High compresion and high overdrive ?

If you had a 12-1 compresion blower motor and put a D or C rotor screw blower how much overdrive can you run without pushing the crank out the bottom ? 481x spun to max rpm of 9000.

 

I talked to a lot of people on my BAE and came up with 10.0-12.0-1 even with a C at 129%. 9000 rpm is pretty low these days so you can get away with more static compression.
There are lots of ways to get there but from what I heard the high compression setups run a lot of fuel volume to make them live/work.

 

Boost

You will have a lot bottom end power... first year with a screw we had 11.7... just took of the roots and re-did the fuel system.

 

Ok Thanks Andy, But what overdrive should I start With, My roots is apx 12-1 comp. and 48 # of boost, Bolt on screw and start at what, 92% over ???, Maybe shorten the rods a bit, thicker head gaskets ? I just had new Venolia pistons made for the roots setup and now want to screw

 

Does your pistons have domes on them? You can cut the dome down as long as you have enough thickness afterwards. You can also go the head gasket route, but depending on what you are already running, it could
be minimal. I think the biggest thing would be to make sure you have enough fuel going in it and start off easy on the timing. Your camshaft also has a bearing on how much compression you can run. We also have some low run flat top pistons laying around after we changed combos if you are interested.