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Originally Posted by mshunter  As for the greater cyl pressure debate, I have to just shake my head at that one. It takes so much pressure to bend metal in an engine, that running oversquare values of 1900rpm and 50" of MP still will not bend metal. The problem more or less lies in the direct corilation of pressure=heat. Your typical light GA engine will not be hurt by running oversquare within resonable limits. Also, as RPM changes, so does VE(lower RPM's = lower VE). The engines are desgined to be at their optimum VE at max RPM. So running an engine that has a redline of 2700rpm at 2200rpm, the BE would decrease by a large enough amount to reduce VE low enough to not hurt things. It is eaiser to bend a con rod by over speeding the engine than by running lowRPM/highMP. But it is eaiser to overheat an engine with lowRPM/highMP's. I would be more worried about detonating the thing than bending something. And properly set up, and monitered closely, you will have nothing to worry about. |
I have been under the impression that the intake manifold is what limits the difference in MP/RPM because it isn't made as strong as things like the cylinders. Is this wrong, if so what is the limiting factor for that chart I have been posting if it isn't the intake, is it really cylinder pressure?
For the bold I assume you mean follow the engine limitations and just like any other limitation if you stick to it you wont' break things?