2. THE BASICS
A four-stroke engine:
➢Is an internal combustion engine
➢Converts gasoline into motion
➢Is the most common car engine type
➢Is relatively efficient
➢Is relatively inexpensive
10. Intake Stroke:
•Piston moves from TDC to BDC
creating vacuum in the cylinder
•Intake valve opens allowing only
air to enter the cylinder and
exhaust valve remains closed
11. Compression Stroke
•Both valves stay closed
•Piston moves from BDC to TDC,
compressing air to 22:1
•Compressing the air to this extent
increases the temperature inside the
cylinder to above 1000 degree F.
12. Power Stroke
•Both valves stay closed
•When the piston is at the end of
compression stroke(TDC) the injector
sprays a mist of diesel fuel into the
cylinder.
•When hot air mixes with diesel fuel an
explosion takes place in the cylinder
•Expanding gases push the piston
from TDC to BDC
13. Exhaust Stroke
•Piston moves from BDC to
TDC
•Exhaust valve opens and the
exhaust gases escape
•Intake valve remains closed
14. The only difference between diesel engine and a four-stroke
gasoline engine is:
•No sparkplug on Diesel engine.
•Has a higher compression ratio.
(14:1 to 25:1)
•Better fuel mileage.
15. ADVANTAGES
●1. Diesels are more efficient. Most gasoline engines
convert about 30 percent of their fuel energy into
actual power. A traditional diesel converts about 45
percent. And advanced diesels can hit about 50
percent.
●2. Diesels are more reliable. Because they don’t
need high-voltage ignition systems, diesel engines
never fail for lack of a spark. They also don’t emit
radio frequency emissions that can interfere with a
vehicle’s other electronic systems.
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16. 22
3. Diesels run cooler. Because they are more
efficient, diesel engines release less waste heat while
in operation.
4.Diesels last longer. Diesel engine parts are
generally stronger than gas engine components, and
diesel fuel has superior lubricating properties. As a
result, diesel engines tend to last twice as long as gas-
powered ones.
5.Diesel fuel is safer. Diesel fuel doesn’t release
fumes like gasoline does. It’s more difficult to burn and
won’t explode like its lighter counterpart.
17. 6.Diesels are more easily turbo-charged. Put under
sufficient pressure, gasoline engines will
spontaneously detonate. By contrast, the amount of
super- or turbo-charging pressures diesel engines can
endure are limited only by the strength of the engines
themselves.
7.Diesels produce minimal carbon monoxide. This
makes diesel generators useful in mines and
submarines, environments in which gasoline engine
exhaust would prove deadly.
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18. 1. Diesel engines, because they have much
higher compression ratios (20:1 for a typical
diesel vs. 8:1 for a typical gasoline engine), as
compare to gasoline engine.
2. Diesel engines also more expensive.
3. Diesel engines, because of the weight and
compression ratio, tend to have lower maximum
RPM ranges than gasoline engines .
DISADVANTAGES
19. 4. This makes diesel engines high torque rather
than high horsepower, and that tends to make
diesel cars slow in terms of acceleration.
5. Diesel engines must be fuel injected, and in
the past fuel injection was expensive and less
reliable
6. Diesel engines tend to produce more smoke
and "smell funny".
20. 7. Diesel engines are harder to start in cold
weather, and if they contain glow plugs, diesel
engines can require you to wait before starting
the engine so the glow plugs can heat up.
8. Diesel engines are much noisier and tend to
vibrate.
9. Diesel fuel is less readily available than gasoline
21. APPLICATION
➢Passengercars-
Diesel engines have long been popular in bigger cars
and have been used in smaller cars
➢Other transport uses-
Larger transport applications (trucks, buses, etc.) also
benefit from the Diesel's reliability and high torque
output.
➢Non Transport Uses-
generators, irrigation pumps,corn grinders
