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

[Beebo Kanelle]

wow! Thanks to all for all the input.

to answer jd74914 questions: 1) initially, I just use a spiral notebook and a pen to gather info, 2) initial dynamic modeling using 'Dynomation", 3) take the data and build one... see how long it takes to blow up!

The #1 concern that pops up from the comments, after 'it can't be done', is the cylinder/head sealing - I can only assume that the Type 4 engine 'flops' around - and what about stability and flex of the crank?

That would necessitate small bore to minimize flex. But please tell me, is the head/cylinder just a registered fit under compression?

As far as air-cooling goes, does anything compare to Mr. Raby's DTM system used in conjunction with Nikasil?

Is there a book or source with all the torques, tolerances and dimensions? I know that after 40 years, there must be a lot of hard data, somewhere.

Thanks again