Horses and Horsepower

Contact: Rick Voegelin
rickvoegelin@compuserve.com
GM Racing Communications
(831) 761-2201
                            


Horsepower Meets Horse Sense: How Competition Breeds Better Engines

SPARTA, Ky., Aug. 8, 2001 - When Ransom Eli Olds began his
fledgling automobile business in 1897, his chief competition did not have
four wheels. It had four hooves, a mane and a tail.

    Olds, the founder of the Olds Motor Vehicle Company and the namesake
of GM's Oldsmobile division, recognized that the horse was a formidable
rival. He had to convince a skeptical public that his horseless carriage
could go farther, last longer and operate more economically than the
familiar horse.

    "Did you ever stop to think what a grand thing it would be to
dispense with the clanking of the horse's hooves on the city pavements and
how much cleaner our streets would be?" Olds asked his potential customers.
He appreciated the value of publicity and participated in land speed record
runs and transcontinental races to demonstrate his products' capabilities.
Olds' marketing plan worked, and by 1904 his Olds Motor Works was selling
more cars than any other car company in the U.S.

    While the automobile has displaced the horse as America's favorite mode
of transportation, the relationship between engines and equines
endures. Horsepower remains the measure of an automobile's performance.
When the Indy Racing Northern Light Series returns to Kentucky Speedway for
the Belterra Casino Indy 300 on August 12, horsepower will occupy the
thoughts of every engine builder and driver.

    Horses are held in high regard in Kentucky, the home of some of the
most prized thoroughbreds on the planet. While the Kentucky Derby features
the power and grace of two dozen high-priced horses, a single IRL Aurora
V8 produces more than 650 horsepower.

    The notion of horsepower predates Indy car racing by several
centuries. James Watt, the inventor of the steam engine, originated the
idea in the 1700s. Like Ransom Olds, Watt's chief competition was the horse
- a proven technology that burned hay instead of coal. The most promising
market for Watt's new engine was the mining industry, which needed power to
pump water out of underground shafts. Watt wanted to quantify his engine's
power output, and he hit on the idea of equating it to the work that a
horse could perform.

    Watt observed that a typical draft horse could turn a water pump
capstan at 144 revolutions per hour, exerting a force of 180 pounds on a
12-foot long pump lever. After working through the mathematics, Watt
concluded that his four-legged rival produced approximately 33,000 lb.-ft.
of torque per minute - and with that, the concept of "horsepower" was
created. Four centuries later, engineers still use a formula derived from
Watt's original calculations to compute horsepower on a dynamometer: rpm x
torque/5252.

    There are three discrete elements in Watt's concept of horsepower:
time, force, and distance. The unit of time is fixed at one minute, but
both force and distance are variable. Therefore there are only two ways to
increase an engine's power output: Increase the force (the horse pushes
harder) or increase the distance traveled (the horse walks faster). Indy
car engine builders focus on these same two objectives. They increase the
force (torque) by burning more fuel, or increase the distance (rpm) by
turning the engine faster.

    Maximum engine speed is regulated in the IRL series to 10,700 rpm by
a tamperproof electronic rev limiter that is maintained and programmed by
IRL technical inspectors. The rev limiter is a cornerstone of the IRL's
commitment to contain costs and maintain safe racing speeds. By eliminating
the incentive to turn the engines faster, the rev limiter compels engine
tuners to seek higher levels of performance by improving efficiency and
reducing internal losses.

    "In order to achieve a competitive advantage in the IRL series, an
engine manufacturer must focus on fundamentals such as improving efficiency
and minimizing parasitic power losses," said Joe Negri, GM Racing IRL/Road
Racing Group manager. "These are topics that have relevance to production
engines."

    There are some crucial differences between horse breeders and
engine builders, however. A horse is a biological organism that converts
hay into work - along with some aromatic waste products. An engine is a
mechanical device that releases the energy stored in the fuel in a form
that can be harnessed to propel a race car - along with heat and byproducts
that go out the exhaust pipes.

     Increasing a horse's intake of hay will theoretically increase
its potential power output - but it may just produce a fat horse. It's the
same for engines: burning more fuel equals more power, but at the risk of
making the engine unresponsive and inefficient. Exceed the physical limits
of the horse by making it run too fast or too far and you are likely to end
up with an ill or injured equine. Exceed an engine's limits and you can end
up with a major repair bill.

    Horses and engines are imperfect energy converters. They consume much
of the energy just to sustain themselves. In horses, it's metabolism that
eats up energy; in motors, it's friction, heat and parasitic losses. But
when you consider that a single Oldsmobile racing engine packs the
equivalent power of 650 horses, internal combustion is obviously a much
more efficient way to produce work - with less mess, as Ransom Olds
adroitly pointed out.

    Like the thoroughbred horses that have made the Bluegrass State
famous, Oldsmobile's IRL Aurora V8 has a racing pedigree. It was inspired
by the modified production Aurora V8 that set 47 speed and endurance
records in 1992. It is directly descended from the IMSA Aurora V8 that won
championships in international road racing in 1995-96. Since the IRL Aurora
V8 made its open-wheel racing debut in January 1997, Oldsmobile engines
have won 45 of the last 47 IRL events (including five straight Indianapolis
500 victories) and have won five consecutive IRL Engine Manufacturer
championships.

    The Kentucky Derby has showcased horsepower of the four-legged variety
for more than 125 years. The Oldsmobile drivers who will compete in the
second Indy car race at Kentucky Speedway will hold the reins on thousands
of horsepower as the Indy Racing Northern Light Series enters the home
stretch in the run for the driver and team championships.

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  E-mail from: Rick Voegelin, 09-Aug-2001