A supercharger is the quintessential hot-rod part. It's that big, polished chunk of aluminum that sits atop an engine and exudes horsepower. The classic GMC-style supercharger is what most hot rodders think about when the discussion turns to blowers, but a new blower on the market now could be a threat to the Roots crown.
Whipple Industries has been quietly selling 12 different sizes of screw superchargers out of its Fresno, California, shop since 1988. Most of these have been tailored toward mild street applications for stock or mildly modified late-model fuel-injected engines. A number of theoretical advantages make the screw supercharger attractive. Foremost is the fact that the screw supercharger is a true air compressor. Roots blowers are aptly named since they blow air, creating boost in the intake manifold by moving more air than the engine can use. Conversely, a screw supercharger actually compresses air as it moves through the mating halves of the screw supercharger. This makes the screw supercharger more efficient than the Roots blower. The improved efficiency means the blower can make more power with the same amount of air because of increased manifold density.
The limitation of the Whipple screw supercharger, until now, was that it was too small to move enough air to make serious horsepower. Combined with a design that required the use of electronic fuel injection, the Whipple was limited to mild-blown applications. But now Whipple has combined forces with the Swedish Lysholm Technologies company to create a bigger screw supercharger that moves more air—a bunch more.
To demonstrate the potential of this bigger screw supercharger, Art Whipple bolted one of the new 2100R, 2.1-liter-per-revolution blowers on a 355 small-block Chevy. Testing took place at Ken Duttweiler's dyno in Saticoy, California. According to the folks at Whipple, the engine ("Nothing special, just something we had lying around") is based on a 0.030-over 350 Bow Tie block, a Velasco steel crankshaft that uses Carrillo steel connecting rods, 7.5:1 compression forged JE flat-top pistons and single-moly rings. The heads are a set of Brodix aluminum -8 heads with a midsize 185cc intake port fitted with 2.02/1.80-inch stainless valves. The larger exhaust valve is used to help scavenge the increased cylinder pressure. Valve action is controlled by an Erson hydraulic roller cam featuring 234 degrees at 0.050 duration and 0.510-inch lift for both the intake and exhaust using Erson 1.5:1 roller rockers.
The Whipple blower for this test was bolted to the carb flange of a stock Edelbrock Torker II Dominator intake manifold, which then supported a Carburetor Shop 1050 Holley Dominator carburetor. Completing the engine was a set of Hooker 1 3/4-inch headers flowing through a pair of Borla stainless-steel 2 1/2-inch mufflers. Ray Zeller of Whipple Industries built the engine and helped with mild tuning while on the dyno.
After the engine was checked out for proper jetting and timing and the 100 octane VP unleaded race gas was added to the fuel delivery system, Duttweiler was ready to pull the handle on the Digilog dyno. We've witnessed plenty of blown motors make gobs of horsepower, but this one really surprised us. By the time Duttweiler and Zeller were through tuning, this 355 cranked out a tire-melting 705 lb-ft of torque at 3,900 rpm and an awesome 632 horsepower at a low 5,400 rpm. These are killer big-block power numbers from an otherwise mild 355. While we did not perform a normally aspirated power test, this engine would easily be capable of 425 to 450 horsepower, which means the bolt-on Whipple blower was worth a stout 40 percent power increase.
Looking at the cam specs, a dual-pattern cam and perhaps greater valve lift would have added more power, but the real story is the ease with which the power was obtained. The Brodix cylinder head certainly helped make this awesome power, but the bottom line is Whipple has made a powerful statement with this new 2100R screw supercharger. If nothing else, it will certainly put the screws to your no-power blues.
