Header pipes

[Traumahawk]

I have a question about header pipes. From what I've heard the main restriction of a stock exhaust system are the small header pipes. Boxenstopp sells some that are 4 mm bigger, and I am wondering what are the size of various aftermarket header pipes...IE marks...UFO?

Someone could buy the bigger header pipes, and then use the slipons of their choice? Correct?

 

[dannymax]

In theory....yes. Not sure what flow rate calculations would be involved to get everything spec'd properly tho.....bend restrictions, etc., sounds a little complex....:confused2:

 

[Traumahawk]

In theory....yes. Not sure what flow rate calculations would be involved to get everything spec'd properly tho.....bend restrictions, etc., sounds a little complex....:confused2:

Hmmm I wonder what the flow rates of the various exhaust systems are?

 

[dannymax]

Hmmm I wonder what the flow rates of the various exhaust systems are?

I was wondering the same thing....good chance it's a closely guarded secret due to all the testing 'n research that probly goes into development.

 

[one2dmax]

I've got a comparison pic in my exhaust folder in the facebook files.

 

[Traumahawk]

Thanks Sean.

 

[cgswss]

There are so many things that effect exhaust tuning. Remember is is not a car where you started with a simple cast manifold. Generally the length of the pipes have more effect on performance then the Dia. And bigger Dia. may not mean better performance. When the valve opens and gas starts escaping the cylinder It takes a bit to get that gas moving. in a bigger Dia. pipe the gas will move slower. When it comes time to shut the valve, there is still burnt gas in the cylinder and to get more performance we leave the valve open even as the piston starts down again. The gad moving out helps suck some fresh mixture in. This is why there is a bit of time while both valves are open.

This is part of why you have to be very careful With tube sizes. The smaller tube makes the gases move faster and does a better job of sucking. This is overcome when you start pumping more mixture into the engine. While bigger tubes will almost always be required when you increase displacement, on a stock engine the big tubes may actually hurt performance- exp. in the mid range which is where we drive street bikes. Its all about balance and frankly the stock bike is damn well balanced!