Actually, when resonating the system produces a pressure cycle every 90 degrees of crank rotation regardless of what RPM the resonance occurs at. So, you can set the valve phasing independent of the resonant frequency, as long as you know how long blowdown takes so you can predict the position...
The valve phasing can be made correct for the resonant case without concern for what RPM the resonance will occur at. This is because when the system resonates the pressure peaks (and valleys) are spaced 90 degrees of crank rotation apart, regardless of what frequency the resonance occurs at...
Look at www.castheads.com and check out his exhaust systems with 2-into-1 collector. If we assume he didn't make up the data, it would appear that joining the pipes can make a large difference on a V8 when exhaust manifolds are used rather than headers.
It wasn't really the roller follower that I expected to make a difference, but the more radical ramp rate it allows.
I'm trying to spec out valve timing for a cam designed specifically to work with a resonant exhaust system. On a V8, if you have the two banks joined by equal length pipes, you...
What is the duration in crank degrees of the blowdown period? I realize it must vary with load and RPM, and am interested primarily in 4000-6000RPM, WOT, on a Chevy small-block. Also, I would expect blowdown to be faster with a roller cam, so if someone could compare blowdown duration for flat...