New Expansion Chamber Theory

[alancrea]

How can you over come?

They've been around for at least half a century but no one has ever offered an explanation of exactly how they work. All explanations have countered laws of physics concerning the action of sound (pressure) waves. I have an explanation that may interest you, not just to tickle your intelligence center but because once you understand how they work then you can figure out a way to solve the long standing problem that pipe builders have always been faced with: build a pipe with a strong hit but a narrow powerband, OR build a pipe with a weak hit and a wider powerband. (Or settle for something in between which has no strong points at all)
Now that I've caught your attention you might as well follow through and read it all at http://www.dragonfly75.com/motorbike/pipes1.html

Hello jaguar i became a member of this site after reading your dragonfly site i dont have a motored bicycle but i do bycycle alot i like to play around with the small 50cc mopeds and have made a total of 5 expansion pipes but i see a problem when i use different exhaust formules they all think your cylinder has a perfect exhaust port to exhaust flange size i have seen on older road going engines 90% of all cylinders the area is to large up to 200% off the exhaust port area the primary pipe or header has a diameter that is to large.

How can you overcome this problem can it be done with the maths or are the theory rules locked and the exhaust port must be welded and resized

Regards Alan

 

[Deleted member 12676]

Yeah, theory does clash with the reality of existing sizes sometimes.
This is how I approach that problem;
I ignore the area between the cylinder and flange because if its too big it can only have a minimal negative effect because its such a short portion of the total header length.