NoPistons -Mazda Rx7 & Rx8 Rotary Forum

Quote:

Originally Posted by mazdadrifter' date='Jun 9 2004, 09:25 PM

Are you kidding me? Compare a rotary power band and torque to a v8. v8 peaks torque at 2500-3000 rpm then falls from there, peak hp at 4000 rpm and falls from there. A rotary making 300 hp most likley will be making it around 6000 rpm but at at 4500 rpm will be making @270. And the torque while it might be a little lower will be a great amount flatter than the the peaky v8. Therefore putting the rotary at a huge advantage everytime.

Yes and some racing rules put the rotary in as a 2.6 litre due to the piston engine ineffeciency. But still it has great power/ displacement.

The discussion was about power effeciency. Fuel never entered the equation, but if it were to, I'm going to say that not many v8's are that much more fuel effecient than a rotary making similair power. Of course you can't base your opinion on someone with a turbo rotary that tunes to 11:1 because they will obviously be less effecient that someone tuning a n/a v8.

And the difference I'm talking about in rotational inertia any type of ROTARY motor means that it moves in one constant direction, you don't have the start/stop of reciporical engines, which makes for smoother torque and greater stability.

How can you call a v8 torque band peaky over a rotary? Regardless they're not even in the same league - to say a rotary's torque figure is 'a little lower' than a v8's is a bit of an understatement. I hope this doesn't make me sound anti-rotary - far from it, but one of the rotaries strengths over a v8 is not its torque band.

Power efficiency is the same as fuel economy in my book. It all comes down to what percentage of energy in the fuel is converted to kinetic energy, and since rotaries are renowned for and the amount of heat they produce and their low fuel economy, it is probably safe to say that they are not vastly more efficient than any other engine. You are right in what you have said, I just think 'efficient' is a bad word to use.

I see what you are saying about the rotational inertia, thanks for the explanation.

Mark