Kenne Bell 3.6L Twin Screw - Bigger, Better Blower

Testing Kenne Bell's 3.6L Twin Screw

From the February, 2010 issue of Muscle Mustangs & Fast Fords

By Richard Holdener

Life is good if you're a mod motor maniac looking for boost, as there are over a dozen different blowers to choose from. If immediate boost is high on your list, the factory Roots blowers offered on the '03-'04 Cobra and GT500 offer instantaneous response combined with plenty of mid-range and top-end power. The average power production of a force-fed Ford has to be experienced to be believed. Those who stand by their decision to run "all-motor" modular combinations have obviously never experienced one with boost!

While the factory (and aftermarket) blowers are impressive, there are always those looking to step things up. These overachievers all but mandated blowers like the Kenne Bell 2.8L H-series. Capable of supporting over 1,000 hp (we recently produced 1,036 hp on a modified 5.4L Four-Valve), the 2.8L H-series has proven to be the class of the field for high-boost, high-horsepower applications. Credit the billet casing for minimizing deflection (allowing higher blower speeds and boost levels), along with the a unique rotor pack and discharge design (port timing) for the impressive packaging and performance of the 2.8L.

Not content to rest on its laurels, Kenne Bell has recognized the need for even higher power levels and recently introduced the new 3.6L. From a size standpoint alone, the 3.6L is capable of supporting over 25 percent more power compared to the 2.8L (yet it still accepts the factory fuel rail and fits under the hood). Not satisfied with a simple increase in displacement, the new 3.6L also offers a number of desirable features including a proprietary rotor configuration, seal pressure equalization, and a revolutionary new liquid cooling system.

The result of these changes is a larger, more powerful supercharger that also offers a reduction in parasitic losses. All superchargers suffer from parasitic losses associated with driving the unit. Different superchargers operating at different boost and power levels require different amounts of energy to drive. When the new design offers more power and boost potential with a reduction in parasitic losses, you know you've done something right. Throw in a decrease in inlet air charge temperatures and increased component life from the liquid cooling and seal pressure equalization, and you have one serious deal.

Naturally, we needed to test the new blower, but before getting to the impressive results (don't sneak ahead and look at the dyno results), we need to understand why the new blower offers so much more power.

First and foremost, the 3.6L is bigger than the old 2.8L. What this means is that for every revolution, the bigger blower will process more airflow. While this bigger-is-better philosophy seems like a no-brainer, there are limitations, or more accurately, proper applications for the larger blower. The ideal application for the larger 3.6L blower is not a stock 4.6L Two-Valve, running 7 psi of boost, but rather a 5.4L GT500 running 15-plus psi of boost. The larger 3.6L was designed for high-horsepower and/or high-boost applications. Given its ability to support 1,200-plus horsepower, it is less than ideal for someone looking to produce just 400 hp. The big blower will obviously do the job at lower boost and power levels, there are just better blower choices for the lower-horsepower applications.

Not just bigger, the 3.6L blower is also better. Better in this case means that with extensive research and development, Kenne Bell has managed to significantly reduce parasitic loses associated with driving the supercharger. Since the parasitic losses are essentially power absorbed by the motor to drive the blower, the power is not applied to propel the vehicle.