UPIC question

[Idontknow]

Seeing that my car is stock right now, will 2.5" piping be too big. Will it create extra lag?
I also plan in doing the following mods pretty soon.
Ported evo III to 7cm
Ported turbo housing 7 cm
custom 3" O2 housing with external dump, still on internal wastegate,
Custom 3" mandrel bent piping, no cat
3" inlet , 4" outlet muffler

After searching the forum I see that most if not all dsm-ers go with 2.5" pipping
I was dvised by the local dsm club to go with 2.25"
Please help me decide.
Thanks.

 

[DSMboostin15]

It shouldn't be too big. I put mine on when my motor was pretty much stock. I run a Dejon 2.5 in. and it does fine. And no an UICP will not create turbo lag because it's not in a direct line with the turbo. The only things that will cause lag is the exhaust manifold, 02 housing, DP, turbo inlet, stock MAF, etc. The reason they create lag is because air is trying to be sucked through the equivalent of a straw. That's why if you go with a GM MAF and port your exhaust mani and 02 housing, your spool time decreases.

 

[romeen]

Actually yes there will be a little extra lag but the difference will be so small that you won't really notice it. The pressurized air that is created by the compressor wheel must first fill the space between the compressor housing and the intake valves before it can enter the combustion chambers. When you increase that volume there is more space to fill and thus slightly greater lag.

2.25" piping will give you slightly better low end response. 2.5" piping will give you more total air flow, particularly in the top end. If you plan on going with the Evo3 16G then the 2.5" piping may give you better results overall. But again the difference on a street car is minimal and either one should work fine.