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3. What are the peculiarities of the construction?
4. What pressure does a two- stage turbocharging operate on?
5. How is the maximum combustion pressure kept as low as possible?
6. What improves starting?
7. What is the output power of the engine?
8. How much fuel does it consume?
V. Compose a plan to the text and tell about the engine using the plan.
Lesson 24
Constructions & Performance Details of
PC 2-6 & PC 4-2 Medium – Speed Engines
The demand trend in the past few years has encouraged fuel economy developments rather
than power increase and SEMT – Pielstick's designers at Saint-Denis, Paris, have concentrated
on reducing specific fuel consumption ratings; a desire to limit the number of cylinders necessary
for a given output, however has stimulated further increase in specific output. The result of these
latest efforts are embodied in the new PC 2-6 and PC 4-2 series which are designed to meet the
market requirement of 1990. The PC 2-6 & PC 4-2 span power upratings of 100 & 150 bhp re-
spectively and give a decrease in specific fuel consumption of about 5–6 g/bhp/h.
The reduced fuel consumption was achieved by improving combustion conditions for PC
2-6 engine by forming a scoop (углубление) on the bottom of the cylinder head to increase tur-
bulence and reduce consumption by 2 to 3 g/bhp/h across the fuel operating range. A design fea-
ture of PS engines is the use of two inlet valves and two exhaust valves on each side of the cy-
linder head, inclined at 22, 5 degrees, so that on entry of the air into the cylinder and during the
exhaust stroke the resulting turbulence improves filling and evacuation of burnt gas from the cy-
linder, respectively. The generous dimensions of the inlet and exhaust valves and the careful de-
sign of inlet and exhaust manifolds have minimized losses and reduced fuel consumption.
The design of injection system was modified – fuel pump diameter was increased, reducing
the specific fuel consumption of high loads. To reduce the consumption under part load conditions
and to maintain a high max combustion pressure a self-advancing fuel pump piston was used.
Another improvement results from the use of a new turbocharging mode. Constant pres-
sure results in good turbine efficiency at mean effective pressure above 15 bar.
The engines are designed to drive their fresh & sea water, fuel and oil pumps directly, re-
ducing the requirement for onboard electrical power. And a direct driven alternator may be
readily coupled to the free end of the crankshaft.
Exercises
I. Read and translate the first paragraph of the text and express its main idea in
English
II. Choose sentences concerning steps taken to reduce fuel consumption. Write
them down and translate.
III. Make up the plan of the whole text.
IV. Ask as many questions as you can. Work in pairs.
V. Retell the text using the plan.
56
3. What are the peculiarities of the construction?
4. What pressure does a two- stage turbocharging operate on?
5. How is the maximum combustion pressure kept as low as possible?
6. What improves starting?
7. What is the output power of the engine?
8. How much fuel does it consume?
V. Compose a plan to the text and tell about the engine using the plan.
Lesson 24
Constructions & Performance Details of
PC 2-6 & PC 4-2 Medium – Speed Engines
The demand trend in the past few years has encouraged fuel economy developments rather
than power increase and SEMT – Pielstick's designers at Saint-Denis, Paris, have concentrated
on reducing specific fuel consumption ratings; a desire to limit the number of cylinders necessary
for a given output, however has stimulated further increase in specific output. The result of these
latest efforts are embodied in the new PC 2-6 and PC 4-2 series which are designed to meet the
market requirement of 1990. The PC 2-6 & PC 4-2 span power upratings of 100 & 150 bhp re-
spectively and give a decrease in specific fuel consumption of about 5–6 g/bhp/h.
The reduced fuel consumption was achieved by improving combustion conditions for PC
2-6 engine by forming a scoop (углубление) on the bottom of the cylinder head to increase tur-
bulence and reduce consumption by 2 to 3 g/bhp/h across the fuel operating range. A design fea-
ture of PS engines is the use of two inlet valves and two exhaust valves on each side of the cy-
linder head, inclined at 22, 5 degrees, so that on entry of the air into the cylinder and during the
exhaust stroke the resulting turbulence improves filling and evacuation of burnt gas from the cy-
linder, respectively. The generous dimensions of the inlet and exhaust valves and the careful de-
sign of inlet and exhaust manifolds have minimized losses and reduced fuel consumption.
The design of injection system was modified – fuel pump diameter was increased, reducing
the specific fuel consumption of high loads. To reduce the consumption under part load conditions
and to maintain a high max combustion pressure a self-advancing fuel pump piston was used.
Another improvement results from the use of a new turbocharging mode. Constant pres-
sure results in good turbine efficiency at mean effective pressure above 15 bar.
The engines are designed to drive their fresh & sea water, fuel and oil pumps directly, re-
ducing the requirement for onboard electrical power. And a direct driven alternator may be
readily coupled to the free end of the crankshaft.
Exercises
I. Read and translate the first paragraph of the text and express its main idea in
English
II. Choose sentences concerning steps taken to reduce fuel consumption. Write
them down and translate.
III. Make up the plan of the whole text.
IV.Ask as many questions as you can. Work in pairs.
V. Retell the text using the plan.
56
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