CNG in a TDI
110 MPG is the goal. My brother operates an aftermarket installation and general automotive repair shop and in the last few months of oil fueled peril has done numerous CNG conversions in vehicles. I visited his shop during an installation in a V10 F350. It was a mess, with ECU harnesses torn apart and an intake manifold in pieces. However, a few days ago, he informed me that this week he will begin the installation of a CNG system into a Volkswagen TDI. Unfortunately, I didn't ask about the year or model. Today though, I got a look at the vitals of the system. Of course, the most inconvienent part is an approximately 5 gallon CNG tank to be mounted in the trunk. The tank was not at the shop at the time, so I do not know the exact dimensions. From there, the CNG will run to the front of the car to a pressure regulator. The regulator has a CNG input and output, as well as an input and output for engine coolant circulation. Apparently, as I was explained, CNG isn't too different from diesel in that it must reach a specified temperature to be combustible, which the engine coolant facilitates. From there, unlike a CNG system in a gasoline based engine with an injector for each cylinder, the CNG goes to a singular injector. The injector is a circular ring with a 4-5 inch outer diameter, and an inner diameter approximately 1-1.5 inch smaller. Inside the ring is an injection "slit" that is open around the entire circumference of the inner portion of the ring, as well as having a helical design on the interior to swirl the incoming air. It is installed in the intake between the IC and manifold. I don't know the exact details of the precise location or fitment, but I would imagine just before the EGR. The injector is signaled by the fuel injection electrical so that with every pulse of a diesel injector, CNG is also injected into the intake manifold. There is a digital "gauge" which consists of four lights to indicate CNG tank level and includes the CNG On/Off button that mounts in the dash a la rear defroster/heated seats style. I hope to be able to document the process of installation. The owner of the car is also allowing my brother to keep the car for approximately 1-2 weeks after installation to serve as an extended driveability road test. The expectations are fuel mileage in three digits as well as a noticeable performance increase. I don't know how much I'll be able to be involved in the process, with school as well as SEMA going on this week, but I'm hoping that I can at least give a rudimentary description and summary of the results. Even if the results only partially fulfill the expectations we have, it will do nothing but further illustrate the versatility and amazing design of the little diesels we love.