1. Engine Design and Classofocation
Chapter Lesson 1
Engine Design and Classofocation

2. Engine Classifications
Even though basic parts are the same, design differences can change the way engines operate and how they are repaired
For this reason, you must be able to classify engines

3. Common Engine Classifications
Cylinder arrangement
Number of cylinders
Cooling system type
Valve location
Camshaft location

4. Common Engine Classifications
Combustion chamber design
Type of fuel burned
Type of ignition
Number of strokes per cycle
Number of valves per cylinder
Type of aspiration

5. Cylinder Arrangement
Refers to the position of the cylinders in relation to the crankshaft
There are five basic cylinder arrangements:
inline
V-type
slant
W-type
opposed

6. Cylinder Arrangement

7. Number of Cylinders
Most car and truck engines have either 4, 6, or 8 cylinders
Some may have 3, 5, 10, 12, or 16 cylinders
Engine power and smoothness are enhanced by using more cylinders

8. Cylinder Numbering
Engine manufacturers number each engine cylinder to help technicians make repairs
Service manual illustrations are usually provided to show the number of each cylinder
Cylinder numbers may be cast into the intake manifold

9. Firing Order Refers to the sequence in which the cylinders fire
Determined by the position of the crankshaft rod journals in relation to each other
May be cast into the intake manifold
Service manual illustrations are usually provided to show the firing order

10. Cylinder Numbering and Firing Order

11. Cooling System Type There are two types of cooling systems:
Liquid cooling system
surrounds the cylinder with coolant
coolant carries combustion heat out of the cylinder head and engine block
Air cooling system
circulates air over cooling fins on the cylinders
air removes heat from the cylinders

12. Cooling System Type
A. Air cooling
B. Liquid cooling

13. Fuel Type Engines are classified by the type of fuel used
Gasoline engines burn gasoline
Diesel engines burn diesel fuel
Liquefied petroleum gas (LPG), gasohol (10% alcohol, 90% gasoline), and pure alcohol can also be used to power an engine

14. Ignition Type
Two basic methods are used to ignite the fuel in an engine combustion chamber:
spark ignition (spark plug)
compression ignition (compressed air)

15. Uses an electric arc at the spark plug to ignite the fuel
Spark Ignition Engine
Uses an electric arc at the spark plug to ignite the fuel

16. Compression Ignition Engine
Squeezes the air in the combustion chamber until it is hot enough to ignite the fuel

17. Valve Location Engines are classified by the location of the valves:
L-head engine
also called a flat head engine
I-head engine
also called an overhead valve (OHV) engine

18. Both the intake and exhaust valves are in the block
L-Head Engine
Both the intake and exhaust valves are in the block

19. Both valves are in the cylinder head
I-Head Engine
Both valves are in the cylinder head

20. Camshaft Location
There are two basic locations for the engine camshaft:
Camshaft located in the block
cam-in-block engine
Camshaft located in the cylinder head
overhead cam (OHC) engine

21. Cam-in-Block Engine
Uses push rods to transfer motion to the rocker arms and valves
Also called an overhead valve (OHV) engine

22. Camshaft is located in the top of the cylinder head
Overhead Cam Engine
Camshaft is located in the top of the cylinder head

23. Overhead Cam Engine
OHC engines may use one or two camshafts per cylinder head
Single overhead cam (SOHC) engine
uses only one camshaft per cylinder head
Dual overhead cam (DOHC) engine
uses two camshafts per cylinder head
one cam operates the intake valves, while the other cam operates the exhaust valves