STEVE LETARTE: People don't appreciate it, nor will they ever appreciate it without actually being able to sit
behind the wheel, I don't think.
JOHN PROBST: You know, to compare a NASCAR engine to something that somebody could relate to
would be difficult to do by itself.
JOSH BROWNE: 850 horses all lined up.
MALE NARRATOR: The roar of the engines, the squeal of the tires, then the race to victory lane. It all says, NASCAR.
A race car is much more than steel, gas, rubber and speed. A race car is a science experiment on wheels.
DIANDRA LESLIE-PELECKY: You've probably heard that energy can't be created or destroyed, only converted
from one type of energy into another type of energy. That's exactly what an engine does. It takes the chemical
energy stored in the fuel, and converts it into kinetic energy, which is energy of motion.
In the case of NASCAR, we're talking about a whole lot of motion.
CHRIS ANDREWS: Everybody knows there's a certain amount of gas that goes in the engine, a certain
amount of air that goes in with it. There's a combustion process that's pretty well-defined in technical terms,
but pretty straightforward. Out the tail pipes comes the exhaust, and out the rotating drive shaft comes the power.
TOMMY WHEELER: Really, the engine, all it is is a vessel to allow the intelligent consumption of that
potential energy that's already housed in the fuel itself.
DIANDRA LESLIE-PELECKY: We talk about engines in terms of power. Power is how fast an engine can
convert the energy in fuel into speed at the wheels.
ANDY RANDOLPH: A modern cup engine is about 850 horsepower. Probably an average power figure for a car on the road
would be 150 to 200 horsepower these days.
TOMMY WHEELER: If you could somehow figure out how to get, like, six engines in your car,
your family car, then you're getting close.
DIANDRA LESLIE-PELECKY: A person can generate about four-tenths of a horsepower for roughly ten minutes before
they're totally exhausted. A cup engine produces more than 2,000 times that power.
TOMMY WHEELER: Power is the ability to do work, plain and simple. If all we did was race engines around the track then it
would be a very simple model. You know, whoever makes the most horsepower wins the lap.
DIANDRA LESLIE-PELECKY: Your body and an engine both convert fuel into energy via a chemical reaction.
But you'd have to eat about 34 plain M&M's every second to equal 850 horsepower. In an engine, the chemical reaction
is called combustion. And instead of proteins, fats and carbohydrates, a NASCAR engine uses hydrocarbon molecules for fuel.
TOMMY WHEELER: The engine's job is to get the highest yield from the fuel to the rear wheels of the car.
And all we're doing is trying to maximize that efficiency through engine performance to create this condition that allows the
fuel to be burned at its highest possible use, and consumed in the best possible manner.
DIANDRA LESLIE-PELECKY: Your car engine uses the exact same combustion reaction as a NASCAR engine. And gallon per
gallon, racing fuel has about the same energy as street gasoline. So why does a NASCAR engine have so much more power?
BRIAN VICKERS: The faster you can take air out of the engine, the faster you can put air in the engine.
And the faster you can put air in the engine, the more power it creates.
ANDY RANDOLPH: If you spin the engine at a higher speed, then you're making this, this power per cycle,
you're producing more cuz you're running more cycles in a given amount of time.
DIANDRA LESLIE-PELECKY: Engine speed is measured in revolutions per minute, or RPM's of the crankshaft.
STEVE LETARTE: The RPM range for a NASCAR racing vehicle has been regulated a little bit by the sanctioning body.
We used to turn upwards of 10,000 RPM. And the smart guys in the engine room, we were getting exotic valve springs,
exotic push rods. And to try to limit the cost they put a gear rule in at most tracks. So now we're in the 9,200 to 9,400 RPM range.
DIANDRA LESLIE-PELECKY: A NASCAR engine runs at about 9,500 RPM. While a typical street car engine runs around
2,500 RPM. That means in 60 seconds the NASCAR engine generates 38,000 combustion events, while the street car engine would only
generate 7,500 combustion events. But the difference in RPM's isn't the only factor.
ANDY RANDOLPH: The other thing you have to keep in mind, though, is that power that's produced in the combustion
chamber and applied to the piston, it has to get from there to the output shaft of the engine. And there's a very large friction
difference between a race engine such as this and a production engine. And friction takes away power that
would otherwise go to the rear wheels.
DIANDRA LESLIE-PELECKY: NASCAR engines are actually more efficient than passenger car engines. They're better
at getting the energy produced during combustion to the wheels.
A NASCAR engine is all about horsepower. The faster the engine can convert the energy from the fuel into motion, through the
process of combustion, the more horsepower the engine has. So the next time you hear those most famous words in motorsports...
TRACK ANNOUNCER: Gentlemen, start your engines!
DIANDRA LESLIE-PELECKY: ...you can thank a chemical reaction.