SCCA Rally Classes

Our much loved Project Rally Beater was hurt, but not beyond repair. It had a minor disagreement with a tree, a serious argument with a rock, and a rather painful scuffle with a berm. The ugly details are here, but the short version is that physics had not been kind to this old Datsun. The hood, fender and bumper were smashed, the rocker panel collapsed, a control arm broken in half and the entire exhaust system ripped off.

Still, it wasn't so bad. A new control arm allowed it to race, sans exhaust, the day after its last major crash. It won that day.

A new exhaust, cobbled together from Project Matrix's stock system, was enough to let it compete in a local rally sprint a few months later. It won that day, too.

A little hammering, welding and scavenging could fix the body damage and it would be back to its old self. The beater could go on.

But it shouldn't.

I realized this at 124 mph. Racing across a remote Indian reservation 100 miles from the nearest hospital, I passed an SUV on its roof. That SUV had rolled going approximately 95 mph slower than I was going. I had about six inches of dirt on either side of my tires before they would hit ice and follow that SUV to a much more spectacular fate. At that precise moment I realized perhaps the beater was getting a little too fast for my own good.

Picking a class and picking a car.

The immediate temptation, when picking a rally car, is to go straight for something turbocharged and all-wheel drive. That first misstep leads immediately to a WRX or Lancer, the sad realization that you can't afford either one, and then the mistaken conclusion that you can be competitive in something older and cheaper. 323 GTX? Audi Quattro? Celica All-Trac? They all make good rally cars, but go up against an equal driver in a WRX or Lancer and you don't have a chance.

Even without the insurmountable competition, the cost and complexity of a turbo all-wheel-drive car should give you pause. Every all-wheel-drive rally car breaks transmissions, so you have to plan to replace the gearbox at least once and possibly several times per season. There is a reason Prodrive has perfected the 12-minute transmission change.

Turbocharging also puts a tremendous thermal load on the engine, making overheating problems common, especially in the hot Southwestern rallies.

There is less glory, less television time and less chance that Prodrive will call you if you race in a two-wheel-drive car, but the sooner you realize Prodrive isn't calling anyway, the sooner you can get on with building a two-wheel-drive car.

Open
This is a very liberal class, requiring only that you start with a production car and that it still be recognizable as such when you are done. Any engine is allowed, up to an adjusted displacement of 5.1 liters, as long as the block is at least derived from a block that was once used by the manufacturer of the car. That means a Mitsubishi 4G63 is allowed in any Hyundai because the Elantra once used a naturally aspirated version of that engine (the current Hyundai factory cars actually use the Tiburon's beta engine, however), or a Pontiac Sunfire could use a Toyota 2ZZ-GE because the Pontiac Vibe does. Creativity in this class is encouraged.

Turbocharged Open Class cars have to run a 40mm inlet restrictor, but this is large enough for some serious power. WRC cars use a tiny 34-mm restrictor by comparison. With the appearance of well-funded factory teams, some new rules restricting active limited-slip differentials have also appeared, as has a spec fuel.

Group N
This is generally considered the second fastest class. Made up of a complex and tightly controlled list of homologated modifications, this is essentially a spec class for mildly modified Lancers and WRXs.

All the gory details can be found at www.fia.com/homepage/selection-a.html

Production GT
The slowest and most attainable of the turbocharged, all-wheel-drive classes, Production GT is actually open to both two- and all-wheel-drive production cars. Production and Production GT are supposed to be classes for stock vehicles with very limited modifications, with Production GT taking the cars with adjusted displacements over 2650 cc or turbocharged or all-wheel-drive cars. Engines have to be stock, but because it is so difficult to enforce boost limitations on turbocharged cars, there are none. Run all the boost you want. A relatively small 32-mm restrictor is required, however, limiting the fun you can have with that unlimited boost. Even though large-displacement, two-wheel-drive cars are allowed, the fact that all-wheel-drive turbocharged cars running unlimited amounts of boost are competing in the same class makes this another WRX class.

Group 5
This is the Open Class of two-wheel drive. The rules are essentially the same as Open Class, but there is no inlet restrictor. The fact that there are only two-drive wheels with which to put power down is restriction enough. Adjusted displacement must be between 2.4 and 5.1 liters.

Group 2
Rules are the same as group 5, but the adjusted displacement is 2.4 liters. This is an attractive low-cost class, but it is destined to be a ClubRally-only class. ProRally rules will be combining these two classes in the near future. The California Rally Series has run a combined Group 2/5 Class for years, and to date the championship has always been won by a group 2 car. More power doesn't always make two-wheel-drive cars faster.

Production
Production cars are essentially stock. The suspension is largely unlimited, though stock mounting points must be retained. The engine has to be completely stock, and even the interior has to be in place except where it interferes with safety equipment. These limitations theoretically limit how much you can spend on a Production car. In most forms of motorsport, the more limiting classes actually end up being more expensive, as money is spent on all the tiny little details needed to gain an advantage over the competition. This is not the case with Production rally cars, partially because rallying is so dependent on the driver, and partially because the competition in this class simply isn't that stiff.

Because modifications are so strictly limited, you can't strengthen inherently weak cars. Pick something durable, and remember, Production Class cars can be no more than 12 years old.

The car:
We started narrowing cars first by deciding to rally something new. One of the many lessons learned on the rally beater is that while everybody loves a beater, nobody wants to put their name on one. Sponsors like new cars. Remember that bit about "the sooner you realize Prodrive isn't calling anyway, the sooner you can get on with building a two-wheel-drive car?" Yeah, well, consider the new car our last naive twinkle of optimism. I'll just be waiting by the phone, guys...

New cars also aren't worn out yet. Racing a 30-year-old econobox was quickly becoming a race against metal fatigue. Cracks were appearing in the chassis, the suspension, the crossmember. Proper preparation could make a Datsun 510 a long-lived, reliable rally car, but we didn't do proper preparation. Our many patches and structural add-ons were starting to pile up. A clean sheet of paper is an opportunity to put lessons learned to work, and hopefully to get a short break from the constant task of repairing an aging car.

Without deciding on exactly which two-wheel-drive class to race in, we started narrowing down cars. Performance, durability, a healthy aftermarket and cheap replacement parts are the most important qualities of a rally car candidate. If we were building another used car, a 1988-2000 Honda Civic would be the car. They're light, have lots of suspension travel, Honda transmissions have proven durable in 600-hp drag cars, and the availability of parts is unbeatable. It's surprising more Civics aren't already rallying.

Of the affordable new cars, however, the Sentra SE-R Spec-V stood out. A big, torquey engine and relatively light weight are important, but it's the transmission that really stands out. The Spec-V's beefy transmission is shared with the much heavier, 3.5-liter Maxima, so it should be invulnerable to whatever power we can get from the Spec-V's 2.5 liters. The factory helical limited slip also saves over $1,000 in aftermarket differential parts and installation.

The Spec-V's 2488cc displacement has to be multiplied by a 1.2 adjustment for having four valves per cylinder, and again by 1.1 for having variable valve timing. The resulting adjusted displacement of 3284cc puts it well into Group 5 where it will have to face turbocharged cars. This could either be a perfect test of my "power doesn't matter in two-wheel drive" theory, or a perfect excuse to turbocharge the Spec-V. With forced induction you have to pile on a 1.7 adjustment, though, resulting in 5583cc of adjusted displacement . Too much for any of the two-wheel-drive classes. De-activating the variable intake cam timing, however, would remove that 1.1 factor, making it 5076cc, just under the 5100cc Group 5 limit. The option is there, but for now, we race naturally aspirated.

The current B15 Sentra chassis is also quite a bit beefier than earlier models. The wheel bearings and axles, for example, are the same size as the Maxima's, and the brakes are nearly interchangeable with the previous generation Maxima as well. This bodes well for durability. Replacement body parts should also be abundant in junkyards, as the lesser Sentra models share everything but the front bumper.

The engine, it turns out, is easy to milk additional power from, though we didn't know that when we chose the car. Power is relatively unimportant in the two-wheel-drive classes, however. Being smooth and focusing on reading the road and maintaining high cornering speeds can make an underpowered car very competitive. The early days of the beater proved that point very well. With 95 hp at the wheels, the beater was able to finish in the top 10 overall on occasion. Conversely, too much power eats up tires with wheelspin and magnifies the consequences when you make mistakes. That won't stop us from trying to make more power, but it does move it down on the priority list quite a bit.

Another strong Group 5 car available next year is the Dodge SRT-4. A rally car was one of the development mules for this turbocharged monster, and it should prove very competitive and relatively easy to prepare. A completely stock SRT-4 engine already makes more than enough power, leaving only chassis prep and a limited slip to make it a rally car.

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