Precision GT4276 Question What AR?

Reply Subscribe

Thread Tools

Search this Thread

Jan 1, 2008 | 09:13 PM

Sideways240sx

Thread Starter

9 Second Club

iTrader: (22)

Joined: Mar 2006

Posts: 1,569

Likes: 1

From: Byron, IL

Precision GT4276 Question What AR?

Ok, so ive gathered all my parts for my turbo kit, and im starting to fab up some of the kit.

Anyways, my question is i got a Precision Gt4276. It has a 4 inch outlet for Downpipe, and i origonally got a .98 ar. I got it cause it seems thats what everyone is running. Well the place i got my turbo from, there not a sponser, but they build most of the fastest supra's in the country kinda suggested i go with the 1.12 ar over the .98. They think it will do better, and im curious what the ls1tech community thinks. There gonna tune the car for me when its all done, and told me if i want to change it out to the .98 they will swap it out for me for free, but they want me to try this.

Car will be a truck manifold setup. 2.5 inch piping to a t4 flange.
Tial 44 wastegate
tial 50 bov
Garret 32x12x3 Ic Bar and plate

ls6 intake mani
Other then that the motor is stock, and will be untill i build a motor. Im going to just tune it to around 500hp on 93. Then when i get my motor i will see what this turbo can do.

Thanks, Chris

Jan 1, 2008 | 09:41 PM

Cheeks

10 Second Club

iTrader: (1)

Joined: Mar 2007

Posts: 299

Likes: 0

From: Pittsburgh, PA

kinda interested to see what is said here as well because I am looking at a similiar turbo

Jan 1, 2008 | 09:48 PM

Sideways240sx

Thread Starter

9 Second Club

iTrader: (22)

Joined: Mar 2006

Posts: 1,569

Likes: 1

From: Byron, IL

More or less they told me as long as i dont build a super low compression motor i will be fine, and even if i build a 370 iron block @ 8.5-1 or so if i add a 2 step i will be fine. They are spooling up this turbo on 3.0 or 3.2's and think with the 5.7 when i start pusing this turbo i will run out on the top end quick, and the 1.12 ar will help with that.

Thanks, Chris

Jan 1, 2008 | 10:06 PM

Drew04GTO

TECH Apprentice

iTrader: (1)

Joined: Sep 2007

Posts: 320

Likes: 0

I'd say go with the 1.12 a/r or larger. I personally think people are too concerned with spool in LS1 powered cars. I've seen gains of 50-60whp on cars by switching from an .69 to a .96 with maybe 400rpm difference in full spool time. Most of this has been in DSM's and a few large cubic inch hondas.

I don't see there being any noticeable difference in spool between the two housings you've chosen. Get the larger one and just make more top end power. What the hell are you going to do with 600ft/lb of torque launching on drag radials/street tires anyways.

Jan 2, 2008 | 07:29 AM

70Stang

11 Second Club

iTrader: (2)

Joined: Mar 2004

Posts: 773

Likes: 0

Make the switch.

Jan 2, 2008 | 08:55 AM

Big Geek

11 Second Club

iTrader: (2)

Joined: Dec 2003

Posts: 535

Likes: 0

From: Montgomery, AL.

1.12 would spool nicely on a 8.5-9.0:1 347-c.i. motor and a 1.28 would do the same for a 370-c.i. motor with the same compression ratio. Both would help reduce backpressure and they would spool better than you might think with the proper tune and camshaft. Good luck to you.

Jim C.