Engines Topics

9 Cylinder Rotary
Rotary engines were used extensively in early aircraft.
ABDC
Abbreviation of After Bottom Dead Centre.
Adjustable Rocker Arm
A type of rocker arm with an adjusting nut that can be tightened or loosened to adjust the valve to rocker arm gap.
AFR
Abbreviation of Air-Fuel Ratio.
After Bottom Dead Centre
The position of the piston as it starts its way up.
Afterburner
Thrust augmentation feature of a gas turbine engine.
Aftertreatment
Exhaust gas treatment after the combustion chamber, such as a catalyst.
Air Cooling System
Air passes over cooling fins to remove the heat from the system.
Air Induction System
The air intake system, that channels clean air and fuel to an internal combustions engine.
Air Injection
The injection of air into a system.
Air Intake Manifold
The air intake manifold of an internal combustion engine performs a number of functions.
Air Intake System
The system that channels clean air and fuel to an internal combustions engine.
Air Intake Valve
Valve that controls the air and fuel flow into an internal combustion engines.
Air Start
An act or instance of starting an aircraft's engine while in flight, especially a jet engine after flameout.
Airflow Meter
A sensor that measures the airflow rate through a duct.
Air-Fuel Ratio
The mass of air supplied to the engine divided by the mass of fuel supplied in the same period of time.
Alpha Stirling Engine
A striling engine that has two separate power pistons, one hot and one cold.
Alternative Fuels
Substitutes for traditional liquid, oil-derived motor vehicle fuels like gasoline and diesel.
API Gravity
An arbitrary scale adopted by the American Petroleum Institute to designate the specific gravity of mineral oils.
APU
Abbreviation of Auxiliary Power Unit.
Articulated Piston
Two-piece pistons incorporating an entirely separate piston crown or dome with a separate skirt.
Aspin Engine
A rotary valve engine developed by Frank Aspin.
Atmospheric Engine
Also known as the Newcomen engine, this admitted steam into a cylinder which was then condensed by cold water and the piston driven by atmospheric pressure.
Auxiliary Power Unit
A device that converts high density fuel into electrical power.
Babbitt
A soft antifriction metal used to line bearings.

Bedplate
The lower part of the engine resting on the foundation.
Beta Stirling Engine
A stirling enging with a single power piston arranged coaxially with a displacer piston.
Big End
The connection between the conrod and crankshaft in an internal combustion engine.
Bleed Air
Hot air, at high pressure, taken usually from the bypass section of a gas turbine engine, for heating, de-icing and other useful work.
Blueprinted Engine
Ensuring the dimensions of the parts in the engine are more accurate and, therefore, closer to the original engine blueprint values.
Boost Pressure
The increase above atmospheric pressure produced inside the intake manifold by a forced-induction system such as a turbocharger or supercharger.
Bore and Stroke
The bore and stroke of the piston sets the swept volume.
Bottom Dead Centre
The position of the crank when the piston is in its closest position to the crankshaft, in its farthest position from the cylinder head. Abbreviated bdc.
Bottom End
The collective term for the internal combustion engine block and the components it houses.
Brake Mean Effective Pressure
This is the average effective cylinder pressure that does useful work calculated from the brake horse power.
Brake Power
The engine power as measured at the output shaft.
Brake Specific Fuel Consumption
The ratio of the engine fuel consumption to the engine power output.
Brake Thermal Efficiency
This is the ratio of Brake Power to Heat of Fuel for a heat engine.
Bypass Ratio
The ratio between the mass flow rate of air drawn in by the fan but bypassing the engine core to the mass flow rate passing through the engine core.
Cam Follower
That part of the push rod that is in contact with the cam.
Camshaft
The shaft which carries the various cams required for the operation of inlet, exhaust, fuel, and starting-air valves.
Carburetor
A device through which air and fuel are atomized and drawn into the engine.
Carburetor Choke
A temporary restriction in a carburetor throat that reduces the flow of air and enriches the fuel-air mixture to aid in starting the engine.
Carnot Engine
An idealized reversible heat engine working in a Carnot cycle.
Cetane Number
A percentage indicating the ignition quality of diesel fuels.
Charge Cooler
A device which cools a gas between the compressive steps of a multiple stage compressor.
Charge Efficiency
The ratio of the weight of the charge actually taken in to the weight of the air at standard conditions corresponding to the piston displacement.
Clearance Volume
The volume of air or liquid remaining in the cylinder of an air compressor or a pump when the piston is nearest to the cylinder head.
Close Coupled Catalyst
A catalyst that is positioned close to the exhaust manifold to reduce the amount of heat lost from the exhaust gases before they reach the catalyst.
Closed-Loop Fuel Control
A mode where input air/fuel ratio to an engine is controlled by using an exhaust oxygen sensor as the input reference.
Cold Stuck Piston Ring
A piston ring that is stuck when the piston and ring are at room temperature, but inspection shows that it was free during engine operation.
Combined Cycle Gas Turbine
A unit whereby electricity is generated by a gas powered turbine and also a second turbine.
Combined-Cycle Engine
Engine concepts using some combination of air-breathing and rocket components which are integrated into a single propulsion system.
Combustion Chamber
The space above the piston in which the fuel-air mixture starts to burn in an internal combustion engine.
Combustion Chamber Recess
The area where combustion occurs in a Wankel Engine.
Combustion Engine
An engine that uses the heat from the combustion of a fuel to operate, fundamentally split into Internal and External combustion engines.
Combustion Pressure
The pressure created during the combustion of the air fuel mixture in the cylinder.
Combustion Residue
Carbon and other deposits resulting from combustion.
Common Rail
A pipe or header from which branch lines lead to each of the fuel valves in the different cylinder heads of a diesel engine.
Compression Pressure
The pressure of the air charge at the end of the compression stroke.
Compression Relief
A device to reduce the compression in a cylinder and thus to make cranking easier.
Compression Rings
Piston rings placed in the upper part of a piston to seal against loss of compression pressure and against gas blowing.
Compression Stroke
The stroke of the piston during which the air charge in the cylinder is compressed by the piston movement.
Compressor Wheel
The wheel on a turbocharge which pulls air and forces into the engine.
Connecting Rod
The part in an internal combustion engine that connects the piston to the crankshaft.
Connecting Rod End
The end of the connecting rod that carries the bearing and connects to the crank and other end that connects to the piston.
Conrod
Abbreviation of connecting rod, the part in an internal combustion engine that connects the piston to the crankshaft.
Constant Pressure Combustion
Combustion of fuel in a cylinder at so slow a rate that there is no rise in cylinder pressure.
Constant Volume Combustion
Combustion in a cylinder so fast that there is no change in volume.
Cooling System
System that extracts heat from a machine and ejects it to the surrounding world.
Cooperative Fuel Research Engine
A standardised single cylinder, overhead valve, variable compression ratio engine used for measuring octane or cetane quality.
Crank
That part of the crankshaft, which is in the form of a crank and crank pin.
Crank Angle
Angle that can be measured between the crankshaft and top dead centre.
Crank Rumble
This is an amplitude modulation of engine noise perceived inside a car with a modulation frequency of 0.5 order.
Crank Web
One of the pair of arms which carry the big-end journal.
Crankcase
The middle part of the engine structure surrounding the working parts.
Crankcase Emissions
Pollutants allowed to escape into the atmosphere from the crankcase of an internal combustion engine.
Crankpin
That part of the crank to which the connecting rod is attached.
Crankshaft
That part of the engine which transmits the reciprocating motion of the pistons to the driven unit in the form of rotary motion.
Crankshaft Journal
The journals running in the main bearings as opposed to those for the big-end bearings.
Crankshaft Pulley
A wheel attached to the front end of the crankshaft which is connected by fan belts to the fan, the alternator, and other devices so that the rotating crankshaft can drive these other parts as well.
Cross Compound Turbine
Large steam turbines with parallel shafts and a generator on each shaft. The steam flows through the high pressure turbine, then is crossed-over to the low pressure turbine.
Cylinder Block
A number of cylinders cast in one piece.
Cylinder Liner
A cylindrical lining that is inserted into the cylinder jacket or cylinder block and in which the piston slides.
Derated Engine
An engine with a restricted power output.
Detonation
Any rapid chemical reaction accompanied by noise and often heat and light, e.g., explosions.
Diesel
Fossil diesel is produced from the fractional distillation of crude oil between 200°C and 350°C at atmospheric pressure, resulting in a mixture of carbon chains that typically contain between 8 and 21 carbon atoms per molecule.

Diesel Engine
An internal-combustion engine in which the fuel is injected into the cylinder near the end of the compression stroke and is ignited by the heat of the compressed air in the cylinder.
Double-Blind Reference Oil
A reference oil, the identity of which is unknown by either the submitting source or the test facility and is not known to be a reference oil by the test facility.
Dry Sump
A lubrication system in which the oil is pumped into the engine's sump under pressure and then pumped out again.
Emissions
The gases and airborne particles produced during combustion.
Engine
A machine which produces power to do work, particularly one that converts heat into mechanical work.
Engine Block
The main structure of the engine.
Engine Breathing
The ability of an internal combustion engine to get air into the combustion chamber during the intake stroke.
Engine Configurations
Various configurations of engine have been developed over the years for power, low noise and vibration, economy or weight.
Engine Crane
A crane designed specifically for lifting engines and gearboxes into and out of vehicle engine bays.
Engine Excitation Mechanisms
The physics behind the vibrations generated by the internal mechanisms of an internal combustion engine.
Engine Knock
Abnormal combustion, often producing audible sound, caused by autoignition of the air/fuel mixture.
Engine Mechanical Efficiency
The mechanical efficiency takes into account friction losses in the bearings, piston sliding losses and valvetrain losses. The ratio of brake power to indicated power is the mechanical efficiency.
Engine Oil
Liquid that reduces friction or wear, or both, between the moving parts within an engine; removes heat, particularly from the underside of pistons; and serves as a combustion gas sealant for the piston rings.
Engine Orders
Engine orders are simply the amplitudes of the frequency components which are the multiples of the rotating frequency.
Engine Radiated Noise
Some empirical noise prediction models have been derived from a sample of 1m radiated engine noise measurements.
Engine Speed
Rotational speed of the crankshaft, normally declared as rpm.
Engine Tuning
The adjustment, modification or design of internal combustion engines to yield optimal performance, to increase an engine′s power output, economy, or durability.
Engine Tuning to Increase Durability
The adjustment, modification or design of internal combustion engines to increase durability.
Engine Tuning to Increase Power
The adjustment, modification or design of internal combustion engines to yield more power.
Engine Tuning to Reduce Fuel Consumption
The adjustment, modification or design of internal combustion engines to yield better fuel economy.
Engine Vacuum
Air depression created by the intake stroke, pulling in the air/fuel mixture.
Engines Books
Lists all Engines Books in the Encyclopaedia
Engines Calculations
Lists all Engines Calculations in the Encyclopaedia
Engines Conversions
Lists all Engines Conversions in the Encyclopaedia
Engines Weblinks
Lists all Engines Weblinks in the Encyclopaedia
Exhaust Cam
The cam that controls the operation of the exhaust valve.
Exhaust Catalyst
A catalytic converter is known to have two distinct acoustic effects: Reactive Effect and Resistive Effect.
Exhaust Catalyst Thermal Management
An exhaust catalyst runs at a high temperature internally and has a high surface temperature that also needs to be accounted for when packaging.
Exhaust Downpipe
The pipe used to route the exhaust flow from the manifold or turbo to the underbody of the vehicle.
Exhaust Gases
Products of combustion which are discharged from the cylinder after doing work on the piston.
Exhaust Manifold
The pipe that collects the burnt gases as they are expelled from the cylinders.
Exhaust Noise
The exhaust system of an internal combustion engine has a number of functions, one of which is to reduce the noise of the waste gases as they are expelled from the engine to the atmosphere.
Exhaust Pipe
Piping through which exhaust gases from an engine pass out to the atmosphere.
Exhaust System
A collection of pipes, silencers, sensors and catalysts or filters that make a system to channel the waste exhaust gases away from an internal combustion engine.
Exhaust Valve
The valve through which the burnt gases are allowed to pass out to the exhaust manifold.
Expansion Period
The portion of the power stroke during which the combustion gases expand from the movement of the piston and thus do work.
External Combustion Engine
An engine that burns the fuel outside of the engine, such as a steam engine or stirling engine.
Flame Engine
The working principle is similar to the hot air engine, except that this engine draws hot air into the cylinder.
Flat Four Engine
A horizontally opposed four cylinder engine.
Flat Six Engine
A horizontally opposed six cylinder engine.
Flat Twin Engine
A horizontally opposed two cylinder engine.
Flathead Engine
Another name for a Sidevalve Engine.
Four-Stroke Engine
An engine operating on a cycle which is completed in four strokes, or two revolutions of the crankshaft.
Free Piston Engine
A linear internal combustion engine, in which the piston motion is not controlled by a crankshaft but determined by the interaction of forces from the combustion chamber gases, a rebound device and a load device.
Friction Horse Power
The power consumed within the engine from friction between its parts.
Fuel
Any substance burned for heat or power.
Fuel Additives
Chemicals added to fuel in very small quantities to improve and maintain fuel quality and/or to lower emissions.
Fuel Consumption
Definitions of fuel consumption calculations.
Fuel Dilution
The amount of raw, unburned fuel that ends up in the crankcase of an engine.
Fuel Injection
Fuel injected into an engine under high pressure so that it atomizes as it leaves the nozzle.
Fuel Injection Pump
The pump used to inject fuel oil into the combustion space of a diesel engine; the fuel pump.
Fuel Injector
Electro-mechanical device that precisely meters fuel into an internal combustion engine.
Fuel Map
A two-dimensional or three-dimensional series of curves storing the information regarding fuel and ignition for the engine, depending on the engine’s requirements.
Fuel Pump
A pump used to deliver fuel to the engine.
Fuel Supply Pump
A pump that transfers fuel from the tank and delivers it to the injection pump.
Gamma Stirling Engine
A beta Stirling engine in which the power piston is not mounted coaxially to its displacer piston.
Gas Turbine
A turbine driven by the expansion of burning fuel.
Gas Turbine Efficiency
For a simple cycle gas turbine the efficiency is determined by the pressure ratio of the compressor.
Generator Set
A generating system comprising a combustion engine driving an electrical generator.
Genset
Abbreviation of Generator Set.
Glow Plug
An electrical device used to heat the air in the combustion chamber of a diesel engine for quick ignition and starting when the engine is cold.
H24 Engine
The basic design is that of two flat horizontally opposed 12 cylinder engines geared onto a common shaft.
Heat Balance
A tabulation showing the percentages of the heat developed by combustion in the engine cylinder that are (1) delivered in the form of power at the crankshaft, (2) lost in friction, (3) lost to the cooling water, and (4) lost in the exhaust gases.
Heat Engine
A device for converting heat into mechanical work.
Heat Shield
Any device that protects something from heat.
Heat Value
The heat developed by the combustion of one pound of fuel, Btu per Pound.
Heavy Duty Engine
An engine that is designed to allow operation continuously at or close to its peak output.
Hero′s Engine
A device which propels itself by shooting steam from one or more orifices. Also known as an Eolipile.
HHV
Abbreviation of Higher Heating Value.
High Tension Leads
High voltage wire from the ignition coil.
Higher Heating Value
The standard measure of the energy released during combustion of a fuel, assuming the product water is in the liquid state.
Highest Useful Compression Ratio
The highest compression upto which no knocking occurs in a given engine.
Horizontally Opposed Engine
An engine with an even number of cylinders that are arranged either side of the crankshaft.
Hot Air Engine
The Stirling Engine is an external combustion engine.
Hot-Stuck Piston Ring
A piston ring that is stuck when the piston and ring are at room temperature, and inspection shows that it was stuck during engine operation.
Hunting
Erratic variation of rotational speed.
IC Engine
Any engine, either reciprocating or rotary, in which the fuel is consumed in the interior of the engine rather than outside of the engine.
Idle
Internal combustion engine operating at no load and minimum engine speed.
Ignition Advance
The amount before the piston reaches the top of its travel that the spark fires to ignite the mixture.
Ignition Delay
The length of time or number of degrees of crankshaft rotation between the beginning of injection and ignition of the fuel.
Ignition System
A system for igniting a fuel-air mixture.
Ignition Timing
The time of occurrence of ignition measured in degrees of crankshaft rotation relative to TDC (Top Dead Centre).
Indicated Horsepower
The horsepower developed in the engine cylinder, as calculated from an indicator diagram.
Indicated Mean Effective Pressure
During the cycle of an engine useful work is only done on the power stroke.
Indicated Power
The power developed in the engine cylinder, as calculated from an indicator diagram.
Inlet and Exhaust Ports
The inlet or exhaust ports allow air to flow into or out of the cylinder head. Run from the manifold face to the valves.
Inlet Cam
The cam that controls the operation of the air inlet valve in a four-stroke engine.
Inlet Manifold
The main pipe that lies alongside the cylinder heads and from which branch pipes take the air charge to the separate cylinders.
Inline Engine
All of the cylinders are aligned and on one side of an aligned crank.
Inner Dead Centre
Also known as top dead centre.
Intake Stroke
The suction stroke.
Intercooler
A device which cools a gas between the compressive steps of a multiple stage compressor.
Internal Combustion Engine
Any engine, either reciprocating or rotary, in which the fuel is consumed in the interior of the engine rather than outside of the engine.
Jerk Pump
A fuel pump which injects fuel into the cylinder by action of a cam having a sharp nose.
Jet Engine
An engine that discharges a fast moving jet of fluid.
Lean Mixture
A mixture in which the proportion of air to fuel is greater than that theoretically necessary for completes combustion.
LHV
Abbreviation of Lower Heating Value.
Light Duty Engine
An engine that is designed to be normally operated at substantially less than its peak output.
Liquid Air Cycle Engine
A rocket engine in which the oxidizer is liquid air obtained by liquefaction of the air entering the air-breathing inlet.
Little End
The gudgeon pin end, the part of the conrod that fits to the piston.
Loop Scavenged Engine
An external blower is used to supply the charge, under some pressure, at the inlet manifold.
Low Tension Leads
The wiring in the ignition system that is distinguished from the high tension wiring.
Lower Heating Value
The standard measure of the energy released during combustion of a fuel, assuming the product water is in the gaseous state.
Lubricating Pump
A pump which handles lubricating oil in an engine.
Lugging
A characteristic of an internal combustion engine that is operating at a point combined point of relatively low-speed and high-power output.
Magneto
An electrical generator that uses permanent magnets to produce periodic pulses of alternating current.
Main Bearings
The bearings that house the crankshaft within the cylinder block.
Manifold Absolute Pressure
the total pressure of air going into the engine, boost pressure plus atmospheric pressure.
Mean Effective pressure
The mean or average pressure which, acting on the piston, would do the same work as does the actual variable pressure in the cylinder.
Mean Piston Speed
The average speed of the piston in the cylinder bore.
Mechanical Efficiency
The ratio of brake horsepower to indicated horsepower.
Mechanical Fuel Injection
Injection with the fuel-valve operated mechanically from a cam.
Metering Jet
A jet in a fuel-injection system that controls the fuel flow rate.
Miller Cycle
A combustion process for the four stroke internal combustion engine where the intake valve is left open longer than it would be in an Otto cycle engine.
Needle Valve
A form of globe valve that contains a sharp pointed, needle like plug that is driven into the and out of a cone shaped seat to accurately control a relatively small rate of flow of a fluid.
Net Indicated Mean Effective Pressure
The ratio of net work per cycle to cylinder volume displaced per cycle.
Newcomen Engine
Also known as the Atmospheric Engine, this admitted steam into a cylinder which was then condensed by cold water and the piston driven by atmospheric pressure.
Normally Aspirated Engine
An engine that uses intake air at atmospheric pressure and temperature to mix with the fuel for combustion.
OHC
Abbreviation of Overhead Cam.
OHV
Abbreviation of Overhead Valve.
Oil Consumption
The amount of lubricating oil an engine uses.
Oil Control Ring
Piston ring that prevents an excessive amount of lubricating oil from being drawn up into the combustion space during the suction stroke.
Oil Seal
Device used to prevent oil leakage past a certain area.
Oil Splash System
Engine lubrication system where the end of the connecting rod dips into the oil in the sump and splashes it around the crankcase.
Open Crank Engine
Early internal combustion engines were of the open crank style, ie there was no enclosed crankcase.
Open Loop Fuel Control
A mode where engine input air/fuel ratio is controlled by measuring the mass of input air and adding the proper mass of fuel to obtain a desired ratio.
Opposed Piston Engine
An engine that has two pistons within the same cylinder, traveling in opposite directions.
Outer Dead Centre
Also known as bottom dead centre.
Overhead Cam
A camshaft used for operating both valves and unit injectors, located on top of or within the cylinder head.
Overhead Valve
The camshaft is within the cylinder block and uses pushrods to actuate rocker arms above the cylinder head to actuate the valves.
Oxidation of Engine Oil
The reaction of the oil with an electron acceptor, generally oxygen, that can produce deleterious acidic or resinous materials.
Oxygen Sensor
Measures the percentage of oxygen in the exhaust, and tells the computer whether the fuel/air mixture is too rich or too lean.
Oxygenated Fuel
Any fuel substance containing oxygen, such as ethanol, methanol, or biodiesel.
Packing Rings
Rubber rings used to form a watertight joint at the bottom of the cylinder liner.
Petrol Engine
An internal-combustion engine in which the fuel is petrol that is drawn or injected into the cylinder along with air and ignited with an electric spark.
Piston
A cylindrical part which reciprocates in the cylinder bore of an engine and transmits the force of the gas pressure through the connecting rod to the crankshaft.
Piston Crown
The very top of the piston.
Piston Pin
A pin that rests in two bored holes in the piston and passes through the eye of the connecting rod, to join the two together flexibly.
Piston Ring
An open-ended ring that fits into a groove on the outer diameter of a piston in a reciprocating engine such as an internal combustion engine or steam engine.
Piston Skirt
The cylindrical part of the piston which sits within the bore.
Poppet Valve
A valve opened by the action of a cam and closed by a spring.
Power Curve
Graphical representation of the changing relationship between speed and revolutions per minute (RPM).
Power Lost to Engine Friction
This can be calculated from the difference between Indicated Power and Brake Power.
Power Stroke
The working stroke of a piston.
Pre Combustion Chamber
A chamber in the cylinder head of some engines into which the fuel is injected, ignited, and partly burned, the rest of the fuel being thrown out into the main combustion space where combustion is completed.
Pre Ignition
Ignition of the mixture of fuel and air in the combustion chamber before the passage of the spark.
Radial Engine
An engine with a number of cylinder arranged in a circle around the crankshaft centre line. A design often used for aircraft engines.
Ramjet
A jet engine with no mechanical compressor, consisting of specially shaped tubes or ducts open at both ends.
Range Extender
A device that extends the range of an electric vehicle by converting an energy dense fuel into electricity.
Rankine Cycle
A mathematical model that is used to predict the performance of steam engines. The Rankine cycle is an idealised thermodynamic cycle of a heat engine that converts heat into mechanical work. The heat is supplied externally to a closed loop, which usually uses water as the working fluid.
Research Octane Number
The octane as tested in a single-cylinder octane test engine operated under less severe operating conditions.
Rich Combustion
Having a relatively high proportion of fuel to oxidizer. Having a value greater than stoichiometric.
Rocket Engine
A reaction engine that carries all fuel and components for combustion and so not requiring intake of any outside substance and hence capable of operation in outer space.
Rocket Fuel
A fuel, either liquid or solid, developed for, or used by, a rocket.
Roller Tappets
Valve lifters that have a roller placed on the end contacting the camshaft. This is done to reduce friction between the lobe and lifter.
RON
Abbreviation for Research Octane Number.
Rotary Engine
The crankshaft is fixed and the crankcase, pistons and cylinders rotate with the propeller.
Schnuerle Ports
The inlet ports are placed on both sides of the exhaust ports so that the incoming air enters in two streams uniting on the cylinder wall opposite the exhaust ports.
Scramjet
A supersonic combustion ramjet air-breathing engine in which air flows through the combustion chamber at supersonic speeds.
Semi Diesel Engine
A term applied to oil engines using rather low compression pressures and requiring a hot surface for ignition of the injected fuel.
Shaft Horse Power
The power delivered to the output shaft of an engine.
shp
Abbreviation of Shaft Horse Power.
SI Engine
An engine whereby the fuel air mixture is compressed in the cylinder and then ignited with an electric spark.
Sidevalve Engine
An internal combustion engine with valves placed in the engine block beside the piston.
Simple Cycle Gas Turbine
Cycle consisting only of compression, combustion and expansion.
Single Cylinder Engine
The first internal combustion engines were single cylinder designs and mostly stationary engines.
Single Shaft Gas Turbine
A gas turbine arrangement in which the compressor and the gas turbine are all coupled to one shaft.
Single Stage Compressor
Compressor having only one compressive step between inlet and outlet.
Skirt
The part of the piston below the piston-ring grooves. Designed to counter the lateral force from the connecting rod and guide the piston within the liner.
Sleeve Valve Engine
In the sleeve valve engine the conventional valve train was replaced by a ported cylinder liner that was then rotated to align with ports in the block so as to achieve the timing for the intake and exhaust strokes for the four-stroke cycle.
Slipper Pistons
Pistons with skirts with material removed, to reduce friction while maintaining strength.
Sludge
A deposit, principally composed of insoluble resins and oxidation products from fuel combustion and the lubricant, that does not drain from engine parts but can be removed by wiping with a cloth.
Sodium Filled Exhaust Valves
The valve stem is drilled and partially filled with sodium to increase heat transfer to the valve guide and hence reduce the temperature of the exhaust valve.
Spark Advance
The number of degrees of crankshaft rotation before TDC (Top Dead Centre) where the spark plug is fired.
Spark Air Gap
The distance between the tips of the electrodes.
Spark Arrester
A device which hinders flames from exiting the exhaust pipe.
Spark Breakaway
The end of spark duration.
Spark Ignition Engine
An engine whereby the fuel air mixture is compressed in the cylinder and then ignited with an electric spark.
Spark Plug
Electrical device that fits into the cylinder head of an internal-combustion engine and ignites the gas by means of an electric spark.
Spark Plug Fouling
A deposit on the electrodes of a spark-plug of essentially non-conducting material that may, but will not necessarily, prevent the plug from operating.
Spark Plug Whiskering
A deposit of conductive material that tends to form a bridge between the spark-plug electrodes or to a ground, thus shorting out the plug.
Specific Fuel Consumption
The amount of fuel needed to provide a given power for a given period.
Specific Impulse
A performance parameter of a rocket engine, the thrust F in pounds divided by the weight flow rate in pounds per second.
Split Cycle Engine
A type of internal combustion engine that divides four cylinder strokes between two paired cylinders, one for intake/compression and another for power/exhaust.
Squish
Action of forcing pockets of air within the combustion chamber back towards the spark plug for better fuel distribution.
Steam Condenser
A device for condensing steam from the exhaust of a steam engine or turbine. Also used to condense steam that may be used in industrial processes.
Steam Engine
An engine that uses steam to produce useful work.
Steam Engine Indicator Diagram
The pressure in the cylinder is plotted versus the cylinder volume. This was developed by James Watt and John Southern to improve the efficiency of the steam engine. The work done is the area within the curve.
Steam Turbine
A turbine driven by steam expansion through the blades of the turbine.
Step Engine
Another name for a multi-stage rocket.
Stirling Engine
An external combustion engine.
Straight Engine
All of the cylinders are aligned and on one side of an aligned crank.
Straight-Through Silencer
A type of absorption silencer with a single perforated tube surrounded by sound-absorbing fibre. This results in a very low back pressure silencer, but at the same time only attenuates higher frequency noise.
Stroke
The distance a piston travels up or down inside the cylinder.
Suction Stroke
Another name for the air intake stroke on an internal combustion engine.
Sump
The engine oil reservoir.
Supercharger
An air compressor used to force more air into an engine than it can inhale on its own.
Surface Gap Spark Plug
A type of spark plug in which the spark is fired across the insulator surface between the centre electrode and the shell.
Surface-Ignition Engine
Another name for a Semi Diesel Engine.
Sustainer Engine
A rocket engine that maintains the velocity of a rocket vehicle once it has achieved its programmed velocity by use of booster or other engine.
Swirl Combustion
The swirl is used to reduce particulate emissions.
Synthetic Oil
A non-petroleum based oil.
Tachometer
An instrument that measures the rate at which a shaft is turning.
Tappet
A tappet is an arm, collar or cam within a machine which imparts intermittent motion.
Tappet Noise
Noise caused by the lash or clearance between the valve stem and rocker arm or between the valve stem and valve lifter.
Tesla Turbine
A rotary engine consisting of multiple ported disks where high velocity gases enter tangentially through a wide nozzle at the periphery of the disks.
Thermal Efficiency
Quantity of heat produced in relation to fuel input.
Three-Way Catalyst
A pollution control device which reduces all three noxious substances: HC, CO, and NOx.
Thrust Specific Fuel Consumption
Fuel consumption per unit of thrust.
Timing
The angle made by the crank with its top or bottom dead-center position at which some valve opens or closes.
Timing Chain
A chain that is used to connect the crankshaft and camshaft by which the camshaft is made to rotate.
Timing Gears
Gears keyed to the crankshaft and camshaft, by which the camshaft is made to rotate.
Top Dead Centre
The position of the crank when the piston is in its farthest position from the crankshaft.
Torque Curve
A graph which shows the engine torque as a function of machine speed.
Turbine Blade
Any one of the blades of a turbine wheel.
Turbine Wheel
A multivaned wheel or rotor, especially in a gas-turbine engine, rotated by the impulse from or reaction to a fluid passing across the vanes.
Turbocharger
A supercharger powered by an exhaust-driven turbine.
Turbofan
Gas turbine engine with large diameter forward fan.
Turbofan-Ramjet
An air-breathing engine consisting of a turbofan engine mounted within a ramjet duct.
Turbojet
Gas turbine engine in its simplest form, producing a high velocity jet efflux.
Turboprop
Gas turbine engine in which maximum energy is taken from the turbine to drive a reduction gear and conventional propeller.
Turboshaft
Gas turbine engine in which maximum energy is taken from the turbine to drive a high speed shaft. It can be used to drive a helicopter′s rotor or any other form of machinery.
Two-Stroke Engine
An internal-combustion engine that has one power stroke per revolution.
V10 Engine
Ten-cylinder engine with the cylinders arranged in two banks of 5 and the shape of a V when looking along the line of the crankshaft.
V12 Engine
Twelve-cylinder engine with the cylinders arranged in two banks of 6 and the shape of a V when looking along the line of the crankshaft.
V16 Engine
Sixteen-cylinder engine with the cylinders arranged in two banks of 8 and the shape of a V when looking along the line of the crankshaft.
V4 Engine
Four-cylinder engine with the cylinders arranged in two banks of 2 and the shape of a V when looking along the line of the crankshaft.
V6 Engine
Six-cylinder engine with the cylinders arranged in two banks of 3 and the shape of a V when looking along the line of the crankshaft.
V8 Engine
Eight-cylinder engine with the cylinders arranged in two banks of 4 and the shape of a V when looking along the line of the crankshaft.
Vacuum Engine
The working principle is similar to the hot air engine, except that this engine draws hot air into the cylinder.
Valve
In electronics, a valve is a device consisting of two or more metal plates enclosed in an evacuated glass bulb.
Valve Bounce
If the speed of valve is closing too high, the valve can hit the seat so hard it bounces off again.
Valve Float
A high-rpm engine condition in which the valve lifters lose contact with the cam lobes because the valve springs are not strong enough to overcome the momentum of the various valvetrain components.
Valve Lifter
The cylindrically shaped component that presses against the lobe of a camshaft and moves up and down as the cam lobe rotates.
Valve Overlap
The amount of time that the inlet and exhaust valves are open at the same time, to allow momentum charging of the cylinder or to scavenge additional exhaust gas from the cylinder.
Valve Seat
That part of the valve mechanism upon which the valve face rests to close the port.
Valve Spring
The spring which is used to close a valve.
Valves
Signifies the total intake and exhaust valves in an internal combustion engine.
Valve-Spring Retainer
Holds the valve spring in a state of compression.
Valvetrain
The collection of parts that make the valves operate in an internal combustion engine.
Vee Engine
One with two banks of in-line cylinders mounted with an angular separation on a common crankcase.
V Engine
One with two banks of in-line cylinders mounted with an angular separation on a common crankcase.
Vernier Engine
A small rocket engine that is used for fine adjustment.
V Twin
Two-cylinder engine with the cylinders arranged in the shaped of a V when looking along the line of the crankshaft.
Wankel Engine
A rotary engine with a rotor rotating in an oval cylinder. Named after it′s designer Felix Wankel.
Water Cooling System
Water passes through the system or through a water cooling jack, this is then sent to a radiator where air is passed over the radiator to remove the heat from the water before it is sent back to the system to be cooled.
Water Jacket
The outer casing forming a space around an engine cylinder to permit circulation of cooling water.
Wet Sump
An engine lubrication system where the oil sits in the sump under the crank, is pumped around the engine and drains back to the sump.
White Smoke
The smoke emitted during a cold start from a diesel engine, composed mainly of unburnt fuel and particulate matter.
Working Stroke
The piston stroke during which the combustion gases exert a pressure on the moving piston.
X Engine
Looking at the end of the crankshaft the cylinders form an X.

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Subjects: Mechanical Engineering Transport