pressures are to be used as a guide and may vary
**Boost pressures will vary with inlet restriction.
For comparison, all tests were conducted with stock inlet systems. For
example: with a 2.75" pulley, '03 Cobra boost will increase approx.
2 psi with Kenne Bell Cool Air Kit.
See Kenne Bell"Tech Info"Ford, Dodge & Camaro Superchargers
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 pulleys. We use only durable long life high grade plated
steel except in a special 10 rib Shelby application. 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.
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.
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.
• WORKS WITH ALL KENNE BELL SUPERCHARGER ONE BOLT PULLEYS
NOTE: Shelby GT500 is only pulley that uses 6 screws vs 1 bolt.