2.75" vs 3" exhaust piping

[Skank_Ass_Bryan]

Is bigger better??

Going with the 3" piping vs the stock 2.75 going to yeild more power or are you going to lose back pressure and exhaust temp?

[GreaseDog]

depends on which engine its behind.

[Skank_Ass_Bryan]

06 chevy 5.3l

[dirtrunner21]

I hate to thread jack but.... Isnt backpresure not a good thing?? I mean you want the gasses to escape as easily as possible right? Cuz i while ago i asked if a forced air induction was worth it but was told a good point.. The valves are only open for a certain amount of time and will only let certain amount of air in that given amount of time, isnt it that same for exiting gasses? It will only let out whats in the chamber.. And even though there is some resistance in that gas escaping, why would backpresure make a diff? Its gas leaving. I dont think gasses creating backpresure will do anything to the gasses beinh pushed out by the cylinder. It can only go one way at on constant speed..i hope that made some sence.. And someone saif that backpresure was made by the gov to keep ppl from taking off their cats.. Lol

[Skank_Ass_Bryan]

U want back pressure and have exhaust temps at a certain level because hot exhaust gases exit the pipes faster than if it were at low temps...

[gwhunter350]

Yes you want back pressure with out it your low end will be gone.

If you are running a single out exhaust then run a 3in if going duals run 2.5in out

[GreaseDog]

i too suggest a 3" single setup, or if duals, keep them to 2 1/4"

[speedracer326]

I've asked this before, and the consensus seems to be bigger is better, backpressure is bad, burning exhaust seats is a wive's tail, etc. Since stock cams don't have much overlap, apparently scavenging is less of a factor as well. All the science appears to be in the headers, and the tailpipes are simply there to route the gases where you want to put them.

[SierraDan]

Backpressure is bad, no such thing as it being good. What you want is high exhaust velocity and scavenging. Meaning you want the setup that will pull the exhaust gases out of the motor the fastest, and have them exit as quick as possible.

Check out this thread and look at what brehnborg says it's very true: http://www.fullsizechevy.com/forums/...ckpresure.html

[gwhunter350]

Originally Posted by speedracer326

I've asked this before, and the consensus seems to be bigger is better, backpressure is bad, burning exhaust seats is a wive's tail, etc. Since stock cams don't have much overlap, apparently scavenging is less of a factor as well. All the science appears to be in the headers, and the tailpipes are simply there to route the gases where you want to put them.

wrong no back pressure equals no low end. Take the whole muffler sytem of your truck and run only cats and then tell me no back pressure is good

[SierraDan]

Then why is it that no exhaust company mentions anything about backpressure when advertizing mufflers, catback system and headers? Because it's a myth. You're confusing backpressure for velocity which is what you want in an exhaust system.

Think of a garden hose. You put your thumb over the end and it sprays out faster, but if you turn the pressure up the water will spray out faster and you don't need to use your thumb. Plus less water is escaping when you do that. See how fast you can fill up a bucket when your thumb is blocking off the end some and when it's not. You want scavenging which is like turning up the pressure but you want no restrictions so it comes out as fast and as much as possible.

[Skank_Ass_Bryan]

gibson advertises that you don't want the fastest flow u want efficient flow... It even says that you will lose low end and gain topend with no restrictions...

I saw it on jegs.com on the truck accesories under chevy exhaust

[speedracer326]

Originally Posted by Skank_Ass_Bryan

gibson advertises that you don't want the fastest flow u want efficient flow... It even says that you will lose low end and gain topend with no restrictions...

I saw it on jegs.com on the truck accesories under chevy exhaust

Like 88vic said, it's all about velocity. That's why the peanut port heads make good low end torque, they have good velocity at low RPM's, but they're too restrictive at high RPM to make power. Back pressure is a restriction.

[Fast305]

Originally Posted by gwhunter350

wrong no back pressure equals no low end. Take the whole muffler sytem of your truck and run only cats and then tell me no back pressure is good

WRONG, BACKPRESSURE = BAD in ANY SYSTEM

BACKPRESSURE will cost you HP/TQ AND Fuel Efficiency

The exhaust in my van has less than 1.5 psi of backpressure even as high as 6,000 rpm in 2nd gear. I have NO issue with lack of low-end torque. The exhaust has tons of velocity though, just no backpressure.

[1989K1500]

Single 3 will be fine on your truck.

[91_bowtie]

Alot of you are confusing back-pressure with velocity. The bigger pipes reduce the velocity, resulting in a loss of low-end torque. A single 3" will be fine for your application.