A mini sprint is an American type of open-wheel racing vehicle. Mini sprint cars resemble the shape of a full-size sprint car and the size of a midget car. Although often used liberally to describe several different types of motorcycle-powered open-wheel racing cars, the term mini sprint actually applies to cars that have an upright-style chassis (the driver sits upright in the seat as in a sprint or midget), a center-mounted 4-cylinder motorcycle engine and dimensions and appearance that are similar to today’s midget. Mini sprints are chain driven and use 13-inch (33 cm) wheels and tires.
The mini-sprint shares overall dimensions that are similar if not identical to a full-size midget. Mini-sprints have a wheelbase that is between 66 inches (1,700 mm) and 74 inches (1,900 mm). In fact many competitors are actually making use of old midget chassis. Mini-sprints are exclusively front-engined cars that have their engines located near the middle of the chassis. The maximum offset from the centerline of the chassis is 6 inches (150 mm). (this is opposed to modified midgets or super-lites that have their engine located radically offset to the left). Mini-sprints also share suspensions that are identical to sprints and midgets. The most popular chassis is the four bar. This is a suspension system that makes use of 4 torsion bars (2 front / 2 rear) that utilize torsion arms and shocks to regulate suspension travel.
However, there are a growing number of cars that utilize a torsion bar rear set-up with a coil-over front set-up. This means the rear of the car utilizes a torsion bar system that is identical to the 4 bar set-up, while the front-end uses shocks with coil springs. Mini-sprints utilize a solid, live rear axle that is positioned in the chassis by a Jacobs Ladder or panard bar. Unlike the midget or the sprint car, the final drive on a mini-sprint is a roller chain. This is one of the keys to keeping the cost of this form of racing down. A chain drive system might cost around $300, whereas a quick-change rear end like those used on sprints and midgets cost upwards of $2,000. Gearing on a mini-sprint is determined by changing either the front or rear sprocket or a combination of both. Mini-sprints make use of 13-inch wheels and tires that are identical to those found on midgets. Most mini-sprints make use of a steering box, however a few manufacturers are utilizing steering racks. Mini sprints carry their fuel in the rear of the car in tanks that vary from 5 to 19 US gallons. They have roll cages that are constructed of at least 1 1⁄4-inch, .095 wall Chromoly tubing. Many organizations are now requiring thicker tubing.