The engine valves resemble the human nose in appearance. The breathing (inhale/exhale) mechanism of an automobile engine is controlled by valves. The camshaft of the machine opens and shuts the valves at regular intervals. The timing of valve opening and closing is defined in degrees, which correspond to the location of the pistons in the engine. The most crucial process in IC engines is valve timing.
How does Engine Valve Timing help?
The mass and velocity of this air-fuel combination, also known as a charge, are present; even when the piston reaches the bottom of its downward stroke, the intake valve's opening is too tiny to allow the total charge to enter the cylinder. As a result, the pressure in the combustion chamber stays below atmospheric pressure, but the charge continues to move at a high velocity in the direction of the piston's motion.
The cylinder will get less charge than it requires if the intake valve shuts at this moment. As a result, the intake valve remains open until the piston begins its next upward stroke or compression stroke. The pressure within the cylinder is almost equivalent to the ambient pressure at this point. Engineers carefully tune the intake valve's real closing point to correspond with the moment at which the incoming charge's motion begins to reverse.
Cam Timing Relationship
If the camshaft is retarded, there is better high RPM breathing but a shaky idle and less power at low RPM.
More steady idle and excellent low-RPM power if the camshaft is advanced, but poor breathing and little power at high RPM.
The Timing Events
Now that you understand timing, it is easy to explain how to modify and set it on your engine valve. Because every engine's timing is different, it's a good idea to have a decent repair handbook available to discuss the specifics of your machine. Newer engines change the timing on their own, so as long as your sensors are working correctly, you won't have to fiddle with it. Unless you remap your ignition machine's chip or purchase an aftermarket performance chip with a new timing map flashed into it, you won't be able to.
This is the sequence in which the valve timing events occur well. This is debatable, somewhat.
Intake valve closing (IVC)
Intake valve opening (IVO)
Exhaust valve closing (EVC)
Exhaust valve opening (EVO)
Reduced valve lift is used to throttle the cylinder, or the intake valve closing time can be changed to minimise pumping losses. Because the air in the manifold is kept at around atmospheric pressure, the situation is somewhat different. The cylinder pressure stays near atmospheric pressure when the intake valve opens.
Engine valve manufacturing companies in India ensure the pressure within the cylinder drops substantially only towards the end of the induction stroke when the incoming airflow gets limited. This implies that the force on the piston due to differential pressure is not constant throughout the intake stroke. Still, it is approximately equivalent to that in a conventional engine when the intake valve shuts.
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