Pro Modified, also known as Pro Mod, is a class or division in the sport of drag racing which began in the IHRA sanctioning body.
This division has specific rules about engines, components, bodies, etc. Pro Modifieds can either be raced on 1/4 mile or 1/8 mile tracks. Pro Modified has only been around for about 15 years, where as other classes are much older. Despite this fact it has become one of the most popular divisions of the sport. The Pro Modified division was a spin off of the IHRA's Top Sportsman division but with less limitations, allowing for significantly higher performance.
The rules of engines in Pro Modified are simple and straight forword. The engine can either have up to 527 cubic inches and be supercharged and methanol fueled, or it can have a larger 740 cubic inch engine that utilizes nitrous oxide and gasoline. Turbocharged engines are not allowed. These engines put out an extremely large amount of horsepower, some at approximately 2500 H.P. The engines propel the cars down the track at speeds of over 200 mph. There are weight limits, according to what type of engine you use, 2375 lb. for nitrous powered cars, and 2700 lb. for supercharged (or blown) cars. Most supercharged engines are based on Chrysler's 426 Hemi engine.