Killing Kones

By: Roger Hewson

Any one who has ever had a drop of gas and oil running through their veins has dreamed of becoming a racecar driver at one point in their life. Every time I drive through a long sweeping onramp, I debate sliding the tires off my car imagining I’m driving through the 300R corner at Fuji Speedway. Most of the time I end up on the brakes because of some Expedition full of kids in front of me, or a group of blue hairs going 15 mph, bouncing curb to curb on their way back from the early bird buffet.

Let’s face it; the street isn’t the best place to learn how your car reacts once it has been pitched into a slide. There is too much going on you cannot control and way too many stupid people just waiting to crash into you and create another “street racing” incident for the nightly news to gripe about. Where can you go then? There are the canyons if you are lucky enough to live near one, but they tend to have pretty big cliffs to fall off of. Race tracks have open track days, but they’re usually rare and expensive plus not everyone lives within a short drive of a Formula 1 course. What to do?

The Sports Car Club of America or SCCA has an answer with the Solo 1, 2 and ProSolo autocross series. Short of having someone else pay all of your expenses, you’re not going to go racing in a car cheaper than if you go autocrossing unless the only direction you want to go is straight. Plus during the season there are events being held all over the country in so many different regions you would have to be living on the moon for there not to be a series of events near you. Cheap, close, often and fun- how can you beat that?

The fine editorial staff at has covered autocrossing in the past but not like this. We’re going in-depth in this series of articles to show you what classes there are, what the rules are, how to hook up with these people and how to make any car you have as competitive as possible in the class it would be entered in.

Before we get into things like car setup and the like we first need to figure out the basics of autocrossing, and the differences between Solo 1 and Solo 2 as the SCCA calls it. Solo 1 consists of time trials. What a time trial is in the eyes of the SCCA is a hill climb or a time attack where one car is allowed out on a mountain road or race track at a time, and the quickest car through the timed section wins. While the concept is similar to autocrossing with Solo 1, it is still very different in the way cars are classed and prepared.

Solo1 cars usually follow SCCA Club Racing classes and rules so they are required to meet the same standards as a real race car. Because the Club Racing side handles professional road racing, this means you need a fire extinguisher you didn’t buy at Pep Boys to stick on the A-pillar, full weld-in roll cage, six-point harnesses, approved racing seat, etc. The race organizers want to replace cars when they go off the side of the mountain road, not drivers. We don’t really see our readers climbing in and out of a Civic hatch with a full cage like Bo and Luke Duke just so they can run a hill climb in Solo 1.

Solo 2 and ProSolo are what people think of when they hear the word autocross. Solo 2 is simply racing against the clock on a tight low-speed track set up with cones in an open area like a parking lot, abandoned air field or even a small race track. Most of the courses take about 55 to 65 seconds to complete. Drivers usually get to the top of second or just into third gear on some of the straights or on faster tracks. Because of the open areas used, when you spin out, slide off course, miss a section of the slalom or just get lost you don’t end up crashing into anything accept maybe an orange cone or two. Cones are a lot friendlier than trees, curbs and guardrails. Cones move when you hit them, unlike the previous three.

ProSolo is identical to Solo 2 except two mirror image tracks are set up side by side and competing drivers start next to each other on a drag race style Christmas tree. It’s the only type of Solo racing with heads up competition. At the end of the day the top drivers from each class compete against one another in the Open Challenge. The slower car gets a head start based on both drivers’ best runs and the last person standing is the winner.

To keep you from competing against a Dodge Viper with your Mom’s Accord EX, the cars are all broken down into different categories and classes. The categories and classes dictate what modifications you are allowed to have and not have, what stock parts you can and can’t backdate and update, etc. The SCCA tries to classify the cars so they are as even as possible. In each class there are usually cars which tend to be quicker than others; but it all comes down to the driver in the end.

A couple of the most popular categories at the moment are Stock (S), Street Prepared (SP), Street Modified (SM), and Street Touring (ST). Each of these categories is broken down into individual classes to place the cars competitively.

For example the Stock class is broken down as follows:

Super Stock
Chevrolet Corvette C5, Dodge Viper GTS, Mazda RX-7 FD (1993-1995)

A Stock (AS)
Acura NSX, Chevrolet Corvette ZR1, Audi S4, 993 Porsche 911, Cadillac CTS-V, Chevrolet Corvette C4, Subaru Impreza STI, Mitsubishi RS Evolution, Mitsubishi Evolution 8, Etc.

B Stock (BS)
Porsche 944 Turbo, BMW M3 (E36), BMW M3 (E30), BMW M Coupe till ’00, Nissan 300ZX TT, Nissan 350Z, Toyota MR2 Turbo, Etc.

C Stock (CS)
1.8L Mazda Miata, Toyota MR2 Spyder, Toyota MR2 Supercharged, Lotus Elan, BMW Z3 (4-Cylinder), Etc.

D Stock (DS)
Acura Integra Type R, Acura RSX, Dodge Neon SRT-4, Audi S4 (V8 Model), Eagle/Mitsubishi Eclipse/Talon AWD, Volkswagen R32, all 24V VR6 Volkswagen Golf and Jetta

E Stock (ES)
Dodge Charger Turbo, Mazda 1.6L Miata, Mazda RX-7 non-turbo (all), Porsche 924S and 944 8V, Toyota MR2 non-turbo, Nissan 240Z, 260Z, 280Z, 280ZX non-turbo

F Stock (FS)
BMW 5 series 6-cyl Not Otherwise Classified, Mustang V8, Not Otherwise Classified, Thunderbird V8 & Supercharged V6, Infiniti Q45, Lexus GS400

G Stock (GS)
Acura Integra (’90+) Not Otherwise Classified, Audi 200 Turbo Quattro, BMW 318is and i (1991), Dodge Daytona Turbo Not Otherwise Classified, Ford Mustang SVO, Taurus SHO, Probe (’93+) (all),Honda CRX Si (all), Civic Si (’86 and ’87), Civic Si (’99 and ’00), Mazda MX-6 V6 and 4 cyl. turbo (all), Protégé MP3, Mini Cooper S (’02-’04), Nissan 240 SX (all),

H Stock (HS)
AMC Gremlin 4 & 6 cylinder, Acura Integra (’86-’89), BMW 318i & is (’92+), Chevrolet Sprint Turbo, Dodge/Mitsubishi Colt/Mirage Turbo (16v), Ford Escort GT 16v (’91+), Ford Focus, Honda Civic Del Sol S and Si (’94+), Honda Civic Si (’89-’91), Volkswagen Rabbit and GTI (all Not Otherwise Classified)

This is not a complete listing of each class, just an example of some of the cars. Each category has its own class listings. For example, the Ford Contour SVT is a G class Stock car, yet it runs D in Street Prepared, not G. Some cars like the Ford Mustang Cobra R, the BMW M3 Lightweight and CSL are not even allowed to run stock classes because they are considered modified or just too fast for stock classes from the factory. This is done to try to level the playing field.

The rules in Solo2 are fairly straight forward. Every class requires cars to be quieter than 95 decibels at all times and cars have to be run on street legal tires. The rest of the rules are set by what class you choose to run in. Stock is exactly that: Stock. There is a little fibbing allowed here and there. Cat-back exhaust systems are allowed as long as they meet the sound limits, and any wheel can be run as long as it is the same size as stock with a little room to fudge on the offset. Tire size is whatever you can fit under the wheel wells without having to modify them.

Classes like Street Prepared, Street Modified, and Street Touring allow you to get a bit more creative with your car. Street Prepared is a less restrictive version of Stock. In SP you’re allowed any intake and exhaust modifications, along with cams, under-drive pulleys, ECU modifications, etc. But you can not go into the motor other than the standard .020″ overbore allowed in stock if the stock oversize pistons are available. No compression bumping, or other tricks are allowed. Port matching the head and manifolds is allowed in SP, but adding of material is prohibited.

SP allows lowering springs, coilovers, strut braces, limited slip differentials, battery relocation, all kinds of suspension modifications as long as you keep the stock mounting points. Camber plates are allowed and you can use any size tire and wheel. You may not modify body parts to fit larger tires and wheels though.

In Street Touring there are two classes, STS and STX. The SCCA came up with Street Touring to fill the slot between Stock and Street Prepared. STS is intended for cars with 4 seats and seatbelts with normally aspirated engines under 3100cc’s and a few small displacement turbo cars like the Volkswagen GTI 1.8t. In STX normally aspirated cars up to 5100cc’s are allowed along with turbocharged cars up to 2000cc’s. A few purpose-built cars like Porsches and some of the BMW M cars have been excluded from the Street Touring classes.

STS is similar to SP in a number of ways but it is more restrictive. In STS, wheel diameter is limited to 7.5 inches and tires can not be wider than 225mm with a tread wear rating of 140 or higher. Like in SP, STS allows any intake and exhaust modifications along with headers but unlike SP, the modifications must be smog legal. Suspension modifications are similar to what is allowed in SP except shocks and struts may not be adjustable while moving unless the car came equipped that way. All cars in STS must be able to pass the federal 49 state emissions standards.

STX allows an 8-inch wheel and tires up to 245mm but still retains the same minimum tread wear rating of 140. STX allows any size brake and caliper as long as they fit inside the wheel without modification and mount to the stock caliper mounting locations. Limited slip differentials are allowed in 2WD cars, and one limited slip differential is allowed in all wheel drive cars.


Street Modified is pretty much the class for the wildest cars. Any modification allowed in SP, STS or STX is fair game. On top of that, engine swaps are allowed as long as engines are used from the same manufacturer or a “Marketing Alias” as the SCCA calls it (I.E. Toyota/Lexus). Brakes are unlimited and so is suspension as long as you keep the original mounting points. If you keep the suspension pickup points, firewall, chassis and doors stock, you can do pretty much what you please in Street Modified.

These are just rough overviews of the class rules. The best places we have found to get in-depth information on the Solo 2 rules and car classifications have been and at . If you want to know the rules, these two places are an excellent source of information.

Autocrossing is affordable, accessible and an incredible amount of fun. Most people you meet are friendly and always willing to lend a hand. In the next installment we’re going to get into the classes a bit more and introduce the first couple cars we plan on preparing for the upcoming Solo 2 season, and what we plan on doing to get them ready. Plus we’ll talk to some experienced drivers about what they have or haven’t learned on the track and pass on some pointers about where to start.

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