Omnipotent Octopus

Planning my supercharged setup, and would it be ideal to upgrade to 3" exhaust? Would be running 8lbs of boost. The whole backpressure debate has me confused, some say you want it some say you dont.

Oxen__

bigger to s certan extent is better. as long as you dont loose too much velocity as the exhaust passes thru the system. you'd be good and safe with three inch pipe.

tavish_g

With forced induction the more exhaust flow the better, three inch on an I6 should be about perfect. do they make a blower cam for the I6, or will you have to get a custom grind? That will make a big difference as well.

Oxen__

for a turbo car the biggest you can go is best because it lowers the amount of down stream pressure the turbo has to over come. less lag more responsive turbo and then it gos on to ball bearing and twin scrolls bla bla bla.

on a super charged engine , you still don't want to go to big on your pipe because you want to keep your exhaust velocity up to ware it will still try to scavenge on its own. this plays into cross draft of the head . cross draft is caused by the amount of over lap your cam has and some other factors like how well dose the head flow. since the jeep is a side drafting head you want to keep your exhaust ideal to that of what a high dollar NA header and exhaust system would bring so that your exhaust flow causes vacuum at the exhaust ports between exhaust pulse of each port while the engine is firing. enhancing your cross draft. this help clean the cylinder of burnt gasses between combustion cycles. which later plays into your tuning , how much timing you can add before it pings. lowering exhaust temps.lower temp more timing , more timing more hp per lb of boost gained. this will be proved by how efficient you can make the engine flow.


also you can run variable boost on a super charger like a turbo. by putting a waste gate on your charge pipe. if you have a min amount of boost you want to run you set your waste gate spring for that so when your boost controller is set to your low setting you can say run 5lbs on a set of 10lb pulleys. when you want more of that boost. turn up your boost controller it will stop blowing off the extra boost in the charge pipe allowing more boost to actually build in your plenum rather than constantly letting by pass to atmosphere, and maxing out your boost to what your pulleys will provide. which hurts nothing at all.


i hope you enjoy listening to it wind up Omnipotent octopus

Omnipotent Octopus

Thanks for all the info, never got that amount of usable info in one post haha.

mr white

Just curious what SC you were looking at and what engine/fuel management?

ct67_72

Omg thank you, you are my hero. I came in expecting to see something about backpressure and I see one of the best answers on here.
And yes, you want to go as large as you can before you loose velocity. You have to get the exhaust out at fast as possible to het the new air fuel mix in.
Smaller piping forces the exhaust hazard to move faster through it and be more efficient than larger piping.
Too large a pipe has no velocity and forces the engine to push the exhaust out through it.
But 3" with a cat should be good for a sc app.

Omnipotent Octopus

Vortech v3 kit through RIPP mods. Only works if you remove a/c. Probably diablosport tuner since I have a shop nearby that is an authorized tuner.

E-Rok

I think a 3" would be ideal for a SC 4.0L


if it was turbo, id say 4"

Omnipotent Octopus

Hell yeah! I cant wait.