Horsepower is horsepower?

transamz9 wrote:

Why would I need to make peak power in OD? Third already runs faster than the speed limit and I personally have yet found a time needed full power in third.

I think you're agreeing with wilber's point. You don't need full power in third. And you're not getting it, either. But yet you're still happy with how it pulls.

What that means is you could get away with an engine that had less peak power, if it were able to put that peak power to the ground when you needed it. That's what gearing will do for you.

Consider two engines:

1. 400HP @ 4000RPM
2. 300HP @ 4000RPM

Assume both are travelling at a speed such that engine 1 is spinning at 3000RPM. At that speed, engine 1 is generating about 300HP. If engine 2 is coupled to the same gear ratio, it will generate only 225HP or so. But if engine 2 is coupled to a lower gear such that it can spin at 4000RPM, it will generate its peak of 300HP.

So both engines are now generating 300HP, although engine 2 is spinning faster. But that will happen only if engine 2 can be mated to that lower gear. Having more gears to choose from makes it more likely that it can.

-- Rob