Twin-screw Supercharger Install - Kenne Boss
Witness the first twin-screw supercharger installed on a ’12 Boss 302
From the October, 2011 issue of 5.0 Mustang & Super Fords
By KJ Jones
There's no doubt we've been on an incredible roll of sorts, with a steady stream of '11-'12 Mustang tech articles here in 5.0 Mustang & Super Fords. While our aggressive pursuit of the latest hotness is in part credited to this magazine's title, we admit the experiments we're doing-especially those that involve increasing Coyote engines' horsepower output-can almost be likened to an addiction.
Some opportunities, such as cover exposes of both the Coyote 5.0 engine (Mar. '10) and its even-badder little brother, the '12 Boss 302's RoadRunner (Aug. '11), have come about thanks to good timing and the perfect alignment of the proverbial stars; others were made possible with the help of Mustang performance shops around the country.
For the sake of science (and marketing), shops have invested time and funds in exploring the performance potential of the newest Pony and its engine, progressing through the upgrade spectrum with a variety of bolt-on parts and improvement systems. Nelson Whitlock, Fred Cook, and their team at Evolution Performance are an ambitious Mustang-performance business. They're always ready (and willing) to try something new-especially if it's cutting edge and ultimately results in a stock 5.0 making unbelievable steam.
While we're of the attitude that no late-model 'Stang is so hallowed that it shouldn't be modified (case-in-point, upgraded '93 Cobras, Big Steve's PVT, and KJ's T-top coupe), we do acknowledge there are some enthusiasts who believe specialty cars should be left alone. However, we were presented with a chance to be the first Mustang magazine to have a go at supercharging a '12 Boss 302 Pony (number 127 of 4,000 cars being made), and as you'll see when you read this report, we really mean it when we say no 'Stang is "that sacred."
That's right-with the help of the teams at Evolution Performance and Kenne Bell, our latest effort involves implementing forced induction on the high-profile bad boy in Ford's 5.0 Mustang lineup. In this case, Kenne Bell's 2.8 Twin Screw is the air inducer of record, and Andy Caufield's bone-stock Boss is the testbed.
If you're saying to yourself, You guys have already tested the KB, yes, we have evaluated what the Mammoth can do on a stock Coyote. Contributor Tom Wilson worked with and reported on the unit for our May '11 issue ("Coyote vs. Condor"), and at 15 psi, the liquid-cooled Kenne helped churn 710 peak horsepower and 553 lb-ft of rear-wheel torque on an otherwise-untouched 5.0 Pony. Since RoadRunner 5.0s pack a lot more punch than their GT brethren, we're anxious to see what happens once the strong wind of a 2.8 Kenne starts blowing through its cylinders.
While the intake-manifold change in this effort is obvious, bolting the Mammoth twin-screw supercharger on a Boss 302 involves working around some of the blower system's installation instructions, as they were written for GTs long before our idea for this particular stunt came about. This being the case, we turned to Evo top wrench Chuck Wrzesniewski and calibration ace Jon Lund to put all the pieces in place and pour on the coals come dyno time.
It's time to get on with our feature presentation, which includes photo highlights of the install and the all-important rundown of our test Boss's rear-wheel performance on the Mustang chassis dyno at Evolution Performance.
Horse Sense: While being present when a Coyote 5.0 engine wails at 7,000 rpm during a dyno session is exhilarating, listening to a Boss version sing at high revs is something that can only be described as something that is truly out of this world. Video clips from this landmark project are on our website (www.50mustangandsuperfords.com). Click on one, then close your eyes and enjoy the experience.
Nicknamed RoadRunner, Boss...
Nicknamed RoadRunner, Boss Mustangs’ 302ci engines are unique in their internal makeup (CNC-ported heads w/bigger valves, higher-lift exhaust cams, forged crankshaft, pistons and rods) despite having the same cubic-inch displacement as the Coyote 5.0s of Mustang GTs...
...The Boss 302 intake manifold—which...
...The Boss 302 intake manifold—which features each vehicle’s serial number—stands out as the big external difference between the two bullets.
This is the parts assortment...
This is the parts assortment that comes with a Kenne Bell 5.0 Mustang supercharger system. Leading the collection is KB’s 2.8 Mammoth (despite this name, the 2.8 is the smallest blower in the Mammoth family) Twin Screw. The all-billet piece features 4x6-inch rotors and liquid (water) cooling for lower inlet-air temperatures and to help keep the blower’s bearings, rotors, and other internals happy when boost reaches the 18 psi we’re anticipating in our test. We’re trying an assortment of steel blower pulleys in this effort, starting with a 4-inch wheel and working down to a small 3.25-inch piece that should make things interesting.
On the Dyno
Our dyno session with the Kenne Bell 2.8 Mammoth installed on Andy Caufield's '12 Boss 302 ultimately proved more of a challenge than any of us expected. However, ace tuner Jon Lund (www.lundracing.com) battled and eventually defeated an imbedded command that forced the throttle shut just as the blower was hitting its sweet spot on several runs.
As the results show, the big KB is no joke whatsoever on the Boss 302. Once tuned (we used VP Racing Fuels' C-16 blend), the blower easily makes killer power across the entire 2,500 to 7,000-rpm rangeùwith either pulley installed. Interestingly, peak torque from the twin-screw-blown Boss is reached at approximately 6,000-6,200 rpm, roughly 1,000 revs past the peak for Coyote 5.0s equipped with the same supercharger. We attribute this difference to the Boss engine's superior breathing and Jon's ability to manipulate the valve events specifically for exhaust.
Yes, we did fall just shy of making 800 hp at the rear wheels. However, if you're thinking 785 hp is "it" for this combination, you're horribly mistaken. What we learned in this exercise is that the '11-'12 5.0 Mustang's mechanical-returnless fuel system understandably has a limit. A lack of fuel at the higher side of the rpm range ultimately led us to stop just shy of eight-hundie, as there was no way to compensate for dangerously lean air/fuel ratios.
Bolting a Kenne Bell blower on a stock Boss 302 instantly gives the specialty 'Stang even more street cred than the Pony has in its original trim. On the street, stock rubber doesn't have a prayer in First, Second or Third gears. However, once the tires actually do grab, acceleration is furious and the speedo is well beyond 100 mph in seconds.
Here are the Baseline numbers...
Here are the Baseline numbers for our test Boss 302. Andy Caufield’s Competition Orange Pony came to us with the window sticker barely removed, and laid down stout rear-wheel power and torque on Evolution’s Mustang chassis dyno.
The KB 2.8 with a big throttle...
The KB 2.8 with a big throttle body and 3.5-inch blower pulley raised horsepower considerably on our otherwise-stock Boss. At only 16.6 psi of boost, this 723 hp had us hopeful that we might see 800 with more boost.
The final dyno pull, made...
The final dyno pull, made with the smallest (3.25-inch) pulley in our collection, brought us just short of the magic number with 18.5 psi of boost. However, we discovered that this mark is at the horsepower/torque plateau for a Boss 302’s factory fuel system, even with a Kenne Bell Boost-a-Pump assisting it.
|Baseline||3.50-inch Pulley||3.25-inch Pulley||Difference|
Parts removal includes the...
Parts removal includes the Boss ’Stang’s front fascia, strut-tower brace, battery, airbox, radiator/reservoirs, fuel injectors, belts, hoses and of course, intake manifold. While installing Ford Racing Performance Parts’ Boss 302 replica intakes is now a popular upgrade for 5.0 Mustang GT owners, Andy’s serialized real-deal piece definitely is a keeper.
OEM knock sensors are retained,...
OEM knock sensors are retained, but the wiring harness must be trimmed and repositioned in the engine valley before the blower’s intake manifold is installed. Kenne Bell specifies using aluminum tape to secure the harness and shield it from excessive heat.
Don’t be deceived by what...
Don’t be deceived by what appears to be a simple placement of the blower’s cast-aluminum manifold. An intercooler that supports 1,400 hp is incorporated into the Mammoth’s intake, which makes it pretty heavy. The task really should be handled by two people (unless you have he-man strength like Chuck).
In Evolution Performance’s...
In Evolution Performance’s previous work with Kenne Bell superchargers and Coyote 5.0 engines, one particular NGK spark plug has proven the preferred igniter for high-boost/big-horsepower applications. Evo Fred was tight-lipped when we asked for the specific part number, but he did share the gapping specifics: 0.028-inch for each plug.
Modified fuel injectors of...
Modified fuel injectors of 75-lb/hr are Evolution-specific components used for all '11-'12 Mustang supercharger applications. According to Fred, the Boss’s OEM 47-pound squirters can’t support horsepower beyond mid-500s at the rear wheels, and 80-lb/hr injectors are too big. With an otherwise-stock mechanical-returnless fuel system, the Evo injectors maintain static 55-psi fuel pressure, without surging or other idling issues. We’re testing the blower using VP Racing Fuels' C-16 race gas and also installing Kenne Bell’s Boost-a-Pump as part of this project. Enhanced fuel octane and pressure are insurance against detonation when boost increases.
An alternator-pulley swap...
An alternator-pulley swap is required when installing a KB on a Boss 302 engine. The pulley diameter doesn’t change; the new wheel simply is an eight-rib piece.
The crankshaft pulley is the...
The crankshaft pulley is the only other pulley that requires upgrading to eight-rib. Kenne Bell offers a stock-diameter piece that is machined with two additional ribs, but we’re using ATI’s 10-percent overdrive crank damper on Andy’s Boss. Previous tests on Coyote-5.0 ’Stangs have found the larger-diameter pulley is necessary when boost exceeds 15 psi.
This is Kenne Bell’s beautifully...
This is Kenne Bell’s beautifully machined mounting plate for the blower system’s idler and tensioner pulleys. The plate is specific to eight-rib idlers, with provisions for mounting each one in positions that will achieve optimum belt tension with various sizes of blower pulleys.
Kenne Bell’s air-to-water...
Kenne Bell’s air-to-water heat exchanger slips behind the Boss 302’s front bumper without much fanfare, as there is basically no difference in the ’11 and ’12 Mustangs’ structure in this area.
The only wiring involved in...
The only wiring involved in this project is for the heat-exchanger pump (harness included) and the intake-manifold-mounted IAT sensor, which Chuck links with the IAT2 pin in the PCM circuitry.
OK, this is the part where...
OK, this is the part where Mustang purists need to look away. No, your eyes are not deceiving you. Using Kenne Bell’s templates for reference, Chuck lays the air saw into the Boss 302’s driver-side inner fender. Cutting the car is something that can’t be avoided with this system, as openings are necessary for the blower’s massive 4.5-inch air-inlet tube, which passes downward through the engine bay and out to cool, fresh air.
The 2.8 is also a heavyweight...
The 2.8 is also a heavyweight (combined intake/blower weight is approximately 75 pounds—most of that being manifold), but can be placed down in one shot if you’re careful.
Pulley changes—in this case,...
Pulley changes—in this case, from 4.00 to 3.50 inches (and eventually 3.25-inch)—are easily handled using Kenne Bell’s Bell Pulley Wrench, which locks into the two small holes in the face of the pulley, and a hex wrench to remove the single bolt that secures the wheel. Mammoth twin screws can be used with pulleys that range in sizes starting at 4 inches and work down (in 1/8-inch increments) to 2.75 inches.
Tuning master Jon Lund is...
Tuning master Jon Lund is known throughout the Mustang nation for his mastery of the new Mustang’s engine-management system. While the Boss 302’s Copperhead PCM includes a lot of Coyote’s engine logic, Ford calibration engineers loaded controls for RoadRunner-powered ’Stangs with, for all intents and purposes, a ton of new coding that presents totally new challenges for tuning and making power. Jon uses experimental tuning software to create custom 5.0 calibrations. “This is a developmental product that is currently able to calibrate and datalog any ’96-and-up Ford, including the ’12 Boss 302. It’s similar to other software on the market, but offers a much wider range of parameter selection and tuning capability,” Jon explained.
With the blower installed...
With the blower installed and bolted down, reassembly is basically a reversal of the disassembly procedures (for the factory pieces that were removed). However, a billet bypass valve and tubing, inlet-air tube, and billet throttle body are the Kenne Bell pieces that are added at this time.
Kenne Bell only uses high-grade...
Kenne Bell only uses high-grade steel pulleys with its superchargers, as the company’s tests found that softer aluminum wheels don’t stand up to the heat and friction a blower generates. While our initial plan was to test with this piece, the call for really big steam (more than 700 rear-wheel horses) led us to opt for smaller pulleys once we strapped the Boss on the dyno.
There is a bit of a variance...
There is a bit of a variance between mods that are required for the EVAP sensor on an ’11-’12 GT and that on a Boss 302. While the sensor’s wiring layout doesn’t change on the Boss and is extended on a GT, the Kenne’s huge intake elbow warrants trimming the EVAP’s tubing considerably for proper fitment in the Boss’s engine bay.
Kenne Bell has developed this...
Kenne Bell has developed this cool 168mm, single-blade throttle body for 5.0-Mustang applications. The new TB is designed with mechanical and electronic components positioned on the same side of the unit, making it plug-and-play with an ’11-’12 GT’s standard throttle-body harness after the factory electronics module is swapped. 5.0