Working of Four Stroke Spark Ignition Engine (SI)

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What causes the vacuum inside the cylinder during the intake stroke?

The movement of the piston downwards (correct)

The opening of the inlet valve

The closing of the inlet valve

The burning of the air-fuel mixture

What happens to the pressure inside the cylinder during the compression stroke?

The pressure remains constant at atmospheric pressure

The pressure fluctuates between high and low values

The pressure increases as the volume decreases (correct)

The pressure decreases as the volume increases

What is the purpose of the spark plug in an SI engine?

To open and close the intake and exhaust valves

To ignite the air-fuel mixture at the end of the compression stroke (correct)

To measure the temperature and pressure inside the cylinder

To lubricate the moving parts of the engine

What is the purpose of the exhaust valve during the power stroke?

To release the high-pressure, high-temperature burned gases from the cylinder (B) Signup and view all the answers

What is the compression ratio of a typical SI engine?

Between 6 and 10 (A) Signup and view all the answers

What happens to the temperature and pressure inside the cylinder during the combustion/expansion stroke?

They both increase (D) Signup and view all the answers

What is the purpose of the intake stroke in a four-stroke spark ignition engine?

To introduce the fuel-air mixture into the cylinder (C) Signup and view all the answers

Which stroke in a four-stroke spark ignition engine involves combustion of the fuel-air mixture?

Power stroke (B) Signup and view all the answers

How many revolutions of the crankshaft are required to complete one full cycle in a four-stroke spark ignition engine?

Two revolutions (D) Signup and view all the answers

What is the purpose of the exhaust stroke in a four-stroke spark ignition engine?

To expel the exhaust gases from the cylinder (C) Signup and view all the answers

What is the process of converting chemical energy into mechanical energy called in a four-stroke spark ignition engine?

Combustion (D) Signup and view all the answers

What is the purpose of the compression stroke in a four-stroke spark ignition engine?

To compress the fuel-air mixture before ignition (A) Signup and view all the answers

What is the purpose of the exhaust stroke?

To push out the burnt gases from the cylinder (B) Signup and view all the answers

What is a key difference between a supercharger and a turbocharger?

Superchargers are driven by the engine crankshaft, while turbochargers are driven by the exhaust gas (C) Signup and view all the answers

What is the relationship between engine speed and compressor pressure in a turbocharger system?

The compressor pressure is proportional to the engine speed (B) Signup and view all the answers

What is the purpose of the waste gate valve in a turbocharger system?

To control the exhaust gas flow rate to the turbine (A) Signup and view all the answers

What is the main disadvantage of a turbocharger system compared to a naturally aspirated engine?

Turbo lag (C) Signup and view all the answers

What is the relationship between the peak pressure in the exhaust system and atmospheric pressure in a turbocharger system?

The peak pressure in the exhaust system is only slightly greater than atmospheric pressure (C) Signup and view all the answers