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CNG Should be a good answer but is it?

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  • CNG Should be a good answer but is it?

    I am new to this board but having been in the automotive industry for the last 30 years and have been tearing apart and putting back together cars for 45 years I have a few questions?
    1) How long has CNG conversions been around?
    2) Besides the high pressure tanks how is the CNG system different from a propane system on carbureted cars?
    3) I am ASE certified in all aspects of auto repair, can I install a CNG kit on my own car?
    4) If I install a uncertified kit on my own car and the emissions are the same or lower than they were with gas is there a problem?
    5) How does a person get certified to install CNG systems?
    Thanks, An old mechanic, Jim
    Jim Younkin

  • #2
    Re: CNG Should be a good answer but is it?

    1) The first car was converted to run on cng in 1913.
    2) Tank, High pressure lines and fittings, pressure regulators, fuel filters, computers, injectors. Nothing is common with LPG. They are 2 completely different fuels,ir gas vrs liquid, 3600 psi vrs 300 psi, rubber lines vrs steel, you get the idea.
    3) As an ASE certified mechanic, can you work on an airplane engine? Sure, you have the tools but lack task specific certification. ASE offers cng training as well. Just go back to school, but that won't get you into the conversion business. Suppliers for EPA and CARB approved kits (depending on where you are) is the next hurdle.
    4) An uncertified kit will make your car unsmoggable, if not unsafe.
    5) Anyone here care to answer this one? It's out of my depth. As many times as it's been asked here... I can't say I've ever seen an answer.


    • #3
      Re: CNG Should be a good answer but is it?

      2- Propane and lng are liquids at low pressures (approx 100 psi). Cng/hydrogen are compressed gasses at 3000+psi that require special tanks for fuel storage. compressed gasses need to regulate pressures down to the 15psi range, often in two stages. It is possible to convert liquids to gasses with special converters that need to heat the liquids to change to gas.

      3- No

      4- hydrocarbon emissions will be significantly lower since ngas is completely vaporized and is clean burning, nox might be higher if you do not have a catylitic converter installed (nox is related to heat of combustion).

      5- You have to attend and be accepted to classes only offered by the individual kit manufacturers- they probably require cng business roots (with financial proof). It is obviously a scam set up to limit the marketplace.


      • #4
        Re: CNG Should be a good answer but is it?

        CNG install training


        • #5
          Re: CNG Should be a good answer but is it?

          Thanks, I totally forgot about Rio Hondo. They have advised me that they will be at my Expo but I haven't had an application back from them yet.


          • #6
            Re: CNG Should be a good answer but is it?

            my 2 cents worth...

            I think you can work on your own car depending upon where you live. but when you start working on other peoples cars for money then your insurance company will get a little nervous.

            LNG , LPG and CNG are three different ways of doing something similar. LNG and LPG are liquid, only LNG is at -260 F at 50 or 60 PSI and LPG gas is liquid at room temperature at 100 psi or so. They both need to go through a vaporizer. But because they are different gases the vaporizers will be different. The pressure the engine will run on will be different. The air mixture will be different. Timing I suspect will be different.

            CNG starts out at 3600 PSI but will go down as the tank empties. This pressure is regulated down to a pressure the engine can use. I suspect that LNG and CNG use a similar pressure at the engine intake. Unless you get to liquid fuel injection which is a different animal. Just as in propane you can inject liquid gas(diesel engines) right into the cylinder.

            They add helper computer modules to adjust the timing for the different fuels.

            How does one learn about a program on a computer chip. You have to be in with the maker of the chip. or buy their troubleshooting tools.
            The reason you have stainless steel lines is because you can not find a rubber line that is rated for 5000 pis or -260 F

            Uncertified kits:

            If they are not certified then you may not get the full emissions benefit. They have been converting all kinds of engine for years to run on Natural gas. Mostly stationary engines such as emergency generators for large freezers. they are hooked right up to the natural gas utility. They were not certified and were not dangerous but the emissions were not optimal and so you will not get the tax breaks if you use them on cars.
            I would start out by learning about the different gases. Check about local classes having to do with high pressure systems.

            like in anything there will be got-ya's. such as in a LNG system if you leave liquid gas trapped in a line it will vaporize over time from 50 psi into 3000 psi or more. There will safety devices which you will need to use and understand the function of.


            • #7
              Re: CNG Should be a good answer but is it?

              Hi all, today I talked to a tech at the Utah County Air Quality Department to find out about smogging CNG converted cars and installing CNG kits? He stated that as long as the car was pre OBD II (96 and older) and the car had the origional smog equipment on it and passed the emission standards for that year it could be smog certified. On the OBD II and newer the kit would have to be able to communicate with the cars OBD II computer to set the readyness codes. I was told that I could install my own kit and that it didn't necessarily need to be certified. Jim
              Jim Younkin


              • #8
                Re: CNG Should be a good answer but is it?

                Do you remember who you talked to? I have a few questions i'd like to ask them. If you could send me a PM with at least the phone number i'd appriciate it!
                You can do anything except light a paper match, on a marshmellow, underwater!

                R.I.P. Taylor and Chris


                • #9
                  Re: CNG Should be a good answer but is it?

                  His name is Jeff, he is one of the tech's there, Jim
                  My Cell: 801 427 2284 call me anytime
                  Last edited by younkin; 05-07-2008, 05:32 PM.
                  Jim Younkin


                  • #10
                    Re: CNG Should be a good answer but is it?

                    Cerritos College is a public comprehensive community college located in Norwalk, California, offering degrees and certificates in 87 areas of study in nine divisions.

                    here is a class in california. notice it is a two day class and covers propane and natural gas.

                    Also try these guys. They will have OEM guys they work with that put the kits together. However, their distributors will have training available to them that perhaps they may sell? Maybe if enough guys get together a community college somewhere would put a class together.

                    notice that in their down loadable catalog they tell you to follow the NFPA standards and local/federal laws. Other then that you should be a lot farther along then most in learning how to convert these cars.