OVERHEAD CAMSHAFT

Overhead camshaft, commonly abbreviated to OHC, valvetrain ValvetrainA traditional reciprocating internal combustion engine uses valves to to control air and fuel flow into and out of the cylinders, facilitating combustion.... configurations place the engine camshaft CamshaftThe camshaft is an apparatus used in piston engines to operate poppet valves. It consists of a cylindrical rod running the length of the cylinder bank with a number of oblong lobes or cams protruding from it, one for each valve.... within the cylinder head Cylinder headIn an internal combustion engine, the cylinder head sits atop the Cylinder and consists of a platform containing most part of the combustion chamber and the location of the poppet valves and spark plugs....s, above the combustion chamber Combustion chamberA combustion chamber is part of an engine in which fuel is burned. The leftover hot gases produced by this combustion tend to occupy a far greater volume than the original fuel, thus creating an increase in pressure within the limited volume of...s, and drive the valves Poppet valveA poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem.... or lifter LifterThe Lifter is an electrokinetic, or electrohydrodynamic device. The term "Lifter" dates back to the 1960s, an era in which EHD experiments were at their peak....s in a more direct manner compared to Overhead valve Overhead valveIn automotive engineering, an overhead valve internal combustion engine is one in which the intake and exhaust poppet valve and ports are contained in the cylinder head....s (OHV) and pushrods.Compared to OHV pushrod (or I-Head) systems with the same number of valves the reciprocating components of the OHC system are fewer and have a lower total mass. Though the system that drives the cams may become more complex, most engine manufacturers easily accept the added complexity in trade for better engine performance and greater design flexibility. Another performance advantage is gained as a result of the better optimized port configurations made possible with overhead camshaft designs. With no intrusive pushrods the overhead camshaft cylinder head design can use straighter ports of more advantageous crossection and length.The OHC system can be driven using the same methods as an OHV system, which include using a rubber/kevlar toothed timing belt Timing beltA timing belt, timing chain or cam belt is a part of an internal combustion engine that controls the timing of the engine's poppet valve...., chain Roller chainRoller chain or bush roller chain is the type of chain most commonly used for transmission of Power_transmission#Mechanical_power on bicycles, motorcycles, and in industrial and agricultural machinery...., or in less common cases, gears.Many OHC engines today employ Variable Valve Timing Variable valve timingVariable valve timing, or VVT, is a generic term for an automobile piston engine technology.... and multiple valves Multi-valveIn automotive engineering, an engine is referred to as multi-valve when each cylinder has more than two poppet valve.... to improve efficiency and power. OHC also inherently allows for greater engine speeds over comparable cam-in-block designs.There are two overhead camshaft layouts: Single overhead camshaft - or SOHC Double overhead camshaft - or DOHC