3" exhuast.
12-07-2006, 02:10 AM
#11
5th Gear Member
Join Date: Mar 2006
Location:
Posts: 2,544
RE: 3" exhuast.
I'll tell you straight up that I don't understand enough about this to tell you how to calculate what your pipes should be.
But, I know enough to know that it is a complicted problem, that's for sure. The resonance qualities of a pipe (such as an exhaust pipe) are determined mainly by the length of the pipe and the diameter of the pipe. This is the same way that woodwind or brass instruments work. When a trombone player has the slide out, that makes the tube longer, which plays a lower note (lower frequency). Pulling the side in makes the tube shorter, which results in a higher note. The same thing happens on a saxophone or a flute, only this time it's with keys instead of a sliding tube.
So if you shorten your exhaust pipes, you are raising their resonant frequency. If you want to keep the pipes short but you don't want to change the resonance, then you have to play with other variables, like diameter. You can also add in resonating devices (that's how a chambered muffler works). But in the end there are a lot of practical considerations too. The length of the exhaust pipe can only be so long or so short for safety and space considerations. Likewise the pipe diameter can only be so big, or it will interfere with ground clearance and suspension travel.
I've made a few other posts about this in the past, but I can't be bothered to dig them up with the search right now.
But, I know enough to know that it is a complicted problem, that's for sure. The resonance qualities of a pipe (such as an exhaust pipe) are determined mainly by the length of the pipe and the diameter of the pipe. This is the same way that woodwind or brass instruments work. When a trombone player has the slide out, that makes the tube longer, which plays a lower note (lower frequency). Pulling the side in makes the tube shorter, which results in a higher note. The same thing happens on a saxophone or a flute, only this time it's with keys instead of a sliding tube.
So if you shorten your exhaust pipes, you are raising their resonant frequency. If you want to keep the pipes short but you don't want to change the resonance, then you have to play with other variables, like diameter. You can also add in resonating devices (that's how a chambered muffler works). But in the end there are a lot of practical considerations too. The length of the exhaust pipe can only be so long or so short for safety and space considerations. Likewise the pipe diameter can only be so big, or it will interfere with ground clearance and suspension travel.
I've made a few other posts about this in the past, but I can't be bothered to dig them up with the search right now.
12-07-2006, 04:55 AM
#12
4th Gear Member
Join Date: Apr 2006
Location:
Posts: 1,541
RE: 3" exhuast.
Well at least you've helped me understand why guys who engineer and design exhaust systems make their money. I remember reading an article in MM&FF about a year ago about why an exhaust works the way it does, it even explained how firing orders dictate the way a car sounds, but it was still layman enough for the average joe to understand. But overall I smell what your stepping in now in a very basic sense, enough to know that I need to watch my own step. Thanks for the enlightening post.
12-07-2006, 06:26 AM
#13
3rd Gear Member
Join Date: Sep 2006
Location:
Posts: 853
RE: 3" exhuast.
Unless you are going to be making crazy amounts of HP is 3" really needed. Plenty of guys are putting out 600+ rwhp on S/Ced cars with 2.5" systems.
And if you are going to spend the money drop MAC and get a higher quality header. Stick with 304 SS and go with the 1 &3/4" primaries if you are looking to make power.
And if you are going to spend the money drop MAC and get a higher quality header. Stick with 304 SS and go with the 1 &3/4" primaries if you are looking to make power.
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