ptuomov wrote: ↑
Thu Jan 09, 2020 7:39 am
To me, it seems like any application that actually uses the pulse energy from one cylinder to scavenge other cylinders would work less efficiently with the additional volume of the "anti-reversion" chamber.
To me, anti-reversion chambers are like those pressure-wave termination boxes: Popular on the internet but never used by engineers who can design the whole exhaust from scratch.
By "pulse energy" do you mean pressure wave energy or particle velocity and momentum? IMO the former is only really effective by reflecting at the end of Particle blowdown length or so, and that is where I have installed them. beyond that they are a detriment, The latter, I would agree which is why I would never use and AR device only at the first tube step on a 4into1 header, would not bother with a 421 and after the header in a system that uses a tail pipe and.or mufflers.
second point I would agree, I only use them in primaries on 4into1 headers in those situations where a 421 isn't wanted but I can talk customer nto that...It can be difficult to fit them in most cars which would be another reason why I would always do a 421, easier to package actually.
It seems most people do not understand my view of exhaust systems. Pressure waves hurt things more than help in uneven pulsing systems. The only reason I do not use a 421 header on high rpm engines is it is usually not possible to get the primaries short enough on most engines and keep them equal length. I am not aware of any time I was not able to maintain the power level of the best 4into1 header with a 421 and the 421 always broadened the power curve. It is true though that the higher the rpm, the less reversion is a problem, and most high rpm engines in racing use multiple gears in order to keep a tight power band so they can stay away from reversion ...Ha. You still have to wonder why 4 cylinder 4valve motorcycle engines still use a 421 design. It is because you still have to drive them around and they do not hurt the power, it really is a no brainer. (I would say thought that they are missing power as they usually use long primaries and short secondaries, but they still benefit).