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^ I would love to, but I don't have the knowledge...At most mine is basic:
Lift: How far the cam lobe moves the valve - higher lift = more area around the valve for the air/fuel mixture to flow = more power in most cases. Too much lift can turn a non-interference engine into an interference engine, which is generally bad.
Duration: How long the valve is held open (measured in degrees), larger duration = longer time for air/fuel mixture to fully fill the combustion chamber. In reality, there is an optimum duration for each engine dependant on how much the head flows, the displacement of the engine, etc. If the piston begins to travel toward TDC and there is less pressure in the cylinder (compared to the pressure in the intake ports), the valve should stay open until the point where there is no difference in pressure. However, this is limited by the movement of the piston -If the piston gets to TDC (combustion stroke) then the intake valve needs to be closed before the spark plug fires.
Overlap: The amount of time the intake and exhaust valves are open at the same moment, don't know too much about the benefits of increasing/decreasing this, so I'll leave that to someone else
Intake velocity: A higher Intake velocity means more air flow into the cylinder when the intake valve is open, this obviously means more fuel can be used, and more torque can be achieved. A high intake velocity at low rpm is achieved by using smaller intake ports, this means the air travels faster into the cylinder compared to an engine with larger intake ports. However, by having smaller intake ports, you 'choke' the engine at higher rpm where the engine needs to flow much more air. Small intake ports are more generally used in Family sedans, V8's, etc. where the aim is to achieve a higher torque for the type of car (i.e. family sedan is likely to be driven around town a lot, it is more efficient to have more torque in the lower rpm ranges).
Larger intake ports cause a slower Intake velocity at lower rpm, which causes less torque, but these engines usually create more torque in higher rpm's (as this is when the Intake velocity is high, and the engine is not being choked by small intake ports), because of the higher rpm, the engine creates more power with the available torque (Power = [Torque x RPM]/5252, increasing rpm while maintaining torque will result in a higher power). Engines with larger ports are generally used in racing, where the rpm's are always kept high, and the larger ports create the same torque at those higher rpm's.
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