Internal Combustion Engines _I_C_ Engines — Part 1 MCQs with Explanations

Engine pistons are usually made of aluminium alloy because it Is lighter Aluminium alloy are used because they are lighter.

The reason for supercharging in any engine is to Reduce weight and bulk for a given output -A supercharger is an air compressor that increases the pressure or density of air supplied to an internal combustion engine. This gives each intake cycle of the engine more oxygen, letting it burn more fuel and do more work, thus increasing power.

Morse test can be conducted for Multi cylinder engines The purpose of Morse test is to obtain the approximate indicated power of a Multi cylinder engine. It consist of running the engine against the dynamo-meter at a particular speed, cutting out the firing of each cylinder in turn and noting the fall in BP each time while maintaining the speed constant.

The cetane (C 16 H 34 ) which is a straight chain paraffin, is assigned a cetane number of 100.

Alpha-methyl-naphthalene (C 11 H 10 ) has a cetane number of 0.

A supercharger is an air compressor that increases the pressure or density of air supplied to an internal combustion engine. This gives each intake cycle of the engine more oxygen, letting it burn more fuel and do more work, thus increasing power. The scavenging efficiency of a four stroke cycle diesel engine is Between 95 and 100%

Scavenging is a process of pushing exhaust gas out of the cylinder and drawing in fresh draught of air or air fuel mixture for the next cycle. Scavenging is usually done to increase power output

Air Alone is compressed in a Diesel engine cylinder

Number of working strokes per min. for a four stroke cycle engine are one half the speed of the engine in r.p.m.

Number of working strokes per min. for a two stroke cycle engine is equal to the speed of the engine in r.p.m.

The thermal efficiency of petrol and gas engines is about 30%

The thermal efficiency of petrol and gas engines is about 30% and the thermal efficiency of diesel engines is about 70%.

The size of inlet valve of an engine in comparison to exhaust valve is more

A spark plug gap is kept from 0.3 to 0.7 mm

Heating oil is made from crude oil Heating oil is a petroleum product refined from crude oil. Heating oil and diesel fuel are closely related products called distillates. Heating oil is a distillate fuel sold mainly for use in boilers, furnaces, and water heaters. When crude oil is heated, then natural gas is given off first

Inlet valve closing before bottom dead center would reduce volumetric efficiency of a vertical compression ignition engine. -It should be quite clear that the volumetric efficiency decreases at higher rpm because the process of pushing the exhaust gases out and sucking the fresh charge inside cylinder gets lesser and lesser time.

carburettor is a device that mixes air and fuel for internal combustion engines in the proper air–fuel ratio for combustion.

A supercharger is an air compressor that increases the pressure or density of air supplied to an internal combustion engine. This gives each intake cycle of the engine more oxygen, letting it burn more fuel and do more work, thus increasing power.

Actual volume = swept volume × volumetric efficiency = 300 × 0.88 = 264 cm 3

The pressure at the end of compression, in diesel engines, is approximately 35 bar

The pressure at the end of compression, in petrol engines, is approximately 10 bar

Air fuel ratio for idling speed of a petrol engine is approximately 10 : 1

The specific fuel consumption per BH hour for a petrol engine is approximately 0.25 kg

The specific fuel consumption per BHP hour for diesel engine is approximately 0.2 kg

The maximum propulsive efficiency of a turbojet engine is at a speed of 2400 km/h

Morse test can be conducted for Multi cylinder engines The purpose of Morse test is to obtain the approximate indicated power of a Multi cylinder engine. It consist of running the engine against the dynamo-meter at a particular speed, cutting out the firing of each cylinder in turn and noting the fall in BP each time while maintaining the speed constant.

The air-fuel ratio of the petrol engine is controlled by carburettor

The air-fuel ratio in petrol engines is controlled by carburetion

No,The supply of scavenging air at a density greater than that of atmosphere mean engine is supercharged

The Compression Ignition engines can work on very lean mixture of fuel. - Compression ignition engine or CI engine is an internal combustion engine in which ignition of the fuel takes place with the help of hot compressed air. - At the end of the compression stroke, fuel is injected into the cylinder and it gets ignited from the heat of compressed air and burning process begins.

Iso-octane (C 8 H 18 ) has octane number of 100.

In a four stroke cycle engine, the sequence of operations is Suction, compression, expansion and exhaust

In loop scavenging, the top of the piston is contoured

The actual volume of fresh charge admitted in 4-stroke petrol engine is less than stroke volume

In order to prevent knocking in spark ignition engines, the charge away from the spark plug should have - Low density - Low temperature - Long ignition delay

The inlet valve of a four stroke cycle internal combustion engine remains open for 230°

The turbine of the turboprop engine is Bigger than of the turbojet engine.

Fuel oil consumption guarantees for I.C. engine are usually based on High heat value of oil

The thermal efficiency of diesel engines on weak mixtures is higher. compression-ignition engines are more fuel efficient (upto 30%) than their gasoline counterparts. diesel has more long chain hydrocarbons, which is 15 percent more energy dense than gasoline.

In compression ignition engines, swirl denotes a Rotary motion of the gases in the chamber. In compression ignition engines, swirl denotes a rotary motion of the gases in the chamber as swirl is always related to rotary motion. Inject fuel in a chamber of high pressure at the end of compression stroke.