The Top Mitsubishi Galant VR-4 Resource

Join the best E39A 1991-1992 Mitsubishi Galant VR-4 community and document your GVR4 journey.

  • Software Upgraded - Reset Your Password to Login
    In order to log in after the forum software change, you need to reset your password. If you don't have access to the email address you used to register your GVR4.org account, you won't be able to reset your password. In that case, follow the instructions here to regain access to the forum.

Running mixed diameter intercooler piping?

I'll explain all this in I.D.

I have 2" pipe coming off the turbo into a 2.5" increasing coupler. I have 2.25 and 2.5" pipe. The 2.25 clears my driver headlight better than the 2.5". The inter cooler is 2.5" inlet and outlet. I can clear 2.5" around the passenger headlight just fine. My BOV is welded to a piece of 2.25" pipe that I would like to use. The GM Maf is a 3" with 2.5" reducing couplers on each end. And then runs into the 2.25" intake manifold elbow.

I imagine smaller to larger is okay. Running the 2" from the turbo to the 2.25 into the 2.5" inter cooler outlet. Correct me if I am wrong.

2.5" from the outlet of the inter cooler into the 2.25" piece that the bov is welded to I'm unsure. Will this be a big deal? Of course I'm on a budget and don't want to spend anymore money, IE: have a bov bung installed into a 2.5" piece.

The large change is from 2.5" into the 3" GM maf and then back to the 2.5" pipe (via reducer couplers). Could this also be an issue? Should I look for a 2.5" maf? It ends up in a 2.25" intake manifold elbow anyways???

What do you think?
 

AnotherNewb

Well-known member
Joined
Apr 25, 2010
Messages
1,472
Location
Orlando, FL
All those reducers and different sized pipe shouldn't be a problem. More than likely you're not pushing so many CFM's that pressure drop will become an issue.
 

turbohf

Well-known member
Joined
Nov 18, 2011
Messages
540
Location
Lake Stevens, WA
guys have been running the GM MAF's for ever with reducers. i have never heard of an issue, even with cars making nice power.
 

curtis

Well-known member
Joined
May 4, 2003
Messages
11,892
Location
Clarksville TN
I had a 3 inch out of the intercooler to a reducer to 2.5 which the BOV was welded to and on to the throttle body. Looked like sh*t and drove me nuts because I knew it was wrong. To many fluid classes in school. One Sunday afternoon I took off the coupler and the pipe to the throttle body. I took the pipe and on the inside cut a slit and made a cone out of it by welding in a piece. Was probably 10 inches or so. Car lost 2.5 to 3psi of boost. This was the only change made. Boost is a measure of back pressure so you make your assumptions.


You can buy cone shaped pieces of pipe in all flavors. stainless/aluminum and mild steel or you can make your own. Start with the largest size mark a straight line , then take a straight edge and mark a angle on both sides of the straight line and cut out the wedge. Then take a hand full of worm clamps or better t bolt clamps and make it touch. Stitch weld , cut to the small size and your done. From the centerline over isn't much figure like a 1/4 inch but all depends on the pipe lenght.
 
Support Vendors who Support the GVR-4 Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications RixRacing RockAuto RTM Racing STM Tuned

Recent Forum Posts

Recent Classifieds Listings

Top