Big Pullin'

When Accessible Technologies Inc. (aka ProCharger), introduced its line of centrifugal superchargers in the mid-'90s people sat up and took notice. Actually, we were so intrigued that we flew out to the Lenexa, Kansas, facility and got a close-up look at this interesting new line of superchargers. At the time, centrifugal supercharging was becoming the rage, but the new P600 ProCharger blower kit was a bit different. It was built to fit the popular 5-liter Mustang, but featured an induction-chilling intercooler that was, until then, mainly used with turbos. The intercooler allowed a stock engine to achieve high-boost levels and make big power, even on pump gas.

Not easily impressed, our staff asked for a test car so we could put the blower through its paces. On that trip to Kansas City we proceeded to drag test three ProCharger-equipped Mustangs with positive results. Months later we backed up the first test with another one and ran 11s with a virtually stock LX. Today, some 10 years later, ProCharger is a household name, at least in many Mustang households. Drag racers have won numerous championships using various ProCharger models and you see plenty of them stalking pitiable Camaros and Firebirds on the streets.

In addition to bringing horsepower to the Mustang public, ProCharger has also brought innovation to the centrifugal supercharger market, including intercooling and the self-contained oiling system used to lubricate the bearings and the transmission drive gears inside the blower housing. This system eliminates the need to tap into the engine's oil system and makes for a cleaner installation.

Recently though, the boys in Kansas took on the task of adapting a centrifugal blower to the '03-04 SVT Cobras.

As you know, the '03-04 Cobras are factory supercharged with a Roots-style Eaton blower that sits atop the engine and makes lots of power with simple bolt-on parts. So why would a Cobra owner replace the Roots-style unit with a centrifugal one? Well, like many of you, we wondered the same thing and we asked Dan Jones of ProCharger if he could successfully market a blower to owners who already have one.

"Actually, the fact that the Cobra is factory equipped with a blower is good for us because the engine is ready to go," stated Jones. "It's good because the engine comes with forged pistons, Manley rods, free-breathing heads and blower-friendly cams. Of course, the stock blower and the other Roots/screw blowers work well, but we're taking a different approach. Here's our advantage: We can make big power on pump gas, like over 600-plus to the tires. And it's softer power because we don't make all the torque at such low rpm, so you get the most amount of powerband power for the least amount of strain on the drivetrain.

"With the centrifugal blowers, there is also less thermal strain on the engine, because the high-helix centrifugal blowers are more efficient than a Roots or a screw at mid-range and high-rpm boost levels. Plus, there is less heat in the blower because it's not mounted directly to the engine."

But as we see it, the challenge for ProCharger will be to make big power and then convince Cobra owners to trade the awesome tip-in throttle response for all-out, higher-rpm horsepower. Fact is that Roots and centrifugal blowers have different characteristics, but that doesn't mean that one is better or worse.

Even with the tough challenge, ProCharger forged ahead and released a blower kit for the '03-04 Cobras. That first kit, which we covered in the May 2004 issue of MM&FF, is a bolt-on setup and it utilizes the P1SC-2 supercharger along with the factory intercooler and heat exchanger. According to ProCharger, the boost level for the P1SC-2 kit is about 15 psi, and it develops upwards of 575 hp to the tires.

And while this sounds impressive, you better keep reading because we just finished testing the F1A ProCharger kit and this baby screams.

"The F1A supercharger was built specifically for the Cobra and it's like a miniature version of the Pro-style blower used on Tony Gillig's 2003 FFW championship engine," Jones says. The compressor is cut from billet aluminum and features a high-helix impeller, a 5.73:1 step-up ratio in the supercharger transmission, and the self-contained oil system. And when used with a serpentine belt it carries a one-year warranty.

Both Cobra kits utilize the stock intercooler and heat exchanger, but the compressed air is pumped through a racy looking sheetmetal upper intake manifold. The P1SC-2 kit also includes a "flashed" computer (actually you have to send the computer to ProCharger), while the F1A kit must be tuned as per the application. As for performance, Jim Summers of ProCharger stated that the P1SC-2 kit is capable of making 14-15 psi of boost and 575 hp to the wheels, while the F1A kit can make 15-24 psi and that equals 575 to 650 hp--or more. Retail costs for the kits are $3,996 and $4,496, respectively. Additionally, ProCharger is about to release a Stage II kit based off the F1A that will feature sequential intercooling, an eight-rib drive, and will produce over 700 hp to the wheels.

Though the F1A kit has only been out for a short time, we we're anxious to get to the dragstrip and feel the power. Jones gave us the chance after installing a kit on ProCharger's own '04 Cobra, which only had 600 miles on the clock when we got it.

Before the test the Cobra was treated to a complete Bassani exhaust, a Ram 9000 clutch, solid 8.8 with 4.10 gears, Strange axles and an Eaton diff. The Snake also had a Steeda rear suspension, Tri-Ax shifter and Energy Suspension bushings. The front anti-rollbar was removed and Mickey Thompson slicks replaced the stock rear rubber. Lastly, 55-pound injectors were installed and the combination was tuned by Jimmy LaRocca of LaRocca's Performance (Old Bridge, New Jersey). Jimmy only had a few hours to dial in the Cobra, but he was able to coax 627 hp and 527 lb-ft of torque from the 4.6.

But we don't race dynos, so we headed directly from the shop to the track. Amazingly, ProCharger got the blower kit and all the aforementioned parts installed and to our drag session in just two weeks time. And while the car showed up a few hours late, the crew arrived with two sets of slicks, a mechanic, and told us to have at it. Now that's confidence.

On The Strip
As we said before, you may ask why anyone would trade the Roots-style Eaton blower for a centrifugal? We did too and we were skeptical, but Jones assured us that we'd soon be believers. He stated that while the Roots blowers can make big power, they do so at a cost and in some cases actually make, what he called, "unnecessarily high-peak torque at very low rpm." And this can make the car hard to drive and it is hard on parts, as many Cobra owners can attest. On the other hand, we've seen Kenne Bell-equipped Cobras running 10s at 133 mph at 4,000 pounds.

We went right to work with the silver Cobra, despite the hot engine. On the first run the engine bogged and we didn't powershift, but the Cobra still ran 11.83 at 123 mph. (The weather conditions for this early May test were abysmal, with temps in the mid-80s, high humidity and a low barometer.) We all agreed that the tall (28 inch) slicks killed some of the effective gear ratio and prevented the engine from revving quickly, thus limiting power. Remember, centrifugal superchargers rely on engine rpm to build boost.

So, we swapped out the 28s for a shorter set of slicks, in this case 26 inchers. Time was of the essence and we wanted to make a few more runs so we hopped back in without the benefit of a lengthy cool down. The shorter tires combined with a harder launch helped improve the 60-foot time from a dismal 1.91 on the first run to a 1.72 and the elapsed time plummeted to a much-improved 11.20, but unfortunately the speed clocks malfunctioned and we didn't get a mph reading. Though we didn't get a speed, I can tell you that the horsepower was unreal. It pulled and pulled and pulled, seemingly forever. I was really impressed. It didn't have nearly as much torque down low as a KB-equipped Cobra, but above 5,000 it ripped.

After a 30-minute cool down we were back at the line and we decided to raise the launch rpm from 4,000 to 5,000 rpm. The increased rpm helped as we improved to a 1.66 60-foot time and it was clear that this car was a player in the blower wars. Unfortunately, we slowed down and the e.t. was only 11.25 at 126.19 mph. While the elapsed time was still somewhat impressive we were not reaching the full potential of the ProCharged Cobra. The reason was simply a matter of getting seat time and finding where the engine liked to be shifted. So we kept on running.

It was getting late in the day, but that has never stopped us from flogging a test car. Nevertheless, time was running out (sooner than we might have thought) so Jones told us to go for it. He said to launch as hard as we wanted and to shift near the 7,000-rpm mark. When it comes to driving a car hard you don't have to ask me twice, so I jumped in and went for it. With the tach needle at 5,800 I dumped the clutch and off I went like a rocket. The Cobra's mill never bogged--instead it stayed in the powerband and pulled like an animal. I nailed a 1.67 short time and then snapped second at 7,000 rpm. Third gear came quick and the Cobra was cruising like a missile so I nailed forth. But in the next instant the Cobra's engine shut down and the acceleration slowed to a crawl.

My first instinct was that something blew up, so I clutched it, killed the ignition and looked in the mirror. I was relieved to see there was no death smoke and I coasted to the turn off and popped the hood. Thankfully, there was no engine damage, save for the drivebelt that was no longer attached to the pulleys. Apparently, the high-rpm operation was not friendly to the belt. And with that I started the engine and drove back to the pits, where Dan Jones and Jimmy LaRocca had already figured out what happened. Amazingly, the Cobra still managed an 11.29 at 111 mph. And when we took a closer look at the numbers we realized that the Cobra ran 7.14 to the eight-mile and that was .170-second quicker than the eight-mile numbers on the 11.20 run. This, we think, would have been an 11.00 or a 10.99 in the quarter, even though the eight-mile mph was down 5 mph, which LaRocca says is a sure sign the belt was slipping the whole run.

According to Jones, we exceeded the design limit of the six-rib belt system and the 3.60-inch drive pulley. At 7,000 rpm the impeller speed was 75,000 rpm, and he stated that 70,000 is the limit. Had we kept the engine below 6,500 rpm it's likely that the belt would have not only stayed on, but not slipped. And with that the Cobra would have probably run in the 10s at close to 130 mph.

The good news is that one week later we got another chance as Steve Baur hopped in the Silver Snake during the WFC 7. ProCharger installed a 3.70-inch upper for more grip, Baur kept the revs below 6,500, and was rewarded with a 10.99 at 130.37. Now that's big pullin!