How Does a CNG Engine Work?

March 15, 2012

CNG conversion kits have become an increasingly popular way to increase fuel economy. Learn how to CNG engine works, and how to find a CNG gas station.

A CNG engine uses compressed natural gas to power the car. CNG is a substitute for gas and diesel fuel, and is considered to be much cheaper and cleaner than gas or diesel. As an efficient and environmentally-friendly alternative to gas powered cars, the CNG engine has become increasingly popular, and many people choose to convert their cars using professional mechanics. It can also be done yourself with a kit.

Why Use Compressed Natural Gas?
As many have noted, compressed natural gas is marginally cheaper than ordinary gasoline or diesel. In addition, the CNG engine is considered to be more environmentally friendly. There are considerably less pollutants associated with compressed natural gas being ignited, and studies show that it gives off 40 percent less greenhouse gas. On the downside, a CNG engine will usually get fewer miles to the full tank than a regular gas engine, and you may also struggle to find a suitable engine and tank conversion kit, which means that the price of converting your vehicle can negate the savings from the cheaper fuel alternatives.

The CNG Engine
The CNG engine uses a second fuel tank which has to be attached to the car, and is usually placed in the trunk (or other place where there is suitable room). This tank is usually very large, as it has to keep the gas used compressed. The amount of pressure may vary from engine to engine, but it is usually compressed to around 3,600 pounds per square inch. The driver can then decide which of the fuels they wish to use by simply pressing a switch on the dashboard. This means that the car can alternate between the different tanks, drawing fuel from either.

How the CNG Engine Powers the Car
Once the driver selects the CNG tank, the compressed gas in the tank is pulled through a series of highly pressurized lines until it reaches the regulator. Inside the regulator, the pressure on the gas is lessened until it matches the amount needed by the fuel injection system of the car's engine. Once the gas has reached an acceptable pressure, the solenoid valve allows the gas to move into the fuel injection system and from there into the engine. Just as with gasoline, once the engine has received the gas, it is ignited in the combustion chamber, and this provides the energy to power the car forward.

Daily Use
The fuel is taken from a pump in exactly the same way as one which uses ordinary gas or diesel fuel. CNG may be harder to find than regular gas. One solution which many owners of a CNG engine use is to build a home gas pump station, which allows their tanks to be filled overnight.

How to Find a CNG Gas Station near You

One of the main challenges with a CNG car is finding a CNG gas station. Currently the only two states that offer CNG cars are New York and California. These states have the majority of the fuel stations. There are about 1,500 stations compared to the 5 million gas stations in the United States, so finding a station can be tricky.

Ask the Dealer
If you are looking to purchase a CNG car, then one of the questions you want to ask the dealer is if they know of any local CNG fueling stations. Naturally, if cars are being sold in the area, then there should be some fueling stations nearby. A dealer should have all of this important information at their disposal and can pass it on to the customer.

Check Natural Gas Producers
Natural gas is used in many homes for central heating. You can contact the natural gas company in your area. If they supply for homes, then they may also supply gas to fueling stations. Many times you can even have a fueling station installed in your own home. This may be the best option if you are having trouble finding a station.

Ask the EPA
All converted cars need to be certified by the EPA, so the EPA will have information about fueling stations and options for fueling. CNG cars are used extensively in government agencies, so while there may not be a public filling station in your area, there may be a privately owned station you may be able to have access to. The EPA has all of this information, or if not, they will know who you can contact.

Consult the Car Manufacturer
The manufacturer of the CNG vehicle will be able to provide information on fueling stations. This is why Honda is only releasing the CNG car in New York and California. These states have the infrastructure and plenty of fueling stations available.

Ask a CNG Car Specialist
There are mechanics that specialize in these types of car conversions and will have plenty of information about where to get repairs and fueling. These professionals can provide you with advice on if a CNG car is a good choice for where you live and what the cost is compared to other vehicles.

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