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

[veekry9]

http://www.amazon.ca/Air-Cooled-Motor-Engi...%2C+London+1961

Julius Mackerle: Air-Cooled Motor Engines, Cleaver-Hume Press, London 1961
Julius Mackerle: Air-Cooled Automobile Engines, The Institute of Mechanical Engineers, London 1961-2

As a start,for your own engineering library,to like,know stuff.
These are the books,thermodynamics as applied the the aircooled internal combustion engine.
Not sure if his later books have been translated.
A few of the designers of both the GM Corvair and the VW T4 perused these tomes.
A guy trying to make his own head might want the same knowhow,for like ideas.