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Old 06-12-2013, 11:50 AM
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Default O.K. To run a N.G. genset on propane ?

I picked up an onan 30 kw (or so) genset with a 300-6 ford engine.

Set up for N.G.

I don't have enough gas to run it, but have a nice big propane
tank sitting idle (350 gallon or so).

Can I run it full power ? or would there be some timing/compression
changes made for N.G. that propane would damage the engine ?
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Old 06-12-2013, 12:07 PM
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I think the propane has more BTUs, if that helps you work your way through the problem. Like 10% ish more, its not allot. I dont think any changes are required, other than watching the heat.

Im not a "genny" guy, but I do play with them. Doesnt Gerry know allot about them, I remember somebody here has genny experience.
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Old 06-12-2013, 01:07 PM
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In my experience, if the engine is optimized for NG, it may well run lean on propane. (higher engine temp, lean popping/hunting at idle) Propane has more BTU's available (by volume) than NG, but will make up a good bit of the difference with gasoline, if the compression ratio is raised and the timing is advanced to take advantage of the higher octane rating (115 to 135 RON) of propane.

There are a couple different way's to run an engine on LNG and LP, depending on how your's is setup, it could be as easy as a jet change or a pressure/flow adjustment to the gas generator/atomizer. (assuming your's is not a dual fuel rig)

The tech at your local propane dealer might well be a good source if advice, most of those guys I have dealt with have a wide experience base and at least some knowledge of automotive applications. (like yours)

RED
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Last edited by RED caddy; 06-12-2013 at 03:42 PM. Reason: I'm soooo confused...
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Old 06-12-2013, 02:28 PM
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The NG regulator is probably a Garret or Impco, and they have springs to change for NG or Propane.
Propane contains 2.77 times more energy than NG or 1 cubic foot of propane contains 2,516 BTU and 1 cubic foot of natural gas contains 1,030 BTU. So the orifice in a furnace must be larger for NG than propane and the pressure is a little higher in pane. In the generator engine application there are no orifices, but the regulator must flow the right amount or you will run lean if at all, like RED said.
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Old 06-12-2013, 02:41 PM
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Different jet size..my generac came with both jets..more BTU's in propane.
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Old 06-13-2013, 06:04 AM
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Thank you everyone for all the info. yes it's an impco regulator.

My concern was that maybe the compression ratio was upped
for the lower fuel value N.g. and when I would run propane,
I would have major kocking problems.

I assume setting lean/rich is just the same as with gasoline ?
Lean out till stumble, crank open till rich stumble, set in middle ?
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Old 06-13-2013, 09:04 AM
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I've done this on a genset powered by a 350 chevy. We put on a impco vaporizer, which draws liquid from bottom of tank and runs it through water from the water pump and vaporizes the liquid. I don't recall rejetting. It has since been swapped back to natural gas, with no problems.
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Old 06-14-2013, 07:46 AM
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Quote:
Originally Posted by Ironman View Post
Propane contains 2.77 times more energy than NG or 1 cubic foot of propane contains 2,516 BTU and 1 cubic foot of natural gas contains 1,030 BTU.
Wow I knew there was a difference but I didn't realize how much.
Thanks
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  #9  
Old 06-14-2013, 07:28 PM
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Default Impco

The Impco mixers are set up to deliver the proper air/fuel ratio with natural gas at atmospheric pressure or propane at minus 1.5 inches of water. Dual fuel engines have 2 primary regulators-one for each gas. No other changes should be needed. A 350 gallon tank should have enough surface area for vapor withdrawal if the outdoor temperature is not too cold.
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Old 06-15-2013, 07:24 AM
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I did not realize there was such.a difference in BTU's either. I learn something every day on this site.
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