Back Pressure

[Ryanator]

Hi all

just a quick question i am going to install a new sports muffler onto my accent, how do i measure the back pressure and what should the back pressure be. It has 2" internals if that helps...
cheers ryan:evil:

[Medic_01]

juz along as it isnt too big, you shouldnt loose too much backpressure. dont go much about 2" unless you turbo, otherwise you could lose tourqe
as for measuring it, i dunno.

ps. as your an aussie, go to http://www.hyperaustralia.com/phpBB2/
these are hyundai forums for australians. (if you didnt know already.)

[Edited by Medic_01 on Sep 4, 2006 5:06 AM]

[Ryanator]

Sweet cheers mate

[Medic_01]

no sweat.

[187sks]

Backpressure is not required in any modern engine. Backpressure being necessary is a myth. This doesn't mean bigger is better though either, just that keeping backpressure is not the reason why. If your exhaust is too big your engine can't force the exhaust gasses out your tailpipe without them slowing and creating a plug of cooled gasses and actually increasing backpressure.

I don't want to explain much more on exhaust theory, so read this if you're interested:
http://www.uucmotorwerks.com/html_pr...torquemyth.htm

As far as choosing a muffler goes, don't pick one with a smaller diameter than your stock piping, 2.25" is about the max you want to go with on an Accent with a pretty much stock engine. If you're putting in an inline muffler (it's going to have some tailpipe after the muffler) then sizing the pipe is pretty important, and do not exceed 2.25". If you're adding a canister style muffler that doubles as your tailpipe then size is more a matter of preferred sound. If you have 2" internal piping that exits into a 4" tip you'll sound very, very ricey most of the time.

[berrjona]

my engine is stock except for a couple of boltons hks pod filter BBTB 4-1 race tuned extractors, i'm running 2.5inch mandrel exhaust with a 3 inch inlet cannon stlye muffler and my car is actually quicker and drives alot better then the 2inch mandrel system i had.... i'm upgrading it soon to 3 inch all the way through....

willl be turboing anyways later...but driving with the 3inch for the next 6 months or so

every car is different...if u go too big on some it can affect performance but on other cars it increases... so all depends on the car

[WytchDctr]

Originally posted by 187sks
[body]
Backpressure is not required in any modern engine. Backpressure being necessary is a myth. This doesn't mean bigger is better though either, just that keeping backpressure is not the reason why. If your exhaust is too big your engine can't force the exhaust gasses out your tailpipe without them slowing and creating a plug of cooled gasses and actually increasing backpressure.

I don't want to explain much more on exhaust theory, so read this if you're interested:
http://www.uucmotorwerks.com/html_pr...torquemyth.htm

As far as choosing a muffler goes, don't pick one with a smaller diameter than your stock piping, 2.25" is about the max you want to go with on an Accent with a pretty much stock engine. If you're putting in an inline muffler (it's going to have some tailpipe after the muffler) then sizing the pipe is pretty important, and do not exceed 2.25". If you're adding a canister style muffler that doubles as your tailpipe then size is more a matter of preferred sound. If you have 2" internal piping that exits into a 4" tip you'll sound very, very ricey most of the time.
[/body]

thanks for the link. I get tired of hearing, keep backpressure........ What you need to measure is the exhaust gas velocity, not back pressure. To low and the scavenging effect is lost.. to high and you have alot of restriction. :ermm:

[dreamriver]

Well, some back pressure is for scavaging to lower chamber temperature...
but it's not so important if our engine has only 10:1 compression and emission standard don't apply to you.

[wilburisthecoolest]

Well.. hmm.. stright piped with no cat my car was faster than stock.. adding a box type turbo muffler made it even faster. You do need something to slow it down i guess.. i cant explain it. I also go shit ass gas milage with the striaghty, like maybe 22, now im doing 31 again.