StyleTEG

Backpressure is resistance to positive exhaust flow.

Again you are talking about exhaust velocity not backpressure. Again, it is not any resistance to the exhaust flowing out of the pipe.. the exhaust is just moving slower because the smaller exhaust pulses do not line up and exit like they would if you were creating your peak HP. When you are creating adequate HP for the piping you have, the exhaust pulses will line up correctly and help pull each other out of the piping. When you have a pipe that is to large for the exhaust pulses, the exhaust gases will not line up, and will bounce off the insides of the exhaust pipe. That is why larger piping is slower for low output engines. Never does it have anything to do, with the lack of resistance to exhaust flowing outward.

Backpressure is always bad.

Take a look at these diagrams, and pay attention to the backpressure and flow area

jgrotkier

don't you understand that velocity and back pressure are related? if you have a narrow pipe, the velocity will be higher until it becomes too small of a pipe....then back pressure becomes a problem. you are right, back pressure is bad, I retract what I said before...BUT in order for the velocity of the exhuast gases to be sufficient at lower RPMs you have to have a smaller pipe...smaller pipe = back pressure at higher RPMs.

Im not saying that back pressure is good, im saying that if you put a 3" exhuast on my stock LS I will loose low end power.

StyleTEG

What you say is true, but again its not backpressure.

Saying you need some backpressure for low end power is incorrect

Saying you need proper exhaust velocity for low end power is correct.

Yes, a pipe designed for low end power will be smaller, which will cause backpressure at a higher end.. but its not backpressure that gives the low end power. Thats what people have been saying this whole thread. Backpressure is the side effect to having an exhaust system designed for low end power (why you would want this is beyond me, but this is not what we are debating).

Its like saying you need tires that wear quickly for good cornering. Which is not true, you need sticky tires that are often softer rubber and the side effect is they wear out quickly. Its not the fact that the tires wear quickly that gives you good cornering, its the soft rubber.

jgrotkier

ok, so we understand each other now

knightridergs-r

im glad those articles helped thanks T-I, and H-V

KirkLS

I dont think you can just remove the header and run it like that. You have to have some compression there or else it will suck a valve.

Also as far as backpressure goes....if we dont want any backpressure why not just get a 4 in pipe so it will just flow out

StyleTEG

Ugh, please read what was posted. Again, that has nothing to do with wanting backpressure and everything to do with optimal exhaust velocity.

The reason why running an open header will often decrease performance is because its cutting off the exhuast exit velocity to quick.

Again nothing to do with backpressure, backpressure is bad, its a bad side effect, you don't want it.

Everything to do with exhaust velocity.

slickboy

StyleTEG...those pics are great..thanx for posting them up!

StyleTEG

NP Slickboy, glad they helped

All the credit goes to surferX though, they are his pictures and his great article.

Read the whole thing here -> http://www.team-integra.net/sections...p?ArticleID=47

Paul

ok, to put it into "lay" terms, take a sniper rifle for example, now compare that to say a high powered handgun, now which bullet will have a higher velocity? obviously, the weapon with the longest barrel, increases the velocity.