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Discussion Starter #1
If I go up .5" diameter on the lower pulley how much will I have to increase the upper pulley to stay at the same boost? Currently I'm running a stock (7.5") lower and a 3.375" upper on this 3.4 Whipple which is getting me about 18/19#'s. I want to go a little bigger on the lower to get me a little more water pump rpm...
 

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Discussion Starter #3
Figured it out...
crank pulley size divided by supercharger pulley size gives you a pulley ratio. Pulley ratio times engine rpm gives you supercharger rpm. So a 3.650 or 3.750 supercharger pulley will get me close. Just need to find one now..:cheers
 

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Sorry but im confused?! How would changing the lower have anything to do with the Water pump rpm?
 

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unless he changed belt drive systems, NOTHING
 

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unless he changed belt drive systems, NOTHING
thats what I thought, either that or I thought I was going crazy?!?!?! lol
 

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Discussion Starter #7
Brain cramp:smt101.. Forgot for a second the blower belt is it's on setup. Would need to change the water pump pulley itself.. Thanks for keeping me straight..[smilie=dr
 

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why do you want to overdrive the water pump?
 

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I doubt that you have a pump flow problem. Maybe need a rad. flush or your thermostat isn't working properly. Overdriving the pump wont do any good if everything else isn't working properly. just my .02
 
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