Measured Backpressure on the Vette
 

Long saga, but finally thanks to ThrottleCrazy and 94cobra69ss296 got to measure the back pressure on my Vette. It has some "resistance to flow". It's about 1 psi on idle and 3psi at full throttle. The cats are the main issue, but unfortunately with recent CA law those have to be EO numbered. I could put on a set of LT headers and hi-flow cats and keep the stock stuff for "contingencies" and probably pick up a fair bit of power. I'm at 391WHP now. The motor with headers and hi flow cats (but an LS1 and not LS6 intake) and a few other differences, made about 430 WHP. It's a guess, but I'm think LT headers, hi flow cats, (maybe a new set of injectors as at least one of my is dodgy sometimes) should put conservatively at 410+ I would think :huh:

Will the LS6 intake not fit? You only have 2 1/4" pipes too right? Need to step it up to the 3" pipes and some long tubes.

I have the LS6 intake. The Vette the motor was on had the LS1. I mean to say in this case I breate even better than it did. I have 3" pipes (I think, definitely bigger than 2 1/4") after the cats. I have stock manifolds and cats and that's where the bottleneck is.

After the cats? :toetap:

The stock manifold are not pipes. I thought you were referring to after the cats. Are we gonna have another semantics smack down.

Good do all that then drop a big cam in it!

If I remember correctly the tubing up near the cat was pretty small. I would guess that it was only 2.25. I would also recommend larger exhaust but I don't think you would need larger than 2.5. You would definately make more power with a free flowing exhaust system.

Hey Ben do you have a dyno chart you can share here? How did you measure "back Pressure?" I may want to try it on my exhaust.

There is a pressure gauage that inserts into the O2 bung ahead of the cat.

Here's my last dyno sheet, with the setup as it is. 391/369.

Would love to, but then I wouldn't pass the sniffer anymore. I'm have a 114LSA 224/224. My emissions are still safe, but pushing the boundary.