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 |
