Chambered mufflers? Options

[dawnoforigin]

Is there any positive experience with these types of mufflers? I know most go with the straight through design, but I know they would be way too loud and not sound the way I would like. I also was considering this because I don't want to lose any low end power by getting a straight through design. Low end is much more important then high end to me. I was thinking about looking into a Dynomax Super Turbo or possibly a Flowmaster. Any input is appreciated.

http://www.dynomax.com/superturbo.stm

[soulshadow]

AHHH all that stuff about backpressure and what not is causing my simple minded brain to explode!! PERIOD PERIOD!!!! Slap on a loud muffler and drive around. If you don't like it loud get a silencer (I can't even spell now Thanks a lot!). PERIOD PERIOD!!!

[RocketScott]

AHHH all that stuff about backpressure and what not is causing my simple minded brain to explode!! PERIOD PERIOD!!!! Slap on a loud muffler and drive around. If you don't like it loud get a silencer (I can't even spell now Thanks a lot!). PERIOD PERIOD!!!

Get ready for a complete mind melt because I'm going to explain something that most people don't consider let alone even know about: Resonance. The Celica actually has two resonators, one in the intake and one in the exhaust. Both intake and exhaust tracts act similarly in terms of resonance but each of them use resonance a little differently.

When a valve opens in the head a shock wave is produced because of the differential in pressure that exists between the inside of the combustion chamber and the intake/exhaust track. This shock wave is negative pressure and travels (at the speed of sound) all the way to the end of the tract where it meets the atmosphere. The pressure difference that it encounters there creates another shock wave, this time positive, which goes back down the tract until it reaches the valve again. If this positive shock wave hits the valve when it's open it will result in pushing whatever gases are in the tract into the cylinder. This is a good thing in the intake tract where you want more fuel/air mixture dumped into the cylinder. It's quit the opposite in the exhaust system where you want the gas in the cylinder sucked out. Therefore you want the pulse in the exhaust system to hit right before the valve opens so when it does the gases in the cylinder are sucked out or "scavenged" by the now leaving shock wave. The frequency at which this happens changes with the RPM. When an engine has a "flat spot" at a certain RPM this is a likely culprit.

I'm sure the engineers at Toyota spent countless hours designing the intake and exhaust tracts to be a good compromise between performance, economy, reliability, emissions, etc. When one part or another is changed from it messes with the resonance and possibly something else needs to be done to correct it if you want to maintain that stock compromise. Most of us don't so we give up a little economy or take some power away from one part of the horsepower curve and give it to another. What's important here is the volume of the given tract. If the exhaust diameter grows the increased volume of the pipe should come out of some other part in the system. This is an over simplification but I hope you get the picture.