The cylinder contains a charge of highly compressed air when the piston reaches the top of its trip. The injector sprays diesel fuel into the cylinder, which ignites instantly due to the heat and pressure inside the cylinder. This is the same procedure that How Diesel Engines Work explains.
What is the operation of a Detroit 2 Stroke diesel engine?
The two-stroke diesel cycle works like this: the cylinder carries a charge of highly compressed air when the piston reaches the top of its trip. The injector sprays diesel fuel into the cylinder, which ignites instantly due to the heat and pressure inside the cylinder.
Is it true that two-stroke diesel engines have valves?
So, which is the ‘better’ option? Here are some of the advantages and disadvantages of both engine designs:
- In terms of efficiency, the 4-stroke is unquestionably superior. This is because fuel is burned just once every four strokes.
- Four-stroke engines are significantly heavier than two-stroke engines, weighing up to 50% more.
- A 2-stroke engine typically produces more torque at higher RPMs, but a 4-stroke engine produces more torque at lower RPMs.
- A 4-stroke engine is also much quieter, whereas a 2-stroke engine is much louder and produces a characteristic, high-pitched “buzzing” sound.
- Because 2-stroke engines are built to run at a higher RPM, they wear out more quickly; 4-stroke engines are more robust. 2-stroke engines, on the other hand, are more powerful.
- Because two-stroke engines have a simpler design, they are easier to repair. They don’t have valves; instead, they have ports. Because four-stroke engines have more parts, they are more expensive, and repairs are more expensive.
- Pre-mixing of oil and fuel is required for two-stroke engines, but not for four-stroke engines.
- Four-stroke engines are more environmentally friendly; with a two-stroke engine, burned oil is discharged into the atmosphere along with the exhaust.
Remote-control cars, lawn mowers, chainsaws, boat motors, and dirt bikes are all examples of two-stroke engines in smaller applications. Four-stroke engines can be found in everything from go-karts to lawnmowers and dirt motorcycles to your car’s internal combustion engine. It’s up to you to choose whatever engine and for what purpose you want to use it.
Is it true that a two-stroke Detroit has valves?
The four stages of internal combustion engine operation (intake, compression, ignition, and exhaust) occur in one 360 rotation of the crank shaft in a two-stroke engine, whereas they take two complete revolutions in a four-stroke engine. As a result, the stages in the two-stroke cycle overlap for the majority of the engine’s activity. This complicates the thermodynamic and aerodynamic processes. The power output of the two-stroke cycle is theoretically twice as great as the four-stroke cycle because the four-stroke cylinder fires every other revolution. In practice, however, scavenging losses make this advantage impossible to accomplish.
- When the piston is at the bottom dead center, intake begins (BDC). Through openings in the cylinder wall, air is admitted into the cylinder (there are no intake valves). To charge the cylinder with air, all two-stroke diesel engines require artificial aspiration, which is provided by either a mechanically driven blower or a turbo-compressor. The air charge is also employed in the early stages of intake to scavenge any residual combustion gases from the previous power stroke, a process known as scavenging.
- The intake charge of air is compressed as the piston rises. Fuel is injected near top dead center, causing combustion due to the charge’s extremely high pressure and heat generated by compression, which forces the piston downward. The exhaust port is opened when the piston goes downward in the cylinder, allowing the high-pressure combustion fumes to escape. Most modern two-stroke diesel engines, on the other hand, use top-mounted poppet valves with uniflow scavenging. The cycle will restart if the piston continues to descend, exposing the air intake apertures in the cylinder wall.
Why are Detroit diesels fleeing?
Working in or near hazardous environments, such as those found in the Oil & Gas business, exposes you to dangers and risks on a daily basis. Between 2013 and 2017, 489 oil and gas extraction employees were murdered on the job in the United States alone, according to the Occupational Health and Safety Administration (source: https://www.osha.gov/SLTC/oilgaswelldrilling/). The dangerous occurrence known as diesel engine runaway is one of the lesser-known yet lethal threats. Engine runaway is explained in this video from AMOT’s Ask the Expert series.
To comprehend runaway, you must first comprehend the operation of a diesel engine and how it varies from that of a gasoline engine. Spark plugs ignite the fuel and air mixture within the cylinders of a gasoline engine. Combustion in a diesel engine, on the other hand, takes place in a very different way. Clean air is drawn into a combustion chamber by a diesel engine’s intake. The air and fuel mixture in the chamber is squeezed to such a degree that it produces high heat and ignites.
The fuel delivered into the combustion chamber is regulated by a governor, which also controls the engine’s speed. The governor controls how much fuel is allowed into the engine. The more fuel allowed in, the faster the engine will run. A diesel engine can only be turned off by withdrawing the fuel supply or cutting off the air supply.
When a diesel engine ingests a hydrocarbon vapor, or flammable vapor, through the air intake system and uses it as an external fuel source, it is known as a diesel engine runaway. As the engine runs on these vapors, the governor releases less diesel fuel until the vapors are the engine’s sole fuel supply.
It can cause the engine to overspeed, the valves to bounce, and flames to pass through the manifold if not halted promptly. These flames can create catastrophic accidents and casualties by igniting the combustible gases present. The Deepwater Horizon explosion in the Gulf of Mexico on April 20, 2010, is a well-known example of this type of mishap.
Even low concentration levels of gas pushed into the engine intake can cause runaway in 3-12 seconds, giving little time to react. A person’s first instinct when an engine starts to runaway is to turn the key off and stop the engine. Unfortunately, because the engine is now running on combustible fumes entering through the intake, this will not solve the problem. The engine will continue to run wildly, and cutting off the air supply is the only possible alternative at this time.
Thankfully, diesel engine runaway can be avoided. Devices that identify overspeed and shut off the air supply can be put on an engine’s air intake pipe to safely and quickly shut down a diesel engine.
When did Detroit discontinue using the two-stroke engine?
The engines’ high emissions proved to be their demise in the end. For a time, electronic controls were able to cut pollution levels enough to allow engines to meet ever-stricter restrictions, but the two-stroke cycle eventually proved to be too dirty and inefficient to meet the new regulations. MTU, which had bought Detroit Diesel from Penske in 2006, finally stopped making two-stroke Detroit Diesels in 1998. (The four-cycle Series 60 Detroit Diesel is still produced by the business.)
What are the benefits of using a two-stroke diesel engine?
Two-stroke engines are smaller and lighter than four-stroke engines, yet they are more efficient because power is generated just once every rotation (instead of once during every two rotations, as in a four-stroke engine). This necessitates extra cooling and lubrication, as well as increased wear and tear.
Are there reed valves on all two-strokes?
Because a malfunctioning reed valve can create a number of issues, understanding if you have one is important. Not all two-stroke engines have reed valves.
Is it possible to turn a two-stroke engine upside down?
Most engines will work perfectly if they are turned upside down. Just make sure the carb’s fuel tank height is correct. If the plane is built to use a two-stroke inverted, the instructions should include a configuration for the proper heights.
Do two-stroke motorcycles have valves?
A camshaft and valves are not present in a 2-stroke engine, as they are in a 4-stroke. Instead, they use a sleeve valve system, which has two permanently open ports in the cylinder wall adjacent to each other. The exhaust port and the inlet port are what they’re called.