Monday, October 21, 2013

Dual-Fuel Converted Vehicles that run on CNG






  This is my BOV
2007 Ford Expedition 3" suspension lift 35" tires.
Converted to natural gas. So it's dual fuel system now.
I fill it up at my house. It cost me around $0.6/ l on natural gas. Regular gas is $1.27 today. 
V-


Nice! I used to have a dual fuel car as well when I lived in Argentina. Very cheap to run, and gasoline prices in Argentina are just impossible for middle class, let alone poor population. Most cars in Argentina run on CNG, over 75% of the vehicles on the streets. It’s safe too when done properly and keeping up with maintenance. 

Dual fuel vehicles have the advantage or having more fuel with both tanks full, it saves money and soon pays for itself, and you have the flexibility of using either fuel, so if there are gas shortages you can just as well keep running on NG. A truck like yours is ideal because a common problem with CNG in smaller vehicles like the one I had is that it ruins the suspension system due to the extra weight of the tank and it leaves you almost no space in the trunk, so a truck is the best vehicle for CNG conversion.
Warning though!

NG dries up the engine a lot. Dont try to save too much money and put some normal gasoline through it once a week, maybe just 10 minutes but do run it some on gasoline to avoid serious and expensive problems on the long run.
A common problem with injection engines is that since NG goes through injector sprays easier than gasoline they eventually get clogged or restricted by a buildup of fuel varnish deposits. Its like a wax or paraffin deposit that eventually restricts the injector entirely so one day you find that maybe one cylinder isnt working at all, or working poorly.
To avoid this put some injector cleaner in your gasoline and as I said before, run it for 10 minutes once a week or so, which also lubricates the otherwise dry engine.
Take care!

FerFAL

10 comments:

Anonymous said...

So...which of the conversion kits do you recommend? Do you have one brand or another that you have had a good experience with?

Thanks again for the GREAT site, Ferfal! Your info is always top-notch. :-)

The Old Coach said...

I must remind the assembled multitude that any CNG tank is a very energetic explosion waiting to happen. Even the tiniest leak would fill a garage with an explosive mix which, if ignited, will spread that garage over a city block. If I still lived in suburbia and my neighbor bought one of those things, I would move away very, very quickly.

Anonymous said...

Old Coach:- Article to back you up on that? Happen a lot?
Australia has millions of LPG and CNG cars. I think most taxis run on LPG(they got a subsidy for conversion and cheaper fuel rates). And, of course, taxis are the safest cars on the road (wink wink). The fear that compressed gasses for fuel are more dangerous than liquid fuel is unfounded. Decades of experience shows that, in fact, a leaking petrol tank is more dangerous than a leaking compressed gas tank.

Anonymous said...

Old Coach -

Your concern is valid; but I must ask: What about propane tanks? In my neck of the woods, peeps will buy REALLY BIG propane tanks and a truck will arrive to fill it. This is common for heating; and the tanks are located outside. Do these kinds of tanks worry you? Maybe I am just ignorant, but how do HUGE propane tanks differ from car-sized CNG tanks? If I park my car outside, would that make it OK? NOT trying to pick on you or start a flame war, just wanted more info from you.

Thanks!

TampaMark said...

Re: Old Coach...

I have never heard nor read of a CNG explosion in residential or rural CNG vehicle let alone a converted one. Is there any statistical evidence that CNG is more dangerous than gasoline? You would think insurers have this figured out long ago.

Do you know of what it takes to convert a gas vehicle in US? Since zoning and safety laws are more stringent in US and CAN such conversions have a greater chance of regulation.

Is there anyone who can answer the above questions?

TampaMark said...

Re: Old Coach...

I have never heard nor read of a CNG explosion in residential or rural CNG vehicle let alone a converted one. Is there any statistical evidence that CNG is more dangerous than gasoline? You would think insurers have this figured out long ago.

Do you know of what it takes to convert a gas vehicle in US? Since zoning and safety laws are more stringent in US and CAN such conversions have a greater chance of regulation.

Is there anyone who can answer the above questions?

Anonymous said...

Coach,
True if an explosion occurs ........but the possibilities are incredibly remote. The vapor concentration has to be within the lower and upper explosive limits and the temp has to be okay, etc.
Gasoline vapors are as dangerous if not more.

Steve said...

very practical advice, old coach on the other hand, maybe he is thinking about whale oil.

The Old Coach said...

Well, just last month in Toledo a house exploded from a gas leak. Nothing left but the foundation. Shreds of the structure over a 600 yard area, according to the newspaper. Two people dead. And that's a stationary installation. In the USA it seems I see a report like this every 3-4 months.

Mobile installations suffer vibration, and are refueled frequently. Every refueling is an opportunity for malfunction of mismanagement of the fueling valves.

On that subject, a little story: A little story about propane. In the dead of winter some time ago my landlord came to me asking me to look at the propane tank at another rental property he had. (He knew I was an engineer.) The tank in question had a huge flower of sulphur surrounding the filler port. The guy who last filled it failed to see that the port had closed properly. The tank was nearly empty by the time it was noticed. It was, fortunately, downwind of the house during the time that it was leaking!

The CNG tanks are at such high pressure that a very substantial regulator is required to reduce the pressure to a manageable level for metering into the engine. Ever have a welding oxygen regulator perforate a diaphragm? I have. You wouldn't want to be there if it were a fuel gas.

Propane worries me less because it's liquid at relatively modest pressure. CNG tanks are are what pressure again?

When Ann Arbor MI bought NG fueled busses, they had to be designed with the fuel canisters on TOP of the bus, so a collision could not compromise the tanks. (Says something about their trust in Michigan drivers.)

This is getting too long, so I won't go into the difference in mixing rates between propane and NG.

BTW it is not possible to get gasoline vapor to detonate, except under 4-5 atmospheres pressure. If you get it to explode at all, it just goes "whuff" and sets anything nearby on fire. NG will detonate very readily, hence the so-called "fuel-air" bombs used in Desert Storm.

And not for nothing do port cities around the world refuse to have LNG terminals anywhere near them.

The Old Coach said...

I might amplify my last comment by mentioning that I was an automotive engineer, and although that covers a very broad spectrum, I frequently had to perform and manage failure mode analyses regarding safety of factory equipment quite often, so I'm a little more attuned to seeing problems with systems, more so than most engineers.