The National Association for Stock Car Auto Racing (NASCAR) began almost 60 years ago. Today NASCAR has grown to become the second-most popular professional sport inside the U.S. in terms of television ratings, ranking behind only the National Football League.

Its popularity grew fast — perhaps as fast as the cars themselves.

Unrestricted, NASCAR cars can run at speeds in excess of 200 mph (miles per hour). An unrestricted motor can complete average lap speeds of 221 mph and top speeds over 230 mph.

"The engine in a NASCAR race car is probably the most crucial component," according to HowStuffWorks.com. "It has to make huge amounts of power for hours on end, without any failures." Relative to regular street cars, the engine blocks in a NASCAR racing car are larger custom-made race-engine blocks. And, "like the original 1960s engines," pushrods drive the valves.

All engines are carbureted, and fuel injection is not allowed. Despite the lack of turbochargers, superchargers or "particularly exotic components," the engines produce over 750 horsepower.

To create this power, some design features include the following, according to HowStuffWorks.com:

• The engine is 358 cubic inches (5.87 L) — larger than most street-car engines;

• NASCAR engines have "extremely radical cam profiles that open the intake valves much earlier and keep them open longer than in streetcar engines," which allows more air to be packed into the cylinders, particularly at high speeds;

• Through tuning and testing, the intake and exhaust can provide a boost at certain engine speeds. They are also designed to have very low restriction — "that is, to provide little resistance to the gases flowing down the pipe";

• There are no mufflers or catalytic converters to slow the exhaust down;

• The carburetors can let in huge volumes of air and fuel — there are no fuel injectors on these engines;

• They have "high-intensity, programmable ignition systems" that allow the spark timing to be customized to provide the most possible power; and

• All of the subsystems (coolant pumps, oil pumps, steering pumps and alternators) are designed to run at sustained high speeds and temperatures.

Engine components in a race-car engine are machined to very tight tolerances. The part precision and accuracy enable it to provide as much power as possible while standing up to the grueling wear and tear that results from operating for hours on end, nearly flat out and with lots of vibration.

To ensure high reliability and peak performance during the race, engines must pass several tests and inspections:

• After a dynamometer measures engine power, filters are checked for excess metal shavings;
• Using the dynamometer again, ignition timing is set to maximize power; and
• Mechanics inspect the cylinders for unusual wear; and examine the camshaft and valve lifters.

Here's an example of a R5P7 Dodge NASCAR engine on a dyno in the shop of Arrington Engines, a builder and researcher of Dodge NASCAR engines:


As a matter of policy, NASCAR restricted entry to American carmakers from the 1960s until 2004, when Toyota was allowed to enter the NASCAR Craftsman Truck Series with the Toyota Tundra. The restriction was relaxed in recognition of the fact that the Tundra, although Japanese in origin, is built in America. Commentators have also noted that the "American" cars are often built or assembled in Canada and Mexico.

"All of the Chevy, Ford and Dodge teams build their engines at their shop or they buy them from another team," according to AllExperts.com. Toyota builds all of its engines at Toyota Racing Development and gives them to the teams in the truck series. All engines are the same size, and, in fact, they're all the same except for certain parts on the engine. "The manufacturer supplies those parts to the teams and they assemble the engines."

One major area of differentiation among the engine design teams relates to valve timing. Some early engine designers prefer the old single camshaft for intake and exhaust valves. Other engineers moved on to the twin camshafts — one for intake and the other for exhaust — which permit variable valve timing. Alfa Romeo pioneered this technology. The problem with older, conventional single camshafts had been that it was impossible to achieve peak performance at both high and low revolutions per minutes (rpm).

Since the mid-1980s, "successful valve-timing variability has depended almost completely on triggering by modern electronic-control systems," according to Winding Road Magazine.

Another valve timing design introduced around the same time was concentric camshafts. A hollow outer shaft carries the exhaust-cam lobes. "In it are slots for pins that anchor the inlet lobes, on the exterior of the camshaft to the inner shaft," according to Winding Road Magazine.

Even your neighbors off the track want in on the action. The Dodge Viper SRT10 — which already has an 8.3-liter, 510-horsepower, 10-cylinder engine — has big changes ahead for the 2008 model year, including even more power. The automaker tried the cam-in-cam technology, and the result has been an 8.4-liter engine that produces 600 hp at 6,100 rpm and 560 pound-feet of torque at 5,000 rpm.

Auto researchers today focus on a cam-less design by relying on direct electrical actuation. Electromagnets or electric servo-valve control create hydraulic forces to open and close valves individually.

Earlier: Extreme Engineering: NASCAR'S BACK!

Resources

What Makes NASCAR Engines Different from the Engines in Street Cars?
by Karim Nice
HowStuffWorks.com

NASCAR.com

Experts: NASCAR Racing
by "Harrison"
All Experts, Feb. 16, 2006

The History and Future of Valve Timing
by Karl Ludvigsen
Winding Road Magazine, August 2007

Additional

American 'Speedking' Russ Wicks Sets New World Speed Record
PR Newswire (via Digital CAD), Oct. 10, 2007