Gas to Propane generator conversion

[GMP]

I have a new Generac I'm considering doing this conversion on. I have a 500 gal in ground tank that would be easy to tap and avoid the hassle of gas availability in a future outage like the one I just went through. I've been looking at a few kits available, but they seem to be a little biased with a big bright picture but no hard facts relative to long term results. I'm concerned about effects on the engine such as valve damage from running a fuel it was not designed for. I know the power will be slightly less due to the slower burn rate. This can be mitigated if necessary with a slight timing advance. Any practical info and experience will be greatly appreciated.

 

[Cruiser]

look at run propane.com,, stay with the bi-fuel systems, so you can go back and forth. I have seen several guys run this system on v-twin air cooled powered zero turns with no issues. seams the slightly less power helps.

 

[iajim]

I'm not sure what the conversion kits consist of but I do know that in LP dedicated engines they usually used valves made with Stellite, a much harder material and I do believe the angle of the valve grind was different from gasoline only. On modern engines a multi-angle, usually 3, is pretty common so that may not be a problem. A couple of advantages with propane is that it has a naturally high octane rating(nearly 100!) so you can raise the compression ratio, but then you'll have problems if you ever switch back to gas. The "less power" aspect of propane is something you'll probably never notice with a generator. The other benefit with LP or Natural Gas is that it enters the cylinder and head as a vapor, gasoline enters in very tiny droplets that can wash off some of the oil film from the cylinder walls. Thus propane engines have a very long life. If I haven't bored you enough, propane is C3H8, three carbon atoms attached to eight hydrogen atoms, this makes up one molecule of propane. Light Naptha, the base material for gasoline has 7 carbon atoms per molecule, pretty big difference. The carbon is where most of the real power comes from in an internal combustion engine, so it does have less power but it burns much cleaner; less carbon going in = less CO coming out the exhaust. Don't worry about advancing or retarding the timing, the higher octane will take care of that and generator engines are a long way from race engines. I personally changed over a propane power tractor(Ford 900, 1957 vintage) to gasoline. I did this for 2 reasons, first- original vaporizer parts were almost non-existant and after market vaporizers were hit or miss, you had to buy one, try it and then be prepared to buy another until you found one that worked. Second- cold weather starting(zero degrees and below), you needed as much/many block heaters and starting fluid for propane as a diesel. I realize you're going the other way, gas to propane. I don't think you'll have any problems as long as you know this kit has worked on near identical applications, you don't want to be the "experiment". Also ask if the vaporizer is adjustable and what instructions come with it, that could be a "make or break point". And on the Ford tractor, I didn't change the timing and I did run regular, not premium fuel with no problems. I hope this helps, let us know how the conversion works out. Jim

 

[twowheels]

I'm going to see my buddy that runs a propane company this weekend so I'll ask him for the "official" word, but in the meantime here's what I know.

They run Ford trucks in their service fleet, and for a while they were buying the factory conversion. Since then they have switched to a different company, and rather than pulling the heads and replacing valves and seats before operation they just run them until they need replacing and then do it. Most of their trucks run a half million miles before the vehicle itself is used up.

One thing they do on all of their propane conversion vehicles is start on gasoline. Easier to light, especially in cold temperatures ... like when you might need a generator most. See if any of the conversion kits allow you to retain some gasoline aspect.

Like I said, I'll see him this weekend and pick his brain. In the meantime, stay warm and well lit.

 

[Cruiser]

The one from run propane.com is a plate that goes between the manifold and carb with an injector. You get to keep all the carb parts on the engine and they still function. May have to lengthen the governor rod depending on location. But the landscapers that use them on the zero turns do the same.. warm up on gas, turn the gas off then run it out and when it stalls out open the propane tanks and run it the rest of the day.. We have been seeing a lot more of that in the smaller fleets as they seem to go farther between refueling and servicing..

 

[GMP]

Thanks guys. I bought this Generac is a semi-emergency, as I was working my 3K hard all week and it was starting to sound a little loud. The first 20 deg morning it stalled a few times. Anyway in my haste I didn't realize that the GP series Generac is made in China! I was pissed, but unless you spend twice the coin thats what you get. I'm a little apprehensive of running anything that might stress the valves in this motor as I'm sure its not the best of materials and construction. I have heard that a lean condition with a propane system is a lot worse than gas and valves will burn fast.

I've looked at the kits, the dual or tri fuel kits add an adapter block with a venturi for propane injection to the FRONT of the carb, between it and the air filter. This allows the carbs throttle plate to function normally. I guess i'd like to see evidence one of these motors run on propane for awhile with no problems. Its a common motor, probably the same motor is found on most 5 to 6.5K generators sold.