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The limit for naturally aspirated engines is about 130%; [6] these engines are typically of a DOHC layout with four valves per cylinder. This process is called inertial supercharging and uses the resonance of the intake manifold and the mass of the air to achieve pressures greater than atmospheric at the intake valve. With proper tuning (and ...
In spark-ignition internal combustion engines, knocking (also knock, detonation, spark knock, pinging or pinking) occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but when one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.
The graph above shows the intake runner pressure over 720 crank degrees of an engine with a 7-inch (180 mm) intake port/runner running at 4500 rpm, which is its torque peak (close to maximum cylinder filling and BMEP for this engine). The two pressure traces are taken from the valve end (blue) and the runner entrance (red).
In theory, the closing of all rear bank valves produces an ‘air spring’ effect. However, the reciprocating effect of the piston with closed valves reportedly produces a vacuum condition where oil can get pulled past the piston rings to flood the cylinder. When VCM disengages, the engine then misfires if needing to clear the cylinder of oil.
Inertial supercharging effect is the result of incoming fuel/air charge developing momentum greater than intake stroke would generate alone. It is achieved by the careful design of the shape of the piston head, the valves and cam profile/valve timing which creates a vacuum that pulls more exhaust gases (and some of the intake gasses) out of the engine.
A direct port nitrous system introduces the nitrous or fuel/nitrous mixture as close to the intake ports of the engine as is feasible via individual nozzles directly in each intake runner. Direct port nitrous systems will use the same or similar nozzles as those in single nozzle systems, just in numbers equal to or in multiples of the number of ...
A turbocharger for a car engine A supercharger (on top of a dark-grey inlet manifold) for a car engine. In an internal combustion engine, forced induction is where turbocharging or supercharging is used to increase the density of the intake air. Engines without forced induction are classified as naturally aspirated. [1]
The first, called Combined Combustion System or CCS, is based on the VW Group 2.0-litre diesel engine, but uses homogeneous intake charge. It requires synthetic fuel to achieve maximum benefit. The second is called Gasoline Compression Ignition or GCI; it uses HCCI when cruising and spark ignition when accelerating.