Forced air iduction collector

[tobyhd1]

R1,sorry but I have to disagree with you on the cam overlap degrees.At least on a harley pushrod engine anyway.According to nightrider.com ,a not for profit type of web site,they only list 3" stock" cams which have either negative or zero overlap.On any decent performance cam the overlap will be anywhere from 30 to 60 degrees of overlap.That`s just the way it is. 30 -40 degrees of overlap will yield the best for low end torque.40 and up will give higher hp. #`s and peak will be at a higher rpm.You don`t have to believe me if you don`t want to ,but if you talk to any reputable engine builder you`ll see that i am correct.There is an excellent tutorial on all engine aspects at the nightrider site-check for yourself you`ll be much more knowledgeable by the readings end.That is not a slam!As far as the e-pipe goes ,it`s a second.It`s been run and didn`t produce the #`s.If you want to try a pipe I can put you in touch with the creator of the system and see if there is one yet to fit your particular yr. and model.Be talkin` to ya.Toby

[R1-rider]

Ok did some more reasearch and you are right, there is a very slight valve overlap, the more radical the cam degree the more overlap there is. But having valve overlap doesnt really have any aid in drawing from the intake valve, it just lets there be more a/f before the next combustion. On a pushrod engine I can see why this would be necessary as you only have 2 valves per cylinder, where as I have 4 on my DOHC design, allowing for easier a/f ratios and relieving spent gases. So while your radical timing is required because your valves are not open as much (also contributes to the rough idle of harleys), only then I think you would get any gains over stock exhaust. I can see the schematic in my head of what is going on, but for your average jap cruiser that is DOHC, I don't think you would get much gains out of it, especially compared to aftermarket exhaust.

[Kennedy200]

Originally posted by R1-rider
...also contributes to the rough idle of harleys...

The Harley idle is a caused by the ignition set up. On a Harley, both plugs fire at the same time. In the early days this was a simple solution for timing and economics. A system that lets both plugs fire at the same time cost less. Harley has continued to use this antiquated ignitions system. But it is the ingition that helps to give the Harley its own sound. There are some aftermarket ignition systems that will allow the front and rear cylinders to fire seperately. Harleys with these systems sound very different that a stock set up.

[tobyhd1]

R1, don`t have any results at my disposal for dohc engines as we speak.When I get something yea or nah I`ll let you know.But believe you may be correct in the assumption that the gains would be more substantial on the push-rod motor.Toby