What is the principle of an oil catch can?
2 Answers
The principle of an oil catch can is to use the vacuum in the intake manifold to draw blow-by gases from the crankcase into the combustion chamber for re-burning. These blow-by gases mainly consist of oil vapor and combustible mixed gases. Since oil is viscous, if it directly enters the intake pipeline, it may adhere to the intake pipe walls, potentially causing carbon deposits that obstruct airflow. More details are as follows: 1. The engine has a Positive Crankcase Ventilation (PCV) system that can directly vent blow-by gases into the atmosphere. However, since these gases contain combustible gasoline molecules, venting them directly into the atmosphere not only reduces fuel economy but also causes severe air pollution. Hence, oil catch cans are used in modified cars. 2. Structurally, it consists of two chambers: the lower chamber is designed to collect and settle oil, connected via a tube, while the separated combustible mixed gases are in the upper chamber. The cleaned mixed gases are then introduced into the intake manifold. This method is both environmentally friendly and prevents oil buildup in the intake tract. However, an oil catch can only prevent carbon deposits, not remove existing ones. 3. The primary purpose of an oil catch can is to protect the engine. During high-speed operation, the crankcase experiences high temperatures and friction due to the rapid movement of the crankshaft, leading to oil degradation and vaporization, which increases crankcase pressure. The degraded oil vapor must be expelled from the crankcase as it is highly toxic. In stock vehicles, this oil vapor is directed into the intake manifold to be burned by the engine. However, this leads to rapid buildup of deposits in the throttle body, negatively affecting performance and fuel efficiency. 4. The oil catch can works by separating oil and gas, collecting the waste oil, and sending only the separated air into the intake manifold. Thus, its main functions are to protect the engine, maintain throttle cleanliness, and reduce fuel consumption. The oil catch can requires regular cleaning, as a clogged filter or blocked internal circulation can cause exhaust gases to enter the air filter.
I've been driving for many years and have researched aftermarket parts. The principle of an oil catch can is quite interesting. Simply put, when the engine is running, the crankcase produces some oil vapor mixtures containing small droplets of engine oil, dirt, and moisture. If this directly enters the intake system, it can cause carbon buildup on the valves and pistons, reducing engine efficiency. The catch can is installed in the engine's ventilation line, acting like a small container where the oil vapor is cooled, allowing liquid oil to settle at the bottom while only clean air flows into the combustion chamber. This helps prevent carbon buildup and extends engine life. I installed one myself and noticed smoother acceleration, but it's important to regularly drain the collected waste oil to prevent clogging. Overall, it's a simple and effective device, especially suitable for performance-oriented car enthusiasts.
