My LPG powered beetle.

[oprn]

Ah! That makes more sense, no I have never seen a LNG filling station.
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Our cars get old, we get old but driving an old VW never gets old!

[raygreenwood]

[oprn]

It doesn't sound anything like the natural gas I am familiar with Ray.

That really sounds like propane.
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Our cars get old, we get old but driving an old VW never gets old!

[raygreenwood]

[oprn]

I don't understand the need for gasoline for start up. Natural gas has no cold weather vices. We start cold Caterpillar gas compressor engines with it at -30 in the dead of winter. If the oil is not too stiff and the starter will turn it over it will start! No fuel enrichment needed like gasoline.
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Our cars get old, we get old but driving an old VW never gets old!

[oprn]

Propane was the big one here at one time but it is rare now. Natural gas does not exist on the road today, only on stationary industrial engines. Very common in the oil patch where the natural gas is virtually free and often burnt off in a flare stack as a useless by-product.
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Our cars get old, we get old but driving an old VW never gets old!

[raygreenwood]

[oprn]

Ya I thought so too but I guess it depends on who posted it. The site I was on termed it critical because in that state it is a bit unpredictable. Not sure in what respect...

Natural gas was tried in our climate in the big cities in taxis and public transportation busses but was discontinued after about a 10 year run. The #1 problem is getting enough into a container to give you any range. The ranges are very similar to electric vehicles. It just did not catch the public fancy because of lack of fueling stations and the tanks are very heavy, of limited shape and capacity.

Due to a surplus of natural gas the Argentine government funded research and implementation of natural gas conversions for vehicles. They set up fuel station networks from one end of the country to the other. One of the locals told me when we were visiting that there was no place in that country that you could drive and not find a filling station. They also capped the price at 25% of gasoline prices. They are now the leading exporter of that technology in the world.
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Our cars get old, we get old but driving an old VW never gets old!

[67rustavenger]

[oprn]

CNG ≠ LNG ≠ LPG acronyms that need clarifying.

CNG - critical natural gas. Methane under high pressure but lacking the full properties of a liquid. May be found at pressures up to 3500psi. This is the most common form found in vehicle conversions.

LNG - liquid natural gas. Methane under high pressure AND refrigerated to a liquid form. Must be kept in a cooled, insulated tank to stay in this state.

LPG - liquid propane gas. The common way to find this gas. It stays in a liquid form easily at moderate temperatures and pressures.

NGL - natural gas liquids. Liquids dropping out of the gas stream in the production of natural gas. May contain various blends of water, propane, butane, pentane, hexane, octane and heptane. Common name, natural gas condensate.

Natural gas has a vapour pressure of 3500 psi at 100*F.

I found this information in a search just to confirm what I wasn't 100% sure of. So as you see we need to confirm that it is actually methane we are discussing.

As far as what you are saying about reversion in a VW FI intake manifold, that is very interesting! I see no reason why either propane or natural gas would not work well in those plenums. There is no fear whatsoever of the gas dropping out and condensing in that manifold.

Your heater block for the liquid fuel is also quite interesting to me. I think it might work just fine for propane if it can deliver enough BTUs to do the job. With natural gas there would be no need for it at all.

I didn't realize such an animal existed! For diesel you say? Or are you proposing we invent one?
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Our cars get old, we get old but driving an old VW never gets old!

[oprn]

It does seem a bit high all right but I am a out of touch with current prices.

That is an interesting evaporator!
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Our cars get old, we get old but driving an old VW never gets old!

[Dake]

https://www.amazon.com/Complete-Straight-Propane-C...&psc=1

I had this bookmarked . But thought it was to high.

[raygreenwood]

[oprn]

[oprn]

LPG is a mixture of Propane and Butane.

NGL is methane or natural gas.

I assumed when you said LPG you were talking about Propane. LPG and NGL are two different animals to put into a tank and store but very similar to burn in the engine. LPG can be stored in a liquid form under a moderate pressure. NGL takes a combination of extreme pressures and refrigeration to get to a liquid form. It will stay in a liquid form at -260*F or at somewhere in the neighborhood of 6000psi if I recall correctly.

I see no reason LPG could not be run through a FI system in much the same way as gasoline with a few refinements. The advantages would be the same as FI has over carburetors, better mixture control. I see no reason to run a vapor system if you have FI already.

NGL on the other hand would not work in a FI system as it is already a vapor in the tank.

If you went with a vapor style carb then yes the injectors would be just sitting there plugging holes and you could put a vapor carb on the inlet of the throttle body and still use the FI throttle plate as is. On my Rabbit I used a stock VW FI throttle body on the discharge of the turbo (blow through) and put the carb without a throttle plate on the suction side (draw through).

Now of course you need full time heat to run an evaporator to supply propane vapor to the propane carb. Apparently they make an evaporator that uses exhaust gas instead of engine coolant for use on air cooled engines.

Yes it could be done the conventional way too. You would miss out on the thermal efficiency benefits I was talking about earlier though. I suppose you could leave the FI system all in tact and have a dual fuel set up. The next step would be to have two separate ignition maps depending on which fuel you were running at the time. You would loose out on the high CR advantage of the propane too. Dual fuel engines are never the best they can be on either fuel in my experiance. Too many compromises.
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Our cars get old, we get old but driving an old VW never gets old!

[raygreenwood]

[oprn]

[busdaddy]

[Alstrup]

If an lpg engine carbons up something is REALLY! off. Back in the 70´s and early80´s lpg was very common around here. Then it got killed through elevated taxes. When a lpg engine converted from gasoline to lpg They usually did about 10% less to the gallon over gasoline. Purpose built lpg engines usually did about 10% better than gasoline. One of the positive sides of lpg was that it left very little deposits in the oil. In those days my dad had a Peugeot 504, then a Volvo 142S and finally a Volvo 164, all running on lpg. When the Volvo´s were in for servive I remember that the oil was just about as clean as the day it was put in. The shop did oil changes every 10000 km (roughly 6600 miles) I believe that was 2500 km longer than if it was on gasoline, and it was due to the fact that the oil did not get contaminated nearly as much as with gasoline.
So, again, if an lpg powered engine soots up, something is definitely not right.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[oprn]

Two comments here. First even the very best of propane carbs are crude affairs in comparison to gasoline carbs. The best of them have 3 adjustments 1) a total volume valve to adjust the flat out mixture, 2) an idle mixture adjustment and 3) the one most guys don't know is even in there, a diaphragm with a plug that has different profiles to adjust the mid range. System pressure is fixed, not adjustable in most systems.

The second comment here is that NO mechanic I have ever met used any kind of instrument or checked plug color when setting these carbs. It's all by ear! We are talking a step back into the 1920 to 1940s when a mechanic set carbs and timing by "that feels about right" technology! If it starts and runs it's good to go!

Are there engines on propane that run like crap? Oh ya! Are there propane engines that get atrocious fuel mileage & have no power? Burn out exhaust valves, develop holes in the piston? Ever wonder why? Now you know why!

What would your car run like if it was tuned like that?
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Our cars get old, we get old but driving an old VW never gets old!