A consumption map or efficiency map shows the

brake-specific fuel consumption Brake-specific fuel consumption (BSFC) is a measure of the fuel efficiency of any prime mover that burns fuel and produces rotational, or shaft power. It is typically used for comparing the efficiency of internal combustion engines with a shaft out ...

in g per kWh over

mean effective pressure The mean effective pressure (MEP) is a quantity relating to the operation of a reciprocating engine and is a measure of an engine's capacity to do work that is independent of engine displacement.Heywood, J. B., "Internal Combustion Engine Fundam ...

per

rotational speed Rotational frequency (also known as rotational speed or rate of rotation) of an object rotating around an axis is the frequency of rotation of the object. Its unit is revolution per minute (rpm), cycle per second (cps), etc. The symbol fo ...

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 co ...

. The x-axis shows the

range. The y-axis represents the load on the engine. The

contour line A contour line (also isoline, isopleth, or isarithm) of a function of two variables is a curve along which the function has a constant value, so that the curve joins points of equal value. It is a plane section of the three-dimensional gra ...

s show the specific fuel consumption, indicating the areas of the speed/load regime where the engine is more or less efficient. The map contains each possible condition, combining rotational speed and

. It shows the result of specific fuel consumption. A typical rotation power output P (linear to

p_ \cdot \omega

) is reached on several locations on the map but differing in the amount of fuel consumption.

Automatic transmission An automatic transmission (sometimes abbreviated to auto or AT) is a multi-speed transmission (mechanics), transmission used in internal combustion engine-based motor vehicles that does not require any input from the driver to change forward gea ...

s, are designed to keep the engine at the speed with the lowest possible fuel consumption, given the power demand. The map also shows the efficiency of the engine. Depending on the fuel type,

diesel Diesel may refer to: * Diesel engine, an internal combustion engine where ignition is caused by compression * Diesel fuel, a liquid fuel used in diesel engines * Diesel locomotive, a railway locomotive in which the prime mover is a diesel engine ...

and

gasoline 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 ...

engines reach up to 210 g/kWh and about 40% efficiency. Using

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon ...

this efficiency is reached at 200 g/kWh. Average valuesTable 1 in Konrad Reif, "''Dieselmotor-Management im Überblick''", Abschnitt Springer Fachmedien Wiesbaden 2014, {{ISBN, 978-3-658-06554-6 are 160–180 g/kWh for slow moving

two stroke A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of t ...

diesel cargoship engines using

fuel oil Fuel oil is any of various fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil, marine fuel oil (MFO), bu ...

, reaching up to 55% efficiency at 300 rpm. 195–210 g/kWh at cooled and pre- charged

diesel engines 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-cal ...

for passenger cars, trucks 195–225 g/kWh. Non-charged

Otto cycle An Otto cycle is an idealized thermodynamic cycle that describes the functioning of a typical spark ignition piston engine. It is the thermodynamic cycle most commonly found in automobile engines. The Otto cycle is a description of what ha ...

gasoline engine A petrol engine (gasoline engine in American English) is an internal combustion engine designed to run on petrol (gasoline). Petrol engines can often be adapted to also run on fuels such as liquefied petroleum gas and ethanol blends (such as '' ...

s for passenger cars 250–350 g/kWh.

Literature

* (German) Richard van Basshuysen: ''Handbuch Verbrennungsmotor'', Fred Schäfer; 3. Auflage; 2005; Vieweg Verlag

References

Internal combustion engine Engine technology Thermodynamics Diagrams