http://www.cheersandgears.com/forums/index...topic=15551&hl=

That is a long discussion about the differences between pushrod engines, and overhead cam engines. It really starts to get interesting when they bring V-TEC into the mix...

Then, I started thinking about MIVEC. How is MIVEC actuated? Is it using the sliders a la V-TEC or "push pins" a la VVT?

And if idle is that big of a concern with MIVEC, why not use different size valves? About 2/3 of the way down are the V-TEC diagrams. This shows that the valves are the same size. Wouldn't it be "more efficient" to have a smaller valve, say 6 mm* opening at lower engine speeds, then the larger, 8 mm* valve open later, and upon reaching the higher RPM band, it would open both? This would, one would think, allow for better "idle-ability" but still have the top end power...

Anyways, I think I am confusing myself, or getting ahead of myself, but any input would be great...

*Numbers are just guesstimates, not exact, so don't kill me for it.

I just can't into it. I'll read it in its entirety eventually.