An exhaust gas temperature gauge (EGT gauge or EGT sensor) is a

meter The metre (British spelling) or meter (American spelling; see spelling differences) (from the French unit , from the Greek noun , "measure"), symbol m, is the primary unit of length in the International System of Units (SI), though its pref ...

used to monitor the

exhaust gas temperature Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline (petrol), diesel fuel, fuel oil, biodiesel blends, or coal. According to the type of engine, it is discharged into the atmosphere through an ...

of an

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal c ...

in conjunction with a

thermocouple A thermocouple, also known as a "thermoelectrical thermometer", is an electrical device consisting of two dissimilar electrical conductors forming an electrical junction. A thermocouple produces a temperature-dependent voltage as a result of th ...

-type

pyrometer A pyrometer is a type of remote-sensing thermometer used to measure the temperature of distant objects. Various forms of pyrometers have historically existed. In the modern usage, it is a device that from a distance determines the temperature of ...

. EGT gauges are found in certain cars and aeroplanes. By monitoring EGT, the driver or pilot can get an idea of the vehicle's air-fuel ratio (AFR). At a

stoichiometric Stoichiometry refers to the relationship between the quantities of reactants and products before, during, and following chemical reactions. Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equ ...

air-fuel ratio, the exhaust gas temperature is different from that in a lean or rich air-fuel ratio. At rich air-fuel ratio, the exhaust gas temperature either increases or decreases depending on the fuel. High temperatures (typically above ) can be an indicator of dangerous conditions that can lead to catastrophic engine failure.

Applications

*Most light piston aircraft still have manual mixture controls, and pilots use an EGT gauge to set the optimal fuel-air mixture for their current density altitude and power. The hottest cylinder-head temperatures (CHT) and highest internal cylinder pressures occur around rich of peak EGT, and risk predetonation, making it essential to avoid that range, and operate either lean of peak EGT or richer than rich of peak EGT. Leaner mixtures result in significant fuel savings, but may result in rough operation of some

carbureted A carburetor (also spelled carburettor) is a device used by an internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the venturi tube in the main meteri ...

or poorly-tuned

fuel-injected Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines. All com ...

engines. Jet aircraft used EGT gauges which were monitored by the flight engineer during engine startup and throughout the whole flight. EGT gauges were then implemented into the interfaces of

EICAS An engine-indicating and crew-alerting system (EICAS) is an integrated system used in modern aircraft to provide aircraft flight crew with instrumentation and crew annunciations for aircraft engines and other systems. On EICAS equipped aircraft th ...

and ECAM in

glass cockpits A glass cockpit is an aircraft cockpit that features electronic (digital) flight instrument displays, typically large LCD screens, rather than the traditional style of analog dials and gauges. While a traditional cockpit relies on numerous ...

. *EGT meters are used for tuning

turbo In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pr ...

-equipped cars. If the sensor is installed at the manifold collector before the turbo, the turbine inlet temperature can be monitored. If the sensor is installed after the turbo, the exhaust temperature can be monitored. Because EGT typically drops across the turbine, installers try to put the thermocouple as close to the

cylinder head In an internal combustion engine, the cylinder head (often abbreviated to simply "head") sits above the cylinders and forms the roof of the combustion chamber. In sidevalve engines, the head is a simple sheet of metal; whereas in more modern ...

as possible to give a true reading, and a reading that will react faster to the engine's condition compared to an installation after the turbo. * Air-cooled engines, like used in

Volkswagen Volkswagen (),English: , . abbreviated as VW (), is a German motor vehicle manufacturer headquartered in Wolfsburg, Lower Saxony, Germany. Founded in 1937 by the German Labour Front under the Nazi Party and revived into a global brand post-W ...

, Porsche and other cars can be damaged by over heating. An exhaust gas temperature gauge can be used to prevent damage. * Air-cooled

motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...

engines also can be damaged by over heating.

Oxygen sensor

Using an EGT meter alone is considered an older technique for getting the most out of

petrol Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic c ...

and

diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-ca ...

s, as gauge-type wideband digital oxygen sensors are similarly priced. However, some advanced racers will use EGT gauges in combination with a wideband oxygen sensor to lean the fuel ratio a bit to safely raise the temperature for more power.

Advanced tuning

Though by tuning primarily by EGT and air fuel ratio values, EGT is still to this day a used data output for engine tuning. When fine tuning an engine, if possible with the ECU manipulation with the cylinder's timing can be made. By adjusting the timing, the resultant cylinder temperature can be used to improve cylinder efficiency. Though this is still widely done, EGT values should be used as a safe guard sensor measure and as a tuning guide.

References

External links

* Engine technology Engine sensors {{technology-stub