Backpressure is a myth???

[JEEPRUSTY]

I lifted the graphic from wikipedia.
I do not know if sound can force unburned air\fuel mixture back into a combustion chamber. The graphic seem to illustrate this.

But seriously we are talking about a WFO engine such as a dragster that sees its low end and midrange as a path to full throttle and little more?

I still recall a lot of voodoo going into race bikes. The Yoshi pipes with the little connector tubes between the headers fer instance.

 

[Tom R]

how come drag bikes get away with it then?

Was tongue in cheek - exhaust valves burn from getting too hot.

 

[Fizzyhair]

Narrowing pipes creates pressure but it's not slowing the flow it's speeding it up. But exhaust pulses coliding with baffles causes reverberation that physically slows the air flow. A muffler is designed to get rid of the uncorking pop from the exhaust end the same way a guns one does. It's got to create eddies within the flow also restricting flow. Don't confuse backpressure with just regular pressure.

 

[sharpy]

They say no back pressure is good but you do have to have a slight reverse cone on the exhaust. This was mine back in the late 70"s/early 80"s and could slip steam a Kawa Mk2 1000 down the straight. Braking was a no contest lol. Little bit loud, them was the days.