Engine Types, Applications and Designs

The term 'internal combustion engine' in this ILM refers to an engine that:

Burns fuel in a furnace outside the engine and pipes heat into cylinders Burns fuel inside the engine cylinders where the working fluid is contained Uses only external steam pressure to move pistons Operates with no fuel, only compressed air

Early internal combustion engines developed in the 19th century were important because they:

Replaced all electric motors in factories Provided compact power sources that led to automobiles, trucks and mobile equipment Eliminated the need for steam engines in ships immediately Could run on any liquid without adjustment

A basic four-stroke cycle engine completes one power stroke every:

Revolution of the crankshaft Two revolutions of the crankshaft Three revolutions of the crankshaft Four revolutions of the crankshaft

The correct order of the four strokes in a typical gasoline engine is:

Compression, power, exhaust, intake Intake, compression, power, exhaust Power, exhaust, intake, compression Exhaust, power, intake, compression

In a two-stroke cycle engine, compared with a four-stroke:

There is no power stroke A power event occurs every crankshaft revolution The engine cannot run on gasoline The crankshaft does not rotate

Bore is defined in the ILM as:

Distance the piston travels from top to bottom Inside diameter of the engine cylinder Clearance between piston and cylinder wall Distance between main bearings

Stroke is defined as the distance:

Between cylinder bores The piston travels from top dead centre to bottom dead centre Between crankshaft and camshaft Between spark plug centre electrodes

Engine displacement is usually calculated from:

Bore and stroke of one cylinder only Bore, stroke and number of cylinders Firing order and compression ratio Cylinder head thickness

Compression ratio is the ratio between:

Crankshaft speed and camshaft speed Cylinder volume at bottom dead centre and volume at top dead centre Intake valve size and exhaust valve size Fuel pressure and oil pressure

Spark-ignition engines, as described in the ILM, normally use:

Diesel fuel injected into highly compressed air A spark plug to ignite a fuel–air mixture in the cylinder Only natural gas with no air Compression heat to ignite heavy fuel oil

Compression-ignition engines (diesels) differ from gasoline engines mainly because they:

Use spark plugs to ignite the mixture Compress air to a high ratio so injected fuel ignites from heat of compression Operate only on two-stroke cycle Cannot be turbocharged

An inline engine is one where:

Cylinders are arranged in two banks Cylinders are arranged in a single row in one block Cylinders oppose each other horizontally Cylinders are arranged in a radial pattern

A V-type engine is described in the ILM as having:

No crankshaft Two banks of cylinders set at an angle to each other on a common crankshaft Cylinders arranged vertically in a straight line Cylinders arranged in a circular pattern around the crankshaft

Horizontally opposed (boxer) engines are commonly used because they:

Have very tall engine height Provide a low centre of gravity with cylinders laid flat in two opposing banks Cannot be air-cooled Require no lubrication

Typical methods of classifying engines described in the module include:

Colour and manufacturer logo only Number of cylinders, cylinder arrangement, displacement, fuel type and cooling method Type of upholstery and wheelbase Axle ratio and tire size

An overhead cam (OHC) engine design places the camshaft:

In the engine block beside the crankshaft only In the cylinder head above the valves In the intake manifold Inside the crankshaft

The firing order of an engine refers to:

Order in which plugs are installed on the bench Sequence in which cylinders receive their power strokes Order of assembly of the engine Sequence of gear changes on a road test

Turbocharged engines differ from naturally aspirated engines because they:

Always run without intake air Use an exhaust-driven turbine to drive a compressor that increases intake air density Cannot use intercoolers Do not require lubrication

The ILM explains that engines using alternative fuels such as CNG or LPG:

Always use diesel fuel backup May require different fuel system components and valve seat materials Use no cooling system Must always be two-stroke

In the ILM, 'engine application' refers to:

Only passenger car use How the engine is used, such as on-highway, off-road, industrial, agricultural or stationary The type of paint applied to the engine The type of upholstery in the cab

A stationary industrial engine application would typically be used to:

Drive a vehicle down the highway Power equipment such as pumps, compressors or generators in one location Power aircraft Operate only marine propulsion

Air-cooled engines differ from liquid-cooled engines in that they:

Have no cooling requirements Use fins and airflow instead of coolant-filled jackets in the block and head Do not require lubrication Can only be used underwater

Most light-duty automotive engines today, as described in the ILM, are:

Large, slow-speed diesels with mechanical injection High-speed, liquid-cooled, overhead-valve or overhead-cam designs Air-cooled, side-valve engines Two-stroke lawnmower engines

Engine torque is best described as:

Rotational force produced by the crankshaft Fuel volume delivered per injection event Oil pressure in the main bearings Electrical output of the alternator

Horsepower in the ILM is explained as a measure of:

Static weight of the engine Rate of doing work or how quickly torque is produced over time Cooling system capacity only Battery reserve capacity

An engine's operating cycle describes:

Sequence of events of air, fuel, compression, power and exhaust in each cylinder Vehicle maintenance schedule Tire wear pattern Order of body panel assembly

Two-stroke diesel engines used in some heavy-duty applications differ because they:

Use carburetors and spark ignition Use scavenging ports and blowers or turbochargers for cylinder filling Have no exhaust system Operate only at idle speed

The ILM notes that advances in engine technology such as variable valve timing and direct injection are aimed at:

Increasing fuel consumption and emissions Improving power, fuel economy and emission performance Eliminating electronic controls Making engines larger and heavier

A common reason for classifying engines by fuel type in a parts environment is to:

Determine vehicle colour Ensure correct specification of fuel system, ignition and emission components Select appropriate upholstery Determine transmission gear ratios

When dealing with engine identification, the ILM stresses the importance of:

Guessing based on vehicle age Recording engine family codes, displacement, VIN and build options Using only visual colour checks Checking radio model numbers

A multi-cylinder engine provides smoother power than a single-cylinder engine mainly because:

It uses larger pistons Power strokes overlap between cylinders as crankshaft rotates It has no exhaust system It has a lower compression ratio

In four-stroke engines, valve timing is coordinated with crankshaft position so that:

Intake and exhaust valves are open at the same time during compression Each valve opens and closes at the correct point to fill and empty the cylinder efficiently Pistons contact valves at high speed Both valves are always closed

The ILM explains that engines may be described as 'oversquare' when:

Stroke is longer than bore Bore is larger than stroke Bore equals stroke exactly Engine has more than eight cylinders

An advantage of oversquare engines is that they:

Are limited to very low speeds Can operate at higher speeds due to shorter stroke for a given displacement Do not require cooling systems Eliminate need for lubrication

Undersquare engines (long stroke) are often associated with:

High-speed racing only Good low-speed torque characteristics for heavy-duty applications No crankshaft balance concerns Inability to use diesel fuel

From a parts technician’s perspective, understanding engine types and designs helps to:

Perform full engine rebuilds Identify correct parts, understand catalogues and explain options to customers Replace transmission internals Service body electrical systems

The ILM identifies hybrid powertrains as systems that:

Use only electric motors with no engine Combine internal combustion engines with electric motors and batteries Use steam turbines only Require no cooling or lubrication

Engine identification tags and stampings are usually located:

On random body panels On the block, rocker cover or front covers where manufacturers place serial and model information On the steering wheel On the muffler only