What is the diameter?

[J57ltr]

What is the supercharger crank pulley that drives the supercharger. Looking for the closest to the exact diameter to do some calculations.

Thanks,

Jeff

[Fivefingerdeathpunch]

The pulley on the supercharger shaft is the same size as the motor, best way to remember.

So 3.8 inches. If stock motor.

[J57ltr]

Crankshaft pulley diameter.

Jeff

[wowitsfast]

the balancer?

[Fivefingerdeathpunch]

I found somewhere that says 7-5/32nd.

[J57ltr]

The diameter of the dampener where it drives the supercharger. I want to know the drive ratio.

Thanks Fivefingerdeathpunch, I'll use that for now.

Jeff

[J57ltr]

I'm not sure that's right according to my calculations the boost would be too low.

[Fivefingerdeathpunch]

Then look up any parts store that sell them. They should all provide details on the product.

Length and width are given.

[J57ltr]

I tried that couldn't find a listing for the supercharged unit. I removed my belt and measured the circumference and came up with 22.75" so right at 7.25" diameter, just about what you said.


Here re are the numbers I came up with for blower drive ratio based on the previous to Gen V blower.

3.8" pulley DR 1.908:1= 7.49 psi
3.6" pulley DR 2.014:1= 8.72 psi
3.4" pulley DR 2.133:1= 9.88 psi

does this sound about right?

Jeff

[Fivefingerdeathpunch]

The way I see it, there are too many variables.

Ambient temps, heat from the supercharger, exhaust flow and intake air flow are just some.

Just the stock numbers seem to be right in the ball park, they normally make right around 7-8ish psi with stock everything.

I wouldnt doubt that if someone tossed a 3.4 on a gen v blower with stock everything else it would make nearly 11-12 psi of boost, enough to kill that motor quickly.

[J57ltr]

Well there aren't really that many variables, and all of them combined will only account for a +/- .5 psi difference based on experience with other supercharged cars using the M90 and M112. These readings are typical of a car with stock type cam moderate exhaust and free flowing intake. Ported heads, headers and cams with lower than 112* LSA tend to have lower boost pressures, since boost is really nothing more than the inabality to pass the air from the supercharger through the engine.

one of the parameters I use in the calculation is barometric pressure and that makes the highest difference. I just wanted to see ihow well the formula I used works for the 3.8l SC'd engine too.



Jeff