I/C piping size

[Ed98GST]

Hi all. I have a question on IC piping that I'm sure someone can help me with. I'm piecing together my own IC piping and want some advice on the best size to use. My setup includes a 6-bolt, a T04B turbo from Bullseye Power, a FMIC with short route piping, and a 3" MAFT set up for blow through.
My issue is the piping between the TB and the FMIC -- 2.5" piping with 2.5"-3" reducers to accomodate the GM MAF is what many run from what I've seen. How would 3" piping from the FMIC to the TB work? My concern is the creation of unnecessary turbulence from the immediate increase and then decrease before the TB. Is there a certain distance from the TB that (placing the MAF) would sufficiently reduce the negative effects of the turbulence to a negligible amt? I've always operated under the rule that increases & decreases in pipe diameter should be no steeper than 35 degrees in order to minimize turbulence. The silicon transition hoses aren't 35 degree angles, so I was considering moving to 3" piping ASAP after the FMIC. Can anyone provide me with input and/or their experiences with this? I searched a bit, but couldn't find specifically what I'm looking for...any help is appreciated.
BTW -- from turbo to FMIC would be 2.5" piping. I'm only talking about FMIC to TB piping here (just to be clear).

Thanks!
Craig

 

[Rick4g63]

2.5" from the turbo to the TB is best. unless you are pumping 30+ psi, 3" is the way to go.

 

[Ed98GST]

I know it's best from a hp & boost standpoint for my application (don't really NEED bigger), but is it best in terms of smooth airflow and turbulence? From what I've read, the 3" most likely would not adversely affect my setup, but I was hoping for confirmation one way or the other on this. I guess I could always run two different sizes of piping to see how the performance differs, but I really don't want to buy the extra couplers, redrill the piping for the bov flange, work out leaks, etc. Any additional input on this subject?

 

[Mirage2LTurbo]

I recall a several page discussion on this from just a week or so ago. Might want to scroll back through the pages

 

[98spydert]

Well you've got 3" worth of air slamming into a 52mm or 60mm throttle body. I don't see the point. but if you're using a reducer to go to a stock or 60mm elbow, it wouldn't be that bad, at least it would transistion down rather than slamming into a wall with a peep hole in it.

If it's easier to go 3" go for it. If it's just either or, I'd stick with 2.5 inch.

 

[Defiant]

Let's work on this over here:

http://www.dsmtuners.com/forums/showthread.php?t=146246

 

[Ed98GST]

I saw that thread, but didn't want to hijack it with a different 3" question...sorry. I'll pose my question in there and make it fit the discussion.