Natural Gas - is this the best alternative - Vivic GX


Civic has its 2008 on Natural gas

Cost $13 for a full tank - gives about 24-36 mpg

Would this be the best alternative for now?


Can you find a place to refuel? If it is just a commuter car, that might be OK, but natural gas refueling stations are not common. Also, is the GX a bifuel car? Here’s a site to help you decide:


I don’t know why you don’t hear more about propane and natural gas cars these days. They’re both fuels with very low emissions and an abundant domestic supply which make far more economic sense than ethanol or bio-diesel. Perhaps some of the other posters can explain.

The price of motor-fuel natural gas varies a lot from place to place, though, since different jurisdictions tax it differently. $13 for a tank of it is probably closer to the bulk price of the natural gas-- by the time it gets to a vehicle dispenser and gets the highway tax put on it, it’s usually something like 75 cents to a dollar cheaper than regular unleaded. Also, I don’t know what a regular 08 Civic gets, but the natural gas mileage is usually low enough that there’s only a marginal advantage over regular gasoline.


I’m currently in the process of converting an old pickup to propane.
GreasyJack is right that the lower price really doesn’t make much difference. Propane prices are going up right along with gasoline. Although it’s still abt. fifty to 75 cents cheaper in my area, the worse fuel mileage with propane is going to eat some of my savings.

So, Why am I doing it then? Three major reasons:

  1. cleaner burning fuel means longer engine life.

  2. So I can shove it in the face of all those dendrophiliac hippies who preach Al Gore’s hypocritical tripe.

  3. Because I can.

Really my main concern is to get off the fossil fuel bandwagon. Not necessarily for global warming (though that is a perk), but because I don’t think something as important as our nation’s energy should be outsourced. And while I realize propane/CNG is a byproduct of the oil industry, it’s at least a step towards the right direction, and it’s the only change my poverty stricken butt can afford.


Define BEST alternative. As far as I am concerned, best would have to be best for the specific owner and society in general. Since NG seldom includes road tax, you would need to start by adding that, then you would need to price your fuel cost at cost per mile. Cost per tank is almost meaningless. You also would need to consider safety and convenience (availability) and supply questions. Last practicality, like does the system reduce useful space in the car.


Natural Gas and Propane both have MUCH LESS POTENTIAL ENERGY then gas. You’ll see a significant drop in hp when converting over to propane or NG.

Couple nice things about running on gas…you can drastically increase your oil change intervals. It runs so clean that the oil doesn’t get contaminated as easily. The power company in upstate NY (Niagara Mohawk) uses NG in many of their fleet vehicles. They increased the oil change interval to 20k miles…And the oil is still very very clean when they drain it.


Natural Gas or Propane, which fuel are you talking about? They are NOT the same. Natural gas can not be liquefied so It’s energy density is low. You must fill up often and deal with high=pressure storage tanks. Converting to propane means using a crude carburetor and disabling the much better fuel injection system you have paid for. With either fuel, both power and mileage will take a big hit. There is no free lunch in the energy business.


I had actually considered doing a conversion a while back and spent some time looking around for a kit or something like that since I wouldn’t be able to figure it out myself from scratch. Are you doing your pickup with a kit? If so, where did you get it?

And you might not like Al Gore or the hippes - but they aren’t wrong.


The conversion kits I’ve seen are for both. The kit will work with either NG or Propane.


Natural gas can be liguified. Ever heard of LNG tankers?


OK, I’ll add my two cents. I have a couple of friends who have natural gas wells in there yards (well, on their farms) and the gas company running them gives them free gas, seriously there are not even meters at there homes. Now I’m sure that would change if they started running all of their vehicles on natural gas, but they figured they could get away with one if they were descrete about it.

Also I would like to note that I have spent time in India where NG vehicles are fairly common. I have seen two vehicles explode from the heat that built up in the cars. OK, let me explain this a little more. The tanks were kept basically in the back of the station wagon-like cars with the sun beating on them, also it was about 90F in the shade. The cars did not explode into flames but rather “popped” from the pressure. The first time it happened I was getting of the plane at the airport and they shut everything down and detained everyone near the airport for a couple of hours, I guess thinking that it might have been a bomb.

Now I’m pretty sure that those kind of bugs would be worked out in the States before they were put on the market, and that people cheating the gas company would not fly to well, but those are my only experiences with NG vehicles.


Here are how the energy contents line up:

Diesel: 138,000 BTU/gal

Gasoline: 125,000 BTU/gal

Propane: 91,000 BTU/gal

Liquefied Natural Gas: 90,000 BTU/gal


The explosions you refer to are from improper installation. The tanks are supposed to have a pressure relief valve to protect the tanks from rupture.

The most also be mounted external to the passenger compartment.


It’s actually Compressed Natural gas.


It’s really not all that difficult-- even for an “admitted amateur” I’m sure. The most important aspect to consider is the type of engine you’re dealing with from the get-go. i.e. is it carbureted or fuel injected? From what I understand, EFI vehicles are a bit more difficult and more expensive to convert, because the computer has been programmed to run gasoline, not propane.

I haven’t looked much into “kits” for conversions, because from what I’ve seen online, they’re pretty expensive! If you’ve got an old carb’ed vehicle like me, all you really need (other than the certified tank) are three main components- and they’re not that expensive if you look around.

The main components you’ll need:

a mixer, a vaporizer, and a lock-off. Plus you’ll need some “aircraft quality” high pressure hose and a hydrostatic relief valve(I have yet to obtain those… damn tuition payments).

Personally, for my old chevy V8 pickup, I got these:
Impco (brand) 425 mixer
Impco Model E vaporizer
Impco electronic lock-off

^^those models are supposed to work on pretty much any carbureted V8 up to approx. 300 hp.

Outside of those, the most important thing is to be sure the tank is solidly secured in a safe place. Not a big deal for a pickup- as you can put it in the bed behind the cab, but if you’re wanting to convert a car and place the tanks in the trunk or something, then you have to take other steps to meet safety and EPA standards. Stuff like cutting vent holes in the trunk floor and reinforcing the forward facing trunk wall (behind the back seats). Don’t quote me exactly on that stuff though, since I’m using a pickup I haven’t looked too deeply into those standards for cars.

Here’s a link to a pretty good write up a rock-crawler did on his conversion:

Of course once everything’s in place and ready to go, you’ll want to do some fine-tuning. Perhaps advancing the timing and so on…

…and I love the planet just as much as everybody else, but don’t get me started on Al Gore… ;p


It is impractical to liquefy methane for a car. The pressure required is too high to be safe; the cannister would be extremely heavy. Or, if you prefer to cool it, that would take way too much energy.


Thanks for all of that! You haven’t started your own website to document your conversion have you? Could be fun.

(No need to get started on AG - I’m not so wild about him either - we can likely just agree to like the planet and not so much Al).


Some of the potential loss in the potential energy department can be recovered in increased efficiency if the engine is really designed for the fuel. Since both nat gas and propane have much higher knock resistance than even premium gasoline, you can have much higher cylinder pressures. That means higher compression ratio or forced induction to a high degree. Of course, if you are modifying an existing gasoline vehicle, you would have to beef up the pistons, rods and lower end at minimum. Then would the head gasket take the pressure. How about the cooling system?


That’s actually what many bus companies did. First they converted their buses to run on NG or propane. Then the bus manufacturer companies started to design the engines to run on Propane or NG. Much better performance…