NHRA Classes Explained
NHRA.com - Top Fuel, Funny Car, and Pro Stock are just three of the more than 200 classes of vehicles featured in NHRA competition. Those classes are grouped into 12 categories, or eliminators, each strictly governed by NHRA rule makers. Class eligibility is based on various requirements and specifications, including type of vehicle, engine size, vehicle weight, allowable modifications, and aerodynamics.
The four Professional categories are Top Fuel, Funny Car, Pro Stock, and Pro Stock Motorcycle. They, along with Top Alcohol Dragster and Top Alcohol Funny Car and the three "Super" classes – Super Comp, Super Gas, and Super Street – feature a single class of vehicle in heads-up competition. The remaining categories – Comp, Super Stock, and Stock – are made up of a variety of classes and use a handicap starting system to equalize competition.
Top Fuel
Among the fastest-accelerating machines in the world, 7,000-horsepower Top Fuel dragsters are often referred to as the "kings of the sport," and with good reason. They are capable of covering a quarter-mile in 4.4 seconds at more than 330 mph.
Powered by a supercharged and fuel-injected 500-cubic-inch adaptation of the famed Chrysler Hemi engine, Top Fuel dragsters can burn up to 15 gallons of nitromethane fuel during a single quarter-mile run. Constructed of chromoly steel tubing and carbon-fiber composite, Top Fuel cars are 25 feet long and weigh 2,250 pounds in race-ready trim.
Funny Car
Similar to their Top Fuel counterparts but with a shorter wheelbase and a carbon-fiber body that loosely resembles a production-based automobile, Funny Cars routinely run in the 4.7-second range and are capable of speeds in excess of 330 mph.
Funny Cars are powered by the same supercharged and fuel-injected 500-inch engines as Top Fuel dragsters. Funny Cars are also similar to Top Fuel dragsters in that they do not use a transmission but rather transmit power to the huge Goodyear rear slicks through a multistage clutch assembly that is activated by timers.
Pro Stock
Often called "factory hot rods" because of their resemblance to production-based automobiles, Pro Stock cars are some of the most technologically advanced machines in drag racing. Built around a sophisticated tube chassis and four-link rear suspension, Pro Stock cars must conform to precise measurements and weigh no less than 2,350 pounds.
Pro Stock engines use two carburetors and spec gasoline and are restricted to a maximum of 500 cubic inches. They can rev to more than 10,500 rpm and make in excess of 1,300 horsepower. A competitive Pro Stock car can run in the 6.6s at more than 208 mph.
Pro Stock Bike/Motorcycle
These highly modified vehicles, which can run under seven seconds at more than 195 mph, feature a purpose-built tube chassis and a lightweight, aerodynamically enhanced replica of original bodywork. The class features a wide variety of makes, models, and engines, including V-Twin entries from Harley-Davidson and Buell and inline four-cylinder-equipped Suzuki and Kawasaki models.
To ensure a level playing field, pushrod-equipped V-Twin engines are limited to 160 cubic inches, and the high-winding four-cylinder engines cannot be larger than 101 cubic inches. Fuel injection is permitted, and spec gasoline is the only fuel allowed.