2 1/2" or 3" downpipe

[kevinz]

I currently have a 2 1/2" downpipe from msa. i am changing my turbo to a t3/t04e 50 trim stage 3. Will I be fine with the 2 1/2" downpipe or should I go to a 3". I currently have 2 1/2" downpipe to 3" mandrel bent exhaust. I don't want to waste money if it's not going to make a difference.

[BrandonR.]

With that stg 3 wheel it wouldnt hurt to have the 3" as it will need more flow than the stock wheel but on that note there are a lot of people running 2.5 downpipes with big turbos. If your going to be running a high boost and high rpm it would be better to have the 3" to keep things efficent. The 3" will also support a cam and throttle body upgrade better than the 2.5 DP

If you dont mind me asking what a/r and trim are you using on both sides of that turbo

[kevinz]

turbonetics t3/t04e. 50 trim compressor wheel, .63 a/r stage 3 turbine housing. f1-57 turbine wheel.

[BrandonR.]

Thanks prolly the most complete answer iv gotten. I have a stock turbo with a 3" down pipe she flows like a fire hydrant.

Boost threshold is around ~2500rpm, With your turbo I would go with a 3" to minamize pressure build up in the exhaust manifold that could be pushed back through the exhaust valves and lower you HP output.

 

Let me know how it works for you im still trying to find the right turbo i was looking at almost the same one T04e- 50trim I dont what ?a/r Compressor thought about a .60a/r? . With 57Trim and .63a/r Turbine minus the stage3 part