Course: B.Tech (Mechanical Engineering)
Semester: V
Subject Code: KME054
Subject Name: I.C. Engine, Fuels & Lubrication
Maximum Marks: 100
Time: 3 Hours
Pattern: Section A (Short), Section B (Medium), Section C (Long)
SECTION A — Short Answer Questions (20 Marks)
Each question carries 2 marks.
Students must answer all questions briefly.
Topics covered:
Difference between two-stroke and four-stroke engines
Relation between mean effective pressure and mean pressure
Explanation of pre-ignition, auto-ignition, and detonation
Importance of spark advance and ignition timing
Principle of carburetion
Fuel injection requirements in CI engines
Advantages and disadvantages of PNG (Piped Natural Gas)
Hydrocarbon emissions in SI engines
Cooling of engine components through lubrication system
Why petrol cannot be used in diesel engines (and vice versa)
SECTION B — Descriptive Questions (30 Marks)
Attempt any three questions (10 marks each).
Topics include:
Valve timing diagrams — theoretical vs actual (with diagrams)
Air motion and swirl requirements in CI engines vs SI engines
MPFI System (Multi-Point Fuel Injection) — types and working
Alternative fuels for I.C. engines — biofuels, hydrogen, LPG, CNG, alcohol
Detailed discussion on ignition timing and its affecting factors
SECTION C — Long / Problem-Based Questions (50 Marks)
Attempt one part from each of the given questions (Q3–Q7).
Q3. Thermodynamic Cycles
Compare Otto and Diesel cycles; derive expressions for work done, thermal efficiency, and mean effective pressure
OR
Numerical on Dual cycle involving compression ratio, pressure, temperature, cut-off ratio, and efficiency calculations
Q4. Combustion Process
Explain delay period and its influencing factors
OR
Describe flame propagation and factors affecting flame speed
Q5. Engine Operation
Explain scavenging in a 2-stroke engine
OR
Explain simple carburetor construction and working (with diagram)
Q6. Pollution & Control
Discuss air pollutants from I.C. engines — CO, HC, NOx, and particulate matter
OR
Explain the catalytic converter as an after-treatment device
Q7. Advanced Engine Systems
Explain valve timing control in stratified charge injection engines (with sketch)
OR
Construction and working of battery ignition system (with sketch)
Key Concepts Covered
Working and classification of I.C. Engines Engine performance parameters
Combustion stages and ignition Air-fuel mixture and carburetion
Alternative fuels and emissions Engine lubrication and cooling
Modern ignition and injection systems
FAQs
Q1. What is the full form of MPFI?
MPFI stands for Multi-Point Fuel Injection, where fuel is injected into each cylinder’s intake port for better fuel-air mixing and efficiency.
Q2. What are the major pollutants emitted by IC engines?
Carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and soot are common engine emissions.
Q3. Why can’t diesel fuel be used in a petrol engine?
Because diesel requires compression ignition, whereas petrol engines use spark ignition — their design and combustion methods differ fundamentally.
Q4. What is the delay period in CI engines?
It’s the time gap between the start of fuel injection and the actual start of combustion. Factors like fuel quality, temperature, and injection pressure influence it.
Q5. What is scavenging in a two-stroke engine?
Scavenging is the process of clearing exhaust gases from the cylinder to make room for the next fresh charge.
