Converting cars from gasoline to propane

gasoline

#1

In the late 70’s to the early 80’s, it seemed the rage to buy kits and convert cars from gas to propane. Even our local county government converted some of their small trucks. Why are we hearing about this today?


#2

My own county had some of these. Propane fuel is well suited to vehicles that remain in the local area at all times and always end up in the maintenance area each night, where there are refueling facilities. Propane cars are not well suited for the family sedan that often ends up a long way from home in need of more propane. The dismal refueling situation is the main reason these things never caught on.


#3

Steve,
If the car that’s to be converted is used only for around town stuff, does the economics work for the conversion to be made? We’ve got a 2002 Beetle that we use for trips and such.
Rich


#4

Why do you want to??

You’ll get MUCH WORSE gas mileage and MUCH WORSE performance. You will however pollute less. And you can extend your oil changes to about 20k miles.


#5

My bad! We won’t br converting the Beetle, but my work car, 1998 5.4l Expedition, which gets about 13-14 around town. Why would the mileage be worse?
Rich


#6

Because the PE (Potential Energy) in Propane is about 1/3 LESS then gasoline.


#7

I think the kits have become scare due to the rigorous and expensive EPA certification process.


#8

Certainly fuel mileage is important, but it is the total cost of the conversion, including future fuel costs, that need to be evaluated. Despite the lower energy output, the cost of propane comapred to gasoline may make it worthwhile.


#9

The kits you are referring to are for carbureted engines. They were common on fleet vehicles and permitted dual fuel operation; a switch on the dash allowed you to switch between propane and gasoline. There are a few companies that sell propane conversion kits for EFI systems, but they require a second ECU to run them and they are really not worth it.

As already stated you fuel economy and power will decrease due to 25% lower energy content:
Propane: 91,500 BTU/gal
Gasoline: 125,00 BTU/gal
Diesel: 139,200 BTU/gal

You can recover some, if not all of the lost power and mileage if you increase the compression ratio of the engine. Propane can run at significantly higher compression ratios than gasoline.


#10

Certainly fuel mileage is important, but it is the total cost of the conversion, including future fuel costs, that need to be evaluated. Despite the lower energy output, the cost of propane comapred to gasoline may make it worthwhile.

It may…But you also have to take into account the decreased engine performance. On some vehicles it will make it undrivable. When bus companies switched over to Propane years ago they had to convert some of their buses back to gas or diesel ecause some routes were very hilly and with a fully loaded bus they couldn’t make some of the hills. They ended up buying new buses that were designed to run on Propane/Natural-Gas and these buses had bigger engines and about the same torque as the older buses that ran on gas.


#11

I think the kits have become scare due to the rigorous and expensive EPA certification process.

From my understanding it’s actually pretty simple…Especially since Propane runs about as clean as you can get from a internal combustion engine. You can pull off ALL the Emissions if you can tune the computer to compensate for it.


#12

“If the car that’s to be converted is used only for around town stuff, does the economics work for the conversion to be made?”

I really don’t know, especially in these times when the current and future price of petroleum products is so unpredictable. You can do your own estimates of course.

My advice? Don’t fix what isn’t broken. Your Expedition is intended to run only on gasoline. Keep it that way. Taking a plunge into the unknown only invites trouble. Or get rid of the gas hog now and investigate a replacement vehicle that is intended for use with alternate fuels, maybe biodiesel or whatever they are comimg up with. Good luck.


#13

The kit may be simple, but getting it certified for sale isn’t. That was the point I was trying to make.


#14

If loss of power is not an issue, the savings will likely pay for the conversion. Where I live propane is available in the immediatre area, but making a long trip in a propane powered car is very risky; you may get stranded.

I would also warn against those 20,000 mile oil change interbvals. Oil in gas engines will nitride, but remain clear (look good), but lose some of its lubricating qualities. So I would go the normal long interval for gasoline engines, i.e. 8000 miles for primarily highway and 5000 for primarily city driving. EXXON Mobil had a special oil for gas powered vehicles, but has discontinued it. By all means, do not use oil for stationary industrial gas engines; it has very few of the additives required for cyclical stop & go automitive use. All in all your engine will last a long time with propane.


#15

If loss of power is not an issue

Why do you say that?? I’ve owned a few cars where if you reduced power by 25% it would undrivable. You’d be risking your life taking the vehicle on the highway…not to mention trying to get up a hill with your kids in the car…Sorry…but it IS an issue.

I would also warn against those 20,000 mile oil change interbvals.

In upstate NY the power company Niagara Mohawk has a lot of vehicles running on natural gas. Their oil changes on their trucks is between 20k and 40k miles. Most of oil’s problem is contamination, which you get very very little of running on Propane or NG.


#16

Sale after the fact may be a problem. Not sure how that will work.


#17

Increase the compression ratio or add a blower. A custom tune to increase the spark advance would help too. I saw a used LPG or CNG Crown Victoria on eBay last week. If you can find the you want vehicle for sale used, it will probably be more cost-effective than conversion. I have seen CNG home-refueling stations for sale on eBay

CNG and LPF used to be good enough to get your single-passenger vehicle into HOV lanes. I am not sure that is true any more.

Is it worth it? I have seen figures that indicate that it is. There is lots of info on the web including some sites dedicated to conversions. Check around.


#18

I’d like to ask a question about converting to alternative fuel. Could the propane conversion kit be used to set a car up to use HHO (Hydrogen+Oxygen)?

Thanks,
30Ford


#19

Maybe and probably not without modifications. Issues include, pressure of stored gas/liquid (If existing propane is higher pressure you waste weight on a tank that is too strong for your needs. If pressure of H2 is higher, you need a different tank.). Pressure regulation of the fuel gas will be an issue. The air/fuel ratio needed may be far enough from the propane mix to require extensive mods. These are just some issues off the top on my head.