Kenne Bell-Boosted Three-Valve 4.6 Picks Up 180+ Horsepower

Last time we met over this 2006 Mustang GT, we noted it was a great example of a real-world, daily driven Mustang about to get a whole lot more fun thanks to a cost-effective supercharger. Other cars and other owners might opt to spend many more dollars and endure many more hassles for four-digit, cocktail-party bragging rights, but this combination was one we could relate to as a ton of fun for an approachable pile of dollars.

We also introduced the main players last time around: enthusiastic owner Melissa Repreza, GTR High Performance Wrench-in-Chief Ricardo Topete, and the Kenne Bell twin-screw supercharger. After the intros we baselined Melissa’s impressively clean, stone-stock, 100,000-plus-mile 2006 Mustang GT both on the dyno and the strip, then broke out the wrenches with Ricardo and installed the Kenne Bell 2.6-liter twin-screw supercharger and 130mm throttle body upgrade.

In keeping with the stock Mustang starting point and the straightforward Kenne Bell blower the installation was trouble-free and was completed in the expected two full days.

All-around Mustang enthusiast Melissa does her own driving, detailing and as so beautifully demonstrated here, modeling. If you’d like to see more of her or her Mustang she’ll be at multiple Southern California car shows this year. We couldn’t think of a better way of dressing up Melissa’s stock Mustang interior than by putting her in the driver’s seat.

Configured as Ford built it, Melissa’s car ran 13.895 seconds at 101.69 mph at the Auto Club strip in Fontana, California, and, as you may recall, spun the GTR Dynojet drum to the tune of 285 rear-wheel horsepower. Those are fine numbers for a high-mileage Three-Valve pushing through an automatic transmission and 3.31 rear gears, but with Kenne Bell promising much more we were eager to hear what Ricardo’s wrench-bending had wrought.

It didn’t take long to find out. The Three-Valve and Kenne Bell combination is a well-sorted pairing, with the most minimal “tuning” required. As Ricardo points out, once the kit is fully installed he merely plugs in the small hand-held device provided with the Kenne Bell kit into the OBD-II port and with a few keystrokes uploads the Kenne Bell 91-octane tune. Melissa’s car was typical in that, once the tune was uploaded, all Ricardo need do was confirm power on the dyno and driveability on the street. This goes with Kenne Bell’s position that it has already done all the necessary tuning and absolutely no aftermarket tuning is needed or desirable.

Blown Results

And the envelope, please… One glance at GTR’s dyno graph shows the Kenne Bell made an exceptional mountain of torque, all nicely plateaued across the 400 lb-ft range. Mathematically the horsepower had to follow just as neatly, making a healthy incline from left to right and starting well above the stock starting point. At its peak, power reached 462 rwhp, a 180 horsepower improvement over stock! Likewise torque moved up a very muscular 125 lb-ft, from 285 lb-ft in stock form to 410 lb-ft. Those are no excuses, can’t miss ’em, kick in the door power increases, the sort of gain any enthusiast would dream about.

Besides putting 461 horsepower to the tires, the Kenne Bell/Three-Valve combination is a handsome unit. Seen here fresh off the post-install dyno test, its exceptional cleanliness is just the way Melissa keeps it.

If the Kenne Bell Three-Valve numbers sound familiar, they are remarkable similar to the 2018 Mustang GT’s outputs of 460 horsepower and 420 lb-ft of torque. Keep in mind Ford’s numbers are measured at the flywheel and our test numbers taken at the rear tires. But, applying the industry standard 15-percent power loss through the driveline (a guaranteed, conservative minimum given the test car’s automatic transmission) the 2018 GT would post an estimated 391 horsepower and 357 lb-ft at the wheels.

To look at it the other way, Melissa’s car would carry something like 529 horsepower and 472 lb-ft of torque ratings if using flywheel power like the carmakers do. This is one Three-Valve that’ll give the newest Mustang fits.

Furthermore, the power gains came without drama. The Kenne Bell is a quiet supercharger, and just driving around no one knows it’s there. Step on it and there’s a fun air whistle but it doesn’t sound like a box of mad cats when all you’re trying to do is get some groceries. For hassle-free daily driving this combination is tough to match.

Melissa opted for the 130mm billet throttle body and enlarged inlet that makes up the Stage 2 option. Compared with the stock throttle body in the base blower kit Kenne Bell says it’s good for at least 21 horsepower at 8 pounds of boost. And the more boost the greater the return from the Stage 2 option. Kenne Bell was a pioneer of worthwhile cold air intakes, and its Stage 2 option includes a larger 90 mm mass air meter and conical air filter. They’re kept out of the hot engine compartment and inside the inner right front fender.

If there are downsides to the Kenne Bell units, they definitely bump up weight high over the front axle and the demand to feed the engine only premium pump gas. If you’re willing to part with seven large for the blower the extra tariff for premium pump fuel is likely no great burden. If you’re constantly open tracking the additional front end weight will be felt — as will the power. On the street the front weight goes unnoticed.

Blower Living

Once installed, the Kenne Bell Three-Valve kit outputs about 8 pounds of boost with the standard 3 7/8-inch-diameter pulley, which in turn requires a steady diet of 91-octane pump gas. Enthusiasts with access to 93 octane premium can opt for a 3 ¾-inch pulley and if race gas or plenty of octane booster is used a 3 ½-inch or smaller pulley can be fitted. A wide range of pulleys are available from KB and are easily changed in a couple of minutes using their inexpensive pulley tool.

A few items get shifted around the front of the engine compartment to make way for the Kenne Bell supercharger drive and charge-cooler tank. Here the tank has elbowed its way between the power steering and relocated engine coolant tanks, plus the relocated ECU is visible between the coolant tanks and the blower pulley. As if there wasn’t enough gloss black on Melissa’s car, Ricardo at GTR powder coated the valve covers during the blower install. It definitely adds a more finished look to the engine compartment. When the situation warrants it, GTR adds its badge under the willing owner‘s hoods. It’s a nice detail for the show scene.

Of course, converting to corn — E85 — opens the boost and power floodgates should Melissa tire of all the easy speed her out-of-the-box Kenne Bell installation yields. But that’s a move to fueling and pulley changing chores in exchange for track glory, which is not what this blower installation is about or what Melissa has in mind.

Of course, the horsepower shot up with the addition of a supercharger, but don’t overlook the impressive torque gain across the engine’s entire operating range. This torque plateau is what makes the Kenne Bell installation feel like a healthy big-block — and the horsepower ensures the engine runs screaming out the back door as well.

Instead, Melissa’s time-tested Three-Valve reinforces the Mustang’s impressive ability to deliver the goods — daily. Running mid-12s at 112 mph on pump premium and through an automatic, this one will hold anyone’s attention on the way to work!

Tastefully unadorned yet somehow still subtle as a mallet, Melissa’s ride looks good from any angle. While Melissa is no goth, there’s something medievally aggressive about those spiked lug nut covers. And for some reason the pointy spokes on the Vertini wheels make us think of stileto heels. Knowing the value of makeup Melissa had Tire Stickers dress up her 255/35ZR-20 Nittos with their permanent lettering kit. These are about $100 for four logos.

Melissa’s theme for her 2006 Mustang GT is Destrier, the best-bred and most highly trained warhorse of medieval times. Her present-day stallion certainly has the oomph to take into battle.

By The Numbers

After testing the car on his in-house Dynojet chassis dyno, Ricardo Topete headed to Auto Club Dragway in Fontana, California, on Test & Tune night. For consistency, he installed Bogart wheels fitted with 26.0/4.5-15 M&H ET front tires and Mickey Thompson P275/60R-15 ET Street Radial rear tires. Fortunately the weather was similar for the baseline and boosted test session, and the GT’s automatic transmission helped deliver consistent passes.

Chassis Dyno

Baseline: 281 horsepower and 285 lb-ft of torque

Supercharged: 462 horsepower and 410 lb-ft of torque

Gain: 181 horsepower and 125 lb-ft of torque

Drag Strip


60-Feet: 2.209

330-Feet: 5.989

Eighth-Mile: 9.050/80.34 mph

1,000-Feet: 11.680

Quarter-Mile: 13.895/101.69 mph

Kenne Bell at 8 PSI

60-Feet: 2.024

330-Feet: 5.357

Eighth-Mile: 8.068/91.70 mph

1,000-Feet: 10.420

Quarter-Mile: 12.435/111.76

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About the author

Tom Wilson

Infatuated by things that make noise and go fast, Tom has been writing about cars and airplanes for over 35 years. So far that’s meant a decade editing Super Ford magazine, plus long associations with Road & Track, MSN Autos and more lately Kitplanes magazine. It’s also meant some SCCA racing and a lot of fun sampling everything from Trans Am cars to F1 chassis as part of “work.” Besides the racing hobby Tom enjoys flying his biplane, plinking tin cans and messing around with telescopes.
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