View single post by Ordinary Biker
 Posted: Fri Jan 11th, 2019 05:59 pm
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Ordinary Biker

Joined: Sat Oct 21st, 2017
Location: Denver ColoradoUSA
Posts: 469
Reputation Points: 999
Gonna have to respectfully disagree about back pressure being unnecessary. Back pressure is precisely what creates the scavenging effect. A little, not a lot. Reflection of sound waves generated in the exhaust system is indeed a large factor in how a muffler can work without being too restrictive, but it is unrealistic to expect any of the waves to travel against the newly formed waves and exhaust pressure to reach all the way to the head in order to have anything to do with exhaust gas scavenging from the combustion chamber. Every exhaust designer that I have ever heard of will speak about the importance of some back pressure at the head being necessary.