Kenne Bell is on a roll. No sooner did we report in depth on the company's supercharger exchange for the '03 Cobra ("Snake-Bite Hit," Mar. '03, p. 71), than we were back looking at its Two-Valve offering for good, old Mustang GTs.
And Jim Bell at Kenne Bell was even more amped up about his GT kit than he was over his Cobra piece. Among other superlatives, he noted his kit on a Two-Valve made more power-about 25 more horsepower-than a stock '03 Cobra with its Roots blower. In fact, Jim went so far as to say his Two-Valve Ford kit is the best one he's ever done.
That's a big claim, so instead of making you wade through this entire article to find the ultimate power figures for the Kenne Bell GT kit, let's note right now that it yielded 433 hp when equipped with optional large air meters, inlets, and throttle bodies. That's with a 271/48-inch blower pulley and 9 pounds of boost. This is the detonation limit with 91-octane pump gasoline, so consider it the hot street setting. The blower can easily double that boost with smaller pulleys, and if you're willing to run racing gasoline for detonation protection and have the piston and connecting rod improvements to withstand such power, then somewhere in the 15-pound boost range and 500 hp makes sense. The brass ring at press time was 24 pounds on a Kenne Bell employee's car. We'd have run it for you, except it had two connecting rods sticking through the block.
Even after half the parts...
Even after half the parts atop the engine were replaced or rearranged, the finished Kenne Bell Two-Valve supercharger installation looks as though it grew there. A single belt is used to drive both the blower and the stock engine accessories. The backward-facing alternator requires a lengthened wiring harness and minor clearancing on its lower face.
The Kit
Given the world is well populated with Mustang Cobras, logically there is little need to attempt huge power from the GT kit. That's what '03 Cobras are for, thanks to their flow-happy Four-Valve heads and stout piston/rod assemblies. The GT kit, rather, is designed to make vertebrae-challenging power at street-able levels, although the nature of the Kenne Bell blower allows high boost levels for those who insist on testing their luck against the GT's cast pistons and pressed metal connecting rods (very weak, these). Therefore, Kenne Bell has packaged its GT blower offerings with a price-conscious, non-intercooled version producing 6 pounds of boost. Kenne Bell says it adds 106 hp.
All remaining versions of the GT kit are intercooled and differ only in the pulley fitted. And there are plenty of pulleys-7-14 pounds in 1-pound increments-so the GT owner definitely has his choice of boost levels. Obviously, the 6-pound kit has clear price appeal that should help it sell, and the 9-pound kit is the limit with 91-octane pump gas, so that seems a logical bestseller as well. It makes an additional 160 hp, says KB.
This Bullitt is wearing "all...
This Bullitt is wearing "all options." That means it has the cold-air kit, the 90mm mass air meter, the Big Tube kit, and the 75mm throttle body. These parts add around $600 to the tab and 20 hp to the tires.
From there on out, race fuel is the rule. Because the Kenne Bell supercharger allows quick and simple pulley changes, we'd say the 9-pound kit should be the top seller, along with a spare pulley for track days when 100-octane unleaded can go in the tank. Fit the 14-pound pulley and enjoy an additional 262 hp, says Kenne Bell.
In general terms, fitting the Lysholm screw supercharger Kenne Bell uses to the 4.6 GT engine follows Cobra practice. The stock GT intake manifold is removed, and the Kenne Bell supercharger and intake manifold assembly are fitted in its place. This nestles the supercharger in the 4.6's valley, with the intercooler (on versions so equipped) in the valley at the bottom of the intake manifold.
Intake air thus passes through the air filter, the mass air meter, and the throttle body, and then enters the supercharger. The supercharger discharges the air downward and through the intercooler core (if so equipped). Then the air turns 180 degrees at the bottom of the intake casting. Flowing straight up, it goes to the top of the intake where it makes a second 180-degree turn to flow down into the cylinder head. The S-bends aren't the last word in airflow, but they don't seem to hurt power production, and they keep the blower from pro-truding through the hood by lowering the packaging height.