Since you’re reading a Micro Sprint Hub publication, chances are you’re already familiar with micro sprint racing. But if you are a new fan, friend of a racer, or simply curious about the sport, keep reading to learn the basics of micro sprint racing.
A micro sprint is an open wheel racecar that races on dirt circle tracks, typically 1/8th of a mile to 1/4th of a mile long. They may seem small compared to other types of racecars, but they have an impressive horsepower-to-weight ratio. Micro sprints consistently put on some of the best racing in grassroots motorsports.
There are five main classes within the sport, with a few additional classes that will be mentioned later. The five main classes are Restricted, A-Class, Stock Non-Wing, Outlaw Non-Wing, and Winged Outlaw. There are variations in rules such as wing size and engine specifications between classes, but a car for any of the classes is built using the same chassis. There are a lot of options for micro sprint chassis manufacturers, Hyper and D1 are a few you will hear often. Now let’s break down each class.
Restricted
Restricted is a beginner class, allowing drivers aged 8-16 to learn the basics of a micro. In the Restricted class, you will see many kids who moved up from Junior Sprints, Quarter Midgets or carts, but there are also drivers who start their racing career in the Restricted class. Excluding special events, Restricted cars always have a top wing and nose wing on, with a 10 square foot maximum sideboard area. They run the same stock engine that the A-Class and Stock Non-Wing classes run, with the addition of a restrictor plate, hence the name. This restrictor plate limits the amount of power the engine can make, typically to about 65-70 horsepower. Though this is considered a beginner class, that is not to say there is a lack of competition, talent, and great racing.
A-Class
A-Class is the first of what many consider the “core four” micro sprint classes. Drivers can begin racing A-Class at 12 years old, though it is not uncommon to see a promoter waive this age restriction for drivers they feel are qualified. A-Class runs a stock 600cc engine that makes around 110-118 horsepower.
A-Class must run a Hoosier ASCS2, RD30, or American Racer 70.0/13.0-10 GT right rear tire and both a top wing and nose wing. A-Class top wings cannot exceed 10 square feet in area. The car, wings, and driver must weigh a minimum of 750 pounds at the end of the race.
Stock Non-Wing
Stock Non-Wing is basically an A-Class car with both the top and nose wings removed. This is reflected in the rules, which are nearly identical between A-Class and Stock Non-Wing except for the removal of the wings, of course. The weight rule remains at 750 pounds, even without the additional weight of wings. While some teams have separate cars for A-Class and Stock Non-Wing, the majority of teams run both classes with the same car.
Though some tracks do only run one stock class per night, most events will run both. This allows a driver to race two classes in one night using a single car. The changes teams make when converting between A-Class and Stock Non-Wing vary, depending on things like amount of time between classes, available pit crew help, and driver preference. Some teams only make minor setup adjustments, other teams make larger changes such as changing torsion bars or springs and tires.
Non-wing cars often require a completely different style of driving than winged cars. Without the drag of the wings down the straightaways, non-wing cars can be faster when looking from a mile per hour perspective but give up a lot of that speed through the corner since they lack the downforce created by wings. Typically, a winged car will have faster lap times than a non-winged car on the same track.
Winged Outlaw
The outlaw classes are where things really change. Outlaw classes allow engines of up to 640cc displacement, making 135+ horsepower. Outlaws are allowed to run any Hoosier or American Racer compound tires. The wings are allowed to be much larger than an A-Class car; the size difference is immediately noticeable. The larger wings and increased horsepower allow drivers to carry much more speed through corners. Many drivers agree that there is a big difference between how an Outlaw car and an A-Class car handle. You can race the Outlaw classes beginning at age 12, sometimes younger with promoter or race director approval. Winged Outlaws must weigh a minimum of 775 pounds, including the driver.
One of the most unique aspects of the Outlaw classes is that they are allowed to have cockpit adjustments. This means drivers can change certain aspects of their setup during a race. These adjustments include shocks, wing position, and Jacob’s ladder/Panhard bar position. This allows drivers to change their car as the track changes and adds another layer of strategy that the other classes don’t have. With cockpit adjustments, a driver isn’t only responsible for finding the fastest way around the track but adjusting the car throughout the race as well. This is where experienced drivers can have a major advantage, because just as easily as drivers can improve their setup using in-car adjustments, they can hurt it as well.
Non-Wing Outlaw
Non-Wing Outlaw mostly follows the same rules as Winged Outlaw. Of course, there are no wings and the minimum weight for a Non-Wing Outlaw is 750 pounds, 25 pounds lighter than a Winged Outlaw car. Just like many teams run Stock Non-Wing and A-Class with the same car, many also run Winged Outlaw and Outlaw Non-Wing with one car, just taking the wings on and off and making some setup adjustments.
Beyond the Core 5 Classes
Now that you are familiar with the five main micro sprint classes, let’s talk a little bit about other classes you may often see at a micro sprint race and how different teams may choose to handle winged and non-winged versions of the same engine class.
Some tracks run a class called Sportsman. This class is typically a more affordable option for more local racing, with rules varying track to track. Sportsman is most similar to A-Class, running a stock engine that is at least 10 years old and a maximum 10 square foot top wing. In most Sportsman rules, nose wings are allowed but not required. Port City Raceway in Oklahoma has a weekly Sportsman program, their rules include those mentioned above, with additional rules like no titanium parts and no carbon fiber body parts.
Another class you will often see accompanying Micro Sprints is Jr. Sprints. Jr. Sprints are not considered a Micro Sprint class. Jr. Sprints look very similar to Micros, just smaller. Jr. Sprints are piloted by drivers aged 6-12 and are often the class a driver starts their career in. Excluding special events, Jr. Sprints always have a top wing attached to the car. They run off a Briggs & Stratton World Formula engine, producing about 15 horsepower.
The Tulsa Shootout, the biggest micro sprint race in the world, provides a good example of how drivers can compete in multiple classes. Though it is important to note that different series, events, and sanctioning bodies have varying rules on what classes a single driver can race at one time.
Eligible Class Combinations
Six classes run at the Tulsa Shootout: Jr. Sprints, Restricted, A-Class, Stock Non-Wing, Outlaw Non-Wing and Winged Outlaw. Let’s start with the youngest drivers. If a driver falls into the correct age range (8-12 years old) they can run both a Jr. Sprint and a Restricted Micro. If they are registered in a Jr. Sprint, they cannot run any other Micro Sprint class outside of Restricted. Drivers ages 12-16 (or younger if approved by the promoter) can compete in all five main classes. It’s normal to see a couple drivers attempt this at the Shootout each year.
One of the neat things about how the Micro Sprint class rules work, is that an A-Class car is completely legal to run in Winged Outlaw and a Stock Non-Wing car is completely legal to run in Outlaw Non-Wing. Of course, the cars built for stock classes will be at a power disadvantage as well as having no in-car adjustments, but it isn’t unheard of for a driver racing a stock engine with the Outlaws to be competitive, especially in the non-wing division. At a race like the Tulsa Shootout, seat time is invaluable. Some teams run the 4 core classes with one physical car simply to maximize the number of laps they get on the track, while others bring a separate car for each class. Most commonly, teams bring two cars: one with a stock engine for A-Class and Stock Non-Wing, and another with an Outlaw engine for Winged Outlaw and Outlaw Non-Wing.
While each class has its own unique rules and driving style, they all share one thing: exciting racing. From young drivers taking their first laps in a Restricted to veteran drivers throwing slide job after slide job in the Outlaw classes, every micro division puts on a show. To many outsiders, micro sprints may look like a beginner class or a stepping stone to bigger cars. But those who know the sport know the truth: micro sprints produce some of the closest, most competitive, and most exciting racing in all of motorsports.
*Note: This article was written using NOW600 rules for the five main classes and Jr. Sprints as a reference. Port City rules were referenced for the Sportsman section. These rules may change with different tracks, events, and sanctioning bodies.
