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23 Cards in this Set
- Front
- Back
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Diesel
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The diesel engine is an internal combustion engine, in which the energy of burning fuel is converted into energy to work the cylinder of the engine.
In the diesel engine, air alone is compressed in the cylinder, raising its temperature significantly. After the air has been compressed, a charge of fuel is sprayed into the cylinder and ignition is accomplished by the heat of compression. The four piston stokes of cycle occur in the following order: intake, compression, power and exhaust. |
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Detroit Diesel 60 III/IV
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It is a four stroke. It is an inline 6 cylinder with 129 cubic inches in each cylinder.
The engine has 774 cubic inches and will deliver 400 HP @ 2100 RPM. Bore is 6.32 in. and the Stroke is 5.12 in. |
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Components:
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1. Operation
2. Intake Stroke 3. Compression Stroke 4. Power Stroke 5. Exhaust Stroke 6. DDEC III/IV ECM 7. EUI 8. ECM 9. ECM Shutdown 10. Cylinder Designation and 11. Firing Order 12. Governed Speed 13. Block Heater |
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Intake Stroke
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During the intake stroke, the piston travels downward, the intake valves are open, and the exhaust valves are closed. The down stroke of the piston facilitates air from the intake manifold to enter the cylinder through the open intake valve. The turbocharger, by increasing the air pressure in the engine intake manifold, assures a full charge of air is available for the cylinder. The intake charge consist of air only with no fuel mixture.
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Compression Stroke
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At the end of the intake stroke, the intake valves close and the piston starts upward on the compression stroke. The exhaust valves remain closed. At the end of the compression stroke, the air in the combustion chamber has been compressed by the piston to occupy a space about one-fifteenth as great in volume as it occupied at the beginning of the stroke.
Thus, the compression ration is 15:1. The air is compressed to approx. 500 psi, and the temperature is approx. 1000 degrees F. |
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cont. Compression Stroke
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During the last part of the compression stroke and the early part of the power stroke, a small metered charge of fuel is injected into the combustion chamber.
Almost immediately after the fuel charge is injected into the combustion chamber, the fuel is ignited by the hot air and starts to burn, beginning the power stroke. |
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Power Stroke
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During the power stroke, the piston travels downward and all intake and exhaust valves are closed.
As the fuel is added and burns, the gases get hotter, the pressure increases, pushing the piston downward and adding to the crankshaft rotation |
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Exhaust Stroke
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During the exhaust stroke, the intake valves are closed; the exhaust valves are open, and the piston is on its up stroke.
The burned gases are forced out of the combustion chamber through the open exhaust valve port by the upward travel piston. From preceding description, it is apparent that the proper operation of the engine depends upon the two separate functions: first, compression for ignition, and second, that fuel be measured and injected into the compressed air in the cylinder in the proper quantity and at the proper time. |
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DDEC III/IV
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The DDEC III/IV ECM receives electronic inputs from sensors on the engine and vehicle, and uses the information to control engine operation.
It computes fuel timing and fuel quantity based upon predetermined calibration tables in its memory. |
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EUI
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EUI is the Electronic Unit Injector. Fuel is delivered to the cylinders by the EUI’s which are cam-driven to provide the mechanical input for pressurization of the fuel.
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ECM
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ECM is the Electronic Control Module. The ECM controls solenoid operated valves in the EUI’s to provide precise fuel delivery.
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Firing Order
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4, 2, 6, 3, 5,1
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Governor Speed
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The engine is governed at 2100 rpm by the ECM. At this RPM the ECM will not increase the amount of fuel injected by the EUI thus limiting the engine to go beyond 2100 rpm. Engine 1, 6, and 7 top speed is 70 mph
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2 Stroke Diesel
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In a two-cycle engine, two phases of work are combined in one stroke or cycle. Therefore, the intake and exhaust phases are combined into one cycle. The compression and power phases are combined in another cycle
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First Cycle
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When the piston reaches the bottom of the stroke, it uncovers the air induction ports in the cylinder wall. The blower forces cool, fresh air into the cylinder through these ports and it also expels the exhaust gases. This one directional flow of air creates a scavenging effect. Once the piston moves upward it will cover the air induction ports, leaving the cylinder full of clean, fresh air. As the piston moves upward, the exhaust valves close and the air in compressed.
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Second Cycle
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Just before the piston reaches its highest point, the fuel injector sprays the required amount of fuel into the cylinder.Heat from the compressed air ignites the fuel air mixture. This creates an explosion forcing the cylinder downward and creating power. The exhaust valves open when the piston is halfway down the cylinder. This allows the exhaust gases to escape into the exhaust manifold. When the piston uncovers the air induction ports, the cylinder is swept with clean, fresh air. The entire combustion cycle takes place in each cylinder for each revolution of the crankshaft.
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2 Stroke: Compression
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Compares the maximum volume of the cylinder when the piston is at the bottom of its stroke or path of travel, against the volume that remains once the piston has reached the top of its stroke or path of travel.
For a ration of 15:1, the 1 represents the volume left in the cylinder when the piston reaches the top of the stroke. The 15, represents the maximum volume in the cylinder when the piston is at the bottom of its stroke. This shows how much compression is taking place to create the temperature to ignite the fuel air mixture. |
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Diesel vs. Gas
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The primary difference between the gasoline engine and diesel engine is the ignition process.
The gasoline engine mixes air and fuel in a carburetor and relies on an electrical spark to ignite the mixture after it is compressed in the cylinder. The diesel engine is designed with much higher compression ratios and relies on compression of heat to ignite the fuel. When air is compressed in the cylinder, fuel is injected; ignition takes place and the expansion of hot gases drive the piston downward producing power. (No carburetor or ignition systems, fewer parts to maintain and replace or repair). |
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Benefits of Diesel
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Quicker Starting, Better dependability, Fewer maintenance problems, Less down time, Longer life, Lower operating temp
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Power loss of Diesel
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Additionally, at higher altitudes the gasoline engine has a decrease in power of 3 ½% for every 1000 ft. above sea level versus the diesel engine, which only loses 3 %.
However, the turbocharged diesel does not have a power loss until altitudes above 4,000 ft. and even then the loss is only 2 % per 1,000 ft. after that. |
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Advantages
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Ignition Reliability (relies on compression)
More complete fuel vaporization due to high compression. Precise fuel metering system Heavier construction features |
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Fuel Advantages
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Safer to handle. Contains more energy than gasoline. Produces usable power with “lean” air-fuel mixtures.
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Fuel Comparison
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Diesel:
BTU: 141K Flash: 100 F Ignition: 725 F Mix: 15 - 50:1 Gasoline BTU: 125K Flash: 45 F Ignition: 850 F Mix: 8 - 15:1 |
