Tom Wilson
December 17, 2013

Horse Sense: Just a reminder, but when modding the Two-Valve 4.6 for 15 pounds of boost or more, besides the forged bottom end bits, you must also fit upgraded oil pump gears. Stock 4.6 oil pump gears shatter at high power outputs, immediately ruining your whole day. Triangle Speed Shop ( in Texas has what you need. Mammoth power also far exceeds the humble '96-'04 Mustang's fuel system, so you can count on replacing all of it as well. Finally, '96-'98 engines require aftermarket or Performance Improved cylinder heads found stock on '99-'04 Two-Valves to work with Kenne Bell supercharger kits.

For a while now the distinction at Kenne Bell between merely fast and outright furious is fairly easy to spot. Standard blower kits with their smaller displacement superchargers and easily packaged standard inlets are affordable and run beautifully on the street, yet can be hustled to race-pace when sped up and fed octane booster.

Kenne Bell's larger blowers, those in the 2.6- and 2.8-liter category, coupled with giant Mammoth inlets and throttle bodies, are really more race pieces. Sure, they run great on the street, but pullied for boost potential they'll make so much power they fracture stock pistons and demand a diet of specialized fuel for their trouble.

That said, nearly 95 percent of Kenne Bell's customers opt for the big Mammoth inlets whenever they're offered, and certainly the larger displacement superchargers are almost as equally popular and tons of them are run on the street. Gee, people buying superchargers have a need for speed. Imagine that?

Just as obviously, Kenne Bell has been working hard for years to offer big blowers and Mammoth inlets for all of its Ford blowers, along with keeping up development of new kits for new Ford engines as they came along. The good news is all of the push-rod 5.0 and modular 4.6, 5.0, and 5.8 Ford V-8s now have standard and Mammoth kits for them. Well, all but one until early 2013, when the final Mammoth kit was released for the Two-Valve modulars in '96-'04 Mustang GTs. It's the kit we're looking at here.

To best understand the new Mammoth kit, let's recall the standard Two-Valve Kenne Bell kit for the first modular Mustang GTs which has been on-sale for years. It's a street-oriented kit, designed to work with the stock 4.6 Two-Valve short-block and pump gas to give a 151 hp increase over stock. It uses a 2.1-liter KB blower, nominally pullied for 9 psi although it works anywhere between 6 and 14 psi of boost. Kenne Bell has been offering this kit in affordable, non-cooled and pricier, intercooled versions for higher outputs and it's a good seller. The natural limit for this blower kit is 525 rwhp, the point where the stock pistons and rods are suspect and pump gasoline no longer cuts it.

An important note with all '96-'98 Two-Valve engines is they require the '99-'04 PI heads or aftermarket heads according to Kenne Bell. Also, for the record, there is no Mammoth for the 2.1 blower kits as the larger inlet physically doesn't fit the more compact supercharger.

Of course, there have always been folks who wanted more from a Two-Valve than 525 rwhp. They used to be few, as the Cobras attracted most of the big-power fans, but today Two-Valve owners are ready for more. Most importantly, many Two-Valve '96-'04 Mustangs are now old enough to have worn out or blown-up their original short-blocks. They've been replaced by forged internals Two-Valve short-blocks and prepped cylinder heads—another must-have for big power with this engine according to Kenne Bell.

This critical mass of potential buyers is looking for efficient, high-output supercharger kits, and with Kenne Bell having just finished developing Mammoth inlet kits for all of their other big supercharger applications, they had the resources to develop a deep-breathing Two-Valve kit.

As you've likely guessed, the new Mammoth Two-Valve kit does not replace the existing standard kit with its 2.1 blower and Big Tube inlet (which doesn't look big at all compared to the Mammoth). Instead, the new Mammoth kit is offered to take over where the standard kit falls off. Kenne Bell rates the Mammoth kit for 15 to 28 pounds of boost, which is great for track duty; for any normal street application the standard Two-Valve kit is still more efficient and far less expensive.

There are two major components in the new Two-Valve Mammoth kit: the blower and the inlet. The blower is actually your choice of either of KB's 2.6- or 2.8-liter twin-screw blowers. The idea here is the 2.8 blower is so air-happy that it's all but impossible to make it run at low-boost, pump-gas levels, so KB offers the 2.6 liter for those currently running a stock short-block or wanting to motor around on pump gas and 10 pounds of boost while still enjoying the reduced inlet restriction and a bit more power the Mammoth inlet will give even on pump gas. A 2.6-liter Mammoth makes a little more power than a 2.1 standard kit at the same boost levels because the larger blower/inlet system is a hair more efficient. Later an upgraded short-block with forged internals can be slid under the 2.6 blower and it can be pullied for up to 26 pounds on race gas or E85. That's over 700 hp, or more than enough for many folks.

As always, Kenne Bell is using a twin-screw supercharger that sits on top of the intake manifold in plain sight and aspirates from the rear. The latter offers less inlet restriction than blowers breathing through the front because the blower drive is not in the way. This is a 2.8-liter Liquid Cooled installation.
There is no mistaking the over-sized Mammoth inlet tube and cast aluminum inlet at the back of the supercharger. Similar to the Shelby GT500 blower kits inlet, the Two-Valve Mammoth inlet helps give the lowly Two-Valve engine GT500-like power.
Previous Kenne Bell testing has proven hot underhood air is death to blower engines, so the Two-Valve kit routes the air intake through the inner bodywork in front of the passenger-side tire. A large open-element air filter mounts just below on the other side of the sheetmetal. The mass-air element is visible just after the tubing emerges from the inner fender.
Liquid cooling for the 2.8-liter superchargers is optional on the 4.6 Two-Valve Mammoth kit. Liquid cooling is increasingly beneficial as boost and engine rpm climbs into the racy regions. It evens the temperature down the length of the blower’s rotors and rotor drive gears, allowing a tighter tolerance and more consistent results. Liquid cooling is best used on seriously high-output applications but is still beneficial on hard-driven, higher-boost street animals.
Looking rather compact here without its throttle body, fuel rail, or injectors, the standard Kenne Bell Two-Valve supercharger assembly has been on-sale for years and will continue as KB’s street blower for ’96-’04 Mustang GTs.
There’s no missing the massive Mammoth inlet and matching throttle body on the Two-Valve Mammoth blower assembly. What is more subtle is the 2.8-liter supercharger is slightly longer than the 2.1 on the standard kit. This is exactly how the Two-Valve Mammoth kit comes out of the box.
Viewed from the rear, the Kenne Bell Two-Valve blower assemblies—Mammoth at left, standard at right—show a few tell-tale differences. Obviously the Mammoth inlet is overpoweringly large, but the intake manifold is slightly different in the way it packages the two water nipples. If nothing else, this precludes swapping a Mammoth blower and inlet onto an existing standard intake manifold.
Mammoth Two-Valve kits come with a six-rib blower drive as stock, with an eight-rib kit optional for those operating in the 20 pounds and higher range. The two AN fittings at left denote this is a Liquid Cooled supercharger, and thus a 2.8-liter. The Liquid Cooling keeps temperatures more even from one end of the rotors to the other, something worth thinking about at high boost outputs, but not a factor in street driving.
Like all Kenne Bell twin-screws, the Two-Valve Mammoth blower is fitted with a large bypass valve and plumbing to aid part- and closed-throttle operation. Unlike centrifugal blowers that typically blow-through the throttle body, the bypass does not need to vent excess boost to the atmosphere and is thus silent.
Kenne Bell supplies the Two-Valve Mammoth kits with a set of their aluminum fuel rails. Like all the rails on the market the KB rails are many times larger than necessary and will never pose a fuel restriction. Injectors are not supplied as KB figures Two-Valve engines at this power level have already been thoroughly hot-rodded and will likely need custom fuel injector sizing anyway.
A close-up of the rear of the Two-Valve Mammoth assembly shows the layout of the various hose fittings and fuel crossover hose. This area is rather difficult to reach once the blower and inlet are installed, but the good news is there is nothing to service back here, so cramped access shouldn’t matter.