mk e wrote:
I'll share this because it kind of broke my brain. The bike needs the lower fairing to be a catch pan to comply with the rules but that is where the muffler is on the V2 so it needs new exhaust. The primaries are 2 3/8"!
I don't think I've ever seen a header pipe that big. Its 478cc/cly vs my engine that is 458, but I only run 1 5/8" primaries, then 2" 1st collector and then 2 3/8" 2nd collector (6>2>1). There is no way my software would tell me that is the right thing to do so now I'm not exactly sure how to guide/help him designing the new system, I've just never seen anything like this ..oh, then the single muffler outlet is tiny...1 1/2"or maybe 1 3/4" (didn't measure) I don't understand that either.....its almost like there is no primary and the collector only? I just don't understand.
It is wild. IMO the breathing requirements aren't related to cc, but rather hp.
That bike is making about 80 hp per cylinder, which is a lot but not way more than something like an LS or BBC making 600 hp. That large primary necking down to a small muffler outlet will send positive pressure waves back up the exhaust - maybe that has benefits similar to the "stuffing" phase of a 2-stroke expansion chamber? I could see that working if the cam has an extra-long exhaust duration.
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