Muscle Mustangs & Fast Fords
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.
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.