On a roots supercharger the lobes have a large mass and do not turn as fast as the impeller of a turbo so the liquid fuel does not harm them, a compressor impeller is very thin and can not take the mass of fuel as well.
A super charger will spin at 9,000 RPM ( if 50% overdrive at 6,000 RPM engine speed), but a turbo will spin 120,000 RPM at 3,000 RPM which when fuel or water hits them they could be harmed, a draw through does work but at a certain point it does become an issue.
Don't give up on a turbo set up. A new rebuild on a stock 250 with only sealed-power pistons (cheap) will hold up to 400+ HP stock rods, head, cam, block, crank, turbos make lots of torque so you don't need a lot of RPM. Gear it high!
RPM is what kills engines
Harry
