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Kenne Bell Supercharger Mammoth 2.8H Kit Upgrade
We Test Kenne Bell's Latest Mammoth Kit For '03 Cobras And Crank Out 643 RWHP With Pump Gas.
When we last spoke, our test Cobra was happily laying down 11.50s and making 471 rwhp and 503 rwtq thanks to nothing more than a few bolt ons and a pair of Nitto Drag Radials. The 2½-inch catted Magnaflow cross-pipe and MAC exhaust that we installed are still letting our neighbors know we're home, and the ported Eaton is making 16 pounds of boost to aggravate the local import tuner wannabes. But this month, we take things to the next level in the form of a Kenne Bell supercharger upgrade. But unlike other kits we've tested in the past, here we will sample the newest addition to the Rancho Cucamonga-based firm's lineup, called the Mammoth. Using KB's existing 2.8H supercharger unit with the massive inlet assembly from its Shelby GT500 kit, this new kit breathes serious life into the 4.6-liter '03-`04 Cobra.
Knowing Our Roots
For the 2003 Cobra, Kenne Bell first offered a 2.2-liter blower that later grew to 2.4 liters in displacement, and then to a full 2.6 liters with increased power potential following each size increase. Eventually a 2.8-liter and a higher-volume model, the 2.8H was introduced and tuners everywhere rejoiced. These larger kits made 700 rwhp Cobras nothing more than an afternoon bolt-on away. But now in 2009, KB has gone wild with its newest kit dubbed the "Mammoth" series. Taking its massive 2.8H blower, KB has introduced a mammoth inlet system (sorry, couldn't resist) to free up the power on the draw side of the supercharger to drastically improve airflow going into the case. This frees up power that would otherwise be lost by the power needed to "suck" in the outside air, and as a result, more power can be realized through airflow efficiency. All together, this new kit has been granted part number TS1000-03C-MAM with an MSRP of $5,299.
The key part to this new inlet system, which drastically changes the Cobra's original inlet path, is the huge 4.5-inch pipe that draws air from the driver's side rather than from the passenger side, like the factory had intended. While this is quite a radical change, it is justified. As Bell explains, "We looked at the flow limits of the passenger side wheelwell and realized that there simply wasn't enough air volume behind the fender when you reached 700 rwhp. Even if you cut the inner fender liner, the 1,200 cfm filter and blower inlet pipe would just start sucking in the bumper cover. After doing some research, we realized there was more air available on the driver's side so we began investigating this. As it turned out, this also allowed us to use the massive inlet and twin 75mm throttle body from our GT500 kit. With a 4.5-inch inlet pipe and mass air meter built in, we were able to package everything neatly and make big power in the process." Now, as Bell has explained, relocating the inlet to the driver's side brings about some other challenges, but none of them are too drastic. Several sensors and control solenoids need to be relocated as well as the most obvious item, the battery. Luckily, nothing is out of the realm for a good at-home mechanic, so we decided to take it upon ourselves to perform the installation in our well-equipped home garage.
Getting Blown At Home
After receiving the kit and laying out all the parts, the most important thing was to carefully read the instruction manual. Normally, we skip this step, but we wanted to take our time to better understand what was involved in working on a 4.6 Mod motor. The Kenne Bell team took the time to photograph every minute detail in the conversion to the Mammoth blower, so you get to appreciate what was involved in engineering the kit. Every step is fully explained and a little extra humor is thrown into the mix as well, making the installation easy to understand and of course, entertaining to read.
The first step is the obvious one--we had to remove the factory supercharger setup. Since we recently swapped on a ported Eaton on our Cobra, we already knew how to handle this. After about an hour of disassembling the array of metric and standard hardware, we found ourselves looking at a 32-valve long-block. The next step involved preparing the engine compartment to receive the massive new blower assembly.
If you are intending to keep your Cobra all-original for a future ground-up restoration, you should stop now. The reason why we say this is because there is some cutting of the factory sheetmetal required. But for the anticipated massive horsepower gains, we forged ahead.
The next order of business is to make room for the massive cast-aluminum inlet assembly that connects the rear of the blower case to the throttle body. The inlet is one of the key elements in the Mammoth kit, so clearancing the firewall is required. Simply trim the lip where the instructions tell you to, and move on to installing the blower assembly, with the intercooler, onto the intake manifold. Once it's bolted into place, break out the soldering iron because we're about to extend some wiring.
Since the design of the Mammoth kit relocates some key items such as the TPS (Throttle Position Sensor), Mass Air Flow meter (MAF) and the Idle Air Control (IAC) motor, you'll need to extend these connectors with the included wiring kit. Also, you'll need to replace the factory throttle cable assembly with the new supplied one and then perform some battery cable extending. Not wanting to take any chances, Kenne Bell gives a good background in the instruction manual on how to properly solder, seal, and re-connect the wires. In addition, the solenoids and vacuum control systems need to be carefully relocated to the firewall to make room for the humongous inlet piping.
The ginormous inlet pipe is what gives the Mammoth kit its name. Looking more like a sewer pipe that anything else, this 4.5-inch assembly connects the 75mm throttle body (that's two 75mm blades, by the way) to the air filter, which mounts in the inner fender. To make this all happen, you'll have to cut a hole where the battery tray used to sit and the template included makes it easy to perform. We used a small pneumatic reciprocating saw to make short work of the fenderwell area. With the tube positioned and in place, we clamped on the massive 1,200-cfm air filter from underneath after trimming the inner fender itself.
When you have this much air moving in, you'll need the fuel to match. Kenne Bell normally provides its Boost-A-Pump system to increase the voltage of the two factory fuel pumps for increased overall fuel system capacity, but in the end the factory 39-pound injectors are simply not up to the task of fueling this fire. So, we relied on the knowledgeable injector experts at RC Engineering in Torrance, California to help us. It was determined that a set of 750cc/hr injectors would fit our bill. Since RC Engineering only specializes in high performance, we knew that its balanced, matched and blueprinted set would help us achieve our goals (read the sidebar for more information.) With them installed, the injectors would provide the fuel as we climb the horsepower ladder.
Finishing up, we set the car up for 21 pounds of boost. To do so, we relied on a pulley system from Metco Motorsports, which allows us to vary the pulley ratios and of course, boost level. Metco's interchangeable lower pulley system allows you to alter the pulley ratio without using an excessively small upper pulley for adequate belt wrap for reduced slippage and greater reliability. In addition, Metco also offers improved billet aluminum idlers, which we decided to upgrade our Cobra with to provide more precise belt alignment and of course, eye candy. We started off with a 7.4-inch diameter crank pulley (0.1 inch smaller than stock) and used KB's 3.25-inch upper pulley, which incidentally, is the largest diameter unit that will clear the factory hood.
To the dyno we go
With our Mammoth bolted down, we cranked our Cobra over and were surprised to see how well it idled. Granted, the check engine light did come on after about 20 minutes of driving, but we later discovered that it was triggered because of the Mammoth's mass air meter readings, which were out of the range of what the stock PCM was expecting to see from the stock meter.
Using 93 octane pump gas, we drove our Cobra to Mustang Magic over in Deer Park, New York, to handle our tuning and dyno testing activities. Once there, Joey Lauzardo was able to match the KB meter to the RC injectors by using his EFI Solutions tuning software. By carefully monitoring air/fuel ratio with his wideband sensor stuck into our Cobra's tailpipe, we were able to lay down some real numbers that were not only safe, but drivable. Our goal was to tune strictly for pump gas to see what the car could handle in true day-to-day driving and then to turn up the wick with more boost and race gas.
The result after about five partial runs was a staggering 643 rwhp before we hit the factory rev limiter at 6,200 rpm. The horsepower curve was still climbing at an incredibly fast rate, however, we immediately witnessed our limit, which was fuel supply. With careful monitoring, thanks to the data logging capabilities of the EFI Solutions software, we were able to watch our fuel pump duty cycle peak at 100 percent by 5,800 rpm and by 5,900 rpm, our rail pressure was dropping. With 643 rwhp, we'd have to say that the limits of our 70,000-mile factory fuel pumps, even with the Boost-a-Pump, was not enough for us to carry on, even with race fuel. After looking at the dyno sheets and the parameters for fuel and timing, we decided not to tempt fate with an overly lean condition.
Now 643 rwhp may not sound all that impressive to the many Cobra guys, but keep in mind that this is a ton of power on an otherwise stock 2003 Cobra with the cast iron manifolds still in place and a "mere" 21 pounds of boost. With a gain of 172 hp at the wheels, the mathematicians in the crowd will notice that the percentage gain is a stout 37 percent increase in peak power. That's 739 hp at the crank, taking a 15 percent driveline loss into the equation. At 739, that's a solid 349 more horsepower than the factory 390-horse rating. Considering that we can do it on pump gas in a car that you can drive anywhere and do so reliably, that's just plain bananas.
If you look at the horsepower line on the dyno sheet, it is climbing at practically a 45-degree angle. This indicates boost pressure and horsepower are both still building and that we're nowhere near the limit. If we had better fuel pumps in our car and were able to add race fuel to our equation, making about 100 to 150 more horsepower is easily attainable at 26-28 pounds of boost. Seeing how Kenne Bell has been able to produce 778 rwhp on a stock lower-mileage Cobra, we think it's quite realistic to make that much power. At this point, we have plenty of injector, but without the fuel, it's not going to happen. Rather than just replace the stock pumps with exact replacements, we will investigate our options. The two most popular setups are the Focus RS pumps or Ford GT supercar fuel pumps and a wiring upgrade. Of course, there is also the billet hat alternative, which is a bit more labor intensive.
Once we do things right and upgrade our car with an appropriate fuel system, we will go after the horsepower we're missing and we'll try to put it down on the dragstrip. Luckily, it looks like we're going to need some more tires.
About Our Injectors
Injectors come a dime a dozen don't they? Often, we can find a set of 50s or even 60s on the internet for outrageously low prices, but we've often wondered just what we're getting. Sadly, some low-dollar options, which many Cobra owners tend to gravitate towards, are risky business as they often are not flow matched or even tested for reliability. If you intend to make big power and want to do so safely, this could spell disaster as we've seen plenty of meltdowns because of a failed injector.
In case you were wondering, there are basically two types of injectors--Peak and Hold, and Saturated. The former uses a low-impedance design and is often found on many European and some Asian vehicles, while the latter is used by many domestics, including Ford. Knowing that our stock 39-pounders were at their limit when we were making 471 rwhp, an injector upgrade was inevitable.
So while we were on the phone with Mustang Magic, Joey Lauzardo strongly recommended RC Engineering. For our power goals, we needed a stout injector, so we looked at the 750cc units that RC offers for the saturated-driver application, which is part number SH4-750 ($98.75 each). Roughly translated, a 750cc/minute injector shows the equivalent of a 71 lb/hr injector and requires no special injector drivers to run with its EEC-friendly 12.5 Ohm resistance.
Because Ford uses a standard Bosch-style housing for its injectors, the SH4-750 fits without any modifications. Since the RC injectors use an EV1 connector, a special wiring adapter is required to mate it to the Cobra's wiring harness, which has EV6 connectors. Luckily RC comes across this often and offers the appropriate adapter under part number CLIP-BCC for $17.25 each.
As you can see from our dyno test, our stock pumps simply couldn't keep up with the injectors as the huge RC units ran the fuel rails dry. Once we get the fuel delivery handled, we know that these injectors will be able to supply enough juice reliably for 800-plus rwhp. See you at the dyno.