05-31-2015, 06:13 PM
I can try to help... direct geared is a Bad Idea for a supercharger, particularly on something that goes through gear changes or can stall suddenly, the belt that's normally used acts as a shock and vibration absorber and plays a big part in preserving the supercharger's internal gearing (which synchronises the rotors), bearings and ultimately the rotors themselves.
A centrifugal compressor isn't as picky, but even they SHOULD have some sort of shock absorbtion or a slipping clutch to allow for sudden engine speed changes - WW2 aircraft used 2-stage, multi-speed centrifugal superchargers and the early development (e.g. the Supermarine racers pre-war) was full of disintegrating rotors when engines seized under test and the compressor tried to do a siudden stop!
If you go for a belt drive and still need gears, google for HPC gears, they do a range in both Metric Module and Imperial DP, materials from Delrin to heat-treated steel, priced accordingly! Bear in mind that you need to size the gears, bearings, shafts etc. according to the blower's pumping load - at high boost and high RPM this could be several tens of BHP! Work from the required BHP and gear RPM to get the torque load and be sure to check the torque limit the gears can take RELIABLY.
The superchargers used on the Mercs are Eaton screw compressors and have limits re RPM etc., Eaton's website is quite handy with lots of speed/pressure curves etc. but be warned that you may (if goiing for "adequate" boost pressure) need a bigger blower than you think to make the pressure you want at the RPM you want, a 12,000 RPM bike engine may need a blower running SLOWER than crank RPM if you want it to last more than a few miles :(
A centrifugal compressor isn't as picky, but even they SHOULD have some sort of shock absorbtion or a slipping clutch to allow for sudden engine speed changes - WW2 aircraft used 2-stage, multi-speed centrifugal superchargers and the early development (e.g. the Supermarine racers pre-war) was full of disintegrating rotors when engines seized under test and the compressor tried to do a siudden stop!
If you go for a belt drive and still need gears, google for HPC gears, they do a range in both Metric Module and Imperial DP, materials from Delrin to heat-treated steel, priced accordingly! Bear in mind that you need to size the gears, bearings, shafts etc. according to the blower's pumping load - at high boost and high RPM this could be several tens of BHP! Work from the required BHP and gear RPM to get the torque load and be sure to check the torque limit the gears can take RELIABLY.
The superchargers used on the Mercs are Eaton screw compressors and have limits re RPM etc., Eaton's website is quite handy with lots of speed/pressure curves etc. but be warned that you may (if goiing for "adequate" boost pressure) need a bigger blower than you think to make the pressure you want at the RPM you want, a 12,000 RPM bike engine may need a blower running SLOWER than crank RPM if you want it to last more than a few miles :(
Rules are for the obedience of fools, and the guidance of wise men...
(Douglas Bader)
(Douglas Bader)