Is it possible to convert the air-cooled VW to run on LPG.
Has anyone done it?
squarebacker Learner Dubber
7 posts · joined Sep 2002 ·
LPG
70AutoStik Insano Dub Head
730 posts · joined Aug 2002 ·
Yes, it's possible, and, I believe, GasResearch have done a few... but it may not be adviseable. It is generally accepted that gas runs hotter than petrol, adding to problems we already face with VWs, and the smallest gas "carby" I know of would have to be run as a single in the VW; which, with the long runner and the known problem of the extra weight (and further expansion of the gas) of a gas/air mix, is going to add to problems.
Oops, forgot to mention: the gas conversion is usually done using engine oil, instead of water - just in case you want to go ahead.
[Edited on 24-10-2002 by 70AutoStik]
Oops, forgot to mention: the gas conversion is usually done using engine oil, instead of water - just in case you want to go ahead.
[Edited on 24-10-2002 by 70AutoStik]
aussiebug Officially Full-On Dubber
246 posts · joined Sep 2002 ·
There are a couple of LPG VW camper/Kombis running around Adelaide though I haven't seen them myself.
There are actually 3 methods you could use to heat the converter.
1. Use hot oil as mentioned above. Lovato here in Adelaide advised me that this caused problems if you use the "right" sized converter, because the oil tends to stratify inside the converter (hot stuff stays in the middle of the fluid path), so you need to use an extra large converter so the oil stays in there long enough to extract enough heat - a 400hp converter instead of the normal 70hp one used for that sized engine. There is a lower volume of oil than there would be with water, but the oil is hotter, so the total heat transferance is about the same.
2. In the UK and Italy they use a fitting on the side of the muffler which "overheats" the liquid LPG so that when it's vapourised it's about at room temp. I don't like the idea of hot LPG in close proximity to hot exhasut gases, but it aparently works OK - I've spoken to an Italian guy with this system in his bug and he says it works fine.
3. Using hot air instead of hot water to heat the converter. The Fesgroup in Wales UK has used this method on a few VW campers. They use one side of the cabin heater air supply from the fan shroud (you could also use an electric blower) to direct air through a "muff" welded along the muffler and then the heated air is piped to a canister fixed over the back of the (Lovato) converter. I believe that they open up the "water" path in the converter (you can do this with the Lovato style of converter without compromising the rest of the assembly) so you get better heat transferance.
I'd love to do it with my bug, but money and time are a problem. I've been driving LPG powered vehicles for over ten years now (currently a 1985 Ford Falcon), and it's a great fuel.
Regards
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.geocities.com/aussiebug1970/
There are actually 3 methods you could use to heat the converter.
1. Use hot oil as mentioned above. Lovato here in Adelaide advised me that this caused problems if you use the "right" sized converter, because the oil tends to stratify inside the converter (hot stuff stays in the middle of the fluid path), so you need to use an extra large converter so the oil stays in there long enough to extract enough heat - a 400hp converter instead of the normal 70hp one used for that sized engine. There is a lower volume of oil than there would be with water, but the oil is hotter, so the total heat transferance is about the same.
2. In the UK and Italy they use a fitting on the side of the muffler which "overheats" the liquid LPG so that when it's vapourised it's about at room temp. I don't like the idea of hot LPG in close proximity to hot exhasut gases, but it aparently works OK - I've spoken to an Italian guy with this system in his bug and he says it works fine.
3. Using hot air instead of hot water to heat the converter. The Fesgroup in Wales UK has used this method on a few VW campers. They use one side of the cabin heater air supply from the fan shroud (you could also use an electric blower) to direct air through a "muff" welded along the muffler and then the heated air is piped to a canister fixed over the back of the (Lovato) converter. I believe that they open up the "water" path in the converter (you can do this with the Lovato style of converter without compromising the rest of the assembly) so you get better heat transferance.
I'd love to do it with my bug, but money and time are a problem. I've been driving LPG powered vehicles for over ten years now (currently a 1985 Ford Falcon), and it's a great fuel.
Regards
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.geocities.com/aussiebug1970/
aussiebug Officially Full-On Dubber
246 posts · joined Sep 2002 ·
I meant to add a few more comments.
The VW engine runs hotter than a water cooled engine and the exhaust valves get a hard workout. Since the LPG arrives as a warmed gas, the engine no longer gets any evapourative cooling effect like you do with petrol, so it tends to run a little hotter - the exhaust valves could therefore be a problem, and should be changed more frequently than the usual 50,000 miles or so. Bob Hoover (VW guru) in the USA did some test on a VW engine on LPG and found that exhaust valve wear was higher than running on gasoline.
LPG has an octane number of about 104, so if you were to run the engine solely on LPG you could increase the compression ratio to about 8.5 or 9:1. This would recover most/all of the power loss which normally happens with LPG. This power loss occurs because the vapourised LPG takes up more space in the induction than petrol droplets (less air supply means less oxygen to burn the mixture.)
LPG has a slightly lower flame speed than petrol, so you should increase the advance a little. If running dual-fuel, you can only increase it slightly (from say 7.5 to 10BTDC) otherwise when running on petrol the engine will ping/detonate. But running on LPG alone you can increase the timing another degree or so.
It would probably be wise to run a one-step colder spark plug.
You would need to check with the rego people about location of an LPG fuel tank in the bug. I believe that it's not legal to mount it in front of the driver (I may be wrong on this), so it might HAVE to go in the "cat box" behind the rear seat. This is quite safe, though laws in SA at least require that any carpet be stripped out from under the tank - it has to be direct-mounted on metal. That would remove a lot of soundproofing, so you might have more engine noise.
Regards
Rob
The VW engine runs hotter than a water cooled engine and the exhaust valves get a hard workout. Since the LPG arrives as a warmed gas, the engine no longer gets any evapourative cooling effect like you do with petrol, so it tends to run a little hotter - the exhaust valves could therefore be a problem, and should be changed more frequently than the usual 50,000 miles or so. Bob Hoover (VW guru) in the USA did some test on a VW engine on LPG and found that exhaust valve wear was higher than running on gasoline.
LPG has an octane number of about 104, so if you were to run the engine solely on LPG you could increase the compression ratio to about 8.5 or 9:1. This would recover most/all of the power loss which normally happens with LPG. This power loss occurs because the vapourised LPG takes up more space in the induction than petrol droplets (less air supply means less oxygen to burn the mixture.)
LPG has a slightly lower flame speed than petrol, so you should increase the advance a little. If running dual-fuel, you can only increase it slightly (from say 7.5 to 10BTDC) otherwise when running on petrol the engine will ping/detonate. But running on LPG alone you can increase the timing another degree or so.
It would probably be wise to run a one-step colder spark plug.
You would need to check with the rego people about location of an LPG fuel tank in the bug. I believe that it's not legal to mount it in front of the driver (I may be wrong on this), so it might HAVE to go in the "cat box" behind the rear seat. This is quite safe, though laws in SA at least require that any carpet be stripped out from under the tank - it has to be direct-mounted on metal. That would remove a lot of soundproofing, so you might have more engine noise.
Regards
Rob
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com
splitbusaustralia Wolfsburg Wizard
487 posts · joined Aug 2002 ·
I converted a bay bus to duel fuel a few years ago...the valve wear problem is somewhat relieved by introducing an upper cylinder lubricant through a venturi in the carb......flashlube has a kit for this..
aussiebug Officially Full-On Dubber
246 posts · joined Sep 2002 ·
Some details of the conversion (vapourise warming et al) would be great.
You don't have it now?
You don't have it now?
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com
squarebacker Learner Dubber
7 posts · joined Sep 2002 ·
Thanks for the feedback. I was somewhat inquisitive about the possibility of a LPG conversion, for perhaps a very future date.
A Couple of sites on the net:
KAMPAMANS LPG PAGE A Beetle conversion with some pic's
AUTOGAS LPG Conversion Kits
[Edited on 4-11-2002 by squarebacker]
[Edited on 5-11-2002 by squarebacker]
A Couple of sites on the net:
KAMPAMANS LPG PAGE A Beetle conversion with some pic's
AUTOGAS LPG Conversion Kits
[Edited on 4-11-2002 by squarebacker]
[Edited on 5-11-2002 by squarebacker]
67Deluxe Casual Dubber
32 posts · joined Aug 2002 ·
Hi,
You might not be interested in this, but a guy i work with a couple of years ago put a golf engine in his kombi and then converted it to gas. He said he hasn't lost and power and it's been going for years and it wasn't very much money to convert. Just thought you might be interested.
Cheers.
You might not be interested in this, but a guy i work with a couple of years ago put a golf engine in his kombi and then converted it to gas. He said he hasn't lost and power and it's been going for years and it wasn't very much money to convert. Just thought you might be interested.
Cheers.
splitbusaustralia Wolfsburg Wizard
487 posts · joined Aug 2002 ·
It was my brother-in-laws work bus - yellow 76 kombi.
Just welded a pipe the exhaust and ran it through the vaporiser. Vaporiser was set up for this (of Italian origin?). Wasn't carrying exhaust - just heat - seemed to work OK.
LPG only conversion, tank in cargo section of bus (legality?), introduced flashlube via a drip (titration) system through a venturi in the carby (most LPG only carbies have a couple of spare venturis).
Had to do the heads once after about 20k miles - but they were the orig heads which we didn't touch when converting.
Not sure what happened to the bus...not sure what's happened to my brother-in-law come to that (they've be in the far north west for years now....)
Just welded a pipe the exhaust and ran it through the vaporiser. Vaporiser was set up for this (of Italian origin?). Wasn't carrying exhaust - just heat - seemed to work OK.
LPG only conversion, tank in cargo section of bus (legality?), introduced flashlube via a drip (titration) system through a venturi in the carby (most LPG only carbies have a couple of spare venturis).
Had to do the heads once after about 20k miles - but they were the orig heads which we didn't touch when converting.
Not sure what happened to the bus...not sure what's happened to my brother-in-law come to that (they've be in the far north west for years now....)
aussiebug Officially Full-On Dubber
246 posts · joined Sep 2002 ·
The method described in Squarebacker's link to the Kampaman's LPG site is No2 in my list of three alternatives (see my post above) for using LPG in an aircooled vehicle...overheating the liquid LPG before converting it to a gas.
Splitbus's description of his brother-in- law's kombi is method No3 in my post above.... using hot air to warm the converter instead of water. This is also the method sometimes used by the Fesgroup in Wales - see the link in Squarebacker's post above.
Splitbus - putting the LPG tank in the load area (open to the passengers) is quite legal in Aus - I have this method in my LPG powered Ford Falcon... in Aus the LPG tank has to have a sealed box on the side containing all the connections and this box must be vented to the outside of the vehicle through a 50mm pipe, so any leaks can not contaminate the interior of the vehicle. So the tank can go in with the passengers.
It's interesting to note that in the UK they sell do-it-yourself kits - anyone can fit LPG to their own vehicle.
Not so in Aus - it MUST be fitted by a licenced converter and a sticker attached to the vehicle with the converter's licence number and details - you also have to notify the rego people (in Sth Aus at least), and have red LPG stickers on both number plates, so emergency vehicles know about the LPG when attending a crash scene etc.
Although the UK system allows something of an "anything goes" conversion (questionable safety), it also creates a group of very knowledgable people out there - Yahoo has an LPG group which is frequented by a lot of UK guys with a lot of useful info to impart about using LPG - tuning, LPGmaps in the ECU and so on.
Regards
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.geocities.com/ausiebug1970/
Splitbus's description of his brother-in- law's kombi is method No3 in my post above.... using hot air to warm the converter instead of water. This is also the method sometimes used by the Fesgroup in Wales - see the link in Squarebacker's post above.
Splitbus - putting the LPG tank in the load area (open to the passengers) is quite legal in Aus - I have this method in my LPG powered Ford Falcon... in Aus the LPG tank has to have a sealed box on the side containing all the connections and this box must be vented to the outside of the vehicle through a 50mm pipe, so any leaks can not contaminate the interior of the vehicle. So the tank can go in with the passengers.
It's interesting to note that in the UK they sell do-it-yourself kits - anyone can fit LPG to their own vehicle.
Not so in Aus - it MUST be fitted by a licenced converter and a sticker attached to the vehicle with the converter's licence number and details - you also have to notify the rego people (in Sth Aus at least), and have red LPG stickers on both number plates, so emergency vehicles know about the LPG when attending a crash scene etc.
Although the UK system allows something of an "anything goes" conversion (questionable safety), it also creates a group of very knowledgable people out there - Yahoo has an LPG group which is frequented by a lot of UK guys with a lot of useful info to impart about using LPG - tuning, LPGmaps in the ECU and so on.
Regards
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.geocities.com/ausiebug1970/
67Deluxe Casual Dubber
32 posts · joined Aug 2002 ·
Nar, this bus wasn't your brothers, Peter Shelley from the Canberra VW Centre, http://www.cvwc.com.au/ (really good mechanic by the way) did it and the friend that owns it has had it since.
You guys should check out the site, Peter's done some pretty amazing stuff!
Cheers,
Tim.
You guys should check out the site, Peter's done some pretty amazing stuff!
Cheers,
Tim.
KruizinKombi Seriously Obsessed Cyber Dubber
3,493 posts · joined Aug 2002 ·
There is another option: LPG fuel-injection. The still-liquid fuel is injected just like in a normal petrol setup, but atomises much more efficiently than petrol. No problems with fuel falling out of suspension like in a petrol motor. I've even seen purpose-made injectors that used a blast of compressed air to really atomise the fuel, although I think this is probably overkill. (Found them on the internet years ago)
Kruizin Kol
aussiebug Officially Full-On Dubber
246 posts · joined Sep 2002 ·
Yes - LPG fuel injection is possible, but it's not as easy as you might think.
First - it vapourises very easily at engine temps and so the injection system must be insulated from engine heat, or you'll have gaseous LPG in the injector lines rather than liquid. So the induction manifold has to sit on insulating seals. The whole injector rail has to be insulated further, and probably even cooled to keep it at about room temp.
Second - the pressure in the LPG tank varied with the temperature of the LPG, which will result in different amounts of LPG being injected for the same timed opening of the injector, so you have to have sensors and an ECU map which can cope with this. Petrol engines use a pressure regulator and feedback loop to run excess fuel back to the tank so you have a constant pressure in the fuel rail - harder to do with LPG.
There is a company here in Adelaide who have been trying to get a dual fuel injection system working so you can feed either petrol or LPG into the same injector rail for instant changover, and so far have not been successful.
There is a university group in the USA who studied LPG injection a couple of years ago - I found a URL (but don't have it now) - very interesting and highly technical information. They determined that it was possible, but very difficult, to do.
First - it vapourises very easily at engine temps and so the injection system must be insulated from engine heat, or you'll have gaseous LPG in the injector lines rather than liquid. So the induction manifold has to sit on insulating seals. The whole injector rail has to be insulated further, and probably even cooled to keep it at about room temp.
Second - the pressure in the LPG tank varied with the temperature of the LPG, which will result in different amounts of LPG being injected for the same timed opening of the injector, so you have to have sensors and an ECU map which can cope with this. Petrol engines use a pressure regulator and feedback loop to run excess fuel back to the tank so you have a constant pressure in the fuel rail - harder to do with LPG.
There is a company here in Adelaide who have been trying to get a dual fuel injection system working so you can feed either petrol or LPG into the same injector rail for instant changover, and so far have not been successful.
There is a university group in the USA who studied LPG injection a couple of years ago - I found a URL (but don't have it now) - very interesting and highly technical information. They determined that it was possible, but very difficult, to do.
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com
KruizinKombi Seriously Obsessed Cyber Dubber
3,493 posts · joined Aug 2002 ·
Yeah Rob, I looked into it years ago - the reasons you mentioned are just some of the reasons why I haven't done it yet!! 😉
Good explanation though :thumb
There was an article published in one of the "Falcadore" magazines maybe 5-10 years ago about a company who had successfully built a prototype of a dual-fuel EFI system for a Commodore. It was from memory production-ready, but I don't know if they actually sold any or not, I've never seen one. Then again, I don't often stick my head under the bonnet of a Commodore either! 😀
Good explanation though :thumb
There was an article published in one of the "Falcadore" magazines maybe 5-10 years ago about a company who had successfully built a prototype of a dual-fuel EFI system for a Commodore. It was from memory production-ready, but I don't know if they actually sold any or not, I've never seen one. Then again, I don't often stick my head under the bonnet of a Commodore either! 😀
Kruizin Kol