The same size motor will not produce the same amount of electric output. I'm very familiar with the small Onan that have been put on Class B's for near forever, because they are relatively compact. The one used for the gas powered B's are rated at 2.8K output. The exact same generator that uses propane is rated at 2.5K output.
Three years ago, I spent Labor Day weekend in Atlanta at a football game. Had to run the gas powered generator for 36 straight hours due to the heat and humidity in my Class B. It uses fuel from the B's regular gas tank. I could not have carried enough propane to drive a propane powered genny for that long.
By the way, they do make diesel powered gennys. All the Class A diesel pushers have diesel generators, but those big machines have the room for the larger sized gennys.
That is the weak point of the diesel powered Sprinter class B's. They aren't large enough to accept a diesel powered generator, so they have to use LP powered generators, yet the propane supply is relatively limited on them.
As for Honda, that company has done a magnificent job ( for Honda) in keeping the going price for a Honda in the stratosphere. Honda, as good as they are, are overpriced.
Capt RonB wrote:
Still a 10hp gas engine vs a 10 hp propane engine produces the same 'lectric output. The difference will be the cost of fuel which as near as I can tell is about break even.
Also while we're on the subject, why does a 'Sportsman' 4000 watt genset cost $900 and a Honda or Yamaha Equivalent cost $4000? I know I want a quality generator but the price difference seems extreme.