You're assuming equal RPM range for both engines, which wasn't stated.

Dmitiy_Guller,

No, in my posts I am not assuming that both engines have equal RPM range.

What I write is:

“Provided you mean that:

1. The rev limit of the first engine is higher than the revs of the peak torque of the 2nd engine (which means the 1st engine peak power is higher then the peak power of the 2nd engine) . . .”, which is completely different

On the other hand, and unless I am wrong,

what you (and others) are assuming is that the 1st engine has a rev limit exactly at the revs of the torque bump of the 2nd engine.

No such assumption is stated by the problem.

With the torque bump of the 2nd engine happening at the middle revs of the 2nd engine, your assumption is a very specific and “convenient” one, which limits the problem making easier its solution; but the “problem” is no longer the original interesting general one.

In a similar way, you can assume that the 1st car has flat tires. The problem does not state specifically that the tires of the 1st car are OK. This way the solution becomes even easier; but is it worthy?

This is why I posted the link for the RoadLoad program that can help somebody to understand how the transmission ratios of a gearbox are selected, the effect of different transmission ratios on the performance of the vehicle, the effect of the way the clutch is used on the performance of the vehicle, how the transmission ratios are optimized, etc. A far more interesting problem.

Here is another problem that fits to the “Torque …it’s Power” title of this thread:

When it is calculated the inertia torque in any reciprocating piston engine, the one way is to calculate the inertia forces resulting from the motion of the parts, then to calculate the resulting torques and then to make the plot of the inertia torque versus the crankshaft angle (as in the balance.exe DOS program at http://www.pattakon....attakonEduc.htm ).

The other way is "the energy approach", i.e. to calculate the energy of the moving parts, and from the energy to take the inertia torque.

With the second way it is easily understood why the 4-cylinder even-firing 4-stroke has such strong inertia torque (besides the crankshaft and the engine block, it loads heavily the gearbox and the rear tire of a motorcycle, as well), and why the 4-cylinder 4-stroke with the cross-plane crankshaft is so smooth (like a turbine) in comparison.

The "energy approach" is a great tool for solving technical problems.

Thanks

Manolis Pattakos

**Edited by manolis, 18 April 2012 - 05:00.**