Canceling out pumping losses of throttle governed engines

[Christ]

Originally Posted by Superturnier

Would a smaller diameter piston be better, since there would be less area for the vacuum at the top of the piston?

So a "long stroke" engine would be more economic?

This is what I've always understood, but not as a matter of the vacuum above or below the piston.

See, if you increase the stroke, and decrease the bore, on a linear scale, (to keep things equal) you're still moving the same volume below the piston.