Things that make you go, "Hmmmmm"

[DJinNH]

Question of the Day...

So why is it when most want to make a bike more high performance, they usually go with a 4 into 1 exhaust?

Yet,

if they want to make their car more high performance, they go with dual exhaust?

Hmmmmmm?

See what I mean?

Don

[79XS11F]

It has to do with the not just gas flow but also the harmonics of the system. On an 8 cylinder engine the collector would have to be too big to be practical to maintain the right gas flow and harmonics. So they treat an 8 cylinder engine like 2 - 4 cylinder engines. On 4 cylinder engines they do do 4 into 1 systems.
Rob

[stereomind]

Louder means faster!

[hamjam]

so by that thinking , shouldn't a 4 into 2 be better? 8 into 2 = 4 cyls per muffler (pipe) s the same as a 4 cylinder divided into 2 and ! muffler per 2 cyl would = the most flow , the pipes ,headers and muffler arn't 2x larger on a 4 into one ,are they?

Jim

Originally posted by 79XS11F
It has to do with the not just gas flow but also the harmonics of the system. On an 8 cylinder engine the collector would have to be too big to be practical to maintain the right gas flow and harmonics. So they treat an 8 cylinder engine like 2 - 4 cylinder engines. On 4 cylinder engines they do do 4 into 1 systems.
Rob

[79XS11F]

You have to have enough cylinders hooked up to allow for exhaust gas savaging and also to keep the exhaust gas hot so it flows faster through the system. There is of coure a linit because collector DIA and length are very important if the flowing gas is to move quickly but not so freely that there is no back pressure pulses. This is why some exhaust systems are nothing more then loud and some are loud but the sound is very smooth and rhythmic. Louder onto itself does not mean faster ... it's just louder. Louder with a smooth and consistent rhythm is faster and often not necessarily louder. We have all heard bikes and or car exhaust that sounds "sweet" regardless of how loud it is. Pipes that deliver this sort of sound are pipes that add horsepower right out of the box and that's why they usually cost anywhere from 6 to 1200 dollars. With exhaust systems .. you get what you pay for.
Rob

[oseaghdha]

Dual exhaust mostly sounds cool.
Headers are more like the 4-to-1 on bikes.


These are 180 degree headers, more tuned than duals.

The latest and greatest street setup is an X Pipe , which allows better scavenging.

Expansion Chambers are even more voodoo. I am amazed at what goes on with those pipes.

[petejw]

the 4 into 1 is about 6lbs lighter
in weight than a dual exhaust system.

the power to weight ratio thing. :-)