Type 4 mechanical compression ratio, Why is the factory compression so low? Options

[Beebo Kanelle]

OK, here's a fun one for the novice to ponder and you experts to answer:

Why is the factory mechanical CR so low?

and for reference, what is the highest mechanical CR that can be physically achieved? assume no octane limitations -

I'm just looking for the design limit for the highest CR that can be / has been in a Type 4 engine using available technology.

Thanks

[Mueller]

The cooling, or lack of is why such low compression.


If you look at almost all street engines the lowest compression motors for car and motorcycle are air cooled.

Water cooled have a point or more higher.

Direct injection water cooled motors have even higher compression due to the fuel cooling off the combustion chamber.