I'm building a custom set of headers, and I'd like to know the math involved. I'd like to see what equations others are using, as well as the theoretical side so that I can derive my own equations.

An old book I read on the topic said that when the exhaust valve opens a high pressure pulse travels down the primary, reflects off the change in cross sectional area going into the collector as a low presssure pulse and travels back up the primary toward the exhaust valve. At the tuning RPM the low pressure pulse arrives as the exhaust valve is closing and helps scavenge the last bit of exhaust from the cylinder.

However, I've read a passing reference in a magazine article to the concept of using the 2nd harmonic of the tube for the greatest benefit, but I don't understand how this would work.

Also, I've never read a theoretical explanation covering ideal flow velocity, etc. for determining primary diameter and collector diameter and length.

Any help?

Thanks

 

I strongly recommend you check out http://www.headersbyed.com
or
http://www.burnsstainless.com


[Modified by kb58, 8:09 PM 6/29/2002]