IC Engine Interview Questions

The full form of an IC Engine is Internal Combustion Engine. It helps automate mechanical engineering to reduce manual labour engagement and hard work. Belgian inventor Étienne Lenoir is the founder of this engine. He developed the first ic engine named "hippomobile," powered by gas.

Let's have a look at a few fun facts about internal combustion engines before you start your interview preparation:

1. In the year 2020 IC Engine market grow by over 28.8% in the USA in the global market. But from 2021 to 2027, China is expecting 7.7% growth.
2. A IC engine design engineer can get 8 to 10 Lakhs per annum.

We have classified IC Engine Interview Questions - 2024 (Updated) into three stages, they are:

• For Freshers
• For Experienced
• FAQ's

Top 10 IC Engine Interview Questions And Answers

• What is a two-stroke engine?
  
• Can you name the IC engine's familiar layout?
  
• What are the IC engine performance measures?
  
• What Is The Difference Between An Octane Number And A Cetane Number?
  
• What is the IC engine compression ratio?
  
• Explain the six-stroke engine.
  
• Explain why we need a cooling system in the engine?
  
• Tell me something about the valve timing diagram?
  
• What is an Idle stroke?
  
• Why do we need a Flywheel in the IC Engine?

IC Engine Interview Questions - For Freshers

1.What is an IC engine?

The internal combustion engine turns chemical energy into useable mechanical energy by burning fuel. When the spark ignites the fuel-air mixture in the combustion chamber, chemical energy is released. The gas created in this reaction rapidly expands on the power stroke, forcing the piston down the cylinder.

2. What is a two-stroke engine?

Dugald Clerk invented a two-Stroke engine in 1880, with suction, compression, expansion, and exhaust occurring during the 2-stroke of the piston. Every one of the crank shifts will give one stroke. Animation depicts a two-stroke engine in action, complete with a tuned exhaust pipe.

3. What is a four-stroke engine?

A 4-stroke engine is an internal combustion engine in which the piston performs four different strokes—intake, compression, power, and exhaust—throughout two crankshaft revolutions and one thermodynamic cycle.
It runs on natural and synthetic gas.

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4. Tell me the differences between two-stroke and four-stroke engines?

Two-stroke engine	Four-stroke engine
A two-stroke engine fires once every revolution	A four-stroke engine fires once every two wheels.
Two-stroke engines are more straightforward and lighter, but they are less adaptable.	In four-stroke engines, ports replace valves; in two-stroke engines, the piston acts as a valve to control the flow of Gasoline.
Two-stroke engines are often utilized in light-duty applications.	In four-stroke engines are employed in heavy-load applications.

 5. What are the primary steps that we need to follow in a four-stroke engine?

• Air and vaporized Gasoline are pulled in through the intake stroke.
• The air and fuel vapour is compressed and ignited during the compression stroke.
• Fuel burns, and the piston is pushed down during the combustion stroke.
• Exhaust stroke: The exhaust is forced out of the system. The piston relies on power and momentum created by the other pistons during the first, second, and fourth stroke

6. In an IC engine, what are the benefits of lubrication?

• It prolongs the life of the moving parts by reducing wear and strain.
• It helps to reduce engine vibration.
• It cleans the moving parts of the machine.
• It tightens the piston gas.

7. Can you name the IC engine's familiar layout?

• Reciprocating
• Engine with two strokes
• Engine with four strokes (Otto cycle)
• Engine with six strokes
• Miller cycle
• Atkinson cycle
• Wankel engine (rotary)
• Burning indefinitely
• Thermoelectric generator
• Jet Engine

8. What are the IC engine performance measures?

Engine types differ substantially in a variety of ways, and the following are some of the performance indicators:

• Efficiency in terms of energy
• Consumption of fuel/propellant
• Weight-to-power ratio
• Weight-to-thrust ratio
• Thrust lapse torque curves (for shaft engines) (jet engines)
• The total pressure ratio for piston engines, the compression ratio, and for jet engines and gas turbines.

9. Why are gas turbines less efficient than Internal Combustion Engines?

In gasoline generators, the compressor consumes 70 percent of the output of the gasoline turbine. As a result, the auxiliary intake on IC engines is much lower. In addition, when compared to gas turbines, the combustion temperature of IC engines is substantially higher.

10. What is Timed Cylinder Lubrication, and how does it work?

Lubrication oil must be loaded between piston jewels while the piston is at the backside of the stroke for adequate lubrication. This allows for the proper storage and use of a large quantity of lubricating oil. 

11. Why is glycerin used in some engines instead of water for engine cooling? 

The boiling point of glycerine is 90°C, enhancing its heat carrying capacity. As a result, the weight of the coolant is lowered, allowing for the use of a smaller radiator.

12. How will you position the Piston Ring?

The top, second, and oil rings are all constant at a 180-degree angle. Place the hoop about 1 inch below the collarbone.

13. What Is The Difference Between An Octane Number And A Cetane Number?

Octane No. - Octane amount is the percentage of iso-octane in a combination of iso-octane and h-heptane expressed in volume. It is the SI engine's score measurement.
Cetane No -The cetane range is defined as the proportion of n-cetane in the aggregate of n-cetane and alpha-methyl naphthalene measured in terms of extent. It is the CI engine's rating scale.

14. What is the IC engine compression ratio?

The compression ratio of an internal combustion engine is defined as the ratio of the volume of the cylinder  (when the piston is closest to the cylinder head) to the combustion chamber volume (when the piston is farthest out). The higher the ratio, the more the air in the cylinder is compressed. The air in engines is compressed because it produces a tremendous explosion from the air-fuel mixture, resulting in more fuel usage. Automotive engineers use this method to build engines as fuel-efficient as possible.

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15. In an IC engine, what is the carburetor?

A carburetor is a device that mixes air with fuel to supply a spark ignition system in an internal combustion engine. It's only utilized in engines that can ignite with a spark, like a gasoline engine. Some of the components used in the carburetor are a choke, a liquid fuel storage chamber, the main jet, an accelerator pump, an idling jet, and a venture-shaped airflow restriction.

16. What is the definition of combustion modelling? 

Ans: One of the essential tools for better understanding engine performance and emissions in internal combustion engines is combustion modelling.

17. What is the Intention of spark ignition engines?

 Ans: It refers to igniting an air-fuel mixture with a spark from a spark plug. This word refers to petrol engines, not diesel engines, which do not require an external spark to start the combustion process.

18. What exactly is a crankshaft?

The Crankshaft is in charge of the engine's proper operation. It converts the linear motion of the piston into a rotating signal. Because crankshafts are subjected to a high level of cyclic loading, they must have a high fatigue strength and wear resistance to function for an extended period.

IC Engine Interview Questions - For Experienced

1. Why do you think the efficiency of gas turbines is lower than that of IC Engines?

The compressor consumes 70% of the gas turbine output in gas turbines.   IC engines consume more auxiliary. As a result, the IC  engine's combustion temperature is too much higher than the turbine engine.

2. Why we do not use the same technology to start both SI /CI Engines?

The SI (spark ignition) engine runs on petrol, whereas the CI (compression ignition) engine runs on diesel. This is because the compression ratios of both fuels are different.

The compression ratio in a SI engine is 8-12:1. The compression ratio in a CI engine is 16-22:1. So, in a SI engine, the compression ratio is insufficient for Gasoline to burn, necessitating the use of a spark plug, whereas, in a CI engine, the compression ratio is so high that the fuel is combusted due to internal heat, eliminating the need for a spark plug. As a result, the SI engine's technology differs from the CI engine's.

3. What are the restrictions of internal combustion engines?

• It needs pure quality fuel.
• All the suitable fuels are very costly.
• The emission rate is also very high.
• You can not use it for a massive volume of power production at a time.
• This kind of engine produces noise also.

4. Explain the six-stroke engine.

• Six-stroke engines internal combustion engine is subjected to these.
• It improves fuel economy.
• It simplifies the mechanical process.
• It lowers productivity.

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5. What were the differences between brake power and indicated power of an IC Engine?

The output power generated in the Crankshaft is called break power. When the fule burns, the engine will generate this indicated power. 

6. What are the basic need for the ignition system.

• After the compression stroke, we should place imagination
• The spark plug should not fail.
• Need to provide enough energy to the engine to keep burning on.
• The engine should get minimum energy from fuel to start initially.

7. Explain why we need a cooling system in the engine?

• The cooling system will protect the piston expansion
• It will cool down the engine and piston too.
• The cylinder temperature will be under control.
• It saves the lubricant and piston rings too.

8. How does the knocking work?

• If the parts inside the engine will overheat, it can damage the engine.
• It creates vibration and noise in the engine.
• It can cause lower power output.
• The coolant is also going to destroy soon.
• More heat is lost to the coolant because the dissipation rate is fast.
• The spark plug can be overheated and cause carbon layers on the spark plug head.

9. Explain adequate pressure.

The piston generates a power stroke to produce the expected engine output at the actual cycle time. We can define the total work volume per cycle by measuring the adequate pressure.

10. How can we do the morse test?

If you want to test the indicated power in the multi-cylinder engine, you must do a morse test. First, you need to follow the engine dynamometer at a particular speed for both cylinders, and then you have to note down the BHP fall in each noting. You don't need to use an indicator diagram also.

11. What do you know about pre-ignition?

The pre-ignition occurs in the spark plug due to the mixture of air and fuel. At a high temperature, the carbon layers form inside the engine.

12. What do you mean by combustion thermodynamics?

It is a chemical reaction due to the gas phase, which sometimes creates light, heat, smoke, and flame. It mainly takes place in the fuel cell. You can be control combustion by reducing the engine's high temperature.

13. Tell me something about the valve timing diagram?

A valve timing diagram is a graphical representation of the opening and closing of the intake and exhaust valves of the engine.   The opening and closing of the engine's valves depend upon the piston's movement from TDC to BDC. This relation between piston and valves is controlled by setting a graphical representation between these two, which is known as the valve timing diagram.

14. What is an Idle stroke?

The idle stroke constitutes a small gap of a few micrometres between the piezoelectric actuator and the control valve, which must be adjusted during the assembly process. Therefore, the identification approach only relies on analyzing the electric signals of the piezoelectric stack actuator.

15. What is Bumping clearance?

Clearance volume or bumping clearance is the space between the top of the piston and the cylinder head of an air compressor. This clearance is an essential aspect of the compressors and should be as less as practically possible to improve the volumetric efficiency of the compressor.

16. What causes white smoke in two stroke Locomotive Engines?

That is because the engine is running too Lean a mixture (lack of fuel).   This condition wilt leads to overheating and failure of the engine.

17. Why do we need a Flywheel in the IC Engine?

Flywheel has standard functions like providing continuous power when the energy source is discontinuous and delivering power faster. However, the primary part of the Flywheel is to store rotational energy. Therefore, the amount of energy stored in the Flywheel is directly proportional to the square of its rotational speed.

Top 10 Frequently Asked IC Engine Interview Questions

1. Do you think IC Engine designers have a bright future?

IC engines come with zero-emission. There is so many ic engine latest version. So if we talk about pollution from machines, it has significantly more minor and decreases day by day as new technologies come with the new fuel system. Ic engine designers have a very bright future in this area.

2. What do you think, the IC Engine will be obsolete?

As new models are coming up, there are no chances to become obsolete. Transportation task is going to create more new implementation.

3. What is the minimum requirement for an IC Engine?

Ignition of the mixture is the minimum required for an ic engine.

4. What fuels do you use in the IC Engine?

We can use Gasoline, diesel, marine fuels, and turbine fuels in ice engines.

5. Which fuel is not suitable for the IC Engine?

We can not use methanol in the ic engine as fuel because this fuel has high octane number and a low octane number. This is because the octane number indicated hit is generated due to the energy. 

6. Which is the most potent fuel, alcohol or Gasoline, for an IC Engine?

Fuel is the most critical component in an engine. Alcohol is effective in case of a power race. It heats less than Gasoline. So once the initial power is required, alcohol consumption will increase. At the end of the race, it will give more energy as the total engine weight will be less because some percentage of fuel has already burned out.

7. Why is methanol best for race IC Engines?

It is more potent than alcohol and Gasoline. Methanol's combined octane rating is 119, while the regular gasoline octane rating is 87.

8. What are the most common engines based on the IC Engine?

IC Engines run many engines like:

• Bus
• Track
• Scooter
• Motorbike
• Cars
• Aircraft
• Motorboats

Conclusion

IC engine research work has led to improving the engine's performance, fuel efficiency, development of new advanced combustion engines, and reducing nitrogen oxide emissions. So let's learn more about IC Engine to gain sharp growth in our professional career.