Backpressure....I might need to change some things.
03-25-2008, 10:52 PM
#21
4th Gear Member
Join Date: Nov 2006
Location:
Posts: 1,016
RE: Backpressure....I might need to change some things.
ORIGINAL: dudeboy
If you call a cat a 'dog' then you are wrong, it is that simple............
You say tamato, I say tomato
You say dudeboy, I say ladyboy
Resonant tuning is what you are talking about, but you keep calling it back pressure.
Were not talking about a car stereo... I used to get a resonant frequency of about 35Hz in my previous truck
If backpressure were the only thing that mattered, then we would all be crimping our exhuast down from the factory size.
WTF?
That would increase backpressure right? And by your theory, increase performance?
We don't want a bottleneck, we need some good flow, but we need something that creates turbulence
Funny, I swapped out my exhaust pretty early on.... Only had 1.7 rockers and a OTS J3 chip (before I knew better guys, sorry...)
I noticed the difference...
Great!
This is becaue 'every exhaust manufacturer' does not do extensive testing for resonance tuning... duh...
Your dumb! They are in the exhaust business and I'm sure there has to be some testing/ researchdone for their reputation.
These guys sell mass produced parts to cookie cutter cars... not a good example to use for discussing design principles...
Maybe cost is part of that????????????
Not really
And, again, I think you are talking mass produced exhaust components?
Designed to 'work' on cars built to a wide variety of specs.......
No, you buy what will work for you
Unless you take the time to 'tune' the primaries... in which case pipe length and diameter are the major factors...
Regardless of the primary diameter, it isn't backpressure that is working here...
I don't know anyone who 'tunes' their primaries, they just buy headers and put them on. (Unless they are serious, and it doesn't sound like you are)
Funny,
My cousin had no cats and dumps on his Mustang when he purchased it. A couple months later, when he had to go through emissions he added cats and dump mufflers.
The care sure felt slower to me.... each scenario will play out differently.
It depends on the rest of the build!!!!!
I'd be willing to bet the car gained quite a bit of low end torque (1000-2500 rpms). It may have lost some top end with this setup.
You just don't know what to look for.
My point is...
It ain't 'backpressure'!!!!!!!!!!
Once you accept that there is something else at work, you can begin to understand it....
This is the same reason people with advanced stages of emphazima that have a shortness of breath use the "pucker" technique. They pucker their lips as they exhale and this causes some turbulanceand draw more air out of their lungs that would not come out normally due to their lungs being screwed up. They're not'tuning' their air flow, their using physicsto their advantage.
good luck,
jason
ORIGINAL: cleanfitty
I said "some backpressure" in other words "some restriction"
I don't give a rats **** if you call it 'pipe length tuning'
I said "some backpressure" in other words "some restriction"
I don't give a rats **** if you call it 'pipe length tuning'
You say tamato, I say tomato
You say dudeboy, I say ladyboy
Resonant tuning is what you are talking about, but you keep calling it back pressure.
Were not talking about a car stereo... I used to get a resonant frequency of about 35Hz in my previous truck
If backpressure were the only thing that mattered, then we would all be crimping our exhuast down from the factory size.
WTF?
That would increase backpressure right? And by your theory, increase performance?
We don't want a bottleneck, we need some good flow, but we need something that creates turbulence
ORIGINAL: cleanfitty
Upgrading exhaust on a stock motor yeilds some very small results and most people upgrade their exhaust for primairly fora louder more aggressiveexhaust note(and looks).
Upgrading exhaust on a stock motor yeilds some very small results and most people upgrade their exhaust for primairly fora louder more aggressiveexhaust note(and looks).
I noticed the difference...
Great!
ORIGINAL: cleanfitty
This is why every exhaust manufacturer suggests that going too big will actually hurt performance.
This is why every exhaust manufacturer suggests that going too big will actually hurt performance.
Your dumb! They are in the exhaust business and I'm sure there has to be some testing/ researchdone for their reputation.
These guys sell mass produced parts to cookie cutter cars... not a good example to use for discussing design principles...
ORIGINAL: cleanfitty
This is why no one runs a dual 3" exhaust system (unless you have a massive build).
This is why no one runs a dual 3" exhaust system (unless you have a massive build).
Not really
And, again, I think you are talking mass produced exhaust components?
Designed to 'work' on cars built to a wide variety of specs.......
No, you buy what will work for you
ORIGINAL: cleanfitty
This is why you don't get headers with real huge primaries (unless you have a massive build).
This is why you don't get headers with real huge primaries (unless you have a massive build).
Regardless of the primary diameter, it isn't backpressure that is working here...
I don't know anyone who 'tunes' their primaries, they just buy headers and put them on. (Unless they are serious, and it doesn't sound like you are)
ORIGINAL: cleanfitty
This is why almost everyone who runs dumps says they felt a loss in torque when they took the tails off, and most people who add tailpipes feel an increase.
This is why almost everyone who runs dumps says they felt a loss in torque when they took the tails off, and most people who add tailpipes feel an increase.
My cousin had no cats and dumps on his Mustang when he purchased it. A couple months later, when he had to go through emissions he added cats and dump mufflers.
The care sure felt slower to me.... each scenario will play out differently.
It depends on the rest of the build!!!!!
I'd be willing to bet the car gained quite a bit of low end torque (1000-2500 rpms). It may have lost some top end with this setup.
You just don't know what to look for.
My point is...
It ain't 'backpressure'!!!!!!!!!!
Once you accept that there is something else at work, you can begin to understand it....
This is the same reason people with advanced stages of emphazima that have a shortness of breath use the "pucker" technique. They pucker their lips as they exhale and this causes some turbulanceand draw more air out of their lungs that would not come out normally due to their lungs being screwed up. They're not'tuning' their air flow, their using physicsto their advantage.
good luck,
jason
You have to remember, a massive build that is all top end, needs the least amount of restriction, as does a turbo setup. On a stock engine, no mufflers and no cats will hurt low end torque, (I would say 1000 - 2 to 3K rpms), but yes, once that obsticle is overcome, it will help top end.
I'm from the old school, where we call it backpressure... I don't know where you "new breed" folks get some of your information, (I assume the internet, and not real life), but I speak from experience. I have expiremented with several (and I mean several) exhaut setups on all my rides.
03-26-2008, 12:29 AM
#22
Join Date: Feb 2008
Posts: 23
RE: Backpressure....I might need to change some things.
I agree with cleanfitty. Everyone continues to say you don't want back pressure but the fact is you need the right amount. Resonant tuning is the act of finding the right amount of BACK PRESSURE.
03-26-2008, 12:49 AM
#24
3rd Gear Member
Join Date: Nov 2007
Location: Washington, Seattle
Posts: 551
RE: Backpressure....I might need to change some things.
ORIGINAL: AllStockPony
I agree with cleanfitty. Everyone continues to say you don't want back pressure but the fact is you need the right amount. Resonant tuning is the act of finding the right amount of BACK PRESSURE.
I agree with cleanfitty. Everyone continues to say you don't want back pressure but the fact is you need the right amount. Resonant tuning is the act of finding the right amount of BACK PRESSURE.
Even if you look just look at intake runner tuning, you will start to gain an appreciation for what is really going on...
03-26-2008, 01:17 AM
#28
3rd Gear Member
Join Date: Sep 2007
Location:
Posts: 798
RE: Backpressure....I might need to change some things.
Backpressure in the exhaust "runners" can lead to hot and spent gases hurting the fresh air coming in past the intake valve.
A sort of reversion would be going on during the overlap period, or during a later exhaust valve closing.
A sort of reversion would be going on during the overlap period, or during a later exhaust valve closing.