what size turbo

**ls1bitches** · 06-25-2008, 03:19 PM

i'm building a single turbo setup for my 98 trans am a4... I'm just wondering what would be a good size... i do have a 125 shot of nitrous, that i plan on keeping to help spool the turbo if i go to big... I'm also planing a 438ci lsx, i'd like to not have to buy a bigger turbo when i do the motor swap

**cailey37** · 06-25-2008, 06:07 PM

If you're going to be putting in a 438ci motor later then I'd go with an 88mm. I dont think a 76mm would fill it.

**zero_proto** · 06-25-2008, 06:55 PM

i agree with an 88mm........76 will probably run out real quick

**ls1bitches** · 06-28-2008, 05:49 AM

ball bearing or journal bearing?

**Snake Slayer** · 06-28-2008, 12:57 PM

s88 from forced inductions the s series turbos are the best. They are a large frame t6 exhaust housing and make sick power. A 438 ci motor is gonna need a t6 framed turbo of at least 88mm.

**CHRIZ28** · 07-25-2008, 03:43 PM

Yea, definatly gonna need alot of turbo for that much ci. I talked to Jose at forced inductions for what to use with my 408. We're going with a S91, the S88 would have been fine, but for a couple more hundred and the same packaging size, why not. 438ci should spool a S91 pretty quick and should make a TON of power! But on stock cubes a 76mm or the like would make awesome power too. Good luck either way.

Chris

**ls1bitches** · 07-25-2008, 04:29 PM

thanks

**Frost** · 07-26-2008, 05:56 PM

An s88 will run out up top with that many cubes. It pretty much has to be an S90 at the smallest, and you could run bigger. These turbos have no business behind a stock displacement engine.

**LSx Heaven** · 07-30-2008, 12:54 AM

Originally Posted by Frost

An s88 will run out up top with that many cubes. It pretty much has to be an S90 at the smallest, and you could run bigger. These turbos have no business behind a stock displacement engine.

I am with him, I was going to say a 91 mm. Good luck

**CHRIZ28** · 07-30-2008, 05:25 AM

Originally Posted by Frost

An s88 will run out up top with that many cubes. It pretty much has to be an S90 at the smallest, and you could run bigger. These turbos have no business behind a stock displacement engine.

Yes, definatly. Just whenever you get ready to do the big ci motor, take your time and talk to alot of shops/knowledgeable turbo people. I got like 3 different turbos suggested for my 408. All were WAY different turbos, now I understand when I see a turbo car that seems slower than it should be at the track...

Chris