Advantages of LPG
1. It is cheaper than petrol
2. It is highly detonation resistant and does not pre-ignite easily.
3. It gives better manifold distribution and mixes easily with air.
4. Residue and oil contamination is small as it burns cleanly: implies longer lubricating oil change period.
5. LPG is lead free – implies- less exhaust emission.
6. Life of spark plug is increased.
7. LPG has a higher octane rating than petrol.
8. It meets emission norms.
9. It can be transported easily to remote places by road and also by rail.
10. It results in increased engine life and smoother engine performance.
11. Crankcase oil dilution is small. So, oil replacement frequency is reduced.
12. Low engine deposits reduce the cost of maintenance.
13. Engine need not be modified. LPG kits are readily available (even for MPFI engines) and the kit cost is mostly affordable.
Disadvantages of LPG
1. It reduces volumetric efficiency due to its high heat of vaporization.
2. Handling has to be done under pressure of about 18 bars.
3. It characteristic odour is faint. An odourant (usually Mercaptan) is usually added so that the people will be aware of the leaks.
4. Much of its advantages can be realized (obtained) in engines of higher compression ratio.
5. Response to blending is very poor.
6. LPG produces 10 % less power for a given engine, at full throttle.
7. The vehicle weight is increased due to the use of heavy pressure cylinders for storing LPG.
8. A special fuel feed system is required for LPG.
9. Reduced Boot space (Storage tank occupies part of the Boot space)
10. Unlike petrol pumps, LPG filling stations are less in number. (Most of the stations are located in cities). Therefore users inconvenience.
11. Operating range (Running Range) is less as compared to that of petrol.
12. Starting problem with LPG
13. It is safe only if proper periodic maintenance of the gas system is done by trained person.