LP/propane has 26% less energy than gasoline. By BTU:
Gasoline: 125,000 BTU/gal (87 octane regular)
Propane: 93,000 BTU/gal
E-10 Gasoline with 10% Ethnol: 120,900 BTU/gal
I live pretty rural - town of 10,000, and regional population density here is less than 1 person per square kilometer - and I could probably find enough propane here to blow half the town off the map. I'm not sure if / why it would be less available in the US than up here. I thought it was actually more popular in rural areas due to lack of natural gas service in outlying areas, and recreational use such as camping equipment.
The general widsom here is that a good propane conversion on a gas engine will net a 15-20% power loss compared to gasoline, just because of the BTU content and detonation characteristic differences between the fuels. Sort of like how propane works fine with a cutting torch, but consumes more oxygen and requires more preheating. In both cases though, the cost savings more than make up for the inefficiency. My old truck has a 305 on propane, and I can put $120 worth of fuel into it about this time of year and work with it all summer on that.
The reason for adding propane to a diesel is that it has a similar effect to NOS in a gas engine - it cools the air down, resulting in more oxygen in a given volume of air, and has the added benefit of also being explosive, unlike NOS. There used to be a guy in town with a Dodge Cummins that had been chipped and also had a propane booster, and it had some absolutely ridiculous torque.
My one question about these little propane engines is lubrication. They say four stroke - do they have an oil reservoir crankcase and a limited operating position, or do they have an oil injector? I do also share the concerns about the tank freezing or being unreliable.
As a final note, I'm going to be rebuilding a bandmill this summer and am considering converting whatever engine I get for it to propane. Most B&S type engines can be converted with not much more than a carb adapter kit. I'm not sure how much runtime one could get from, say an 18HP engine on a 20-pounder of Propane though.
You will have to adjust the valves every 25 hours.
Enter your email address to join: