combustion chamber

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internal-combustion engine: four-stroke cycle

Diagram of the German A-4 (V-2) rocket from World War II, showing an exterior view above and a labeled cutaway below that highlights internal components such as the warhead, alcohol fuel tank, liquid oxygen tank, turbine and pump, combustion chamber, guidance and control devices, and control vanes.

Diagram of a gasoline engine showing a cross-section of a piston and cylinder. Key parts such as the spark plug, valves, camshaft, piston, connecting rod, and crankshaft are labeled.

combustion chamber

engineering

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June 24, 2026

Quick Summary

internal-combustion engine: four-stroke cycle — internal-combustion engine: four-stroke cycle An internal-combustion engine goes through four strokes: intake, compression, combustion (power), and exhaust. As the piston moves during each stroke, it turns the crankshaft.

A combustion chamber is a confined space within an engine where fuel is burned. In a gas-turbine engine, air is slowed and split. A smaller portion mixes with atomized fuel and burns, while a larger, cooler stream reduces the overall temperature for the turbine.12

In a gasoline engine, the combustion chamber's volume is determined by the piston's position within the cylinder. The space between the cylinder head and the piston at its closest point (top dead centre) is crucial for the engine's compression ratio, which significantly impacts theoretical efficiency.3

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compression ratio
…the maximum volume of the combustion chamber (with the piston farthest out, or bottom dead centre) divided by the volume with the piston in the full-compression position (with the piston nearest the head of the cylinder, or top dead centre). A compression ratio of six means that the mixture is…
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…the maximum volume of the combustion chamber (with the piston farthest out, or bottom dead centre) divided by the volume with the piston in the full-compression position (with the piston nearest the head of the cylinder, or top dead centre). A compression ratio of six means that the mixture is…
Read More

diesel engine
Diesel combustion
…induces only air into the combustion chamber on its intake stroke. Diesel engines are typically constructed with compression ratios in the range 14:1 to 22:1. Both two-stroke and four-stroke engine designs can be found among engines with bores (cylinder diameters) less than 600 mm (24 inches). Engines with bores of…
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…induces only air into the combustion chamber on its intake stroke. Diesel engines are typically constructed with compression ratios in the range 14:1 to 22:1. Both two-stroke and four-stroke engine designs can be found among engines with bores (cylinder diameters) less than 600 mm (24 inches). Engines with bores of…
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emission control system
…fuel-air mixture and enter the combustion chamber. The recirculated exhaust gases serve to lower the temperature of combustion, a condition that favours lower production of nitrogen oxides as combustion products (though at some loss of engine efficiency). In a typical air-injection system, an engine-driven pump injects air into the exhaust…
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…fuel-air mixture and enter the combustion chamber. The recirculated exhaust gases serve to lower the temperature of combustion, a condition that favours lower production of nitrogen oxides as combustion products (though at some loss of engine efficiency). In a typical air-injection system, an engine-driven pump injects air into the exhaust…
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gas-turbine engine
Combustion chamber
Air leaving the compressor must first be slowed down and then split into two streams. The smaller stream is fed centrally into a region where atomized fuel is injected and burned with a flame held in place by a turbulence-generating obstruction. The larger,…
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Air leaving the compressor must first be slowed down and then split into two streams. The smaller stream is fed centrally into a region where atomized fuel is injected and burned with a flame held in place by a turbulence-generating obstruction. The larger,…
Read More

gasoline engine
Combustion chamber
The combustion chamber is defined by the size, location, and position of the piston within the cylinder. Bore is the inner diameter of the cylinder. The volume at bottom dead centre (VBDC) is defined as the volume occupied between the cylinder head and…
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The combustion chamber is defined by the size, location, and position of the piston within the cylinder. Bore is the inner diameter of the cylinder. The volume at bottom dead centre (VBDC) is defined as the volume occupied between the cylinder head and…
Read More