CNG Conversion?

First, I am not an expert in CNG conversions, but here are some points to consider.

CNG is a gas at normal temp and pressure, so it's fairly easy to convert a carbureted, non-fuel-injected gasoline engine - just let the engine breath the right mixture of gas and air and it runs just fine. The throttle opens the gas valve at the carburetor.

Fuel-injected engines could probably be retrofitted to inject gas instead of gasoline, but I think it would involve replacing all of the injectors with a different kind of gas valve, as well as the fuel lines since CNG is higher pressure.

Also, since CNG has less energy than gasoline, all the computers that control fuel, engine timing, spark, etc., would have to be reprogrammed. Possible, but not easy.

 

Now there are so many ads on TV touting all the CNG available right here in the US and how we can quit transfering wealth to the Middle East I'm all for it!

Sounds like it's been perfected and a kit is ONLY $5,000 and extends your miles to fill up to about 800 miles if using both CNG and gasoline up.

Green Car Congress: Bi-fuel Prius II CNG on Display in Geneva

Way better than pushing food costs up, spending more on tractor diesel and machinery to farm corn for "Yellow" fuel.

Maybe we can get a Priuschat discount, you in?

 

In the UK it's called LPG (liquid petroleum gas) The Greenfuel Company - About LPG - LPG - The Established Alternative Fuel

A work colleague has her SUV converted.. it starts on regular petrol and then switches to LPG automatically a minute or so later. It has a manual bypass for petrol only mode.

She gets around 250 mile per tank of LPG (don't know the qty of LPG), I know the MPG figures are worse for LPG but it's half the price of petrol here in UK I think.

It's a dual fuel system... it still needs petrol to start. It just won't startup on LPG alone.

Maybe the high starting speed (1,000 rpm) of the Prius ICE would overcome this.

I found this article about a successful Prius LPG conversion I Love My Prius - Forums > Modifications > View Topic > LPG conversion

 

CNG & propane are not the same thing. Do a Google search. I did a LPG conversion some 20 years ago on our '76 Ford Econoline. Very simple to do back then. But it's a little more complex to do CNG. And as stated above, runninh CNG through a modern car's EFI? Forget about it. Too complex with newwer car's multiple ECU's.

 

Nice thread V8Cobrakid!

Wildkow

 

One of the big problems with CNG is that it is stored as high pressure compressed gas. Put another way, that means that CNG fuel tanks are really large SCUBA tanks. They weigh a lot, take up a lot of space, and are under a tremendous amount of pressure.

None of this makes it impossible to use CNG, it just makes it less convenient. CNG refilling is also more complex since it is done at high pressure. You can't simply pour it into a tank. The good news is that the filling technology exists and is deployed at many locations around the country.

We looked at CNG as a cooking fuel for our boat. CNG is attractive as a marine cooking fuel because it works with normal gas stoves and is lighter than air. The lighter than air characteristic is important when your kitchen is down inside of a hole. Any leaking gas can float safely away. The main problems with CNG are the size and weight of the tanks and the lack of refilling stations.

Propane is a popular marine stove fuel. It's easy to get and stores easily in small propane tanks. The main disadvantage is that propane gas is heavier than air. When you have a propane leak, it sinks into the bilge of your boat, waiting for just the right mixtaure before blowing you boat into little pieces.

We ended up using alcohol. It has lower specific heat and flame temperature, and a higher cost, but is simple and safe to use. Vaporized alcohol is lighter than air, and alcohol fires can be extinguished with water. Everything has its trade offs.

Tom

 

cng kits fool the computer into thinking its working with gasoline. but really its simular to a lp system. with a valve purging cng into the air stream. remember cng is a gas commpressed to 3000psi. unlike LP aka liquid propane . however with an expensive commpressor you can fill at home overnight.

 

does anyone know if CNG kits are available now?

Thanks

Ed Lin

 

I looked into it a few years ago for my wife's Mustang.

Pros
Cleaner burning than gas.
Local fuel.
Cheap! ~$1.30 a gallon equivalent.

Cons
Expensive conversion (~$3000)
Your trunk is gone (on a Mustang).
Less mpg.
Potential bomb in the trunk.

We still haven't done it, but it's still a possibility.