I have a 4.9L gasoline only engine in my 1996 ford f150. I also heard there is a bi-fuel model made of my engine. How hard would it be to retrofit the euipment to run propane and how much $$$?


Thank you.

 

Starting from scratch all new equipment and tank $3000-4000
If you can locate a used tank (biggest expense) and some take-off rebuildable euipment you might get by for less than a grand. There are some factors to consider on a older unit so if you decide to continue let me know.
Regards
Gasman

 

I have been curious on how to build mine as a full propane engine, i have bought a Road Demon Jr. 525cfm carburator so far for my modifcations, but still need an intake to fit it. The engine is in an '85 Bronco...are there any guide lines as to what compression i should use? I would'nt mind going through getting the tanks and certain things but it seems hard to find info as many people don't go with propane as a fuel.

Thanks for any of your help!

 

Bi-fuel fumigation conversion kits are available for your engine. Technocarb makes one specifically for the Ford 4.9L engine. You also try fitting an Impco system and a Model 225 would probably work well and a Model 200 might fit a bit easier.

There are universal propane injection kits available but likely not in the USA due to EPA certification. Prins, EcoFuel, and Technocarb are common in Canada. You can also install a DIY bi-fuel propane injection parts package on your fuel-injected engine. This would work better than installing a propane mixer upstream of your throttle body.

If you're building a full propane engine, you won't be needing the Road Demon Jr. The Impco Model 225 would fine if you kept the revs low or you could try the Model 425. Many people like the OHG X-450 (Woodward CA475) better than the Impco 425. A pricier option is the Technocarb 4bbl off-road carburetor.

Keep the CR below 11:1 (preferably below 10.5:1) for best reliability. See Propane Best Practices.

 

Will running propane effect the comp? If so, how would I adjust the computer to run Propane?

 

From the research that I've done, with Fuel Injected Engines you would need a custom tune for it to properly work.

 

Aftermarket propane conversion kits have no effect on the OEM computer. However, these systems require a working EFI system to operate. The propane computer intercepts the gasoline injector signal, modifies it, and then sends it to the propane injectors. The signal modification is done with a fuel map that relates the signal modification (a multiplication factor) to gasoline injector pulse width and RPM. If the the multiplication factor is correct, the fuel trims on propane are identical to those on gasoline.

While increasing the CR will give an improvement to fuel efficiency, it is not required. Injection systems typically have propane fuel economies of around 90% of the gasoline economy. This is better than the BTU ratio (~75%) because the OEM computer will automatically advance the timing due to the absence of engine knock (propane has an octane rating of 104).