2 to 1 merge pipe question.

95sporty150

95sporty150

Member
I'm going to run a single and have used 2.5 exhaust over to the driver side, what size tube should I use after the merge to the turbo? Is 3 inch enough?
Also should I keep the single tube short after the merge to the flange or does that matter?
My plan was about 4 to 6 inches just enough to mount the wastegate.
 
You want as little pipe volume between the head and the turbo without impeding flow (and by flow, I mean what you need for the turbine, not what you'd need if you didn't have a turbo - very different) as possible. Tubing with any more area than the turbine inlet is pointless and just creates wasted volume that has to fill up and pressurize at any given power level.

What turbo are you going to be using? If it's anything with a T04 inlet, tubing over 3" is too big. 2.5" is actually perfect. That said, I have way too much 2.5" and 3" tubing in the setup I'm currently building, but that's just because of what I had laying around.
 
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S475, T6 housing. If I'm understanding what you saying that bigger tubing would result in slower spool times.
You think 3 is still to much?
 
THANKS!
2nd part of my Q was how long of a pipe would you run from the merge to the turbo?
I was just gonna run enough 3in pipe to mount the waistgate. Or would it be more ideal to merge and then run a longer 3 inch pipe up to turbo?
 
I used 2.25" tubing when I was running my single. It probably was making well over 800 rwhp. Now with twins I used 2.5" tubing. Going for around 1200 wheel. The turbo itself will always be the biggest restriction.

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