What is a Camshaft in a Car and How Does it Work?
The importance of the camshaft to an engine cannot be overemphasized. Only a camshaft can alter the performance of an engine. Usually, there are specific mathematical rules that are used to calculate the camshaft. Camshafts are usually designed with a profile or curve. This will offer more airflow in your engine, and also offer the valve with a suitable amount of lift. So as to understand how the camshaft affects the engine, we will be taking a look at some camshaft basics
The main function of the camshaft is transforming its rotating motion into a lift or linear motion. A typical Chevy V-8 having 16 lobes can be used to achieve this. It will be attached to an unusual shape often referred to as a lobe. This makes it possible for each lifter to fall and rise above a base circle. The lobe lift refers to the extent at which the lobe can raise the lifter. The lift can be a valve or gross lift. It can be mathematically obtained by multiplying the lobe lift with the ratio of the rocker arm. To add valve lift and a little duration, simply replace the standard rocker arm ratios with something higher.
When the cam lobe moves the lifter away from the base circle, the crankshaft will rotate. The amount of crankshaft rotation is known as camshaft duration. Duration is measured in crankshaft degrees. The cam can be checked in degrees to ensure that it is properly positioned in the engine. The majority of camshaft companies make use of a standardized checking point, which is often used in referencing lift. The generally accepted duration checking point in the camshaft industry is 0.050-inch lift
Usually, high-rpm engines are more efficient when the duration is increased. The additional time that the valves are left unclosed in high-rpm engines makes it possible for airflow to enter or exit the cylinder. However, added duration opens up the valves in for a longer period. Hence, the pumping pressure will be lost.
Valve Opening and Closing Points
The intake opening (IO) is known to happen before the top-dead-center (BTDC), while the intake closing (IC) happens after bottom dead center (ABDC). The exhaust opening (EO) occurs before the bottom-dead-center (BBDC), while the exhaust closing (EC) is known to happen after top-dead-center (ATDC). You can crosscheck the points by degrees the camshaft in the engine. You can also achieve this by simply making reference to the information as written on the cam card that comes with the new cam.
Another name for camshaft lifters is followers. They come in various designs ranging from hydraulic roller to solid flat tappet, hydraulic flat-tappet, and solid roller. The hydraulic flat-tappet is prevalently used. It can operate with little or no noise. It comes in the majority of camshaft profiles that are designed for very high-performance applications and pure stock operations. After adjusting a good hydraulic lifter it simply stays in that position. The valve-controlled plunger which can be found inside the lifter helps in maintaining a preload from engine oil pressure.
Mechanical lifters are usually used for an application that requires very high RPMs, in fact as high as 8,000 rpm, if not more. Mechanical lifters make use of a particular valve lash clearance. This can be found at the rocker arm. It gives room for expansion which is known to occur when the temperature of the engine varies.
Single and Dual-Pattern Camshafts
The intake and exhaust of a single pattern camshaft feature the same specs, while it is different for a dual pattern. The dual-pattern camshaft typically offers more exhaust duration. This helps in improving the flow of the exhaust port of the cylinder head.
The centerline specification of the camshaft can be used to know the lobes position on the cam and the engine. The intake centerline number is the position of the intake lobe centerline.
Cam Timing Marks
The car timing marks can be varied by degreeing the camshaft once it has been installed in the engine. When the cam is advanced, the intake valve will be able to close sooner. This help in improving the low-speed torque and top-end power.
The lobe separation angle (LSA) can be defined as the distance between the intake and exhaust lobe centerlines, expressed in camshaft degrees. It helps to establish the amount of overlap between the intake and exhaust.
Now You Know
It is important to put into consideration the frequency of use before selecting a camshaft. A camshaft with shorter duration and relative lift is the most ideal if your car is used for everyday transportation. The type of racing or driving you use the car for is also important. Other factors include transmission type, stall speed, vehicle weight, cylinder heads, compression, and so forth. By understanding the basics of the camshaft, you will be able to select the right camshaft for your engine.