Setup
370ci
Dart pro 1 cnc heads 250cc
Twin 7875 vs racing turbos
4l80e

My question is would it be a benefit using 2 1/4 piping over 2 1/5 piping to the turbo from the headers. More velocity to get the turbos moving faster in a shorter time?

 

This can be a touchy subject for some but yes in my experience the smaller pipe will help with spool time but I see it more helpful at recovery if you have to pedal. I had 2.5 inch pipes to a single t4. It was what I had when I built my first kit. Read a why does everyone use 2.5 pipes for the hotside thread on here and wild hair tried a hotside built out of 2.25 headers I cut up and damn night and day difference. If I had to pedal with the 2.5 inch set up it was lag city. After the 2.25 set up it was back almost before I got the pedal back on the floor. Ever since I've done smaller pipe. As an aside I did run the pipes different and alot shorter because they fit through a place the 2.5 didn't so I eliminated a few bends and about a foot of pipe. I'm sure that helped too.

 

I would think that the smaller diameter would give the higher velocity.

 

I just had to make a choice on this, had enough pipe to do a 2.5 crossover, but reading comments I decided to order 2 1/4 pipe and used that. I was more interested in lower end perf. I guess it's like anything else, cams, etc, you lose low end to gain top end, lol.

 

2.25 it is. Thanks for the info guys. I appreciate it.