Kenne Bell 2011 Mustang Supercharger Test - Mammoth Gains

"You and I will never talk about this kit again," said Jim Bell as he sat behind the stacks of yellow legal pads overflowing his desk. We'll admit he had our attention at this point.

And with that introduction, we were off and running on one of our most anticipated Mustang and supercharger combinations, the Kenne Bell-assisted '11 Mustang GT. Kenne Bell specializes in blower kits for the too-much-is-just-right crowd, and with ample torque and power guaranteed from the twin-screw, positive-displacement Kenne Bell blowers, we were eager to see how the new Coyote 5.0 would respond.

To avoid undo suspense, at this early stage in the game we saw 604 rwhp on the KB Dynojet. Light-duty you say? Sure, until you know that this was with a mere 10 pounds of boost. The blower and its supporting pieces hadn't even broken a sweat and the power was approaching '03 Cobra levels using much the same KB equipment. But the Terminator needed more like 17 pounds of boost to make 650 rwhp, while the Coyote was trotting into that territory with plenty more on tap. Less boost and displacement making about the same power means a better-breathing engine.

In fact, in all early supercharger development tests we've witnessed, the Coyote is fulfilling its promise of eventually making nuclear power. The trick is picking the 5.0's formidable electronic lock, a daunting task thanks to all-new software code that runs in closed loop at all times except deceleration, frequency-based mass air metering, a mechanical-returnless fuel system, and especially the electronic throttle. In a nutshell, understand that the '11 Mustang GT engine-management software is mind-numbingly complex, fraught with endless stumbling blocks and an electronic policeman intent on ensuring excess power is not made. So far, Kenne Bell has reached into the mid-600-rwhp range, but once the electronics are figured out, four-figure power numbers are only a short-block away.

As is normal with Kenne Bell, its '11 Mustang GT blower kit uses a KB-built twin-screw supercharger sitting atop a new intake manifold in the engine valley. All the '11 GT kits are charge-cooled using air-to-water heat exchangers, and in all but the base kit, some of the charge-cooling water is run through the front of the supercharger drive section. This evens temperatures front-to-rear in the blower, allowing tighter tolerances, and is the source of the Liquid Cooled nomenclature. Because Jim Bell is adamant intake air must be sourced from outside the hot engine compartment, a new inlet tube is cut through the inner fender and radiator support. That puts the air filter behind the driver-side headlight, just in front of the tire.

As Jim Bell said, his '11 Mustang GT kit is super-sized from the get-go. That is, the vital naturally aspirated side of the air stream-everything upstream of the supercharger-is heroically over-sized to ensure maximum power. The same can be said for everything downstream of the supercharger-namely the newly enlarged heat exchanger and no-runner intake manifold. Like the inlet side, these pieces are designed to support mega power.

That leaves two adjustable portions of the kit: the throttle body and the supercharger itself. Throttle body choices are reusing the stocker for all street applications, then moving directly to Kenne Bell's gigantic, 168mm, single-blade billet throttle body for anything up to 1,400 hp.

The supercharger choices begin with the 2.8-liter for the 8- to 23-pound boost range, then the 2.8H variant featuring slightly different porting to favor the 15- to 28-psi boost window. For dedicated big-power applications, you can move up to the 3.6-liter for 15-30 pounds of boost, and if anyone really needs to, Kenne Bell has a 4.2-liter screw blower on the shelf that is yet more efficient at the outer limits.

From a packaging perspective, these blowers differ only in their length, which has been accommodated in the drive snout and manifolding. In other words, any of these blowers can be easily used from the kit's initial installation or retrofitted in 20 minutes.

As for adjusting boost in the field, all Kenne Bell blowers are designed for rapid blower drive-pulley changes. Most pulley swaps can be done in three minutes, 10 on the outside. The entry-level Kenne Bell 5.0 kit starts at 8 pounds of boost using a 4.125-inch pulley; the limit for 91-octane pump premium gasoline. East Coasters with access to 94-octane can step down to the 3.875-inch pulley for 10 pounds of boost (and not have to bother with re-flashing the computer's tune), and in any event, KB can supply pulleys in 0.125-inch steps until your connecting rods are scattered a hundred yards on either side of the dragstrip-call it 28 pounds of boost with the 2.8 and 3.6-liter blowers.

Note that even the 2.8-liter blower is generously sized for the deep-breathing 5.0-liter Coyote. It's loafing at 8 pounds of boost with cool discharge temperatures, so you can consider 8 psi as a minimum pulley choice for this kit. We doubt few people will ever really need the 3.6-liter, much less the 4.2. Need and want, of course, are two different matters.

Street applications drive nicely with the stock six-rib pulleys, but 12-psi or higher kits need Kenne Bell's eight-rib pulley set. Jim Bell didn't have one on hand to show us during our visit, but he's promising a trick, compact method of adding two ribs to the stock crankshaft harmonic damper/pulley sheave. The eight-rib layout will also require a smaller water pump pulley to physically clear the crank pulley.

Kenne Bell pricing reflects the inherently expensive nature of a screw blower on one hand and the fact KB sells only direct to the customer on the other. The base '11 Mustang GT kit is $6,599. That gets you a charge-cooled, black 2.8-liter supercharger without liquid cooling and an 8-pound, six-rib pulley, plus you re-use the stock throttle body to reach right around 550 rwhp on 91 octane pump gas. It's a big old kick in the rear, and if you're just giving it a squirt now and then or never going over 10 pounds of boost, you won't miss liquid cooling the blower. If you're planning on more boost in the future (who isn't?) then liquid cooling is more beneficial. It's an additional $300, or $6,899 on the otherwise base kit.

The huge KB throttle body is a $400 upgrade, the eight-rib pulley kit is $349, and polishing is $500. As you go up the Kenne Bell price list (already available on the Kenne Bell website), polishing becomes a standard feature and bundling the big throttle body is sometimes included.

Of course, you can always spend more. Step up to the 3.6-liter blower (you guys with 1,000hp dreams) and you're looking at $8,099, but that includes the big throttle body and polishing. Pricing on the 4.2-liter blower wasn't set at our press time.

Getting back to the real world, poking around the price list we see a black, 2.8-liter, liquid-cooled blower with the big throttle body ($6,999), a couple of extra pulleys ($69 each) for test and tune night, and the required pulley changing tool ($25) make a great package that will put out all the power you can handle for $7,162. That'll range from 8 to 28 pounds of boost and last the life of the car. If you want to make life easy on your wife at Christmas time, you could have her step you up to the eight-rib pulley kit or a Boost-a-Pump, so everybody wins.

Because we prodded Kenne Bell into letting us take an early look at its Coyote kit, this article reflects early low-boost information. So, despite how Jim Bell opened our interview, we'll be back for more boost and tuning tips, including some huge power numbers. Given the airflow-happy Coyote engine, and what looks like an average of about 20 hp per pound of boost at this point, it's going to be a wildly fun ride.

Driving Impression Jim Bell was kind enough to turn us loose in his red '11 GT automatic test mule. Fitted with the standard kit pullied to 8 pounds of boost and tuned enough to start, run at wide open throttle, and that's about it, our goal was simply to sample the Coyote/Kenne Bell combination as a preliminary check.

It's fast. No joke-pulling out onto the street and rolling swiftly into the throttle had us talking out-loud to ourselves, "This is how a blown V-8 is supposed to feel!" There's a big, grin-inducing torque hit anywhere on the tach, followed by excellent pull to the fuel shut-off. Heavy as the Kenne Bell blower kit is, it seems to magically take hundreds of pounds off the car when you have your foot in it. We didn't have time to evaluate the car in turns, but the extra weight up high must be noticeable to the sensitive driver.

Romp the throttle from a standing start and be prepared for generous tire spin; she lights 'em up right now thanks to all that instant torque. The same easy power is a great match for the automatic transmission. Hit the gas and it downshifts one gear, then gets out of Dodge. With a manual, there's less need to shift due to the torque, and there's absolutely no need for steep rear-axle gearing. Stock 3.31s are fine.

Noise is not a factor. If you know what you're listening for, you might pick up the faintest gear grrrr during idle or maybe cruising, but for any practical purpose, the KB is silent. While making boost there is a slight scream, but the long intake tube muffles that to the-people-next-door status. Exhaust noise gets amped up with boost-which is all part of the fun with stock mufflers-and rowdy with aftermarket mufflers, so you might want to take that into consideration if you're trying for stealth status.

On The Dyno

We must explain that the baseline figure was set in totally stock configuration, with the ignition timing advancing as far as Ford has it tuned: 26 degrees total advance. The 8-pound number was set as KB normally sells its kits, with the ignition timing capped at 22 degrees-the practical limit with 91-octane fuel. If 94-octane fuel is available, then a smaller blower drive pulley can be installed and the ignition timing (electronic tuning) can be left alone.

Of course, it can't escape your attention that the entry-level 8-pound Kenne Bell kit made a staggering 177 hp and 136 lb-ft of torque over stock. This is outstanding performance, so good compared to other reported dyno results (even elsewhere in this magazine) that a reasonable person would want an explanation.

First, remember that besides differences in superchargers and electronic tuning, all dynos do not read equally (sometimes by 40-plus horsepower), and also remember the Kenne Bell is using a huge inlet breathing outside the engine compartment while others suck through smaller tubes inside the engine compartment. In addition, the manual transmission KB test car was wearing a Pypes muffler and tailpipe kit.