BOOT wrote: ↑Tue Dec 12, 2017 4:08 am
ptuomov wrote: ↑Sun Dec 10, 2017 8:53 pmThen I’d run the muffler all the way at the rear bumper after exhaust gas has cooled and all the pulses have been combined. The key is to cool the exhaust with minimum restriction before the muffler, how about running aluminum exhaust pipes to maximize cooling?
I've always thought keeping the gas hot was the goal because it's less dense. I was also told wrapping a header primary makes it seem shorter.
My understanding: Given a pipe size, hot gas has to flow faster, generates stronger pulses, and has a greater pressure loss. I think that, in net, tuned header should benefit from keeping the gas hot?
I think the situation reverses in the tailpipe after the blowdown pulses have been combined, there's been one chamber muffler, etc. Now, one just has a tail pipe to a rear muffler. If the gas has cooled, one can force more air mass thru the same size hole.
So I'd say keep it hot early and then cool it after the cross-over between banks. Whether it's right or wrong, that's how we're doing it. Thermal barrier coating until the cross-over and then bare metal pipes after that.
In any case, I don't think this is terrible relevant to the original poster, who's got a single cylinder engine. The whole pipe probably needs to be pulse tuned, but it's also very restrictive size so whether hot or cold is better is a question above my pay grade.