Saturday Night Overview

There are three divisions of race cars that regularly compete on the banked half-mile oval at Mosport Speedway, each with their own unique rule package. These classes of competition are: Pure Stock, Sportsman, Open and Late Models.

All cars must pass a technical inspection before they are allowed on the race track.  Generally, the top five cars in each division are inspected at the end of the evening to ensure that they conform to their respective division rules. These different classes provide an opportunity for racers of all skill levels, from novice to expert, which allows each driver to enjoy a level of competition suited to their financial situation and driving experience. Each division’s rule package is updated yearly to keep the cost of racing under control and to equalize the level of competition so that fans will be treated to more exciting race action.

Outlined below are more detailed descriptions of each division and an explanation of the basic rules to help make the races more enjoyable and exciting experiences for the fans. If you’re interested in becoming a race car driver or crew member, come down to the pits after the races, talk to the drivers and pick up a rule book for the division of your choice.

Pure Stock

This entry level class is the place to start if you have never raced before. It provides fun, excitement, and competitive car racing to novice drivers at a minimal financial cost. This division is comprised of North American-built Ford, Chrysler, and General Motors cars that are in the intermediate to compact car classification. They are restricted to using four and six cylinder normally aspirated or fuel injected engines with displacements up to 4.3 litres. Vehicle weights are based on engine size and the number of cylinders. All parts of the cars must be kept in original stock condition and require a six-point roll cage for safety. Minor suspension changes are allowed, and the cars can be lowered by altering spring heights. These cars use an aluminum racing seat, a window net, a fire extinguisher, and a five-point racing harness (seat belts) ensuring a high level of safety for the drivers. The tires on the Pure Stock cars are the same as those found on ordinary street cars, but the use of racing wheels is allowed. If you’re interested in becoming a race car driver, this is the division for you. With a minimal amount of money and a little bit of time, you can be out on the track having fun racing a Pure Stock car.

Sportsman

This class is similar to the former ThunderCar division and is also where the biggest changes among the classes occurred. Not only has the name changed, but the rules in this division have been stepped up to meet the challenges of the more progressive racer and fan.

The frames of Sportsman cars are allowed to use a stock front clip with a fully fabricated frame from the front firewall back. Mounted to this fabricated frame is a complete roll cage made of 1 ¾” round steel tubing for the driver’s protection. The suspension springs will also be fully adjustable using load bolts which will allow the driver to change the handling characteristics of the car.

The engine rule has remained the same for this division and the use of the “602” GM crate engine and a Holley 4412 two-barrel carburetor has become a popular choice for the racers. These new engines are sealed by the track and offer a less expensive alternative to the engine program for the drivers and car owners.

They must use a completely stock working automatic transmission and have a limited rear axle gear ratio rule. For safety reasons, a Ford 9” rear axle assembly is allowed and the rear axles are required to be welded together. A mini spool can also be used to connect the two axles, but under no circumstances can they use a limited slip differential.

These cars can use original steel bodies as manufactured, which are lightened by the removal most of the interior bracing. Aftermarket aluminum or fiberglass bodies can also be used. The driver is equipped with a padded racing seat, an approved helmet, a five-point seat belt restraint, a fire extinguisher, an ignition kill switch and a remote fuel shutoff valve. For added safety the 8” racing wheels are held on with 5/8” wheel studs and an approved treaded racing tire is used. The trunk area is where a foam filled plastic fuel cell is located, which is rigidly fastened to the rear section of the frame and generally encased in a metal container for added protection.

Sportsman cars have a minimum weight of 3200 lbs., including the driver, with a restriction of 53% on the left side and 50% on the front of the car with a 5 1/2” frame height. All frame, steering, and suspension parts must be stock and in their original location. In order to allow the old style ThunderCars to be competitive in the Sportsman division, vehicle weights will be adjusted to allow for closer racing throughout the field and provide some excitement for the fans.

Late Models

This class is the next division up the racing ladder at Mosport, and new rules have been incorporated to make the class quicker and more competitive. Although they appear like your family car they use aftermarket aluminum or fiberglass bodies designed for racing.

The frames of these cars are fully fabricated with 2” by 3” or 2” by 4” steel tubing with 1 ¾” round tubing used to fabricate a complete protective roll cage for the driver’s protection. This roll cage extends from the extreme front to the rear of the car and is designed to provide maximum safety for the driver.

The cars in this division use small block GM, Ford, and Chrysler engines that can be modified within the track rules. Some of the engine modifications allowed are a 10:1 compression ratio, 0.060” overbore, any hydraulic camshaft, aftermarket cylinder heads, and a Holley 4412 carburetor. These engines produce from 300 to 350 HP.  The division is rapidly expanding with a crate engine rule, which permits the use of a brand new complete racing engine purchased from General Motors. The benefits of a crate engine are the fact that it’s sealed by the race track and therefore won’t be subjected to a tear down for inspection, as well as providing a less expensive engine program for the racers. Cars that are using a crate engine are given a 100 lb. weight break and this year more cars will be using the GM crate engine program as an alternative.

This class uses a Ford 9” floater rear axle and a manual transmission and clutch assembly. They must also use a mini or full spool to lock the two axles together and cannot use any traction aiding device. The suspension features fully adjustable racing springs and shock absorbers. The steering and suspension can be modified and is totally adjustable to help the car through the corners. These cars are also required to use racing wheels with an 8” Hoosier racing slick.  Quite often you can see the race teams adjusting the ride heights, steering, and suspension systems during the evening trying to improve the handling of the car.  Late Models weigh 3000 lbs. (2900 lbs. with crate engine), including the driver with a restriction of 55% on the left side and 50% on the front of the race car and a 5” frame height.