Supercharger boost calculation

[bobnova]

I'm considering putting together a supercharged motor, and i'm rather curious as to if/how i can calculate how much boost a given pulley size will make.

For instance, it would be a 1998cc four banger, with an eaton M90(yeah, too big, i know) on it.
The engine sucks in about a liter (61ci) per single rotation, while the blower puts out 90ci per rotation.

In theory, if i had the blower drive at 1:1, would that give me 7psi of boost? (50% more air then the normal 61ci)
Or am i way off base?

Looking around online i've only found rough HP calculators based on pre boost output and given boost levels, nothing to actually calculate how much boost a setup would run.

[Big Creek]

Your pretty close to the applied therory but the truth is it doesn't usually get you very close. I am putting together about the same combo and I am quite sure it will not obtain that amount of boost. I have conversed with others who are supercharging and the math just doesn't come out. Usually on the low side.

For your setup I would expect about 4psi. The good news is you have plenty of headroom with that large of a huffer to make it interesting witout building the heat the little ones do. But, the faster you turn a super charger the faster the boost will come on at lower rpm's due to the fact they are not very efficiant at lower speeds.

I would strongly suggest you start your project by buying Corky Bells "Supercharged" book and start reading. It is a wealth of info and formulas.

Todd

[bobnova]

Interesting, i'll check that book out, thanks

[karlo]

Second that! "Supercharged!" has all the equations you need for computing pulley sizes, estimated hp, etc. etc. Very easy read, and when you're done, you actually have a pretty good clue.

I've read a few other books, and none of them are nearly as useful as Corky Bell's book.

- Karl