Both of these superchargers are roots-type positive displacement superchargers.
The rotors are fluorine resin coated. The units have their own lubricating
oil, 130cc. Stock boost is regulated to about 0.7 bar, and the units are
normally driven at 1.25 times crank speed (4A-GZE has a 7500rpm redline).
Oversize pulleys are available. The stock crank pulley on 4A-GZE is 145mm
in diameter, the HKS pulley 157mm.