Most roots type blower makers use numbers to describe their blowers (ie Holley 420, Littlefield 10/71, B&M 250, etc.)

These are not just model #s. What do the numbers mean? (Long answers accepted, so weigh in mcollinstn!)

Well, I know one part of it. The GM blowers are from Diesels. 2-71 is a from a 2 cylinder 71 cu/in per cylinder engine. 6-71 from 6 cylinder 71 cu/in per cylinder and so forth. There are 110 cu/in per cylinder engines-very old, 53 cu/in per cyinder engines-newer and the 71's.

Ok, next trivia question...of the popular blower sizes available today...which were never available as a GM diesel?

BTW-I believe all the numbers are relating to their displacement, not just the GM engine series.

I'm withcord on the 144, 174, 177, 250, and 420's.
Gary

Meaning what?

i would think that the only blowers used on automotive type engne were the 6-71 and the 8-71. beyound that the 10-12-14-71's were aftermarket blowers the used the standard means of measurement i dont think the smaller blower 171 and 144 are a diesel direvetive.
later

Oops, kind of short on that answer/guess.
That series is numbered by displacement. cu inches of air in 1 revolution?
Gary

All pretty much right so far. Back in the old days we did fit a 2-71 blower to a motorcycle engine.

alright,reading an encyclopedia one day,helping my kid do his homework I came across this,in what application did they use transmisions to actually switch the speed of the superchargers while underway and why? and wouldnt that be kick butt in a boat!

I know the WWII Merlin engines had two speed superchargers (the P-38 Lightning had turbos in place of the centrifugal superchargers). The big bombers with radial engines had mulitple settings for their turbochargers. Some bombers, like the B-29, had both turbos and superchargers.

One reason for multiple blower speeds, for aircraft, is to have the same power at high altitudes as well as at sea level. The higher the altitude, the lesser air density, more boost is needed to maintain power level.