You wouldn't belive how many answers are available on the manufacturers website. No idea how to tell the difference though... might just have to call KB and read them the serial number.
There is now a big difference in Twin Screw superchargers. The longer compression distance between the inlet and outlet results in a higher “Internal” Pressure Ratio (2.0) for the “H” and a 15-24 psi efficiency range. The “S” uses a 1.4 PR which consumes less engine HP and cooler air charge temp in the 6-14 psi range. Minimum recommended boost for the “H” is 12 psi.
Note: The “H” and “S” Series superchargers are identical in construction and boost output. Only the “H” discharge port shape is revised to lower air charge temp and reduce parasitic loss (engine HP to drive supercharger) at 15 psi and higher boost levels (See Tech Info and Dyno Tests).
the only #s i see are A7594H on the ft plate of the s/c between the s/c body and the drive at the front.? does the h stand for h? if these arent the ser #s where can i find them at? thanks
If you look at the link I provided it has a picture of the two different models and it's pretty evident the dischrage port on the "H" model is smaller than the "S" model.
Well both of those blowers are capable of making not only 18, but all the way up to 24 PSI at max RPM's. The difference is the "H" model is more efficient when running between 15-24 PSI while the "S" is more efficient at boost levels between 6-14 PSI.