Supercharged By Saleen

It's no secret that superchargers do wonders for late-model Mustangs. Boost equals horsepower, and in most cases it's just attach and go. We learned with the older 5-liter stuff that the sky's the limit in terms of supercharged performance, but when it comes to the modular engines, there are fewer hard-core aftermarket parts. So you're faced with adding bolt-ons, topping the package with nitrous, a blower, or any combination of the three.

Of those choices, supercharging ranks as one of the most economical on a horsepower-per-dollar basis. Of course, nitrous can produce serious power for a small initial outlay of cash, but eventually the bottle runs dry. This makes a shot of juice great for drag racing, but for an increase in power that you can tap into at all times, a blower is the way to go.

Recently, we had a chance to sample some supercharged Three-Valve performance in the form of an '05 Saleen S281 Supercharged ("Earning Its Chevrons," Sept. '05, p. 50). Acceleration was great, as the blown 4.6 made awesome midrange torque, and power carried right up to the 6,100-rpm rev limit. The increase over the standard 300-horse GT engine was due mostly to the Saleen Series VI Twin-Screw blower that features an integrated long-runner intake manifold along with a two-stage, water-to-air intercooling system.

According to Saleen, "The blower assembly contains twin screws, which push 2,300 cc of air per rotation [compared to 1,600 cc for the '04 Saleen blower]. As a result, the supercharger turns slower for equivalent boost, producing lower stress and lower air-charged temperatures. In addition, the supercharger portion of the assembly is mounted inversely, orientating the super-charger upside-down, thereby locating the outlet of the compressor above the intake ports of the heads. This allows for nice, long, straight runners, transporting the air directly into the combustion chamber with no restriction."

This system also sports an air inlet bypass, which allows air to bypass the blower at part throttle, which helps reduce heat buildup during normal driving.

Thankfully, Steve Saleen and his crew didn't forget about the rest of the Mustang population, and with that the company is now offering its blower kit for all '05 GT owners.

"With this kit we're going after the person who wants power and reliability," says John Spruill, a powertrain engineer at Saleen. "It's not a kit that is tuned on the ragged edge, but one that makes a great daily driver. Calibration is based on 91-octane fuel, and it will survive anywhere in America. It's also 50-state legal and the development is designed around meeting [Ford's] three-year/36,000-mile warranty."

When testing the first Saleen S281, we were surprised to see the system developed just 3.5 psi of boost, but according to Spruill, that's all Saleen needed to reach its goal of 400 hp. "We had an expectation of output, and the efficiency of the design allows for a lot less heat," he says, "so we are able to reach the performance goal with less boost. The kit is designed to make 4 psi. It would have taken a lot more boost with older designs to accomplish that level of power."

Realizing the performance potential, we decided to do our own install on a typical GT. And the timing was right as JDM Engineering was preparing to put Saleen boost to an '05 Mustang belonging to Downs Ford Motorsport's Joe Amato.

Prior to the install, Amato's GT was upgraded with JDM/Kooks headers, a Steeda cold-air package, and underdrive pulleys. The plan was to leave the exhaust and the cold-air, but we'd have to switch back to the stock pulleys to get full boost from the blower kit. In addition, JDM went with larger injectors and its own tune, rather than using the Saleen PowerFlash computer that comes in the kit.

The GT was chassis-dyno tested to get the obligatory baseline horsepower and torque figures. It performed nicely, making 315 hp at 6,000 rpm and 327 lb-ft of torque at 4,200 rpm.