Engine Design Classifications

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

Common Engine Classifications Cylinder arrangement Number of cylinders Cooling system type Valve location Camshaft location Type of fuel burned Type of aspiration

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

Cylinder Arrangement

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

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

Cooling System Type A. Air cooling B. Liquid cooling

Fuel Type Engines are classified by the type of fuel used: Gasoline Diesel Liquefied petroleum gas (LPG), gasohol (10% alcohol, 90% gasoline), and pure alcohol may also be used

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

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

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

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

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

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

Overhead Cam Engine Single overhead cam (SOHC) engine uses only one camshaft per cylinder head Dual overhead cam (DOHC) engine uses two camshafts per cylinder head One operates the intake valves, while the other operates the exhaust Animation Link

Type of Aspiration Supercharger – Pump driven by crankshaft forces air into engine. Turbocharger – Pump driven by exhaust gases forces air into engine.

Alternative Engines Vehicles generally use internal combustion, 4-stroke cycle, reciprocating piston engines Alternative engines include all other engine types that may be used to power a vehicle

Rotary Engine

Rotary Engine Operation

Used on some of the first automobiles Steam Engine Used on some of the first automobiles

Gas Turbine

Typical Automotive Engines

Provides the lowest center of gravity of any piston engine Horizontally Opposed Provides the lowest center of gravity of any piston engine

Features four chain-driven camshafts and 32 valves Overhead Cam V-8 Features four chain-driven camshafts and 32 valves

Inline SOHC This 16-valve, four-cylinder engine has a belt-driven camshaft and a balance shaft

This engine uses many aluminum parts Fuel-Injected V-8 This engine uses many aluminum parts

Each cylinder head contains two camshafts DOHC V-6 Each cylinder head contains two camshafts

Note the reciprocating assembly and the valve train V-8 Engine Note the reciprocating assembly and the valve train

Six-cylinder engine with a rear drive belt for the injection pump Inline Diesel Six-cylinder engine with a rear drive belt for the injection pump

Two roller chains drive the overhead camshafts V-12 Engine Two roller chains drive the overhead camshafts

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