Pulley setup

Douglas Walker

Registered User
I am wondering if anyone has done any testing on pulley set ups. You have underdrive accessory pulleys, overdrive sc pulleys, 10% crank pulley. What is the best way to go.

Currently im running 15% OD and have stock wp & alt with a stock size alum crank pulley. Im wanting to OD 20%. What set up would show the best power gains with little belt slippage.

optional pulley set ups

stock acc pulleys, 10%js & 10% sc

UD acc pulleys 10%js & 10% sc

stock wp, alt 10% crank & 10% sc

stock wp, alt 10% crank 5%js 5%sc

stock wp, alt 10%crank 10% js stock sc


Besides the gains with aluminum pulleys what configuration would be ideal?

Doug
 
the only pulley's you can change that will overdrive the blower are the Crank (inner half), Jackshaft, or Blower pulley. The alt and waterpump have nothing to do with the blower rpm.
 
I understand that. Im wanting to know what is the best set up to give the best performance. Im looking at it as 2 seperate systems to gain hp. acc pulleys and then sc pulleys. Is there a combination of the 2 that is better together.

For example if I go with a set of underdrives and then od the js and sc pulleys. will that be the max gain in hp and performance. Or will I go backwards because there is excessive belt slippage
 
I ran March UD pulleys with a 10% JS and 10% SC pulley this year on a ported late model blower. You must have MP tensioner springs and a good Gates belt to prevent slippage, but its inevitable with that combination. My SC pulley was actually getting polished in the grooves but no large amounts of belt dust were produced, nor did the belt show signs of glazing.
 
If I recall, the Mangnum powers aluminum overdrive crank pulley is lighter than the stock steel one which is a win. The jackshaft pulley is as well a lighter device. Both of which would be a better option then a SC pulley, as as the Sc pulley gets smaller, belt slip becomes more common.

Now you could go underdrive, then you get a stock size SC drive for the crank and would need to make up the 20% overdrive you want all in the jackshaft and blower pulley.

Any of the aluminum pullies are going to be lighter than the stock pullies. Just swapping the jackshaft pulley from steel to aluminum (same size) was dyno tested to gain ~10rwhp. So cutting weight on the front of the motor is significant.

That said, I guess my choice would be: stock wp, alt 10%crank 10% js stock sc
 
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Best would be mp 10 rib pulleys for less belt slippage. Best to overdrive crank and jackshaft. This option is also the more expensive, but more effective on slippage.
 
The accessory pulleys do not help in performance (well the ALT does not). The alternator only runs when needed to recharge the battery, as for the WP its best to only use it to keep it in the optimal RPM range.
 
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