Stock Eliminator is often misnomered as an entry-level category. It is one of the cheaper ways to get involved in IHRA or NHRA racing on the national or divisional level, but the range of vehicle/engine combinations available can be overwhelming, and the technical expertise required to build and run one of these cars is very demanding in its own right. Some of the best class racer and bracket racers in the country populate Stock, coupled with some of the most brilliant minds in motorsports.
The premise of Stock Eliminator is to take a large pile of nothing, work within a very restrictive set of rules, and make the car go fast. While it's true that Stock appears to be primarily a bracket race, there are other factors to consider. First, each car must run quicker than its class index, and secondly, if a pair of like-classed cars match up in eliminations, then it's a “real” drag race: heads-up, with no breakout. The first to the finish line wins.
Cars are placed into letter-designated classes, based on the engine's horsepower rating and the vehicle weight. NHRA and IHRA use a Classification Guide that lists each make, model, and engine combination, along with the factory horsepower rating. Most combinations have shown more or less potential over the years than what was claimed by the factory, so the sanctioning bodies also list an Adjusted Horsepower rating. The Guide lists a horsepower-to-weight ratio that determines what class a given car falls into. Cars are permitted to add or remove some weight, to move to the top of their natural class, or to move down to the next slower class.
Each class has an “index”, which is a baseline of performance. Cars qualify based on how far under the class index they run. Cars are paired on a ladder right for first round, based on their qualifying position. The index acts as a maximum dial-in, in E.T. Bracket style eliminations. If a car runs quicker than the index, the driver can put a dial-in on the window. If you're over the index, you're probably out of luck, as the index becomes your dial-in.
With literally dozens of classes, including stick shift, automatic, truck, front-wheel drive, Pure Stock, GT, and Crate Motor categories, it seems unlikely that two cars in the same class would come up against each other. The fact is, there is usually at least one heads-up run at each event, and sometimes several. While it doesn't sound like much, one round can have a profound effect on the complexion of not only an event, but possibly the entire season.
The first letter of the class designation is the weight break, which is followed by the major subcategory of the class. For instance H/S (H-Stick Shift), H/SA (H-Stock Automatic), HF/SA (H-Front wheel drive Stock Automatic), H/CM (H-Crate Motor), H/PS (H-Pure Stock), HT/SA (H-Truck Stock Automatic), H/FIA (H-Fuel Injected Automatic). So, the weight break letter designation may have different meanings, depending on the subcategory it is referencing. H/SA may be a small block Camaro, while HF/SA may be a four-cylinder Sunbird.
With super-restrictive rules, the most frequently asked question from a newcomer to Stock is “then how do they go so fast?” The trick is more in what is not in the rules, rather than what is. Traditional Stockers are limited to the stock lift on the camshaft. The other specs on the cam, however, are not specified, except in Pure Stock. That allows racers to play with duration, overlap, ramp rates, etc., that maintain the stock lift, but still make more power. Production tolerances also aid racers. For instance, if the sanctioning body has a spec on the size of the combustion chambers, and your cylinder head's chambers are bigger, you can cut the head down until it reaches the stock spec. Apply that thinking to every component in the car, and the ET gains will quickly add up.
Not all of the ET is in the engine bay, however. For Stockers, the proper selection of gear, converter, and transmission is essential. Most Stockers do not have a lot of compression, cam, or carburetor, so it is important for them to make as much power as possible in the first half of the track. They also need to do so efficiently . The trick is to get up in the peak power range quickly, and stay there as long as possible.
As a side benefit to a proper “Stocker” combination, Stockers are generally very consistent cars. They have lots of gear, lots of converter, and the cars tend to fall back into the converter on the gear changes, allowing it to multiply torque once again. By bypassing the lower rpm ranges, Stockers spend less time in that range where the car is most variable and susceptible to weather changes than their ET Bracket counterparts, who tend to be under-geared, under-convertered, and over-tired.
Stroll the Stocker pits and the staging lanes, and you'll see about every kind of car and combination imaginable. It's a rolling car show, and in many cases, a history lesson. Racers are proud of their rides, and will often tell you about their cars. With a little background information, you should now be on your way to understanding Stock Eliminator a little better!