Pulley/boost calculations

[Tom]

Shelby Rampage and I have discussed the pulley size for an increase in boost to the 8 lb range and it was suggested that a 3" dia blower pulley was called for. I would like some help with the math to calc the expected boost from a certain sized pulley as I'm getting ready to have a new pulley made and would feel better is I had the numbers to prove we are in the ballpark.

I did find this on the web but either I've missed something or it's a dud...


.......................... (supercharger size liters X pulley ratio)
Theor boost (psi)=------------------------------------- X 14.7-14.7
...................................engine size liters / 2

where pulley ratio is the dia of the crank pulley divided by the dia of the blower pulley in inches.

by my figurin'...
circumference ofblower pulley 10.25"
circum of crank pulley 19" For a ratio of 1.853
engine size 2.2L
blower size by the manual 66 cu in (1.0815 L)

for a theoretical boost of ......12psi !!??

Any math whiz in the group? Anthony, I don't remember where the 3" dia number came from, do you?

[Shelby-Rampage]

Quote:

Originally Posted by Tom Any math whiz in the group? Anthony, I don't remember where the 3" dia number came from, do you?

I had JonyMopar measure his 8 psi pulley that was the dia. of his.

In order for someone to make the pulley properly they would also probably need the one you have to get all the correct specs, offset etc., to ensure proper belt alignment.

The 8 psi specs were:
4 Rib
3 inch
.800 Shaft size

If you get one made up let me know how you make out.

[Tom]

Quote:

Originally Posted by Shelby-Rampage I had JonyMopar measure his 8 psi pulley that was the dia. of his. In order for someone to make the pulley properly they would also probably need the one you have to get all the correct specs, offset etc., to ensure proper belt alignment. The 8 psi specs were: 4 Rib 3 inch .800 Shaft size If you get one made up let me know how you make out.

I didn't realize that JonyMopar was running a 8# pulley setup, thought that he was using the 5# that came with the kit...wonder if he is getting the full 8# and how he decided on 3" as the pulley that would provide that much of a change.

Was put in contact with a machinist that has an excellent rep through a buddy at work. He does want the pulley but at least he is local and I'll be assured that I can get it back.

Still would be happy if I could get the numbers to work....

[Shelby-Rampage]

Quote:

Originally Posted by Tom I didn't realize that JonyMopar was running a 8# pulley setup, thought that he was using the 5# that came with the kit...wonder if he is getting the full 8# and how he decided on 3" as the pulley that would provide that much of a change. Was put in contact with a machinist that has an excellent rep through a buddy at work. He does want the pulley but at least he is local and I'll be assured that I can get it back. Still would be happy if I could get the numbers to work....

I think Jony is still running the 5psi, but he also has the 8psi and a 12psi. You'd have to get with him on the rest...

I have a few places lined up that said they could make me one for under $100. If you get one made up let me know how it works. Save the specs and maybe I'll get one made up through your guy too if he's willing.

[JONYMOPAR]

HELLO GUYS, YES I HAVE THE 8PSI PULLEY STILL LOOKING FOR THE PART # BECAUSE THE PULLEY IS CHROMED IT COVERD THE #, THE 12 PSI IS ONE FROM B &M BUT IT WAS A 6 RIB STYLE SO I HAD IT CUT DOWN TO 4 SAME SHAFT SIZE, HOPEFULLT WILL GET A CHANCE TO PLAY SOON, I ALSO HAVE A FIXED IDLER DESIGN TO IMPROVE THE BELT WRAP PROBLEM ANY BODY HAVE ANY LUCK ON A REPLACEMENT BELT FOR THAT BANDO 4PK1415 TAHT CAME WITH THE KIT???

JONYMOPAR@AOL.COM
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