The mini-modified class is a highly specialized and custom built tractor to be fitted with a naturally aspirated engine, at minimum. NTPA Minis are limited to (always an aftermarket V-8 engine block) and uses up to a 14-71 hi helix supercharger. With the driver, they weigh only . Today's engine is capable of a minimum of on methanol or ethanol. Their reputation is known as the wildest ride in pulling, as naturally it is a very high horsepower to weight ratio. Whereas, their larger counterparts, the Modifieds, will weigh , utilizing the same engine that a Mini has, but, with multiple powerplants per custom built tractor chassis. Usually, a maximum of five engines is all that will make the weight limit. Nitromethane and oxidizers were outlawed in 1976.