The two important aspects of a camshaft, in terms of engine performance, duration camshaft, or duration cam and a lift. The two cam duration, valve lift is determined by the camshaft lobe. Cam duration is the time that at least one valve of a cylinder is still open, ie from its valve seat, measured in degrees of crankshaft rotation, while the valve lift is the maximum distance the valve head moves from the valve seat.

VALVE LIFT HEIGHT

Variable valve height is somewhat linked to the head diameter intake valve. An engine with a valve diameter of 1.400in admission head 1.500in generally better with a 0.395in to 0.475in lift, an engine with a head diameter intake valve 1.750in to 1.875in broader generally better a valve lift 0.425in 0.550in, and 2.000in with a big engine intake valve head diameter 2.250in generally better with a lift to 0.475in 0.650in. But these are only general guidelines, ultimately you must take measures gas flow on a flow bench to determine the best valve lift for your vehicle.

Several factors affect the valve lift. More importantly, the gap between intake and exhaust, piston clearance of the valve and the boost pressure for admission. These factors also influence the duration cam. Another factor which influences the valve lift is compressing the valve spring. It is clear that when the valve springs are completely compressed, it can give more and the valve can be pushed further into the combustion chamber.

CAM DURATION

As I mentioned earlier, the duration of the cam is measured in degrees of rotation of the crankshaft and camshaft, crankshaft, and is accompanied by two full turns of each rotation of the cam. In other words, a camshaft 310 degrees, the valves are open only to 155 degrees of rotation of the cam true.

A performance camshaft for a naturally aspirated engine will last about 270 degrees to 310 degrees or more, with a camshaft of 270 degrees is described as “light” camshaft and camshaft 310 or degree is described as a camshaft “savage” race. Action of the camshaft usually runs for about 270 degrees, but what differentiates a camshaft of 270 degrees of performance of a stock camshaft is higher valve lift and a much slower rapid rise of the valve. With a rapid onset rate of the valve, the valve reaches full lift more quickly and stay full longer cooking. This increases the volumetric efficiency (VE) that the flow of air into and out of the motor is possible.

A crucial factor when choosing a camshaft duration, the purpose of the vehicle. Over the duration of the camshaft, the highest passage rev broad power band, and over rough yesterday. Naturally, when the power band moves further up the rev range, less energy is lost. In addition, as the length of cam and valve overlap increases, the torque is lost. Energy efficiency also decreases and increases as the exhaust valve overlap increases.

Powerful nose start to 280 degrees duration. These camshafts have increased valve overlap, but not too much to reduce emissions and fuel economy is not serious. These are generally good nose and a tram and modified to produce good power at 2500 rpm to 7000 rpm, but have not set a minimum because of the increased valve overlap.

A camshaft 290 degrees, we have to work the cylinder head according to the conservation of the stock and flow of gas as they work best when the engine volumetric efficiency (VE) is better. As expected, these camshafts produce a very rough idle. These camshafts are generally good for rally cars and produce electricity from 3,000 rpm to 7,500 rpm. A camshaft 300 degrees impose even higher levels of Victory in Europe, where natural gas comes from the confines of a cylinder valve double overhead camshaft with a single. These camshafts are good for racing and modified to generate cheap power from 4,000 rpm to 8,000 rpm. However, they have a very rough idle.

A camshaft with a duration of more than 300 degrees is indeed the camshaft race with a power range of 4500-9000 rpm rpm rev range. Efficient use of a camshaft of 300 degrees, make sure the engine has a very high EV. You must also ensure that the engine can rev the red line for most stock engines.

VALVE OVERLAP

Limit to open the exhaust valve is about 80 ° before bottom dead center (BBDC). Opening the exhaust valve earlier tend not to increase electricity production, but moves the power band further up the rev range and reduce the pressure low end torque down on the piston during the power stroke is released. The same goes for closing the intake valve of 80° after bottom dead center (ABDC) is the limit for power generation has increased.