, but if its on an engine rated to create 320 hp, i would say it probably flows better than the maf for the 1uz.

and if this is something you're aware of, please don't be offended that i told you. in forums, i've found its most helpful if you take nothing for granted and cover all the bases. sometimes it offends people, but thats just a chance i take i guess

Problems with 20psi.. hmh? time to do modify combustion chambers and/or chose a better ecu and intercooling?


SAAB 9-5 AERO can push approx 22psi 100% STOCK on pump gas.

The trionic ecu is a Nm request ecu that in some cases will allow 22psi to compensate for great load on ac, alternator and so on to reach its 350 Nm target. The compression ratio is 9.3:1

2.3-LITER 4-CYLINDER HIGH OUTPUT TURBOCHARGED 250-HP ENGINE

4-cylinder high-output turbo
Displacement—139.6 cu. in. (2,290 cc)
SAE horsepower rating—250 @ 5300 rpm
SAE peak torque—258 lb.ft. @ 1900-4500 rpm (Standard on Aero)

http://www2.saabusa.com/95w/specs.asp

 

[rarson]

I thought I already replied to this, but I guess not. .68 seems too small for a 4.0L V8 IMO.

Also, when talking about high compression and boost, fuel atomization is critical. Doing whatever you can to increase swirl for better mixing helps. If you're doing head porting, check out some of the dimple features that a lot of racers use, it's exactly for this purpose. Other methods are available too, but the biggest mistake people make when porting is making the intake ports smooth.

 

[MRRUDE]

how about 75 shot of gas to spool turbo ( gt45r) @ 18PSI BOOST WITH THE RIGHT COMPUTER DOING THE JOB YOU COULD CONTROL THE GAS DOWN LOW AND LET THE TURBO DO THE REST?:feedback:

 

[Lextreme II]

GT45R is HUGE.... Where are you going to put it? I wanted .68 A/R was because i wanted early spool.

 

[LTLRKT]

how about 75 shot of gas to spool turbo ( gt45r) @ 18PSI BOOST WITH THE RIGHT COMPUTER DOING THE JOB YOU COULD CONTROL THE GAS DOWN LOW AND LET THE TURBO DO THE REST?

WoW!! Back up a second!!! Are you stalking me?? hehehehe

Its as if your reading out of my book of notes and ideas ive written over the past 6months - but i think we're gonna run alot more gas with alot more boost, see how the dyne testing goes. There is a HUGE amount of work going into this guys car.

Whats the spec of your turbo? We got the same one it looks like, & from the same place. Boys at gcg are awesome and come extremely recommended.

Well we went for the GT42/45R 1.05 A/R on the back from memmory. After we see how it responds on the dyno, might go up to 1.15 or lower. See how we go. Car should hopefully be ready for summer!

Will post up pics and a write up once the car is finally done.



Lex, i'd stick with the snail you've got and work from there. But It all comes down to what "you" want out of your car, and the kind of drive and power your after.

Riste.