Words And Photos: Richard Holdener

One of the best methods to improve the performance of any motor is supercharging. Adding more air to the combination than the engine is able to ingest alone is a surefire route to extra power.

On the root-style, Weiand 174 Powercharger, this is accomplished by spinning a pair of rotors more than twice as fast as the engine. Each rotation of the rotors grabs a fixed amount of air through the carb and pumps it into the motor. The Holley supercharger is able to pump more air into the little 302 than the engine is possible of processing on its own, resulting in positive pressure in the manifold (boost) and a healthy dose of additional power.

The great thing about a supercharger is that it can be applied to just about any combination, from mild to wild. The supercharger can drastically improve the power output of even a stock 5.0L, like our test motor, with the blower on top and the short block on the bottom, what happens when you change the heads and cam in the middle?

To illustrate the power gains offered on a supercharged application, we assembled a dedicated test mule. Starting with a factory 5.0L, hydraulic-roller block, we combined a stock crank and rods with a set of JE forged (flat-top) pistons and Total Seal rings. The valve reliefs in the JE pistons allowed plenty of room for wilder-than-stock cam timing. For the baseline test, the fortified short block was equipped with a stock 1992 5.0L (stick) cam and factory iron E7TE cylinder heads. Basically, we had a stock 1987-95 5.0L long block with forged pistons. The induction system was anything but stock, as we topped the combo with a Weiand 174 Powercharger. In addition to the lower intake, tensioner assembly, and crank pulley, the kit also included a low-profile, 174 supercharger with the required offset drive to clear the Ford distributor placement. Topping the supercharger kit was a Holley 750 HP carburetor designed specifically for the supercharger.

The plan was to run the Weiand supercharged 302 with the stock 5.0L heads and cam, then replace those with aftermarket performance pieces. Would the supercharged motor respond well to the additional airflow offered by the aftermarket heads and cam, or does boost simply overcome those restrictions? Only one way to find out!

Equipped with the stock heads and cam, the supercharger produced a boost curve that started at 5.4 psi at 3,500 rpm and rose to a peak of 8.5 psi at 6,100 rpm. Boost supplied by the Weiand 174 allowed the 302 to produce peak numbers of 440 hp at 6,100 rpm and 435 lb-ft of torque at 4,600 rpm. The torque curve was naturally broad, exceeding 400 lb-ft up to 5,700 rpm.

After swapping out the stock heads and cam for a set of 170cc, Canfield aluminum heads and COMP XE266HR cam, the peak power numbers jumped to 494 hp and 467 lb-ft of torque. The free-flowing heads and cam also dropped the peak boost to 6.8 psi.

The final test involved a crank pulley change to increase the boost. Stepping the max boost supplied by the Weiand 174 up to 10.4 psi, the supercharged 5.0L produced 524 hp and 508 lb-ft of torque.

Having a Weiand supercharger on your small-block Ford is rewarding enough, but boost from the blower is just the beginning. This test illustrated the gains offered by adding a mild cam and ported heads to a supercharged 5.0L Ford. Equipped with the stock heads and cam, the Weiand supercharged 5.0L produced 440 hp at 6,100 rpm and 435 lb-ft of torque at 4,600 rpm (at a peak boost reading of 8.5 psi). After replacing the stock iron heads and 5.0L cam with 170cc Canfield aluminum heads and an XE266HR from COMP Cams, the peak power numbers jumped to 494 hp and 467 lb-ft of torque. The head and cam swap also dropped the peak boost pressure down to 6.8 psi. The final test was to (of course) increase the boost pressure with a pulley change. Stepping the boost up to a peak of 10.4 psi resulted in a jump in power to 524 hp and 508 lb-ft of torque.

Sources

COMP Cams
compcams.com

Holley/Hooker
holley.com

JE Pistons
jepistons.com

Lucas Oil
lucasoil.com

Total Seal Rings
totalseal.com