The PEPCO

The Pepco supercharger is a kit that the Progressive Engine Products Company, Inc. (P E P C O) designed and marketed for VW cars in the United States as early as 1950. The compressor was designed and put into production by Emmer Kelley and Arthur Hilf, who worked in the Porsche dealership of Lou Fageol, a famous hydroplane racing pilot originary from the U.S. West Coast.

The hand typed mounting instructions that accompany the kit are presented on a « stencill » copied folded folio and are as simple as the compressor itself and as the ancillary parts that compose the kit. The designers of this VW supercharger knew what they were doing. 

Simple, efficient and reliable, what else can one ask of a boost accessory ? Oh, you also require it to be good-looking ? Well, you be the judge, just check the pictures of this vampiress among my superchargers collection.

Being a Roots type blower, the Pepco owes its splendid reputation to its capacity to be rev’ed up like no other VW blower. Just ask the guys in the sandrails and bajas or the drag strip fellows, they have spinned these tiny poor creatures without mercy for years obtaining quite impressive boost. Of all the VW superchargers, the Pepco mounts the smallest diameter pulley. 

On normal daily driving operation the unit can turn at up to 8K rev/min, thanks in part to the big crank pulley that fits on top of the original crank pulley using a slightly longer crank bolt, a solution Judson adopted some years later.

The internals are formed by two three-lobe rotors, in extruded aluminum, like on a MAG compressor. The casing and the two end plates are cast in aluminum. This all aluminum construction gives as a result a light weight compressor.

The crankcase is in the front, right behind the pulley – note that the MAG has the crank case in the rear end of the blower. In the case there are the two cogwheels that synchronize both rotors, in a 40 to 50 SAE oil bath, the front bearings are lubricated by this same oil, too.

The rear plate hosts the bearings only, if non-lubricated bearings are used one may forget about the rear part of the blower, which, by the way, falls almost flush with the air fan shroud tin when installed on the 36 hp VW engine.

Some have installed Pepcos in bigger later engines with success. Larger pulley ratios, multiple carburetors, custom positioning of the blower in relation to the engine, all this and more is possible with a Pepco. Its small size plays in favor of its adaptability.

It had a drawback. The kit, as sold in its original configuration had a defect of design: the top of the Solex 28 PCI carb sitting on top of the blower ended up just one finger bellow the decklid. This is why the kit was marketed without an aircleaner. And many VW owners of 1955 and the following years did not appreciate this somewhat serious inconvenient, some nodded their heads and decided to purchase the Judson kit instead. A few trusted the possibilities of this kit and installed it in their cars, simply covering the carburetor inlet with a small handmade cushion of wire mesh and cloth, imbibed in oil, that worked as the air cleaner.

There were two sizes of Pepco blowers:

- the 4 inch model that was marketed for VWs as a kit and for the Crossley marine and motor car engines. The Crossley ones had a snout that rigged the pulley some 2 inches away from the front end plate. The 4 inch model (the VW kit) was also used to supercharge the early Porsche engines, it required a special inlet manifold for that application.

- the 6 inch model that was intended for MGs and some late Porsche models. All elements and parts of both blowers are interchangeable, except for the rotors and casings that have different lengths on each model.