Think supercharger and you might imagine a beefy, high-performance muscle car driven by a speed-hungry guy who believes having too much car power is like having too much money: impossible.
Think again.
How about a family car driven by a mother of three who wants engine efficiency and considers acceleration a safety feature?
Cleveland-based Eaton Corp., the world’s biggest producer of superchargers and one of the nation’s largest automotive suppliers, is enjoying supercharged success in its supercharger business, selling more of the auto-performance enhancers last year than ever before.
Sales of Eaton’s superchargers doubled from 1996 to 1997. And last year’s 150,000 sales accounts for almost one-third of all 500,000 superchargers Eaton has sold for production vehicles since 1989.
The sales increase, which has carried into this year, comes despite some confusion about what a supercharger is and how it works.
“Either they have no idea what it is, or they think it’s just for hot rods or racing,” said Dan Davis, Eaton’s manager of global automotive communications. “People (looking for increased power) have been taught for years to count cylinders and look at cubic inches. But they don’t have to.”
But while the buying public may just be starting to understand superchargers, carmakers are falling in love. Superchargers are sold as original factory equipment on General Motors’ Pontiac Bonneville SSEi and GTP, Oldsmobile 88 LSS, Buick Park Avenue Ultra and Riviera; Mercedes’ SLK; and Jaguar’s XJR. The supercharger also will be available for Ford’s F-150 NASCAR truck. Other car companies also are looking at using the supercharger.
Last spring, Buick held a press event in Arizona to showcase the benefits of its superchargers. And General Motors has billed its Pontiac Bonneville as the “Official Car of the Supercharged Family.”
A supercharger is basically a compressor that shoves air into the engine at high speeds. More air creates more combustion. More combustion means more power. A supercharger can increase engine power up to 50 percent.
And because a supercharger does not require any additional fuel, a supercharged engine operates more efficiently, said Ken Streeter, sales and marketing manager for Eaton’s supercharger division and one of the original engineers on the company’s first production version.
A supercharger can give a 4-cylinder engine nearly the power of 6 cylinders, but without the increased weight of a larger engine. And because a supercharger is engaged only about 5 or 10 percent of drive time, motorists still can enjoy the fuel economy of the smaller engine.
In the Mercedes SLK, the supercharger produces as much power and torque in the car’s 2.3-liter engine as in a 2.8-liter engine.
“Mercedes-Benz engineers selected supercharging to boost the car’s performance because they believe it can balance fuel consumption and low emissions,” Automotive Engineering magazine wrote in its January 1997 edition.
The common knocks on previous superchargers were that they were noisy, unreliable gas-guzzlers.
Not anymore, says Eaton’s Davis. Engineering changes have taken care of that.
The Eaton supercharger uses two counter-rotating rotors twisted 60 degrees, forming a helix. That design produces constant pressure and less noise. Each rotor has three lobs that interlock as the rotors rotate. Those rotors, which can spin at up to 12,000 r.p.m., are operated by a belt connected to the crankshaft.
When the supercharger is not boosting the engine, air goes through a bypass until the supercharger is needed again.
The friction caused by pumping as much as 550 cubic feet of air per minute into an engine causes heat. Hot air is less dense and therefore less effective in the firing chamber.
To cool the air before it reaches the engine, some superchargers have an intercooler attached to its own radiator.
A supercharger is not the same as a turbocharger. A turbocharger also compresses air going to the engine, but it uses turbine fans that function off the engine’s exhaust. The supercharger is connected by belt directly to the crankshaft.
Turbochargers produce greater maximum horsepower, but superchargers offer more torque at lower speeds. Also, the supercharger is easier to maintain and install and has an internal lubrication system.
Eaton developed its first helical, or twisted-rotor, supercharger in 1949. It was never developed–and not needed–because engine displacement and output grew in the 1950s and 1960s. But when the gas crunch hit in the 1970s, development picked up again.
Eaton began to fine-tune its supercharger concept in 1984 while working with Ford Motor Co. on its 3.8-liter engine. In 1989, the Ford Thunderbird became the first American-made car in 22 years to offer the supercharger. The car grabbed Motor Trend’s Car of the Year award.
Eaton controls about 75 percent of the worldwide supercharger market and has almost all of the North American market. About 95 percent of its sales are as original equipment, with the rest as aftermarket.
The supercharger costs $200 to $600 as original equipment and a little more as an aftermarket add-on, Streeter said. A complete aftermarket kit will cost about $2,500.
