Turbo Back setup, will this cause creap??

[Batmobile]

The awd is about 1inch or so off the ground. I am plaining on going with a megan down pipe 3 inch and then have the rest of the pip'n to the exhaust to be 2.5 since it's going to scrap if 3inch was there. Is this a good thing to cause boost creep? Or do i want to keep it all a 2.5 inch all the way. ???
Any sugestions?

james

 

[NOSLO2PT0]

It most likely will cause boost creep. Best way to fix it is to pull your turbine housing off and port the wastegate hole.

 

[Batmobile]

so are you saying having a 3inch dp to a 2.5 pip'n is fine? just aslong as I port the housing?

 

[Cgillies86]

I have massive boost creep with full 3 inch exhaust. I am running off manifold vacuum so my boost should be around 8 psi; instead my boost is 30+ psi. I have a tubular O2 housing but a stock wastegate. I am getting my wastegate ported, and turbine inlet ported, I am hoping this will fix my problem. If I could do it all over again I would get the 2.5 inch Downpipe; so, i wouldn't have to deal with boost creep. The moral of my story is: you should get a 2.5 inch downpipe unless you plan on running sub-12s, but there are some people in the 11s with 2.5 inch downpipes anyway.

 

[NOSLO2PT0]

so are you saying having a 3inch dp to a 2.5 pip'n is fine? just aslong as I port the housing?

Actually, that's kinda silly. Either, get a 3" catback, or get a 2.5" DP. Going from smaller to bigger is ok, but bigger to smaller is robbing hp, via tha bottleneck. As the exhaust gases cool off, they expand. When they expand, and go into a smaller diameter pipe, it slows the exhaust velocity down, which creates more backpressure. Not good.

 

[NOSLO2PT0]

I have massive boost creep with full 3 inch exhaust. I am running off manifold vacuum so my boost should be around 8 psi; instead my boost is 30+ psi. I have a tubular O2 housing but a stock wastegate. I am getting my wastegate ported, and turbine inlet ported, I am hoping this will fix my problem. If I could do it all over again I would get the 2.5 inch Downpipe; so, i wouldn't have to deal with boost creep. The moral of my story is: you should get a 2.5 inch downpipe unless you plan on running sub-12s, but there are some people in the 11s with 2.5 inch downpipes anyway.

If you are running a manual boost controller, you should be tapping the line from the manifold to your BOV for a boost source. Porting the wastegate hole WILL fix the boost creep problem, assuming you port it properly.

 

[thegreatms]

As the exhaust gases cool off, they expand.

not sure about that, any gas I know contracts when it cools. Ideal gas law: PV=nRT.

 

[NOSLO2PT0]

not sure about that, any gas I know contracts when it cools. Ideal gas law: PV=nRT.

oops. My mistake.

 

[Batmobile]

Actually, that's kinda silly. Either, get a 3" catback, or get a 2.5" DP. Going from smaller to bigger is ok, but bigger to smaller is robbing hp, via tha bottleneck. As the exhaust gases cool off, they expand. When they expand, and go into a smaller diameter pipe, it slows the exhaust velocity down, which creates more backpressure. Not good.

Great thats what I really wanted to here! Thanks for all your comments..I'll plain to just get 2.5 turbo back. Thanks to all!!

 

[BacknBlack92ESi]

I creep only about 3lbs on my Turbo-Back without any porting to the waste-gate passage. Still on the T-25. Mostly likely I will upgrade soon rather than porting.