I started using LPG as fuel on my Fiat car around 14 years back. I started experimenting with it during my college days. Started just with a length of tube, Manual Flow Control and few modifications in the carburator air intake chamber and then slowly made advancements like Electrically controlled Solenoid Valve for Gas on / off (Switch needs to be operated manually), then Electronically controlled automatic Solenoid switch (using 555 IC based extendable monostable circuit that senses ignition firing and activates solenoid thru relay only when there is a pulse and switching it off within a preset time in absence of firing activity). This electronic controlled solenoid switch helped me alot as it automatically switched on the Gas and stops when the engine is Off - helpful so that I can simply start the car and drive, this was most helpful as even in case of an accident and with unconscious driver the cylinder switches off automatically. This configuration & setup worked very well for me except for few adjustments occasionally. Due to lack of time, except for few improvements like automatic change-over from gas to petrol, LED Status indicators and servo controlled Air Inlet aperture Control my experiments stopped in the mid.
I used the same setup for years without any problem. I even shifted the entire setup whenever I changed the Car. I was able to clock nearly 350 km per Cylinder in my old Fiat and checked the mileage whenever I Travel from Chennai to Trichy which is nearly 315 km and then using it for few kms locally. At that time it worked out to around 50 paise per km, a huge saving that too when we travelled with nearly 6 passengers.
Though it saved lot of money and very cheap it was not free from some hitches. The Cylinder temperature reduces rapidly and drops to such levels, the cylinder will be soaked with water droplets all over. This matters when we travel for a long distance. The maximum speed you can reach is only around 80 km and that to drops to around 60 for the last 50 km. Whenever there is need for more power in a situation like overtaking, temporarily I change to petrol mode and then continue in LPG. Pickup will be like that of a diesel car, responding slow and steady but not to a complaining level. The Spark Plugs even after covering thousands of km stayed clean like new, there was no carbon deposits. I covered nearly around 20 K km in that old car in LPG with out any problem.
But after running the engine in LPG for a long time it refused to run smoothly in Petrol. Is it an addiction to LPG? no, actually what happened is though it is free from carbon deposits, it deposited a rubbery like layer all over the insides of the Carburator including Jets and float needle and made all its part somewhat sticky. This rubbery deposits stuck so hard it refused to get out of the Carburator permanently inspite of using many solvents like Petrol, Carburator cleaner etc. This rendered the engine almost unusable in petrol except for shorter durations. As the value of the Fiat car is very less I never cared about it. I was using the car for nearly five years. After the completion of my education I never had time to continue my experiments due to my profession as a Software Engineer and the related tight schedules.
Today I do not have enough guts to run my expensive cars in LPG due to the fear of unknown damages it may cause to the engine as most of the current engine are very complicated and managed by computers sensing various parametrs like exhaust temperature, engine speed, fuel quality and many many more. Also I am worried about the resale value of the Car. Now I am using only Petrol in all my cars for the Past nine years. Nowadays I can see many cars that are running in LPG with company fitted kits but no dealer of such kits are able to convince me to use it in my Cars.
Now I love to drive my car with my Wife and Kids, but only in Petrol. Is the safety of my family that made me to stick to this choice or the ease of the Petrol - ’’Just Fill it Shut it and Forget It’’? I dont know.