Deinonychus
FRF Addict
I believe the term "back pressure" concerning exhaust optimization is very misleading. Velocity is what you're looking to optimize.
If the cross-sectional area is too large the exhaust velocity will slow to the point that the pulses won't create a vacuum which aids in pulling the next exhaust pulse from the combustion chamber.
If at high rpm's the volume of gas is too much for the cross-section of the primary, such that it reaches a choke point, the velocity is maximized due to pressure differential and area. This choked condition limits HP potential.
Ideally, the primary cross-sectional area would change in proportion to gas volume, maintaining the perfect velocity for the exhaust pulses to draw the next pulse.
If the cross-sectional area is too large the exhaust velocity will slow to the point that the pulses won't create a vacuum which aids in pulling the next exhaust pulse from the combustion chamber.
If at high rpm's the volume of gas is too much for the cross-section of the primary, such that it reaches a choke point, the velocity is maximized due to pressure differential and area. This choked condition limits HP potential.
Ideally, the primary cross-sectional area would change in proportion to gas volume, maintaining the perfect velocity for the exhaust pulses to draw the next pulse.
