trq/hp curves of V-twin

[visitor]

Can anybody shed light on the reason for a V-twin's torque/hp curve always crossing at 5250 rpm(or even if it is true)? I heard it from (more than one) questionable source (electrical engineers).

 

[FireLover]

Yes, it actually crosses at 5252 rpm, and only when plotted in units of foot pounds torque and horsepower. The relation between power and torque simply depedent on speed. The equation is: power = engine rpm x torque / 5252. So at 5252 rpm, power = torque. When plotted in metric units (power in kilowatts, torque in newton meters), they would cross at 9545 rpm. But not many engines rev this fast.

 

[FireLover]

By the way, any and all engines have this behavior.