My LPG powered beetle.

[ozzo]

I do have a natural gas t2.... natural gas conversion much easier, gas tanks, tubing and a pressure reducer, if you want to improve the system you run the engine oil of full flow in pressure reducer, this willcool oil and make gas temperature stable.
Only negative point i had a broken exhaust valve in 40.000 km, it was a new aa 043 had with ss valve.
17 euros of natural gas give me same driving distance as 60 euros of unleaded fuel....
Lpg has smaller and lighter tank, has less power loss, cng is easier to install and you is cheaper to run, but tanks are very heavy... no less than 300kg

[oprn]

Yes my experiance was in the much same time frame.

The part that was not understood by many was that propane takes a huge amount of heat to change from a liquid to a gas state. In the summer they start fine on propane and you could drive away immediately, no issues. There is enough heat transfer in the antifreeze at those temps to sustain the change of state. Come colder weather it becomes a different story. You can easily demand more gaseous fuel than the heat transfer in the evaporator can supply. What happens then is that liquid propane makes it past the evaporator into the carb and floods the engine. As we all know liquid fuel of any kind does not burn. The engine then stalls and won't restart because the propane is trying to evaporate and drops the temperature of the system even lower. The more it tries to evaporate the lower the temps go resulting in a snowball effect. It just gets worse and worse the more you try.

Propane by the way is used as an industrial refrigerant. Yes you could put it in your AC system and it would work super well, just has a but of an explosion hazard if you have a leak. So by flooding your engine and continuing to try and start it, you have created your own perpetual refrigerator!

The common reaction then is "The propane froze off!" No it didn't, you flooded the engine with liquid! The freezing temperature of propane is -304*F!

The proper cold weather starting procedure down to -40* is - start the engine AT IDLE, it WILL idle! DON'T TOUCH THE GAS PEDDLE!!! Walk away! Go make a cup of coffee for your travel mug, use the bathroom (your mother kept reminding you to do that before taking a trip right?), shovel the walk if it's below -20. Now get in and go. All is good!

Some would treat propane like a diesel and below -30 would leave it running all night. That works as like diesel you can hardly see the difference on the fuel gauge in the morning whereas a gas one would run out of fuel at 3 AM! I never found that necessary.
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Our cars get old, we get old but driving an old VW never gets old!

[oprn]

[Alstrup]

Using the oil as a temperature stabilizer is not a bad idea at all. That said you would HAVE to use a full thermostatic controlled system in colder climates or the engine (oil) would never warm up properly, or it would at least take something like 20-25 miles to do it.
Back when ACVW´s were still used as a daily transportation around here there was several solutions to get better cabin heating and defrosting capabilities. A gas heater was of course nr. 1, but for several reasons they were not that common. I think price was the most normal excuse. 50% air recirkulation was another solution. It worked fair, but was still not the best in humid weather since the moist was naturally also recirkulated. Heating via an oil heat exchanger was a third option of which I installed a fair amount. But I soon realized that in order to get some real heat out of the engine that way you had to run the feed hose directly to the exchanger, and then to a thermostat and back to a real oil cooler. If you just routed the oil to the heat exchanger and then to the cooler and back into the engine the oil would have a hard time getting above 50 degrees C. If you added a thermostat you could relatively soon have about 70 degrees C. and it would stabilize there unless you went Autobahn driving.
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[PEPPE]

Due to volume of air/fuel in stochiometric situation, the CNG is the less favorable, it is like loosing Engine capacity, in example a 1800 acts like a 1600. The result is loosing some torque and power.
This happens also with LPG but the effect is less evident.

About the advance the LPG often likes 2/3 degrees static added timing.

The mixers less invasive are of this model
https://it.aliexpress.com/item/32904707055.html
These can be put just between carburettor and air filter and are connected to a regulator that has to be the model for "carburettor".

but the easiest, oldschool and universal method is the threaded tube in the carb. an hole usually 10x1mm at the height of venturi and this is the more sensitive method that usually cures the vacuum problems of modified engines

[oprn]

[auro]

Guys,

I`m quite interested. I have an old 1600 engine and I would make an electric generator running natural gas (city gas). Here in North Carolina, NG is gaseous, 10-15 PSi (not much pressure beyond 1atm), and a mixture of methane, H2O vapor, and a few % of helium/argon. He/Ar come from the reservoir and cant be changed. During the winter they reduce the water-vapor percentage to increase specific heat. Propane and butane concentrations are minimal.

Engine would start by itself in the event of loss of power after few minutes (I have a bunch of Lead batteries running the computers) and instead of generating electricity through inverters, it would feed battery chargers pumping back hundreds of amps into the batteries, so I use the stabilization and the frequency of the UPS inverters.

thanks
Stefano

[oprn]

The carburetion is simple enough and the parts readily available. There are governors to be found on the VW industrial engines I have one but I'm sure there are fellows close to you that have taken them off to use the engines for cars and would happily part with them.

So you want to use the batteries as a power sink and an inverter to clean the
power up? All good if it's a big enough inverter to handle your expected load. What do you plan to couple to the engine to generate the power?

I find it strange that any water content is allowed in your natural gas. It tends to accumulate in the low spots in the lines and causes grief come colder weather. In our country the gas has to be virtually dry before it is accepted for sale to the public.
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Our cars get old, we get old but driving an old VW never gets old!

[raygreenwood]

I wonder....any advantages to running LPG on a type 4 with fuel injection runners and plenum....with the vaporizer right between TB and plenum?

How hot does the plenum need to be? One could park a couple of these in the intake in a strategic spot.....or screw them into a block of aluminum that the gas flows through first.

https://www.summitracing.com/parts/smp-dih4?seid=s...C4QAvD_BwE

Ray

[Alstrup]

[oprn]

[mark tucker]

the only lpg engines Ive messed with were at work, forklifters...and they carbon up worse than diesels...but the diesel is oillyer and stinker...and heavyer. I would think there are better systems than whats on the flrklifts. when I was a kid in japam the city /island busses were all lpg...school busses were diesel kawasakies. most all seems to smoke & stink a lot less than what we have hear.

[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!

[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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[busdaddy]

[oprn]

[raygreenwood]

[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!

[oprn]

[raygreenwood]