On summits webpage, they mentioned a calculation to find your "correct" static compression ratio, based on your altitude. It's not quite complete (errors), so I was hoping someone else had heard of this? Should I be building my motor for higher compression since i'm at 4000' ?

I know about all the factors in reference to desired compression ratio etc, but i'd never heard of altitude coming into play when finding your static compression ratio, in order to pick a cam.

or would it be better to just give it more ignition timing? (which can easily be changed if I moved to sea level), would it do the same thing?


Thanks

 

Unless 64cc's become 76cc's at 4000 feet, nothing changes as far as your "static compression ratio."

 

Your dynamic compression ratio will differ. But not the static compression because of its definition. Static compression is just the ratio of max volume divided by min volume.

 

ok ok, fair enough then, dynamic compression ratio, does anyone know how that is effected?
or can answer my other questions?

 

THANK YOU!!!!

Finally someone else said it!!!

Dynamic compression cannot be measured by some computer program that some guy made based on the IVO, stroke, static compression, etc.!!!

By definition, dynamic describes something that changes.

Anyway, it would only make sense that the dynamic compression would change due to altitude. The higher up you go the less dense the air would become, therefore lowering the dynamic compression. Vise-versa with going down.