ANSI - American National Standards Institute
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Revised SAE Horsepower Standard to Give Confidence to Consumers

New York, Oct 24, 2003

According to consumer advocacy groups, many carmakers have joined in a trend of inflating horsepower claims in recent history. To address this issue, the Society for Automotive Engineers (SAE), an ANSI member and accredited standards developer, is revising a standard to verify car manufacturers’ claims for the power of their engines. Adherence to the revised standards will help to give consumers more confidence in their assessment of vehicles that best meet their needs.

Horsepower is defined as work done over time. One horsepower is the amount of power necessary to lift 550 pounds 1 foot in 1 second, or 33,000 lb.ft./minute. In automobiles, torque measures the turning force generated at the wheels. A high horsepower rating generally indicates higher top speeds, while torque signifies a vehicle's acceleration and ability to pull heavy loads.

Automakers can test for horsepower and torque in a variety of ways. SAE J1349 Engine Power Test Code – Spark Ignition and Compression Ignition – Net Power Rating Standard specifies a basis for net engine power rating, and a method for determining net full load engine power with a dynamometer. A dynamometer places a load on the engine and measures the amount of power that the engine can produce against the load.

The current test, which originated in the early '70s and was last reviewed in 1995, allows automakers to claim horsepower and torque figures higher than what most owners will actually experience. The SAE Power Test Code Committee – chaired by David Landcaster, General Motors Corp. engineering group manager – is revising its standard for measuring horsepower and may suggest that automakers have an independent observer verify the numbers they claim for horsepower and torque. The standard will also set a procedure for how to test torque, which is also heavily advertised by car manufacturers.

According to SAE, the revised standard is expected to be written by the end of the year. An SAE advisory committee will then decide whether to adopt the procedure and the use of outside witnesses, such as Underwriters Laboratories Inc., to verify automakers' claims.

Although manufacturers are generally expected to base their horsepower ratings on SAE net power standards, the practice is voluntary and horsepower numbers presented in advertising and brochures aren't always accurate. Jaguar, Hyundai, BMW, Ford and Mazda are among manufacturers that have made exaggerated claims.

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