I am sure this question has been asked before, but:

Is a straight, smooth pipe faster on the top end than a silencer?

For example, if you took the silencer off and added a pipe extender, would you develop more HP at the top?

 

If a pipe was designed for no silencer (drag pipe), then the exhaust will probably make more power with no silencer. On the other hand, an exhaust that was made with a silencer and designed around a silencer should make more power up top with the silencer.

 

So, what you are saying, is that silencers and head pipes are designed together. And, they need to be properly matched up to get the best power. Correct?

 

Exactly!

 

And the logic continues.....

So, if I take off my silencer and extend my pipe and rejet using a dyno, there is no way I will get more HP.

Man, you'd think with the free flow, you could get more HP.

Are there any technical people out there that know why this happens?

 

Because a good exhaust system is designed to actually draw / pull exhaust air faster than it would normally travel. This is the case with or without a silencer. So if an exhaust was designed with a silencer, odds are with everything else the same, without the silencer performance will be lost.

 

I have heard that. They try to time the shock wave such that it the first wave creates a vacuum that pulls the exhaust gasses out of the cylinder.

But, the frequency of the shock waves is contantly changing with engine rpm, so, if the lenghs of the pipe are set for this phenomenon, then it would only happen at a certain RPM range.

Don't you think that these pipe desingers are just a bunch of guys tinkering in the garage, fit the pipe to the bike, and see what the dyno reads?

Or are they these highly talented acoustical engineers that set up data aquisition systems run tests, tweak pipe lengths, change jetting to produce the most HP?