Kenne Bell 2011 Mustang Supercharger Test - Mammoth Gains
Kenne Bell Boosts The 2011 Ford Mustang's Coyote 5.0 For Huge Power
From the February, 2011 issue of 5.0 Mustang & Super Fords
By Tom Wilson
Photography by Tom Wilson
"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.
If you think it looks bright...
If you think it looks bright and shiny in polished trim, think of how luminous the Kenne Bell blower is when you hear it added 172 hp and 101 lb-ft of torque to the 5.0 Coyote engine with only 8 pounds of boost.
"There will never be another [Kenne Bell] 5.0 Mustang supercharger kit; this is it," he continued. Then, as explanation, "We sell as many '90 kits as we sold in 1990 and 20 years from now we'll still be selling 5.0 kits. I don't want to redesign this 5.0 kit later... I got the big pipe that will flow all the air I need. The restriction is in the throttle body, and I can replace it, and if that isn't enough, I'll replace the supercharger. You can change the supercharger in about 20 minutes."
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.
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.
The 2.8-liter, liquid-cooled...
The 2.8-liter, liquid-cooled Twin Screw is the backbone of Kenne Bell's '11 Mustang GT offerings. Here it is mounted to its adapter plate under the blower and Mammoth cast-aluminum air intake. The bypass valve and its vacuum motor are on the far side of the intake. Because of the 5.0-liter Coyote's prodigious airflow capacity, KB isn't bothering with its older "standard" inlet; all '11 GT kits include the giant Mammoth intake.
From the rear, the drainpipe...
From the rear, the drainpipe dimensions of the Mammoth air intake are even more apparent. Low-restriction airflow is vital to the inlet side of the supercharger because this portion of the system is naturally aspirated. At around 1,800-cfm capacity and with gentle bends, the Mammoth supports all the power anyone is going to make with this kit.
Turn the blower upside down...
Turn the blower upside down and its discharge port is visible. KB offers its 2.8-liter blower in standard or high-pressure (2.8H) configurations. The difference is the high-pressure blower has a higher internal compression ratio and is more efficient at higher boost levels, starting at 15 psi. From 8 to 12 pounds of boost, the standard 2.8 is definitely the better choice; up in the 18-psi range, the 2.8H could free up an additional 50 hp or so.
Another Kenne Bell option...
Another Kenne Bell option is liquid cooling, denoted by the pair of hose nipples on the blower's front face. These admit charge-cooling water to the front of the blower, cooling (actually evening) supercharger temperatures front to rear. This maintains better rotor clearances at higher boost levels and is a help as boost reaches well into the teens.
Low air-charge temperatures...
Low air-charge temperatures are a screw-blower advantage over Roots designs, but an efficient charge-cooling system is still a must. In front is the heat exchanger from all recent Kenne Bell Ford kits. In back is the new, approximately 25-percent-larger intercooler used in the 5.0 kit. Both taller and longer, it's the largest cooler KB could package, and a major reason 5.0 discharge temps are nominally a chill 110-120 degrees. The extra cooling is a big help with the Coyote's 11.1 static compression ratio, which is higher than ideal for a blower motor.
A two-piece aluminum casting,...
A two-piece aluminum casting, the Kenne Bell intake manifold assembly is essentially a relatively thin "adapter plate" for the blower, combined with a big breadbox housing for the charge cooler. (The blower sits on top and blows air down through the charge cooler; the air turns upward, then downward into the cylinder-head ports).
There is no runner length...
There is no runner length because the twin-screw makes too much torque; any runner length would only stifle high-rpm airflow. The irregular relief in the side of the charge cooler housing is for knock-sensor clearance. KB says it had to raise the knock sensor's sensitivity cylinder-by-cylinder in the 5.0 kit.
Kenne Bell uses a relatively...
Kenne Bell uses a relatively large heat exchanger radiator mounted behind the front bumper. A Bosch electric pump-everybody in the blower business seems to use this pump-circulates the coolant. Hefty steel brackets provide mounting-KB kits would benefit from a weight reduction program, but nothing ever falls off!
From a plumbing standpoint,...
From a plumbing standpoint, all there is to the liquid-cooled blowers is the hose kit shown here with the standard intercooler system. The LC fittings plumb into the two large holes facing the camera in the rotomolded tank, while the hoses run to the front of the supercharger.
Jim Bell fiddles with his...
Jim Bell fiddles with his hot-rodded flow bench while demonstrating the 5.0 air inlet to us. After turning up the voltage to the bench's motor, he can pull over 2,300 cfm of air through it-along with birds, small aircraft, and so on. In the foreground is the 5.0's oversized 2,000-cfm air filter (also used on KB's GT500 kit) hanging from the 4.5-inch-diameter, polished inlet tube. It's hanging from a stock throttle body, Mammoth intake, and the flow bench's tall funnel adapter. The noise this bench generates is incredible.
Hiding behind the big throttle...
Hiding behind the big throttle body's adapter plate are the stock 80mm Ford throttle body and Kenne Bell's 168mm billet piece. KB says the stock throttle body flows 976 cfm and is good up to about 650 rwhp-anything burning pump gas, in other words. The Kenne Bell unit flows 2,150 cfm and is good up to the kit's 1,400hp maximum.
KB's standard 5.0 fuel injectors...
KB's standard 5.0 fuel injectors are these 39-lb/hr '03 Mustang Cobra units. These are tall injectors compared to the '11 Mustang's short style, but they plug right into the stock fuel rails (which KB mounts backwards on the engine). If necessary, Kenne Bell steps up to 60- and 80-lb/hr injectors on the 5.0. All KB injectors are the same length, so they easily interchange.
Because the KB kit reuses...
Because the KB kit reuses the stock fuel rail, but mounted 180 degrees from its stock position, it is necessary to add a fuel line to make up the longer run to the relocated fuel rail. This is done with a single length of braided hose; we're using two hoses here to simultaneously show both ends. One end has the appropriate OEM pop-on fitting; the other uses an AN fitting plus an adapter to a standard fuel line.
There isn't much wiring involved...
There isn't much wiring involved in the KB 5.0 kit, and a plug-and-play wiring harness is provided in each case. Most folks will only install two jumper harnesses; a third is required with the big KB billet throttle body.
Kenne Bell doesn't need a...
Kenne Bell doesn't need a blower bracket, but an idler pulley bracket is required at the passenger-side front of the engine. It's shown here with the three idler pulleys and associated hardware that attach to the bracket.
Looking at the idler pulley...
Looking at the idler pulley bracket edge-on shows the six press-in spacers used by the mounting bolts. KB says they've gone to anodized-black for the plate finish because the previous polished-aluminum plates are worked so hard by the polishers, they dig divots into the plate, leading to cockeyed idler pulleys and thrown belts. The three bolt holes at the top of the bracket in this photo are for idler pulley adjustment with varying blower pulley diameters.
This low-profile billet-aluminum...
This low-profile billet-aluminum breather is a good example of Kenne Bell's bulletproof but heavy way of doing business. The billet piece is necessary to provide clearance for the intake air tube running over the engine's valve cover; the Ford plastic unit it replaces is too tall to work
More clearance is gained by...
More clearance is gained by relocating the evaporative emission canister purge valves to the inner fender. The valves are unchanged, only a new mounting is provided.
Hastily installed for testing,...
Hastily installed for testing, the red box in the corner of the trunk is a Boost-a-Pump module. It increases fuel flow by bumping up the fuel pump voltage, something that shouldn't be necessary on cars burning pump gas (under 600 hp), so the BAP remains an option for the high-power crowd. Ford made several changes to the '11 fuel system-which is obviously sized for forced induction as the pump, lines, and so on, are large enough to support 900 hp, according to KB. Stock fuel pressure is 58 psi, with a pop-off valve inside the fuel tank right next to the pump. That means no easy way to increase fuel pressure, but flow can be augmented with the BAP. That's how Ford does it-the engine management computer commanding 8 volts to the pump at idle and low speeds; then battery voltage at higher-power settings.
Here's how we found the KB...
Here's how we found the KB manual transmission test mule in mid-installation. It looks like a body shop was up to something here, but actually the front fascia, headlamp, and so on remove fairly quickly.
Eyeballing the engine compartment...
Eyeballing the engine compartment where you'd normally find the air-filter box shows the curved opening cut into the inner fender to clear the KB intake tube. The rubber edging is provided in the kit, but you get to saw the fender.
Peering up at the car from...
Peering up at the car from the front shows the rest of the air tube clearance cutting, this time in the radiator support. Making room to make the cut is why the inner fender must be removed.
Here's the top of the engine...
Here's the top of the engine with the Kenne Bell intake manifold and intercooler installed, but before the blower is set atop them. Plastic is used to keep debris out of the air path; the black tube with blue tape on it is the bypass passage.
A strong young man can get...
A strong young man can get the 2.8-liter blower in place by himself, but doing so with the aid of a helper is always best. Again plastic is used to keep ruinous foreign objects out of the intake path, plus protect the blower from tool dings.
Ken Christley-the talented...
Ken Christley-the talented all-rounder at KB who lays out the kits, does all the electronic tuning, dyno testing, and instruction-manual writing-guides the air inlet tubing into position. Interestingly, KB retains the stock plastic inlet scoop because it blows cold air on the outside of the big, chromed KB inlet, cooling it off. KB says typical underhood temps are 180 degrees, and the inlet air temps drop when driving if the scoop is retained.
Ken fits the air filter for...
Ken fits the air filter for the camera. The giant filter poses no inlet restriction, is surprisingly quiet off boost, and allows a delicious moaning scream when doing it's thing, but you might want to be careful fording rain-swollen intersections. The stock mass-air electronics are swapped into the inlet tube just upstream of the filter.
Ken demonstrates the simple...
Ken demonstrates the simple KB pulley change during dyno testing. A single nut in the center of the pulley does all the clamping and is the only fastener requiring attention. Remove the bolt and the pulley about falls off; the bar of aluminum is KB's $25 pulley changing tool and is required to hold the pulley when torquing the bolt. Depending on the blower pulley diameter, it may be necessary to relocate one easily accessed belt idler pulley, or rarely, swap to a different belt. Generally this is a three-minute job, so pulley changes to accommodate different fuels on grudge night are easily done.
On The Dyno
We tagged along as Ken Christley labored on his development work with the KB manual-transmission test car. This was a major pain as the computer kept closing the throttle (something the automatic test mule never did, interestingly), but we were able to obtain good baseline 8- and 10-psi numbers.
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.
However, if race gas is available (KB tests using 109 research octane unleaded for these conditions), then the 10-pound pulley can be run with 26 degrees of timing. Due to the difficulties in sorting the new Ford software, this was the only 10-psi run we obtained by press time, so we're showing that result and estimating what the 10-pound pulley would make with the timing at 22 degrees. Thanks to all variables being controlled and the linear response of the Twin Screw blower, such guestimates have proven surprisingly accurate with KB blowers.
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.
|3.875||10||22||583 est.||486 est.||94-octane limit|
| ||Baseline ||KB, 8 PSI ||Baseline Vs. 8 Psi|
|RPM ||HP ||TQ ||HP ||TQ ||HP ||TQ|
| ||KB, 10 PSI||8 PSI VS. 10 PSI|