[NESW20]

Originally Posted by bigbcraig

I can't imagine the geometry of a couple millimeters really having much of an effect...
When you increase rod length, you're decreasing cylinder volume (even though stroke, thus "displacement" is the same). So while you can play more with the gas and air you can get in, does it really still end up more effective than before with more combustible volume, but perhaps harder tuning?

I'm curious, don't know the answer so if anyone is well-qualified, please clarify for me.

you can't actually (in most cases) just put longer rods in. the pistons would hit the cylinder head. i'm mostly talking about when the block was engineered. they make the block a little bit taller, put longer rods in, and leave the stroke/bore/CR/etc all the same. apparently the "ideal" ratio is 2:1 or thereabouts.

there would be no change in the amount of intake charge let into the cylinder on the intake stroke. it would not be compressed any more or less, only at a slightly different rate at a slightly different time. it could be the difference between running 17 degrees of timing safely and running 20 degrees of timing safely (just throwing out numbers).