Supercharger pulley question

randall01 · Feb 1, 2012

Hey guys. I am getting ready to install a used MPI stage one supercharger on an Apex. Running 6-10,000 ft. It came with a 27 crank and 23 top pulley. Any idea on what kind of boost it will make with this combo. I believe the Apex stage one ships with 26-22 pulleys. From the other info i have read going bigger on top or smaller on bottom will reduce boost numbers.
I am curious to know if one tooth is more significant on one pulley or the other,kinda like changing the gearing on a motorcycle. One tooth on the countershaft sprocket has a much greater effect than one tooth on the rear.
Thanks

←snow∞motion→ · Feb 1, 2012

MPI actually shipped a 27 bottom and a 25 top to me and I wasn't making any boost, so they sent a 23 for my top and now I'm making about 10 pounds. I think you'll be fine.

347strokin · Feb 1, 2012

Would maybe have a chat with MPI just to make sure you are running in the proper efficiency range for the blower too. I know with my combo at 12 lbs on a stage 2, I'm at the bare minimum I can run for the blower speed with my pulley combo. Sorry cant remember what I've got on there.

allaboutdaz · Feb 17, 2015

how much boost would the 27t bottom and 25t top make?

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Supercharger pulley question

randall01

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←snow∞motion→

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347strokin

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allaboutdaz

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