Horsepower What it is and how it works.

1. HorsepowerWhat it is and how it works. Welding and Small Gas Engines Original Power Point Created by Eric Haselhurst Modified by Georgia Agricultural Education Curriculum Office June 2002

2. The History of Horsepower • The term was invented by James Watt in the 1700’s. • He wanted to be able to talk about the power developed by horses used in coal mines. • He determined that the average horse could complete 33,000 ft-lbs.. Of work in one minute.

3. The History of Horsepower • This unit of measure is still used today for cars, lawnmowers, and vacuums. • To further explain HP, a horse exerting one HP can raise 330 lbs. of coal 100 ft in a minute.

4. Measuring Horsepower • You can measure horsepower by using a dynamometer. • This machine places a load on an engine at different RPMs and measures torque which is converted to HP. • The formula = Torque*RPM’s/5252

5. Measuring Horsepower • The following graph is an example of a typical horsepower curve of an automobile.

6. Measuring Horsepower • What can be learned from these graphs? • It shows peak horsepower at specific RPMs as well as torque. • Example - 320 HP @ 6500 RPM • 290 ft-lbs. torque @ 5000 RPM • these figures are for the 1999 Shelby Series 1. • To be first off the line at a stop light, rev your engine to the RPMs for maximum HP and dump the clutch.

7. How to increase Horsepower • Change your computer chip • Increase air flow- bigger air filters, blowers • Increase exhaust flow- bigger pipes, mufflers, headers • Change heads and cams- 4 valve heads improve intake and exhaust flow • Add turbo and or super chargers

8. How to increase Horsepower • Cool the incoming air- the hotter the air, the less it will expand when combustion takes place • Make everything lighter- aluminum is a popular material • Increase the compression ratio • Increase displacement- cubic inches V-6 vs. V-8

9. References www.howstuffworks.com