![]() ![]() The exhaust stroke continues to about 10 degrees BTDC at which time the cycle starts all over again. The power stroke goes to about 12 degrees BBDC. The compression stroke then continues to the ignition point, about 15 degrees BTDC. To begin, the intake valves open about 10 degrees BTDC. During the four cycles of operation, the crankshaft revolves two complete revolutions or 720 degrees of rotation. Two circles are shown to represent two complete revolutions of the crankshaft. The mark at the bottom of the graph would illustrate the position of the piston at BDC. Any event that happens after top dead center is called ATDC or after top dead center. Any event that happens before TDC is referred to as BTDC or before top dead center. For example, at the top of the diagram, the piston would be located exactly at TDC (Top Dead Center). One way to look at this diagram is to think of these events in terms of the position of the crankshaft and 360 degrees rotation. The diagram is set on a vertical and horizontal axis. So, we highly recommend giving our Combo package a try to enhance your knowledge on the subject.Describing the Principle: A timing diagram is a method used to identify the time at which all of the four stroke events occur on a typical four-stroke engine. Watching the videos will help you grasp the topic better and make learning more enjoyable. This package covers all the important details and presents them in an easy-to-understand format. ![]() ![]() It’s a great way to dive deeper into the subject through video explanations. If you want to learn more about this topic, we suggest checking out our Combo package with the given link. Two stroke low speed engine can burn fuel of cheaper quality because of the very long stroke which adds more time for scavenging and exhaust process.Ships don’t have gearboxes, if you need to back your ship up, you have to shut the engine down and restart it going the other direction. The most important advantage of 2-stroke over 4-stroke in a ship is that they can be run either clockwise or counter-clockwise.Two-stroke engines are therefore capable of generating more power for the same size and weight as a four-stroke engine. This is important for ships, where weight is a critical factor. Power-to-Weight Ratio: Two-stroke engines have a higher power-to-weight ratio than four-stroke engines, which means they are able to produce more power relative to their weight.Two-stroke engines are commonly used as the main engines on large ships instead of four-stroke engines for several reasons: Why are two stroke engines used on ships? It is crucial to carefully monitor fuel quality and throttle settings to make appropriate adjustments to the fuel injection timing for optimal engine performance. By adjusting the fuel injection timing based on fuel quality and throttle position, the engine can maintain an optimal air-fuel ratio for efficient combustion, ensuring adequate power output, and minimizing emissions. This reduction in fuel quantity results in a shorter fuel injection timing, where the fuel is injected closer to TDC.Ĭonversely, when applying more throttle, indicating a higher power demand, a greater amount of fuel is injected, leading to a longer fuel injection timing, where the fuel is injected further in advance of TDC. When applying less throttle, which indicates a lower power demand, the fuel quantity injected into the cylinder is reduced. Moreover, the fuel injection timing changes according to the throttle position. However, if lower-quality fuel is being used, the fuel injection timing may need to be adjusted to around 20 degrees before TDC to ensure optimal combustion. When using high-quality fuel, it is advisable to inject the fuel approximately 5 degrees before the top dead center (TDC) position. In a two-stroke marine engine, the fuel injection timing can vary depending on the quality of the fuel. 1st process is that scavenge port opens 42 ☌ before BDC.Ģnd process is that the piston reaches BDCģrd process is that scavenge port closes 42 ☌ after BDC.Ĥth process is that the exhaust valve closes 60 ☌ after BDC.ĥth process is that around 15 ☌ before TDC fuel injection starts.Ħth process is that the piston reaches TDC.ħth process is that around 20 ☌ after TDC fuel injection stops.Ĩth process is that the exhaust valve opens 75 ☌ before BDC. ![]()
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