Ok so we already know that too big of piping causes lag. Well how about too small? I just recently had a flange made for my compressor outlet. The opening on the turbo is 1.5". Half of my lower IC pipe is now 1.5" and flares to 2" before it goes to the IC. Then the rest of the system from there is also 2". It's probably about an 8" section of 1.5" piping. The thing is I have lots more lag than I did before. It's a new turbo but it's the same size as the old one. Everything else is also the same. It used to be when I was cruising on the interstate I could give it 3/4 throttle and peg my max boost (15psi) almost instantly. Now even when going 75+ it takes a while to reach full boost. Does anyone think the piping would cause this? If not I will check for leaks with the tester I'm getting ready to build. I just want to narrow down what it possibly could be. Thanks for any input!

is it 1 1/2 into 2 or 2 into 1 1/2....... if it's 2 into 1 1/2 out of the turbo then this will cause friction......

It comes out of the turbo at 1.5" then expands to 2" on the way to the IC.

Sorry, this is a little off topic, but I will have my turbo kit in about 2 weeks or so, and I'm going to use my 1G SMIC with it. I already have a AEM short ram intake, and I was thinking about having the new pipes welded on to that, but the AEM pipe is rather large. Much larger then the inlet/outlet on the SMIC. Would this be a bad idea? The holes on the I/C are pretty small...


1996 Eclipse RS / 5-Speed / Body Components by Aerogear / Coated in Magnetic Red Metallic v2 - More at http://home.insightbb.com/~mgalyan/
Mark Galyan - Greenwood, Indiana

Use the AEM for the turbo inlet. It's 3" DO NOT use it for ANY of the IC pipes. It's way too big.

I don't think it's turbo lag this time. The 1.5" pipe diameter is probably causing some restriction to air flow, since you're running at least 15 psi. How big was the old turbo opening? Email me and we can meet up at my place; I could weld up a transition piece to the 1.5" lower i/c pipe to make it a 1.5"-2." piping at the turbo outlet. Let me know.

I just completed my i/c pipe project; I made the fmic inlet pipe 2.25, and the i/c outlet 2.5" and I could tell it really made a difference. The turbo really spools up a lot quicker, especially, when I'm boost higher than 15 psi.

The way I had it set up before went straight to 2" with a coupler on the turbo outlet. And Kon I e-mailed you.

hmm I think I'm running like 2.25 or 2.5 in certain places of my piping and it spools fine. Only reason it didn't was because I had low compression. The only difference I really noticed is that my HKS STD BOV started fluttering. But yeh the more boost you run the bigger the pipes you want, I was running with 8 psi and your running 15psi so it might be a good idea to increase your piping diameter.