Bill Elliott won the 2002 Brickyard 400 even though he was down 50 horsepower to others in
Clearly, circle track racing is not drag racing. It is all about turning left. In 2002, Bill Elliott won the Brickyard 400 beating Rusty Wallace. NASCAR ran all of the top cars across a chassis dynamometer immediately following the race, and Elliott's was down 50 CBHP (corrected brake horsepower) to the best car. By any account, Indy is a "horsepower track." But Elliott had the best corner exit speed of any car on the track that day. That day, corner exit speed was worth more than 50 horsepower! Imagine a drag race where one car has a head start. It takes a considerable amount of horsepower to chase someone down.
Aerodynamic performance is a key aspect of any motorsport involving speeds that reach triple digits. At speeds over 100 mph, down-force becomes as important as mechanical grip (traction). As speeds pass 150 mph, down-force becomes more important than mechanical grip, and aerodynamic drag is interchangeable with engine power.
Here's an example: The pitch (nose attitude) of a NNC directly affects the drag. An optimal pitch would have the front valance sealed against the ground, thereby providing the minimum frontal area and preventing air from passing beneath the car. As the nose rises, more area is presented to the air (effectively increasing frontal area) and air passes underneath the car. In acceleration from 165 mph to near 200 mph, an increase in valance height of only two inches equates to a loss of 50 horsepower. The importance of aerodynamic performance increases as the square of vehicle speed. If you do the math, this is significant.
In Cup racing, it's many times easier to pass on pit road than on the racetrack. A team can often make up seconds on pit road. This is very hard to do on the track. How many horsepower would it take to make up a second on the racetrack?
Pitting at the right time can also play a significant role. On tracks where passing is difficult, passing in the pits may be the easiest pass you can make. The best example of how important pit strategy can be is seen in Formula One. Because of the aerodynamic configuration of these cars, the only way to pass is often on pit lane.
Engines last on the list of priorities? Well, we said unless they break. Smokey was an innovator, but he always knew that you had to finish. In 2003, Matt Kenseth won the Cup Championship. From NASCAR's chassis dynamometer we know that the Roush cars were 25 CBHP down (compared to other major teams) all season. Engine power was clearly not the deciding factor in claiming this Championship. However, note that the #17 car had only two engine failures that season, one of which was after Matt had clinched the Championship. Reliability was the key engine performance feature for winning the Championship that year, not power. By the way, Matt Kenseth and his Ford finished Second at Indy in 2003, despite the power deficit.
|CHART A|| |
| ||HP & TQ ||TQ ||RPM |
|Peak HP to baseline ||3.3% ||0.0% ||1.2% |
|Peak TQ to baseline ||1.8% ||2.2% ||-1.2% |
|Maximum RPM ||9,200 ||9,200 ||9,900 |
Engine performance becomes more critical when the percentage of on-throttle time is high; e.g. at tracks with long straights and during qualifying.
How do you evaluate how important your engine performance is to your racing?
First, start with the track or tracks where you race. Break the track down into the percent of lap time that you spend at wide open throttle (WOT) vs. what percent of the lap you spend in the corner and off the throttle. Clearly, if most of your lap is spent in the corner, then this is your area of concern.
Let's look at an example: Graph A shows engine speed (blue) and throttle opening (red) for a Cup car at Atlanta Motor Speedway. Atlanta is one of the fastest tracks in Cup racing, if not the fastest. This track should emphasize engine performance.