Since the first automobile bounced down a cobblestone lane in a cloud of smoke, the internal combustion engine has continued to be refined. But despite the technological advancements that have been made over the years, gasoline engines, as we know them, are still basically air pumps. That means even with the technological improvements and regardless of how many carbs, injectors, cams, or valves they are equipped with, the amount of power produced is a direct result of how well they process the air required for combustion.
One of the limitations of most engines is that they rely on atmospheric pressure to fill the cylinders. As the piston descends on the intake stroke, a vacuum is created and atmospheric pressure causes air to flow through the intake tract, past the open valve, and into the cylinder. But atmospheric pressure varies with the weather and particularly with altitude. As a result, the same engine will run better at sea level-where there is more atmospheric pressure-than it will going over a 10,000ft mountain pass where the pressure is less.
Of course another factor that influences the in-with-the-good-air-out-with-the-bad scenario is the engine itself. Some engines are more efficient than others and that, of course, brings us to one of hot rodding's favorite subjects-the Ford Flathead. As if being at the mercy of nature and atmospheric pressure wasn't bad enough, Ford's venerable L-head is cursed with the automotive version of asthma; the convoluted intake tract doesn't allow the engine to breathe very well. But thankfully there's a cure, and that's a supercharger. Basically a pump that forces air into the engine, they may be exhaust driven, like a turbo charger, or engine driven like the Roots blower (named for the brothers that invented its supercharger).
Probably the best-known supercharger in hot rodding is the GMC Roots-style blower. Originally used on General Motors two-stroke diesels to blow fresh air in and exhaust out of the cylinders, when converted for use on a gasoline engine they pressurize the intake manifold so the engine no longer has to rely solely on atmospheric pressure to fill the cylinders. Commonly referred to as boost, blowers may supply as little as 4 to 6 lbs on a mild street engine, 10 or 12 on a heavily modified engine, or 20 to 40 lbs or more on a race engine.
One of the best-known names in the blower biz is Jerry Magnuson. The head honcho of both Magna Charger and Magnuson Products, he's made it his business to be on the cutting edge of supercharger technology. To that end, Magnuson began working with the Eaton Corporation in 1981, ultimately becoming the exclusive distributor and remanufacturer of Eaton superchargers for the automotive aftermarket.
Eaton superchargers are essentially a hybrid version of the twin-rotor Roots blower. What makes them unique is the twin counter-rotating rotors have a 60-degree twist that forms what is called a helix. This advanced rotor design, along with specially designed rear inlet and front discharge port, helps to reduce pressure pulses and improves efficiency over traditional Roots top-to-bottom superchargers. Another unique feature of the Eaton/Magnacharger supercharger system is a device called a bypass valve that reduces parasitic loss to less than 1/3 hp under cruise conditions.