Test: SI & CI Engines - 1 - Mechanical Engineering MCQ

Match List I (S.I. Engine Operational Mode) with List II (Air fuel Ratio by Mass) and select the correct answer:  

Match List I with List II and select the correct answer. 

Stoichiometric air-fuel ratio by volume for combustion of methane in air is:

Velocity of flame propagation in the SI engine is maximum for a fuel-airmixture which is 

Which of the following cannot be caused by a hot spark plug?  
1. Pre-ignition
2. Post-ignition
3. Detonation
4. Run-on-ignition
Select the correct answer using the code given below:

Match List I with List IT and select the correct answer using the codes given below the lists: 
List I                                                               List II
(S.l. Engine problem)                       (Characteristic of fuel responsible for the problem)
A. Cold starting                                1. Front end volatility
B. Carburetor icing                           2. Mid-range volatility
C. Crankcase dilution                      3. Tail end volatility
Code: A B C                         A B C
      (a) 1 2 3                    (b) 1 3 2
      (c) 2 3 1                    (d) 3 1 2

Which of the following factors increase detonation in the SI engine?
1. Increased spark advance. 
2. Increased speed.
3. Increased air-fuel ratio beyond stoichiometric strength
4. Increased compression ratio.
Select the correct answer using the codes given below:

The tendency of petrol to detonate in terms of octane number is determinedby comparison of fuel with which of the following? 

For minimizing knocking tendency is SI engine, where should the space plug be located? 

In spark ignition engines knocking can be reduced by: 

Which of the following are the assumptions involved in the auto-ignition theory put forth for the onset of knock in SI engines? 
1. Flame velocity is normal before the onset of auto ignition.
2. A number of end-gas elements auto ignite simultaneously.
3. Preflame reactions are responsible for preparing the end-gas to ignite.
Select the correct answer using the codes given below:

Match List I with List II, in respect of SI engines, and select the correct answer by using the codes given below the lists: 
List I                                                            List II
A. Highest useful compression ratio         1. Ignitable mixture
B. Dopes                                                   2. Knock rating of fuels
C. Limiting mixture strength                      3. Detonation
D. Delay period                                         4. Chain of chemical reactions in combustion chamber
Codes: A B C D                        A B C D
        (a) 2 3 1 4                    (b) 3 2 1 4
        (c) 2 3 4 1                    (d) 3 4 2 1

Consider the following statements 
1. Octane rating of gasoline is based on iso-octane and iso-heptane fuelswhich are paraffin
2. Tetraethyl lead is added to gasoline to increase octane number.
3. Ethylene di-bromide is added as scavenging agent to remove lead depositson spark plugs.
4. Surface ignition need not necessarily cause knocking.
Which of these statements are correct?

The volumetric efficiency of a well designed SI engine is in the range of  

Knocking in the SI engine decreases in which one of the following orders of combustion chamber designs? 

Which of the following combustion chamber design features reduce(s) knocking in S.I. engines? 
1. Spark plug located near the inlet valve.
2. T-head.
3. Wedge shaped combustion chamber
4. Short flame travel distance.
Select the correct answer using the code given below:

Find the absolute and atmospheric pressure difference at the depth of 2 m in water lake ________.