Jackshaft Pulley?

1QuikV6

Registered User
I am negotating a trade with a gentleman who has a 10% blower pulley as well as a 10% jackshaft pulley... I have never heard of a jackshaft pulley, where it is, or how to get a smaller one. Im sure this post may look really stupid to the veterans around here but Ive only been an SC owner for 3 months now.
 
I believe the jackshaft is the "middle man" between the crank and supercharger. If you follow the supercharger belt down, the only other thing it wraps around is the jackshaft. And there should be another belt coming off the jackshaft that goes around the crank and other accessories.

Installation is pretty easy. Take off the two belts, remove 4 bolts, and slide it off (although that can be a challenege) I don't know of anyone making a 10% JS pulley, but I believe SCP has a 5% JS pulley.

-Andy "Melon"
 
The jackshaft pulley achieves the same boost result as the blower pulley but eliminates the slippage problems common with blower OD pulleys.
 
The jackshaft pulley sits below the A/C compresser. A belt runs from the crank pulley to the jackshaft and then another belt to the supercharger. I would not run a 10% jackshaft pulley as well as a 10% blower pulley. That would mean you are overdriving your blower by 20%. Some people go with a different jackshaft pulley as it has more surface area than a 10% blower pulley and you would have less belt slippage. I have a stock size light weight jackshaft pulley and I think it's great.
 
XR7 Dave said:
The jackshaft pulley achieves the same boost result as the blower pulley but eliminates the slippage problems common with blower OD pulleys.

Would a 5% OD blower pulley and 5% OD JS pulley be a good combo to have? I'm wanting to squeeze a little more out of the blower and think the 5% OD JS pulley may be the way to go.

-Andy "Melon"
 
I got a 5% overdrive jackshaft pulley in aluminum from Bill at supercoupe proformance. It has two advantages. First it drives the blower faster. Second it is a ton lighter. Any time you can lighten the weight of the pulleys you are turning the engine will make more power and wind up quicker. One of the best mods I have done. I have a steel 5% blower pulley too and am going to change that to aluminum also. Like I said I got so much success with the javkshaft pulley I plan on going with all aluminum pulleys next.
 
A 5% jackshaft plus 5% sc snout is a good combo. Net around 10% with limited belt slippage compared to what you would get with 10% snout pulley only.
 
Here's a pic of my ESM 10% OD 10 rib jackshaft pulley (right).

The one on the left is the stock diameter ESM 10 rib pulley. The small portion of the pulley (crank to jackshaft ) remains the same size, the large portion of the pulley (jackshaft to supercharger) is 10% larger than stock and requires a slightly longer belt to accomodate the larger pulley diameter.

JackshaftPulleys.jpg


David
 
Last edited:
I OD my blower from the aluminum crank pulley that was
machined to over & under drive. And my blower pullies are 2
10% OD.One 10% pulley I machined a little smaller than 10%.
My aluminum jackshaft pulley is stock size for now(ryan harris).
I would like to end up with the OD ratio I want.With a gear
ratio that uses the least amount of hp to turn the blower.

I would like to try a 5 or 10% OD jackshaft pulley.I would
be able to go over 30% OD on my blower.I think that may
make the air to hot.I don't know if my FMIC & with co2
freezing the IC pipes will cool the air down enough.

I have been tring to build most efficient power I can without a cam.
I don't know what boost I have been running with my stock IC.
The boost gauge maxs out .So I may be running 18lbs+ or so.
I know that my IC tubes have been almost to hot to touch.
So I hope this new MP FMIC helps get the temps down.Once
I add some cryogenic IC tubes. I hope that 20lb+ boost will
work ok for me when racing one or two times a year.It works
just fine now with the small IC.But I am sure I will pick up
some more horse once I get the air cooler.Or I may need to
lower boost.

Randy
 
Last edited:
So will I need a different belt when I go to a 10% sc pulley with a stock jackshaft? If so, where do I get one?
 
Back
Top