At the rate we are raising prices of petrol and diesel, every day more people considering converting their petrol engines using CNG fuel (Gas Compressed Natural) or LPG (Liquefied Petroleum Gas). CNG and LPG are fuels used in various parts of the world for over 60 years. Today there are thousands and thousands of cars converted from petrol to CNG or LPG in the U.S., Canada, Italy, Russia, Argentina, Venezuela, India, and other countries.

The conversion is easy, but the concerns rose by users and mechanics outdated scary when making the decision. Many believe that:
• The gas forms deposits in the combustion chamber and exhaust.
• The dry gas pistons.
• The gas causes more engine wear.
• The use of gas allows the use of inexpensive oil.
• Once converted to gas, the engine has to be repaired more often.
• Gas weakens.

While it is true that there is little loss of strength, this loss is similar to loss of strength to operate the air conditioning or opening a window at 80 miles per hours on the road. All these myths are completely false. Then we will see which the root cause is of and how to avoid these problems. From the outset, we must understand that an engine should never be spoiled converted to gas. If the engine has no compression, if it lacks the thermostat, if the water radiator is without Coolant / Anti-Corrosive, or if the fan is not working well, not be improved with the conversion to gas. There are many taxi drivers arriving to workshops for conversion, and refuse to install thermostats, changing spark plugs or make repairs that it requires the vehicle. You cannot expect good results in poor engine. If the mechanic recommends no repair parts in disrepair, change of spark plugs, Installation of thermostat or other component that is in poor condition, is a mechanic who does not aware and the conversion will not be satisfactory. The burning of gas is more complete, occurs at higher temperatures, and for being cleaner than burning petrol, oil does not stain as much as petrol does, or contaminate the atmosphere by exhaust gases. But this cleaning depends greatly on the temperature of the combustion. When the engine is running too cold, white or yellow deposits form in the cylinders, pistons, valves and exhaust. Every day cars to gas gathering with the exhaust yellow. These deposits are oil nitration. This indicates operating an engine without a thermostat or cheap oil to form deposits and shortening engine life and oil. If we operate the engine with the correct thermostat, the fan correct, the refrigerant cool, we can maintain the temperature in the range correct for that engine, and we can walk 10 to 15 years without touch the motor. Note: An exhaust pipe is yellow a symptom of cold combustion, improper mixture of air and gas oil, poor quality, inadequate spark, or a combination of these problems. Maintenance proactive dictates that we must correct the problem or oil temperature before allowing the accumulation of deposits in the combustion chamber.

A good system will have a heating gas circuit through the water hot radiator to maintain the pressures and temperatures required for a good combustion and better economy. If there is no thermostat, hot water will not gas heating system, reducing power, efficiency and economy of the conversion.

The course actually respected engine deposits are formed by the nitration and carbonaceous deposits lack of "normal" in the eyes of the mechanic. The mechanics are used to seeing wet deposits formed by gas-saturated coal. At the gas is not liquid at temperatures temperature, does not wet the few deposits forming or existed. The only deposits should see are the residues of organo-metallic additives used in the oil. These deposits are oil is minimized when the last generation and not wear engine cause burning of the oil. Among the thousands of cars converted to gas the world, there is no evidence more frequent corrections in engines converted to gas than petrol engines. Actually wear, all else being equal, is lower so that there is no possibility of dilution of the fuel oil or petrol leaks settled by spark plugs not work.
OIL
After the temperature of the engine, the most important factor in the performance and service life the motor is converted to gas oil. To this we must combat the myth that the gas demand for both oil and oils can be used below. In fact, many cheap oils on the market that indicate on the label are for gas engines: They are API Group I base oil, high in compounds aromatic, have few additives and low rating API. These oils have a very short life, many engine deposits by nitration and increased viscosity caused by oxidation by nitration. The increased viscosity causes an increased wear and increased consumption of fuel.
The primary difference between motor oil natural gas and other oils of internal combustion engines is the need to withstand various levels of oil degradation caused by the process of combustion gas which results in the accumulation of nitrogen oxides. This condition, called commonly nitration should be checked regularly if both lubricant and life motor want to be maintained. Then we analyze the characteristics necessary for oil. We can say that oil has two elements. Base oil and additive package. The life and resistance to oxidation and nitration are mainly dependent on the quality of base oil.

A cheap oil is API Group I, typically contains between 68% and 77% of molecules saturated, leaving between 23% and 32% aromatic compounds to decompose. It is these molecules reacting with combustion residues, evaporate, form acids, oxidized and leave deposits on the engine. Oils a little more expensive to use the same base oil or sometimes up to 85% saturated molecules, but fighting and nitration oxidation with more additives. In simple terms, is the addition of this quantity of oil additive which raises the level of protection API SL.? API SL oil can resist oxidation and nitration much longer than an oil that meets only the specifications API SF, SG, SH or SJ. Have oil analysis Taxi in Santa Cruz that travel 8.000 kilometers in the city oil change and oil using a good Group I API SL classification and shows no problem nitration and oxidation in this period.

The lubricant industry continues to evolve. Today there are oils in the base oil market API Group II base synthesized, traditional synthetic, and mixtures thereof. These oils ensure a longer life without nitration and oxidation. The key elements for efficient engine operation converted to gas. We summarize the critical elements for successful engine conversion from petrol to CNG or LPG.

1. Ensure that the engine is in good condition before converting. This includes proper operation of the thermostat, the cooling system, the quality of spark reaching cylinder compression, the sludge in the crankcase and the valve cover, and deposits coal. Never enter a new variable to solve problems known.

2. Choose a workshop with qualified personnel and specialized equipment needed to ensure the installation and performance. Conversion is an investment in the future, playing with his long-term economy and the future maintenance of the car. The best systems for cars to tear the engine automatically injected in the cold with petrol to keep parts wet rubber and turn quickly without increased wear of the battery. Flights or system depend carburetors user to do this. Calibration of the system will determine success. This is not possible without sophisticated electronic equipment. The conversion will cost a lot to craft throughout.

3. Ensure that the conversion does not endanger the passengers. Facilities should be noted that the vehicle is traveling on paved streets, the tiles, potholes and gravel roads or dirt. Will always vibrations, sudden braking, etc.

4. Observe the safety regulations of your country or locality. For reasons of quality LPG underground facilities and hazards in Bolivia is not recommended conversion to LPG.

5. Once installed the system, consider the variable elements affecting the shelf life and maintenance costs.

A. the right mix is important.
i. If the mixture is very poor (very little gas and air), temperature motor is lower, the reduced strength and increase nitration, causing deposits, short intervals between oil changes and creating sludge in the engine.
ii. If mixture is too rich (too much gas and little air), temperature increase and power increase, but can cause several fronts combustion in the cylinders, causing detonation. The detonation can cause serious damage to the cylinder head, pistons, valve seats and times until the piston skirt and torch. Like any adaptation, the mixture must be adjusted according to the results to reach the optimum for each type of engine. This will determined by measuring the exhaust gas with electronic equipment. Once determined, we must write it down for the future.

B. The engine temperature must be between 82 degree Celsius and 93 degree Celsius as a rule. Each brand has its engine design. As an example we note studies made in large CAT engines which showed twice the nitration 86 degree Celsius thermostats to 88 degree Celsius. CAT recommended operating temperature between 88 degree Celsius and 93 degree Celsius, while Waukesha recommends a temperature between 82 degree Celsius and 85 degree Celsius. It should keep the thermostat factory, unless having long nitration before the mixture at the point optimal.

C. Oil quality determines the operating economy. An oil art, API SL, formulated with synthesized base oil, synthetic, or Group II will give a good interval between oil changes without problems nitration. In addition to resist oxidation and nitration, the best of these oils maintained until 45% greater film thickness in areas of high pressure in the engine (cam, rings, and bearings) than traditional oils.

D. The viscosity of the oil will determine the ease of starting, wear motor and the battery life. Never use oil SAE 40 ("Special 40") converted to gas engines. Follow the recommendations of the factory self, indicating SAE 5W-30, SAE 10W-30, SAE 15W-40 or SAE 20W-50, depending on the model. Today will never find a recommendation SAE 40 for a manufacturer or an engineer updated. If the mechanic recommends SAE 40 oil, find another mechanic.

E. Eliminate pollution insisting that they do not clean your air filter with air compressed. Blowing air filter opens the pores and sheets of paper allow the entry of dust. The sand becomes dust passing through the engine. Noting these points, you can turn your car or truck from petrol to gas, economize on fuel, reduce exhaust emissions to air and reduce costs maintenance. Finally, when the engine is over, will be for the type of service or maintenance, not fuel.

Copied from indiagarage forum, posted by bacardi in Aug 2011.