LSA Supercharger Upper/Lower Pulley & Belt Guide

Upper pulleys.. lower pulleys.. tensioners.. idlers and of course, BELTS! In the never ending search for the most boost at the lowest heat level we have to play the mix and match game to ensure our belt-train powering our LSA supercharger is working at its sweet spot. This guide is meant to help you in your LSA supercharger pulley selection, belt and idler selection. It's important to understand a few things about this matrix before you get rolling:

  • All of this data applies to the stock LSA cubic inches
  • The faster you spin a supercharger the hotter it gets and the more strain is put on its components. A faster spin rate is not always better so: 1) pushing stock LSA blowers past 23,000 RPM is not recommended. and 2) pushing the stock LSA blower belt train over a 35% overdrive level is also not recommended and 3) using an idler smaller than 50mm is not recommended as it may over stress the bearings.
  • This is a guide - XtremeCFM takes no responsibility in how you use it, how your motor likes and/or how many times you gap (or get gapped) after reading it.
  • If you're curious how the upper and lower pulley choices affect boost levels check out our LSA blower boost calculator.

Here are the stock sizes for the components so when you see "stock" in the table cell it'll be clear what it means:

LSA Stock Supercharger Sizes / Dimensions

Crank Pulley (Lower) 7.8"
Belt 1680mm
Supercharger Pulley (Upper) 3.0"
Upper Idler 90mm
Lower Idler 70mm
Supercharger Spin Rate 16,900 RPM

LSA supercharger pulley matrix

Crank Pulley [Overdrive %] LSA Supercharger Pulley Belt P/N Upper Idler Lower Idler Total Overdrive % LSA Blower Speed
Stock (7.8") [0%] 3.0" (stock) 12628026 (stock) 90mm (stock) 70mm (stock) 0% 16,900 RPM (stock)
2.55" K080653HD 90mm 70mm 18% 19,900 RPM
2.35" K080645 90mm 70mm 26% 21,300 RPM
8.25" [6%] 3.0" 12628026 90mm 70mm 6% 17,900 RPM
2.55" K080660 90mm 70mm 25% 21,000 RPM
2.35" 12628026 100mm 70mm 34% 22,500 RPM
8.66" [11%] 3.0" K080675 90mm 70mm 11% 18,800 RPM
2.55" K080670 90mm 70mm 31% 22,100 RPM
2.35" 40% 23,700 RPM
9.17" [18%] 3.0" K080675 90mm 70mm 18% 19,900 RPM
2.55" K080670 90mm 70mm 38% 23,400 RPM
2.35" 48% 25,000 RPM
9.55" [23%] 3.0" K080685 90mm 70mm 23% 20,700 RPM
2.55" K080675 90mm 70mm 44% 24,300 RPM
2.35" K080675 90mm 70mm 54% 26,000 RPM
10.0" [28%] 3.0" K080700 90mm 70mm 28% 21,700 RPM
2.55" K080685 90mm 70mm 51% 25,500 RPM
2.35" K080685 90mm 70mm 62% 27,300 RPM
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