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Discussion Starter · #1 ·
I know that everyone that has underdrive pulleys goes back to the stock pulleys when they install a supercharger. Can the underdrive pulleys be used with the supercharger?
 

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underdrive pulleya will lower your boost, except if you go TURBO.
 

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If you use a positive displacement SC you do not want to turn it slower. That is what underdrive pullys do. Turn the accessories slower. If you get a SC that has its own drive belt and does not use the orignal serpentine system than you may be able to use your underdrive pully, depends..... All in all you should just go back to the stock pully so you are as close to the conditions that the SC manufactures had when they tested their setup. If your going to add more boost and get a custom tune than it really does not matter.

If you have an underdrive crank pully and then put on a smaller SC pully you may just wind up with what the SC should be pulling if everything was stock. Someone out there should be able to do the math. The bottom line is that the faster you turn the SC the more boost you get. To a point...G
 

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Discussion Starter · #5 ·
OK, I was trying to figure out if it would spin it faster or slower, I was haveing a brain fart and couldn't determine if the smaller crank pulley would cause the SC to spin faster or slower
 

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If anything, with a supercharger you'd want an overdrive crank. Underdriving the compressor defeats its purpose.
 

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Technically, if you went to a smaller pulley on the supercharger, you could do an underdrive on the crank and could hit your target boost. HOWEVER, the few horsepower you picked up from running your alternator, steering pump, water pump, and AC compressor slower probably wouldn't be enough to justify the effort. Furthermore, you would end up with less surface area on the supercharger pulley meaning you would have more potential for belt slippage.
 

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Technically, if you went to a smaller pulley on the supercharger, you could do an underdrive on the crank and could hit your target boost. HOWEVER, the few horsepower you picked up from running your alternator, steering pump, water pump, and AC compressor slower probably wouldn't be enough to justify the effort. Furthermore, you would end up with less surface area on the supercharger pulley meaning you would have more potential for belt slippage.
Agree... Which is why an overdrive crank is often better than going with a smaller supercharger pulley.
 

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If you get a SC that has its own drive belt and does not use the orignal serpentine system than you may be able to use your underdrive pully, depends..
Prochargers have their own dedicated drive belt, with a pully that bolts onto the front of the crank pulley and does nothing except drive the sc. So all accessories are still driven by whatever crank pulley is on there and boost is unaffected, whether it be an underdrive or overdrive pulley (or stock).

Right, or am I having a Friday brain fart? The only thing that affects a Procharger's boost is the pulley on the sc head unit itself.
 

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Discussion Starter · #10 ·
Sound logical, I guess I won't get rid of the stock pulleys then.
 

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Does an overdrive crank pulley aid any in balancing too ? I mean not just for the crank, but also having a bigger SC pulley help balance that better as well ?
 

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Discussion Starter · #12 ·
I'm do like my SFI approved crank pulley that doesn't rust.
 

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Prochargers have their own dedicated drive belt, with a pully that bolts onto the front of the crank pulley and does nothing except drive the sc. So all accessories are still driven by whatever crank pulley is on there and boost is unaffected, whether it be an underdrive or overdrive pulley (or stock).

Right, or am I having a Friday brain fart? The only thing that affects a Procharger's boost is the pulley on the sc head unit itself.
I agree. The Techco does the same thing. The size of the accessory pulley has no effect on the SC drive pulley in this case. I went back to the stock pulley only so I could drive the water pump at least the stock speed because of the extra heat the SC makes. G
 
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