How do I Check the Horsepower of a Chevrolet Engine?
Horsepower is the measure of engine power expressed in terms of work done over a fixed time. Expressed mathematically, one horsepower equals lifting 33,000 pounds one foot in one minute of time. Horsepower can be measured directly or calculated and estimated using mathematical formulas. Ratings claimed by manufacturers are often estimates, based on ideal conditions and perfect engine condition. Since these are usually not the case, determining the exact horsepower of your Chevy engine can be informative and useful.
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Instructions
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Purchase time on a dynometer. Dynometer time is often available at performance or race shops in your local area. Measuring horsepower on a dyno is the best way to get as exact a reading as possible. If your Chevy engine is not yet installed in a vehicle, you can measure horsepower by a flywheel dynometer. This device measures actual engine horsepower before it goes through the transmission and the drive line to the wheels. If the engine is in a vehicle, you can use a rear-wheel dyno to determine horsepower at the rear wheel and to estimate flywheel horsepower.
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Estimate horsepower based on your elapsed quarter-mile time. Take a series of quarter mile runs and average the three best times. Calculate the weight of your vehicle with you sitting in it and plug these figures into the following formula:
hp=weight/(ET/5.835) to the 3rd power
This will give you an estimate of the on-pavement horsepower of your car on that day, under those conditions. This is only an estimate; temperature, humidity and air pressure can affect horsepower ratings.
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Estimate horsepower using your trap speed in the quarter-mile. This formula, similar to the one above, uses trap speed instead of elapsed time. The formula is weight * (speed/234) to the third power. As with the formula in the preceding step, this is an estimate only.
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Average your results. To get the most accurate horsepower, average the results of your on-pavement tests and perform the tests on several different days under different conditions. This will give you the most accurate estimate of the on-pavement horsepower of your Chevy engine.
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Tips & Warnings
Dynometer time is by the hour, so be prepared and have your car ready to test. The more tuning you do while your vehicle is on the dyno, the more the testing will cost you.
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