Evan J. Smith
Mustang360 Network Content Director
December 1, 2007
Photos By: George Trosley

In the modern-performance era, horsepower comes easier than it used to. A big breakthrough for Mustang fans came in 2003 with the 390-horse Cobra, which introduced factory supercharging to the Mustang. More importantly, in doing so, Ford provided the foundation for owners to push for over 600 proud ponies at the wheels, all with a stock long-block.

Whipple Superchargers' new twin-screw 3.4L blower is one bad mofo, capable of supporting 30 pounds of boost and about 1,000 hp.

We now have the '07 Shelby GT500, which reaches a once-never-dreamed-of level of factory performance with a Four-Valve supercharged 5.4 powerplant, which makes 110 additional horsepower over the Terminator and more than double the power of the 225hp 5.0L workhorse. While impressive, those 500 ponies just aren't enough for some owners.

Enter the vast array of aftermarket companies dedicated to Ford performance, one being Whipple Superchargers, which recently introduced its huge 3.4L bad-boy blower for the GT500. Thankfully, kicking up the power of a Shelby or other late-model Ford is a simple matter of adding boost, a shot of go-juice, or both. As we see it, the question is not, "Do you add power," but "How much?"

The Shelby is a clean slate because there's so much potential left in the stock combination. One could simply add a free-flowing exhaust, a flash-tuner, and a smaller blower drive pulley (the very mods our tester had) to add about 100 hp. To unlock the full potential of those 5.4 liters, though, what you really need is a bigger blower.

There are already a few aftermarket blowers out there, but the newest is the big 3.4L Whipple, officially dubbed the W210ax. The catch, for those who have tried to install one, is that this particular unit is so big, it won't fit under the stock hood-until now.

"For this kit, we utilized our W210ax twin-screw blower, which has 210 ci as compared to the stock hybrid Eaton that is sized at 122 ci," says Dustin Whipple. "We use a Teflon coating on the rotors, which creates less drag and less parasitic loss. It also helps improve airflow through the blower and keeps the rotors cooler. If you use our Whipple throttle body, mass air meter, and air kit, the blower is a 50-state-legal item.

Before slapping the Whipple into place, we ran a dyno test to see how much power the Shelby GT500 was making. It produced 530 rwhp with the addition of a JDM flash tune, a JDM cold-air kit, and a MagnaFlow after-cat exhaust.

"It's currently the biggest supercharger available on the market [for the GT500]. This means it's turning 4,000 rpm slower than its closest competition, and the lower compressor rpm equals lower discharge temperature and reduced parasitic losses. It works with factory or aftermarket air-inlet systems and has optional pulleys from 4.0 to 2.75 inches."

In the months to come, Whipple will offer a 2.9L kit for the GT500, and it will fit under a stock hood with no modifications. We wanted to go for the big one, however. Fortunately, JDM Engineering in Freehold, New Jersey, has the solution to make it work, and soon Whipple is likely to be offering the JDM kit as part of its package.

Shortly after, we got to the task of removing the stock blower. First, we disconnected the battery; then we removed the air inlet and the throttle body.

As we learned, finding 650 hp is not hard to do with this blower. In fact, the W210ax is capable of supporting about 1,000 whopping ponies. All the action takes place around the Whipple W210ax twin-screw compressor, which has the ability to run nearly 30 pounds of boost.

"First of all, we believe in the durability of Whipple-style superchargers," says Jim D'Amore of JDM Engineering. "Our customers wanted this particular unit to fit under the factory hood. These cars are special, and people want to keep the stock look, and that means retaining the stock hood. Our first customer, former Pro Stock racer Don Beverly, had Purvis Ford drop off the car and said give him as much power as we could. We started with 575 rwhp on pump gas and 605 on 100 octane, but that wasn't enough. He also wanted the stock hood, so we started doing the fabrication and engineering. I got the idea [to lower the engine and raise the body] from Ford.

"Ford put spacer blocks between the K-member and the body, with front lowering springs to fit the 4.6 Four-Valve under the stock '93 Mustang hood during the original engineering phase, and that car ended up in my hands and on the cover of MM&FF. Essentially, you're raising the body in the front and using springs to bring the ride height back. We also use drop motor mounts. We raise the body 1/2 inch and drop the engine 1/2 inch, and drop the front antiroll bar mounts 1/2 inch where they connect to the chassis. Other small mods are necessary. For instance, we have to shorten the coolant hoses and do a few other things."

Side by side, you can see that the Whipple out-guns the stock Eaton.

With all this potential on the table, we decided to put one of these blowers to the test. Todd Rothschild dropped off his GT500, a white model with blue stripes, and the JDM gang got to work hammering out the install, which is anything but conventional.

After a few days of work, the blower was in place, and a turn of the ignition key brought a sweet rumble and a whine from the huge, white, powdercoated Whipple. JDM also added a set of Ford Racing Performance Parts' blue valve covers, which brightened up the engine bay.

It wasn't long before the Shelby was strapped to JDM's Dynojet, where we put the Whipple to the test. D'Amore went easy at first to ensure that the air/fuel ratio was in check; he then dropped the hammer for a full pull.

Naturally, we first set a baseline before any wrenches were flung, and the Shelby, which had a 2.80-inch upper pulley, a MagnaFlow after-cat exhaust, and a JDM air kit and tune, rolled the Dynojet to the tune of 530 rwhp. With the Whipple in place, we saw 642 rwhp with the supplied 3.500-inch drive pulley. We swapped on the slightly smaller 3.373-inch pulley and traded the 93-octane gas for a stiffer mix of 103. With that, the GT500 belted out an impressive 708 rwhp at just over 6,000 rpm. Amazingly, it did so with stock exhaust manifolds and a stock throttle body, which Dustin Whipple and D'Amore agree is now a big restriction.

While 700-plus horsepower is enough to motivate the Shelby, Rothschild wants more, so you can look for us to install Whipple's monoblade throttle body that's capable of 1,900 cfm, along with a set of headers to push this 5.4 even higher. The question now is, "How high will it go?"

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