STEEL SUPERCHARGER PULLEYS - No one offers more steel pulleys for the Kenne Bell Twin Screw and Eaton Roots superchargers - because pulleys and superchargers are our business and not a sideline. Supercharger/driven pulleys are only 1/3 the diameter of crank/drive pulleys and therefore spin at approximately 3 times the speed of the crank - 750 ft/sec. This equates to over an 1/8 mile per second! That's a lot of heat and friction. Could that be why the OEM's use steel supercharger pulleys exclusively? It's precisely why Kenne Bell has never used the softer aluminum supercharger pulleys with serpentine belts - and never will. We use only durable long life high grade plated steel for both Kenne Bell and Eaton superchargers. It's common practice to switch pulleys to vary boost levels for street, weekend racing etc. Kenne Bell Steel Pulleys can be quickly and easily replaced with one bolt using the Kenne Bell Pulley Wrench (Twin Screw) or the Kenne Bell Billet Pulley Puller (Eaton). Stock Eaton pulleys are pressed on, constructed of relatively soft high lead material and are therefore easily bent by "old style" pullers when removed. Reinstallation is also difficult, requiring a press if a good installation tool is not available. Kenne Bell Steel Pulleys are virtually indestructible. Big selection. Precision machined steel and plated for corrosion resistance.

BILLET PULLEY PULLER (EATON SUPERCHARGER) - There are 3 ways to change pulleys on an Eaton. The most expensive and time consuming is to replace the entire drive assembly with a new one and a smaller pulley. So if you're alternating 3 pulleys, you would need 3 new expensive drive assemblies. Why buy a drive assembly just to get a pulley? The second method utilizes old style pullers that usually bend and ruin the pulley the first time. The new lightweight Kenne Bell Billet Aluminum Pulley Puller is the easiest and most economical way of removing pulleys from the stock Eaton drive. It doesn't distort and ruin your pulley and you don't have to buy new drives for each pulley change. A pulley can be removed or replaced in 5 minutes with this tool. Great for alternating "street" and "race" pulleys. Note: We DO NOT recommend aluminum supercharger pulleys because of the high belt speed and resultant wear.

PULLEYS, RATIOS & BOOST - See chart for boost numbers. Plus (+) psi boost numbers (+2 psi, +5 psi etc) is a non scientific, inaccurate and confusing method of rating pulleys. At Kenne Bell, we prefer to also use "ratios" (crank pulley ÷ supercharger pulley = ratio) to describe a potential boost increase. In other words, list the boost AND ratio. Why? Is a supercharger pulley a +2 with the stock 7.5", 9" or ? crank pulley? And is the +2, +4, +6 crank pulley with a 3.5", 3" or 2.7" supercharger pulley? To make matters more confusing some superchargers, such as the Eaton, do not develop the same boost at 2000, 3000, 4000, 5000 and 6000 rpm. They suffer from "boost drop off." For example: What plus (+) pulley rating do you give a Cobra '03 pulley that is 15.3 psi at 4000 but only 10.3 at 6000 when the stock pulley was 8.3 at 4000 and 7.8 at 6000? We refer to the stock pulleys as a 2.11 ratio and 7.8 psi (7.5" ÷ 3.55" = 2.11 ratio) and the 3" pulley as a 2.5 ratio and 10.4 psi (7.5" ÷ 3" = 2.5 ratio). Now take the same 3" pulley with a 9.25" crank pulley and you have a 3.1 ratio instead of a 2.5 ratio. On our superchargers, that's around 6 psi variance. Get the point? Kenne Bell lists the ratios and boost for all applications. We offer Lightning/Harley SC and crank pulley combinations of 9.5, 11, 14 and 16 psi. The Cobra combinations are 10.4 and 13.3 with sc pulleys only. Note: We don't recommend a larger crank pulley for the Cobra Eaton, but for those who prefer one, we have an 8.25" Cobra which works with the Eaton or Kenne Bell. Want to know if your supercharger is producing the boost it's supposed to.