The heightened state of competition requires successful racers to constantly upgrade and get the ultimate performance from every aspect of their program. In the minds of many, there are no huge horsepower gains remaining. When it comes to power, the sport is speeding toward parity like never before. Now, the challenge isn't finding 10 hp; the challenge is finding a single-unit gain in power.

The use of racing fuel is an area where the modern engine builder and racer are turning their attention. The drive for maximum efficiency begins and ends with the fuel's performance.

Competition to provide the fuel is as heady as the on-track action itself. Many of the major touring series do not restrict a driver's choice, even though some of these same series have fuel companies as sponsors. This freedom gives the driver a chance to work with his engine builder to provide the maximum power.

Changes in the sport have led fuel companies to be on their toes for developments to enhance their products. Steve Burns of VP Racing Fuels said the changing demands of racing applications have been a boost for the fuel maker.

"It has helped us because these changes make you get more and more specific with the product," he said. "Now you're looking for a 1 or 2 horsepower gain. Your fuel has to be specific for its purpose, for the type of racing being done. You have to develop it to suit the exact need.

"We've been doing that with drag racing and motorcycles. We've had to come with 15 different fuels for NHRA classes. In motorcycles, the needs are so different that they give us different ways of looking at things and that can help development. It's like everything: The more sophisticated you can get with it, the better it's going to perform."

A fuel is expected to allow for the engine to provide maximum performance on a consistent basis. In order to do that, the variables need to be reduced or eliminated. Each gallon of fuel has to mirror the gallon before it with tight tolerances.

Because there are different types of engines with different demands, there are also different fuels to adjust to those demands. This is not a one-size-fits-all scenario.

"To develop a fuel, you have to essentially be a partner with an engine builder," Burns said. "You want the cars to be competitive when they're out there. The fuel needs to have enough octane so there won't be detonation."

Detonation and pre-ignition are the biggest enemies of any fuel's performance. The spark within the internal combustion engine needs to occur at the right time. The perfect time is when the piston is starting its downward stroke. If the fuel ignites too late, the piston has already begun the process and efficiency is reduced. Ignition that's too early will create a force opposite of the piston force, again reducing efficiency.

In the case of detonation, the fuel becomes heated to the point of explosion without the needed controls. A common cause of detonation comes from amounts of uncombusted fuel, still in liquid form, remaining after normal ignition has taken place. When this fuel ignites, it is often out of synch with the expected process and reduces efficiency. By their nature, racing engines can be highly susceptible to detonation, a constant concern of engine builders and fuel manufacturers.