No conundrum if you understand it. Ford describes it as the buildup of pressure in a running exhaust system and has nothing to do with harmonics at all. So who's right?
Lore indeed.
'Lore is a body of KNOWLEDGE (caps mine) or tradition that is passed down among members of a culture, usually orally.'
Let me know when you guys understand wave tuning enough to work on 2 cycle expansion chamber design, I was butchering them long ago and easily understand them. With cars you are only doing half the wave tuning. If that much. The exhaust length necessary to get to the back of a car severely hampers true hardcore wave tuning. Motorcycles are the only vehicles you can really wave tune hard.
'Back pressure refers to pressure opposed to the desired flow of a fluid in a confined place such as a pipe. It is often caused by obstructions or tight bends in the confinement vessel along which it is moving, such as piping or air vents.
Because it is really resistance, the term back pressure is misleading as the pressure remains and causes flow in the same direction, but the flow is reduced due to resistance. For example, an automotive exhaust muffler with a particularly high number of twists, bends, turns and right angles could be described as having particularly high back pressure.'
Long story short............the engine shoves out more gaseous matter than the volume of the exhaust system can handle to have it end up in a more compressed state. That is a function of flow vs. tube size and bends rather than wave tuning, it will show up even with no wave action there at all. You can easily read it with a pressure gauge in the pipe.
Understand wave tuning? Most of the book writers don't even understand it, I've yet to see one 'expert' detail the difference in exhaust vacuum tuning and true sound wave tuning, they are very close but NOT the same. Both can add big power if done right.
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