Alternative Heat Source

[tdonaldson]

I am looking at converting a 68 VW Type 1 engine to propane. This engine is mounted in a Rail Buggy chassis, so many design implements are possible that might not be reasonable in a normal vehicle. I do not have any coolant in the engine as it is completely air-cooled. I do not want to rig up any coolant system via and small system heated by the exhaust, nor a small system that intercools with oil.

I have spent a couple weeks trying to gather up as much information as I could find. This forum seems to be one of the primary sources available. I am wondering how many people have successfully used an alternative heat source for their regulator on a automobile. It's not a terrible high flowing application, but the aircooled aspect is making it challenging for me to put it all together in my head.

Here's what I was thinking of using:
2 10 gal forklift tanks
1 J or Cobra series regu;ator
1 100ca impco mixer

You guys here are the experts, so I was hoping you could give me some feedback on these products for my use. I hear good things about the 100ca and the Cobra.

Here's my primary questions about them:

For the 100ca mixer, should I use the lean valve for it since the vehicle only makes in the range of 60 hp? Everyone on here says the 50/55ca is terrible and wears poorly with throttle use.

I have read on another site that the E and L can only be heated with coolant, but that the J series regulators has a sealed system that could be oil heated. I was hoping that although oil would not be ideal, the low flow necessary for a small displacement engine may not produce such a high heat demand.

I have also read that a company manufactures an electrically heated regulator, but I haven't been able to find one that works on 12V DC current.

I was also considering the idea of externally heating the regulator by coiling a strand of self regulating heat trace around the body of the regulator. Does this seem at all feasible? I know of one VW owner who used a similar solution on an aircooled intake manifold where the gas flow/vapor reduces temperature to the point where they would freeze the butterfly valves in the throttle body. A one foot string of this only draws about 5 amp. If I used this electrically heated idea, would I be better off purchasing a larger converter/regulator? I don't know if running a larger converter at less demand requires more heat than a smaller converter at high demand.

I apologize if this is a request for a lot of knowledge; but this site has already been the starting place for most of this idea, and it seems to be the best source for a possible solution.

Thank you for any help you can give, or any experiences you can relate,
Terry

[tdonaldson]

I apologize, I forgot to mention. I have already looked a little bit at the air heated regulators made by impco and one other company. I like the idea, but I think they are only rated to produce 50 hp, and their only valve is more suited for a forklift or other low power application.

I don't know if there has ever been a larger valve produced. The only application I can find for them is the .5 I was under the impression that a person would need 1.5 for an automobile.

The Type 1 Beetle engine has low demands, and I know that the air cooled regulator was used in many zambonis, but I do not know how well it might operate at freeway speeds.

I have also heard of a metal insert that would allow an operator to route exhaust gases to the regulator, but I haven't found any websites that offer the conversion for the J or Cobra series regulator. Any help on that front would also be appreciated.

Thanks again, sorry for so many questions.

[GASNXT]

Hey, Glad to see others like the idea of LPG VW'S. I also own a 68vw and wish to turbo and gas. My thoughts were to run coolant through the converter to the sump and through the sump via copper lines back to a hopper (tank) via a pump back to converter. My thoughts were that when loades on the engine were high and the oil temps raised also the demand for warmer coolant for the converter would exist. What do you think?

[tdonaldson]

Makes sense to me.
Have you looked at the idea of a heat exchanger, that way you could just run the lines from your oil cooler to the heat exchanger, then run the coolant lines out of it to your resevoir? Seemed easier that putting copper lines through the oil pan, but might not get as much heat transfer as your idea.

I guess you don't really have to run the lines through the actual engine sump at all. You could probably just use a modified inline oil filter filled with coiled copper line. Lotsa ways to get the stuff hot I spose if you add enough stuff to your engine

[franz]

If you were looking at 60 bhp max, you would be using around 25 to 30 bhp 90% of the time. The Impco 55 would be ideal, and if it sits vertical, it will last for a very long time. Keep clean air going through it, this helps preventing gumming of the air-valve. Coupled with that would be a model J vaporizer. Both of these are rated for about 125 bhp, but when at full operating temp. An air cooled engine adds the complexity of how to heat the vaporizer. See if you can find the Century G-85-A vaporizer. If it is mounted in a warm air area, it can produce 85 bhp of fuel.

Look at: http://goo.gl/Yt0sB for reference, I claim or make no endorsement of the vendor or website.

I also like the 100 mixer, especially because it is dirt simple and easy to maintain. Start out with the stoichiometric gas valve and change later as needed. Both the 55 and the 100 are common forklift units and parts are readily available.

Franz

[Steptoe]

We used to run an external oil filter/cooler on the off roader decades ago..it would not be hard to route thru the vapouriser????

[Frank]

This topic reminds of some earlier posts

• air-cooled automobiles and propane
• air cooled VW stationary engine
• Converting Motorcycle Engine to LPG

I had a customer a few years ago who was converting his Pinzgauer 710 (2.5L air cooled engine) to propane with a pair of Impco Model 60s and a single Century G-85a. He found that as he tried to get it started in the winter, the reg kept freezing up. I wanted him to clamp the G-85a directly to the exhaust pipe for more heat but I believe he ended up switching to a completely different vaporizing system that he came across on the internet. I can't find web reference to it now but I believe the LPG was directly heated by exhaust gas.

[tdonaldson]

franz: Thanks for the info, I like the capacity of the 55, but wasn't sure about the reliability. I may still get the 100 just in case I rebuild the engine with higher compression and want more hp out of it. I looked at the G85 and maybe mounting it inside of an extended enclosure with the engines oil cooler. My only concern is that the air warmed converters by both Century and Impco are made with an outlet pressure of only -.5

Don't I need -1.5 for an automotive application, or would -.5 function? I am not completely sure on this. Also the converter has to function below freezing, and I may have to alter some of the engine working to keep the oil at a good temperature as is. I have had some aircooled motorcycles that never reached operating temperature when riding at highway speeds below freezing, so I am hesitant to count on warmth from air from the oil cooler.

Interrupted. I will post more shortly.

[tdonaldson]

Sorry for posting in two replies, work was interrupting.

So. Engine operating temperature: Im very worried about trying to warm the vaporizer with air coming from an oil cooler because I do not know that the oil will reach a goo temperature. I am fairly certain it won't.

Steptoe: Yes I had thought about plumbing it in using the oil cooler route. I was planning on using some plumbing to put the vaporizer in leading to a thermostat which would in turn lead to an externally mounted oil cooler.

here is a link to a pic of the factory style oil cooler. In a normal vehicle it is mounted inside the tinwork on the right hand of that blower fan. That fan pulls air in and pushes it through the oil cooler and down over the cylinders. I had thought about mounting a G85 inside that housing, but I think it would be poorly heated in a winter climate as the oil going to the cooler wouldn't be that warm.

http://images.thesamba.com/vw/gallery/pix/540457.jpg

I was also considering using the lines from that oil cooler, eliminating the stock cooler, and using the thermostst, the converter, and external cooler. This would keep the oil out of the cooler, thus keeping the oil warmer in the winter, warm a vaporizer more directly, and allow for a bigger oil cooler for more efficient cooling in summer. (Which I anticipate a need for due to the hot heat temps caused by no liquid vaporization taking place within the cyclinder).

Here is a link to a forum posting from an australian vw enthisiast site. This guy converted his bus to propane using oil in the vaporizer. It obviously worked great short term. I am posting under the same name there trying to get some long term results from the OP or anyone who knows him. Propane is a lot more common in Australia, so I have been trying to start searching there.

http://forums.aussieveedubbers.com/view ... ?tid=72067

Frank: I have looked over each of those topics for inspiration. That is where I originally read that the vaporizers could not be oil heated. I have seen a few pictures where people did oil heat them, but I can't find any long term results. If anyone has heard of them, please forward me any oil heated vaporizer results if you've heard any.

[Steptoe]

This guy converted his bus to propane using oil in the vaporizer. It obviously worked great short term.

Am I getting old decrebid and suffer alzmers as my bloosdy up son says and missed something in that link?

A note on engine cooling/ oil temps etc..well applies to water coolded and I asume air colled also
There is more engine heat approx 60% disapated thru tappet covers , sump etc
Which is why sumps are usually black and race cars do not have polished or cromed sumps.
Where a polished tappet cover is used they have cooling fins which at usually painted.

And oil temps..it is better to use the correct temp grade for yor engine than try to cool the oil to a temp/grade.
If I was going down this route..and done as u have a lot of reading asking questions....I would get a vapouriser, no need for a full install and just run oil lines thru....check a few temps under the exteme temps u intend to work under.
Maybe think about pre heating oil....some thing never seen in NZ where ppl who live in cold places plug the car into a heater over night...thats my limit of knowledge on that subject.

[MLGPropane2]

The Impco model L can be used with Oil..simply copy the rectangular rubber gasket
with engine gasket materiel. worked on a Corvair for more than 7 years Oil from the oil pump is
hot....use a remote cooler Model L first then cooler. Choose an oil with a below zero "pour point"
The Model L has 0.5 and 1.5 springs available The Model 55 carb is designed for engines
with strong intake pulses (4cyl/2cyl) The cylinder head temp on the Corvair... 400deg F on gasoline
300deg F on LPG

Roger

[Frank]

I do not believe that the converter needs to be very warm to vaporize propane. There must be enough heat transferred from the hot fluid passing through it to keep it from frosting - that is, where the heat required for vaporization exceeds the heat supplied.

Besides issues with the gasket compatibility with oil, the converter needs to stay within its maximum operating temperature, which on Impco's is 250°F. Engine oil can easily exceed this temperature so that's why Roger suggested putting the converter after the oil cooler.

I think the suggestion to use a Model L is good because it has more vaporization capacity than the Model J or the G-85A or AHR50D. The heat transfer with thinner oils is better than with viscous oils (more turbulent vs more laminar flow) so cold weather operation would probably be better. Don't forget that 0W multigrades are not just for winter. Only synthetics can be formulated as 0W weight oils (ie, 0W-30, 0W-40) and they often have higher hot viscosity than mineral oil multigrades.

[MLGPropane2]

More about the Model L with engine oil...temp needs to be above 55deg f to ensure the
vaporization of the Butane componant of LPG. Temp monitering on the Corvair ambient 120deg F
model L 150deg F. Ambient 10deg F model L 70deg F. Corvair pickup full of camping gear for
a Boy Scout Troop. Two carbs....Intake pulses too strong for Model 100/125 (3cyl per carb)
Absolutly zero "heavy end" accumulation in the Model L

Roger

[DODGEN1]

i ran a volks for a lott of years and the thing that makes the survive is oil temp. you could use the adapter for the external oil cooler and run it thru the model j and help drop oil temps under heavy load, the century vaporizer clamps to the exhast pipe sean picts of a conversion once tank in the back seat. it should work dont over rev till it warms up they had a header on it.

[DODGEN1]

http://www.youtube.com/watch?v=x5yergnpc-M