Tom Wilson
July 1, 2008

Horse Sense: Expect all sorts o of things to work overtime when pumping 700 hp to a Mustang's rear tires. As if synchronized to last only as long as the test, Kenne Bell's prototype mule started slipping its stock clutch at the end of the Mammoth development program. A Centeforce DFX clutch installation was the cure.

Five years ago, Kenne Bell released its stunning '03 Mustang Cobra kit. With little more than swapping the stock Eaton supercharger for the Kenne Bell Twin Screw compressor and minor tweaking of the fuel and spark, the KB kit pumped the Four-Valve Terminator engine into the 620hp neighborhood.

Yes, it took more than 20 pounds of boost and race fuel to reach that much horsepower, but not much more. As amazing as it may seem, the Kenne Bell Terminator got darn near two thirds of 1,000 hp with a stock short-block and cast-iron exhaust manifolds while blowing through the stock cats.

Since then, Jim Bell, the major rotor at Kenne Bell, has introduced larger high-boost-optimized superchargers. He has also pondered his Terminator offering, looking for a way to get even more from it. The combination of Jim's power quest and specialized compressors has now been finalized. That's the kit we're looking at here.

To save you from flipping to the end of this article, the new kit takes the same stone-stock Terminator engine, cast-iron exhaust manifolds, and cats to 704 rwhp, a 101-rwhp improvement with the same pulley as the original 2.2-liter KB Terminator kit.

There's one point that we should emphasize before going any further: The original KB Terminator kit remains available for anyone satisfied with approximately 525 rwhp while running pump gas, or anyone happy with about 700 rwhp with prepped heads, hot-rod cams, and race gas. Why? The original kit is less expensive, and its 2.2-liter and 2.6-liter superchargers are slightly more efficient at lower street boost levels than the larger 2.8-liter compressor used in the new Mammoth kit. The Mammoth is for those wanting great street horsepower and the ability to quickly swap pulleys and gasoline to run hard at the track. It also offers tremendous potential to the cam and heads crowd; with the right supporting pieces, it should post 850 hp to the tires. We also caution that the extra power needs careful throttle manipulation to avoid wheelspin-which isn't such a bad thing if you know what you're doing.

With no hope of getting enough air under a stock Mustang hood to feed a Mammoth kit a full suction, nor room to package a correspondingly huge air filter, Kenne Bell turned the intake pipe down and through the sheetmetal to take air from under the driver-side front fender. The relocated stock mass air electrionics and intake air temperature senor show here as well.

Mammoth Proportions
So, what did Kenne Bell do to come up with its new Mammoth kit? The company began by understanding its 2.8H supercharger was more efficient at high boost levels (15 psi or higher), and it therefore took less power to drive than the 2.2/2.6H blower did at high boost. If that larger compressor could fit into the Terminator engine, it would free up power compared to the 2.2/2.6H blower.

The crew also realized that the inlet-the curved, aluminum intake air casting that sweeps the incoming air into the rear of the supercharger-is restrictive at high boost, even on the 2.2/2.6H supercharger. The deeper-breathing 2.8H compressor would need even more air, so a much larger, much freer-breathing intake casting was developed. Because castings in production volumes are expensive, this wasn't a casual commitment.

With no need for a separate mass air meter, the stock Cobra air meter innards were relocated to a pad on the side of the 4.5-inch tubing. That gives the Mammoth kit a 4.5-inch (114mm) mass air, if you will.

With the new inlet in place, the remainder of the intake air path proved undersized as well. The throttle body, inlet tubing, mass air meter, air filter, and the air path past the Mustang sheetmetal were undermatched to the needs of a 700hp force-fed engine. Therefore, all of those parts had to be redesigned.

Perhaps the most fundamental change was to move the inlet from the passenger side of the engine compartment to the driver side. There simply wasn't enough airflow available on the passenger side due to the air-blocking hardware. However, there was greater airflow on the driver side once the battery was removed. So Ken Christley, Kenne Bell's secret weapon and all-around engineer, relocated the battery to the passenger side, where it belonged in the first place. He put a huge oval air filter in the driver-side fender and connected it to 4.5-inch-diameter metal tubing leading to the supercharger.