There are two approaches that are available for conversion of a diesel engine to CNG. The cheapest and simplest method is to merely inject CNG into the air intake before the turbocharger as a supplement to the diesel fuel that the engine is using. The reasoning behind this method is that the diesel ignition will burn the natural gas also, and therefore produce more power and need less diesel fuel. This of course is not a true conversion, and it still needs to burn diesel fuel to run.
The other method is a true conversion. It requires cylinder head modification to add spark plugs, addition of an ignition system, piston replacement to lower compression ratio, a delivery system for the natural gas, and installation of a throttle body. This method does not allow for continued use of diesel fuel, but the installation will allow for the addition of a gasoline delivery system so that the engine can run on CNG or gasoline. This conversion will usually not produce as much torque as the diesel version of the engine did. So with a price range for the conversion of $15,000 to $25,000, it is rarely practical for an RVer, especially if you consider the availability of CNG on the road and the shorter range that you will receive on a fuel fill.
Gerald
