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LP Gas Conversion
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drs1023
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PostPosted: Tue Oct 08, 2013 1:43 pm    Post subject: LP Gas Conversion Reply with quote

I asked this in the 68 and above forum with no replies, so I will ask you engine gurus this question.
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Any of you guys running an LP GAS conversion on your VW? My whole house generator (25 hp Honda engine) is hard plumbed into my propane tank, and my older skid steer (mid-70's New Holland L775) has a 65 hp V-4 air-cooled engine and it's on the bottle as well.

My gas tank on my woods buggy is an old propane tank, so the mounting bracket is already there. I've rebuilt a couple of regulators in the past (skid steer and my dad's '57 MF tractor), so I have "some" knowledge of how they are supposed to work.

I understand the loss of efficiency and retarding the timing to get correct service from an LP gas conversion - I am just looking for some information as to how your VW performs on LP.

Thanks in advance.
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slalombuggy
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PostPosted: Tue Oct 08, 2013 4:46 pm    Post subject: Reply with quote

Search this forum for LPG or CNG and you'll find a few topics related to this already

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Ghia Nut
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PostPosted: Tue Oct 08, 2013 6:49 pm    Post subject: Reply with quote

Uhhhh isn't lap gas different the propane that u use on gas grill? Aren't true lp gas tanks rated for higher pressure?
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Komissar
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PostPosted: Wed Oct 09, 2013 1:56 am    Post subject: Reply with quote

I have done a LPG conversion on by beetle- here is the topic: http://www.thesamba.com/vw/forum/viewtopic.php?t=460412&highlight=lpg

- about timming: you have to advance, not retard.

Also, if you were to build from the start a LPG powered ACVW engine I would shoot for higher compression ratios than with gasoline. LPG can handle bigger compression and more advance, and thus make up for lost energy (it can be said that the LPG has roughly an octanic NO of 115 ) .
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Dale M.
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PostPosted: Wed Oct 09, 2013 6:39 am    Post subject: Reply with quote

Normal LPG gasses (propane) have a pressure of about 125 psi at 70° f..... LPG or "propane" pressures increase or decrease with temperature... At approximately 110° f. propane has a pressure of about 200psi...At -40° f. pressure drops to almost "0"...

From this article about CNG....

http://en.wikipedia.org/wiki/Compressed_natural_gas

CNG is made by compressing natural gas (which is mainly composed of methane, CH4), to less than 1 percent of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of 200–248 bar (2,900–3,600 psi), usually in cylindrical or spherical shapes.

Much information on propane as motor fuel or cooking/heating fuel out there...GOOGLE can be your friend....

The difficulties (pressure and tanks volumes/size) of storing CNG probable make it impractical for a bug/buggy, but LPG (propane) is very practical as a alternative fuel...

Bunch of information about propane and small engines here... Just have to scale it up to engine size of your choice...

http://www.propanecarbs.com/propane.html

Dale
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drs1023
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PostPosted: Wed Oct 09, 2013 10:41 am    Post subject: Reply with quote

I appreciate all the replies. And, I did type a slip-up - of course the timing is advanced. As I said, I and my dad both run LP gas engines - his tractor, my skid steer, and my house generator (gasoline/LPG/CNG tri-fuel set-up) - so I probably know just enough to climb above stupid in that area. I had not considered converting to a dual fuel like Kommisar did. I only wanted propane, but dual fuel is also a good option .

The water circulation through the regulator sounds great, but still seems a little complicated. I believe it's possible to capture enough hot air off the VW engine to heat the regulator as needed. Pipe in hot air and just let it escape through the other side of the regulator instead of recirculating anything. It's a fact that I don't operate my skid steer year round, so I've never experienced the effects of icing.
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LivinInnaVWBus
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PostPosted: Mon Oct 14, 2013 2:15 pm    Post subject: Reply with quote

Advanced timing and higher compression ratio are only recommended to take up the power loss from running LPG. Both will contribute to higher head temps which is the Achilles heel on LPG VW engines. Gasoline has valve/valve guide lubricating properties that LPG does not so they tend to run hotter even without the advanced timing or higher compression.
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