As Gordon Murray, the South African engineer who designs Prost's cars, describes it, ''The extreme centrifugal forces, added to the violent vibration and noise of the engine, makes driving a Formula One car like riding inside a washing machine, or being strapped to a bad roller coaster, for two hours.''

When he is passing on a straightaway, Prost's engine can reach more than 13,000 revolutions per minute, while his own heart revs up to nearly 200 beats a minute -roughly the same pulse rate as an Olympic sprinter in the 100-meter dash. In Rio de Janeiro, when the outdoor thermometer reads 100 degrees, the temperature inside his cockpit can reach 160 degrees. Inside this thundering kiln, the sinewy, 5-foot-6-inch Prost sheds up to 9 of his 125 pounds during a two-hour race. ''In the midst of all that violence and force,'' says Murray, who is one of Formula One's top designers, ''Alain can feel the slightest quirks in his car. He has a knack for coming into the pits and explaining quietly and quickly to the mechanics precisely what's wrong.''

THE GOVERNING body of Formula One racing is the Federation Internationale du Sport Auto (F.I.S.A.), which sets standards for the racing cars: turbocharged racers must weigh at least 1,200 pounds and their engines can be no larger than 1,500 cubic centimeters.

Last March, F.I.S.A. began a long-awaited crackdown on the sometimes-lethal turbocharged engines. Popularized in Formula One racing by Renault, the turbocharger recycles the engine's own exhaust through a turbine capable of forcing several times the normal amount of air and fuel into the combustion chamber, thus multiplying the engine's horsepower. For years, these octane gluttons have powered the lightweight Formula One cars - ''the equivalent'' says one pit-crew member, ''of strapping a Peterbilt engine to a motorbike.''

In an effort to curb the danger, and the spiraling costs of these machines, F.I.S.A. has decreed that turbo engines be outlawed by 1989; in the interim they will be fitted with ''pop-off valves,'' (Continued on Page 90) which spill off excessive turbo boost. While F.I.S.A. still places no limit on expense - Prost's 130-member British McLaren team and its major sponsors, Marlboro and Shell Oil, spend as much as $2 million per race - no car is allowed more than 195 liters of fuel (slightly more than 50 gallons) during each race.

The impending disappearance of turbocharged engines does not seem to worry Prost much. ''During the last decade, Formula One has gone through various fashions: radial tires, aerodynamic design, space-age materials like carbon fiber, and now turbos,'' he says. ''Going back to atmospheric engines should be no problem. The technology moves so quickly in this business that we may soon be able to squeeze the same power and excitement out of the normal cars.''

WHEN PROST first came on the circuit seven years ago, cheeky mechanics derided him as ''The Little Frog'' and scrawled ''Tadpole'' on the side of his car. Now, Prost is called ''The Professor,'' less for his wild haircut than for his implacable tactical genius. Like a chess grandmaster, he calculates, laps in advance, his opponents' moves, gearshifts, turbo boosts and passing attempts. In one race, Prost's digital fuel gauge blanked out; so he mentally computed - to the drop - his gasoline consumption, readjusted the turbo boost and took the checkered flag as his tank ran dry.