I got one of those wild hair ideas, I know it probably won't work, but I would like to know why.

Here's my idea, run a Propane kit like the diesels have.

 

You mean, like high compression and no spark plugs?

 

If that's what he's going for, he'll be on the cutting edge of technology. I believe the inventor(s) of the "quasiturbine" engine are trying to do the same thing with hydrogen. Isn't it called photodetonation or something like that?

 

No, that does sound cool though. But what I was talking about is like what the diesels have and just add propane into the air intake.

I know a really crazy guy that has an older duracrapper that he put a homemade propane kit on with a 5 gallon propane bottle and a ball valve to adjust home much propane goes into the air intake.

 

It could work. But would this be used in addition to a gas carb or EFI? As soon as you turn the propane on won't it run too rich?

I think it would be most efficient to just switch to a propane carb and disconnect the gasoline altogether.

 

The diesel systems are triggered by engine load (vacumn) and release the lp into the manifold thru a metered orifice. A dual-fuel (bi-fuel) engine uses a mixer (air valve) that mixers fuel and air outside of the manifold and are connected usally by the oem air cleaner tubing. By not using a mixer to control the fuel you will run way to rich probaly backfire, stall and create some very pretty blue flames

 

Fumigating propane into an EFI intake is bad idea because these intakes were never designed to convey air-fuel mixtures. Because propane is heavier than air, propane can separate from the air through centrifugal force in these manifolds which could result in some cylinders getting a different fuel mixture than the others.

The other problem is that the the large volumes contained by these intake manifolds can result in intake backfires due to fuel transport delay.

If you want to use propane, use a bi-fuel propane injection system.

Also, backfires are generally due to very lean fuel mixtures rather than rich mixtures. Rich propane mixtures can cause exhaust valves to burn.

Diesel/propane systems also are controlled by manifold pressure rather than load. There are only commercially available diesel/propane systems for turbocharged applications. The better systems use computer-controlled propane injection rather than a metered orifice or a mixer.

 

Propane on a diesel acts as a catalyst in the combustion reaction, improving the combustion and thus the power output of the engine. A diesel engine has no throttle and is capable of ingesting how ever much air can be crammed into the cylinders, while a gasoline engine has a finite amount of inlet air for a given condition that may be used in combustion. Whether the fuel is gasoline or propane, adding more of it without an increase in the amount of air available for combustion will not produce any additional power.

 

There is a lot of misinformation on the internet and propane acting as a catalyst to improve diesel combustion is one of them. By definition, a catalyst is a substance that initiates or accelerates a chemical reaction without itself being affected. Since propane is consumed in the reaction, it cannot possibly be considered a catalyst.

Diesels normally operate very lean which means they have a great deal of excess air in the combustion chamber. Propane is often added to consume some of this excess air. Diesels, therefore, produce less smoke with a diesel/propane dual fuel system because they are burning less diesel fuel in proportion at higher loads. For more information, Franz Hofmann explains this in better detail on his Dual Fuel web page.

 

Thanks for that correction - I definitely mis-used the term catalyst. However, diesels vary fueling primarily in relation to accelerator pedal position, whether this is done by a mechanical pump or electronic injection. If there is less smoke for the same amount of diesel fuel when injecting propane, something has been altered in the combustion process making it burn more efficiently since black smoke is unburned or incompletely burned hydrocarbons. I admit, catalyst is not the proper term for what propane does, but certainly it alters combustion more than simply using more of the excess air in the diesel cycle.

Thus, point being, propane using more of the excess air or altering combustion, gasoline engines has neither excess air nor compression ignition, meaning propane injection on a gasoline (or spark ignited) engine will not produce the same gains as propane injection on a diesel (compression ignited) engine.

 

I think that's accurate.

Propane injection on a diesel a bit analagous (in a way) to nitrous oxide addition on a spark-ignited engine. The propane adds more fuel to use the excess oxygen while nitrous adds more oxygen to allow more fuel.

 

Hello

I am new to the site. Can someone direct me to where I can get information on whether Ford has offered Propane versions of its Expidition model?

Or alternately, how to research the cost and reliability of converting one?

Thank you

 

CNG was the factory installed alternative fuel of choice for the last decade or so. I think the reasons were emissions and the type of fleet buyers, such as big cities with their own natural gas utilities. I do not believe Ford ever provided a factory LPG setup.

Jim

 

There were and I beleive still are are Factory LP F150's Aimed at the fleet market. But Ford has never offered an Exp or any other SUV that I am aware of. If you want alternate fuel you will have to go aftermarket.

Regards

 

Most of what you said is correct. Except for that statement. Diesels don't have manifold vacuum. If they do, it's extremely low.




And that is why. Unless the air filter is plugged, there is no restriction to air flow into the cylinder and therefore little or no vacuum.