Thread: AR comparison opinions

Anyone try a bigger AR housing on their turbo after having a smaller housing before? or vice versa.

I am torn between getting a .82 to replace the .63 housing for my gt3076r but I am worried about lag and having the engine revving past 7500rpm in order to make power. I would like power to level off around 7k to 7.5k. However, I can't find a good comparison writeup anywhere, and sr20forum.com is practically useless anymore as a lot of people have stopped goin there.

My cams have a lot of overlap and I figured the bigger housing would help cure the reversion problem. Should I keep the .63 and dial out 10* or so of overlap or get the bigger housing to get more power? Anyone with a decent writeup on their experience please elighten us.

i feel alot of peoples opinions are going to be geared more towards the fact that the smaller AR is going to give you faster spool. than the larger one, which i feel in your case is good becuase of the rev limit, which will give you a larger band than having a larger AR pushing full boost higher in the rpm.

the larger AR is going to give you more top end flow than the .63, but given the fact that the build is geared towards the rev limit being 7500rpm its going to i think be in the way.

but till even if this wasnt about a rev limit, you are wantin to build this for street, and having a car that rev out real high, and see's full boost later in the rpm isnt really 100% street friendly.

also smaller= faster spool larger= more top end

what type of tuning are you going with? the reason i ask is because i know with using the boost solenoids to control boost and being able to control the boost maps you can tweak the boost to have faster turbo spool, ive talked with my tuner and he says he averages around 3-500rpm faster spool, by tweaking the boost maps, but it all depends on what type of engine management you go with

Using a jwt computer. 8.5:1 comp. shootin for 22psi on pump gas. I think I will try the .63 with less overlap first, but all the honda guys love the big housings and only see like 3-400rpm slower spool. I love the responsiveness of this turbo though. Maybe I will just keep it the way it is.

most the honda guys around here are also revving there motors to 8500+, i would stick with the .63 for now, i think it would be the best option at this point, get the overlap figured out and go from there

Coheed,

Im running a GT3076R w/ a .82 back. I dont think there's much of a lag to tell you the truth. And the horsepower.....sure as hell doesnt level off at 7-7.5k lol its still climbing and peak torque is at 5k with the torque curve flat all the way up. Ive gone 21psi on Pump but not with a JWT.

When do you guys experience really experience this thing called "lag"? lol

I have full spool at 5k right now, but 12psi at 4k. It kinda builds up smoothly. Once I am past 5k the throttle response is pretty good, barely any lag.

^ i agree i am running the gt2871r with .86ar , however running hks camshafts that pick up on the more mid range which i think really helps with ''lag'' ive heard people complain with the .86ar but i really think the cmashafts make the big difference on making low to mid range power to pick up on spool faster..

the lag really won't be to noticeable, but depends on what you consider laggy....if your going to stay at 22psi, than you should posibly be fine with the .82 housing although I think 22psi on pump gas is somewhat lofty for a JWT tune just cause you cant fine tune your a/f enough to maximize power and timing..... just watch for detonation carefully. You will have a hell of a kick when you hit that 22psi!!!!

You know what is amazing, is every jwt tune I have had is always way conservative. A/F ratio stays around 10.5-11.2 and timing is way conservative which is perfect for pump gas. I ran 91 octane on my jwt program and 1.2 bar ie 17.5psi of boost and there are zero signs of detonation. However, I have not run the bigger cams yet so I don't know the effect that will have on the detonation threshold. I wonder if the VE head design has better cooling ability, or maybe the oil squirters help prevent detonation. I don't really know, but this formula seems robust.

i suggest you get the motor running right, or have it tuned before you even consider swapping the exhaust housing. with the .63 you should have full boost much sooner than 5k and it should hit hard. i had a .82 on my gt30r, jwt ecu, 8.5:1 compression, sr20vet cams, had 15psi around 4.5k.