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Cylinder head porting refers to the process of modifying the intake and exhaust ports of an internal combustion engine to improve their air flow. Cylinder heads, as manufactured, are usually suboptimal for racing applications due to being designed for maximum durability. Ports can be modified for maximum power, minimum fuel consumption, or a ...
In an engine designed to use the squish effect, at top dead centre the piston crown comes very close (typically less than 1 mm [2]) to the cylinder head. The gases are suddenly "squished" out within the combustion chamber , creating turbulence which promotes thorough air-fuel mixing, a factor beneficial to efficient combustion .
Historically, many car model names have included their engine displacement. Examples include the 1923–1930 Cadillac Series 353 (powered by a 353 Cubic inch /5.8-litre engine), and the 1963–1968 BMW 1800 (a 1.8-litre engine) and Lexus LS 400 with a 3,968 cc engine.
It is similar in concept to the hemi engine, both in design and purpose, but a hemispherical cylinder head is limited to only two valves without the use of a more complex sub-rocker assembly. The four-valve penta engine design was invented by Peugeot of France, [ citation needed ] to be first used in the 1911 Indianapolis 500 race.
Absolute cylinder pressure is used to calculate the dynamic compression ratio, using the following formula: = where is a polytropic value for the ratio of specific heats for the combustion gases at the temperatures present (this compensates for the temperature rise caused by compression, as well as heat lost to the cylinder) Under ideal ...
The main advantage of the reverse-flow cylinder head is that both the entering inlet charge and the exiting exhaust gas cause a tendency to swirl in the same direction in the combustion chamber. [1] In a crossflow head the inlet and exhaust gases promote swirl in opposite directions so that during overlap the swirl changes directions.
The cast iron cylinder heads are a cross-flow design with wedge-shaped combustion chambers and a single spark plug. In early versions of the engine the inlet and exhaust valves were arranged in a "mirrored" configuration around a longitudinal midpoint in each head i.e. I-E-I-E-E-I-E-I.
The cylinder head intake and exhaust ports and intake and exhaust manifolds are shape optimized for better volumetric efficiency. Mitsubishi lowered the friction of the engine by including elastic grinding of the valve stems, adopting a high-efficiency shroud equipped plastic impeller in the water pump and using 0W-20 low- viscosity oil .