Consider the following statements with regard to IC engines: 1. For best fuel economy of spark ignition engines, the fuel-air mixture should be lean 2. With supercharging, the specific consumption in compression ignition engines increases 3. With increase of load, knocking tendency in compression ignition engines increases Which of the above statements are correct?

1 and 2 only
2 and 3 only
1 and 3 only
1, 2 and 3

LohaHridoy

4 views

2025-01-04 04:42

1 Answers

AhmedNazir

Option 3 : 1 and 3 only

Concept:

Performance of SI engine

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To achieve maximum power and quick speeding/overtaking, the engine needs a rich mixture. (12:1 to 13:1)
To achieve maximum fuel economy the engine needs a leaner air-fuel ratio of 16: 1 to 17: 1

Effect of Supercharging

The power output of a supercharged engine is higher than its naturally aspirated counterpart.
The mechanical efficiencies of supercharged engines are slightly better than the naturally aspirated engines.
In spite of better mixing and combustion due to reduced delay, a mechanically supercharged Otto engine almost always have specific fuel consumption higher than a naturally aspirated engine.

The tendency of knocking in CI engine

Due to an increase in load, the knocking tendency in the CI engine increases.
Low ignition temperature, speed reduces knocking tendency.

4 views Answered 2022-09-04 04:29

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