I am in the process of upgrading the turbo on an 04 msm, from the ihi to a little larger garrett 2860. I have a larger intercooler but have used the OEM piping.

The OEM intercooler piping is 2 1/8". Is this too restrictive? What sizes would be optimal for a boost level of 10-12#?

 

2"

 

Curly may think he is right. I think he's right also.

corky

 

I run 2-1/2". well I take that back, it's 2-1/4" in some spots. But to be honest, it doesn't feel sluggish or laggy to run slightly larger piping. you certainly wouldn't notice it on a 60mm compressor.

course the poster above this post may have welded my pipes or at least delegated the work so I'd defer to him.

 

The MSM piping is 2". That will be plenty for 10-12". If you move away from stock piping, the MSM has that elbow connecting to the throttle body that you'll have to replace as well. It has a bung for the second IAT sensor on it. Honestly if you're going to make the piping bigger, I'd use either the Begi or the FM intercooler->throttlebody solutions for the MSM.

Easiest thing to do is plumb the new intercooler into the existing piping and not worry about it. Definitely the most cost-effective route.

My plumbing is 2" compressor to intercooler, then 2.5" to the throttle body.

 

I run 2.5 all around with my Rotrex. I use to run 2'' hotside and 2.5'' coldside with my ole 10psi GReddy set up. I'm going to go to a new bigger IC with 3'' in/out and keep my 2.5'' hotside and go to a 3'' coldside pipe when I up the boost.

 

The stock MSM throttle body elbow is crappy rubber that will balloon at best and split at worst so make sure it is replaced with the BEGI or FM part no matter what you run before it.

 

I'm willing to bet that 2" hot side and 2.5" coldside is the most common

stock throttle body is 2.5"
a lot of turbo outlets are 2"