1. Small Engine Performance Jesse Morris Spring 2002 Virginia Tech This presentation has not been edited by the Georgia Curriculum Office.

2. Performance Objective Students will be able to describe all performance applications that are used in a small engine setting Jesse Morris Spring 2002

3. Enabling Objectives Explain small engine displacement Interpret small engine force & pressure Describe work and energy principles Explain horsepower and how it is derived Describe small engine torque

4. Engine Performance could mean the difference in taking the blue ribbon or going home a loser!

5. Small Engine Displacement Displacement is the total volume space increase in the cylinder as the piston moves from the top to the bottom of its stroke

6. Force in a Small Engine Force is the pushing or pulling of one body on another The entire small engine design is based on force Ex. The crankshaft pushes and pulls the piston Force is also achieved by the rotation of the crankshaft Force is often measured in pounds, ounces and grams

7. Small Engine Pressure Pressure is a standardized measure of force, it is force per given unit of area Pressure is measured in P.S.I.(pounds per square inch) PSI= Force Area Ex. PSI can be determined by the amount of combustion in the combustion chamber

8. Work & Energy of a Small Engine Work = Force X Distance, and the answer is usually expressed in foot pounds The work of a small engine usually varies in different applications Energy = the capacity to perform work Small Engines change stored energy of gasoline to mechanical power

9. Small Engine Horsepower Rate of power output by a small engine Engine horsepower can be derived by dividing the total rate of work by 550 (ft lbs. per sec) 3.5, 3.75, 6 are all common HP #’s in small engines

10. Small Engine Horsepower Small Engine Horsepower Brake HP-is the usable horsepower delivered at the crankshaft An engine’s rated horsepower is usually 80% of its maximum brake horsepower (10 hp motor is rated at 8 hp)

11. Small Engine Torque Torque is the turning force that is created by the crankshaft Torque curves varies at different engine speeds The larger the horsepower motor the more torque it will have

12. Key Points Small Engine Displacement Small Engine Horsepower Work & Energy of a Small Engine Small Engine Displacement Small Engine Pressure Force in a Small Engine