How small can a centrifugal compressor be made?
 

Hey guys new to the forum. Just came by to get some information on compressors. Also like any good noob, I abused the sites search bar and didn't find anything useful.

Ive recently decided to super/turbo charge a model glow engine. The engine has a displacement of .70 cubic inches and it is a 4 stroke.

So the first step I took was to ask on a forum (rcgroups.com) but there this guy who claims to have yrs of experience says that turbochargers are inefficient when the compressor impeller is less than 40mm, something I've never heard of before. So I went and started searching, reading, sent some emails out etc. I've looked every where for information but nothing. I even started reading about flow dynamics and characteristics of air. But again no luck.

So that's why I'm here seeking help.

Thanks...