Dual fuel-propane and gasoline

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04-17-2011, 11:39 PM
1gary

Dual fuel-propane and gasoline

Well Dave kind of brought this question to light.Dual fuel-propane and gasoline.He was saying in his gasser thread the thought of using propane for his tow rig.I went to the Indian reservation to buy cigarettes which is about 40 miles away from Roch,NY.While there I got some gas and even there it was 3.70's per gallon.The propane was 2.59 a gallon.I have been concerned about the gas pricing and how it will effect my project 383 sbc Astro van which I am building as a tow van for my traveling business.

So I don't know anything about dual fuels like this.I would want to have the option of either propane or gas if I got to a area where I couldn't get a refill on propane.I have intended to use a TBI.

Does anyone build a system using a TBI??.How do they work??.Just for the sake of discussion,lets say I figured a way to get a 100lb tank mounted,what kind of gas mileage could I expect??.If propane burns hotter to create more torque,does it have a effect on the engine long term??.If I have to run a high compression engine to run propane,does that mean I have to run high test gas when I can't refill with propane and that fact would cancel any savings using propane??.

All these questions aside,I still need to know how dual fuel systems work.How is the propane introduced to the intake of a engine??.What does it take to make this conversion??.

Thanks
04-18-2011, 02:36 AM
lamin8r

Gary,you guys dont appear to run a lot of propane up there,,I suppose its because you have always had cheap petrol..
We have it down here for an alternative to petrol,and we produce the stuff in large quantities..:DThe system I have,was built for American engines...Its IMPCO brand,works well on the 302w,will work better on the new engine with higher CR..The Australians make a good kit,and in fact,they produce 6cyl.and V8 Ford Falcons dedicated LPG,from the factory..[All injected]
It pays to run hardened valve seats in an LPG engine,you shouldnt need a higher CR with an injected engine,as I think most computers have an anti-knock sensor to adjust themselves to different fuels..
On a carburetted engine,the LPG is routed through the carb,like the petrol,but it is necessary to purge from one fuel to the other,cos they dont like each other..:DI am no mechanic,so I cant tell you the ins and outs of the workings of it,apart from,when I switch from petrol to LPG,I flick a switch,and as soon as the engine starts to run out of fuel,throw the switch to the other side..[three position switch]
I have an 80 litre tank on my truck,which,because of regulations,is only filled 80%..about 68 litres..I can do a little over 4 hours driving on that tankful..You do use a little more LPG as against petrol,but the difference in price down here,means we go further,or we go more often in the truck,than the car..[I make a $100 saving over petrol on an eight hour trip]
Probably no help to you,but I have a friend,who was up in Chicago somewhere,Murray Thomas,who worked for Rod Millen,in Ca.,for several years..He moved up there and set up a business,Ithink it was called TAD,,Thomas Auto Development.When Murray was still down here,living in Auckland,he ended up running the LPG dept.of the Ford dealer he did his apprenticeship with..He would be the guy to talk to..Are there no dealers/LPG fitters in New York??
I hope this is of some use to you,Gary..I think its a darn good fuel,and if the fitter knows what he is doing,there should be no probs..Maybe we need to send some Kiwis up there and start converting you guys to dual fuel...:D
04-18-2011, 04:18 AM
rspears

Gary,
There are a lot of US companies doing Propane/LPG conversions, and I'm sure when you start digging there will be dual fuel, switchable systems, too. In the midwest we've had propane run trucks for years - I remember seeing cars and trucks that had propane tanks back in the 50's. Here's the first listing when googling Propane Conversion Kits, Propane Conversion Kits – Convert Car to Propane – LPG Vehicle Conversion
and there are selections there for kits, DIY kits, and companies that do the deal.
04-18-2011, 05:53 AM
Smiliesafari

Hey Gary........Some years ago I did some research on propane conversion and the one thing that changed my mind was the fact that the cost was not worth the change over. I was told by a conversion dealer that the only cost saving came if you had a fleet of vehicles. Here in FL the price of propane is always neck in neck with gas. No real savings there either.
04-18-2011, 06:44 AM
Dave Severson

The dual fuel conversion is more expensive and requires comprimises when using either fuel....With straight propane the compression can be higher, more timing, more cam, more power! Went for a ride Sat. afternoon with a guy who has the straight propane conversion on his 460 Ford in a one ton, lots more power then my 460 on gas. Still searching for the "right" pieces for mine, sending a spare set of heads to the shop today for freshening along with some super hard seats and stellite exhaust valves. I'm doing the conversion on a 100,000 mile plus engine that needs to be freshened anyway, so the cost of the pieces needed to run propane will be more then offset by the gains in performance and mileage....

The numbers I played with showed the dual fuel conversion to be more spendy, less efficient, and a much slower return on the cost of the conversion. Also, because I'm doing this on a 1 ton cube van, I've got lots of room for a bigger tank, or even dual tanks so I'll have plenty of range and not have to worry about landing someplace that doesn't have propane. A bit of planning makes availablility a non-issue....
04-18-2011, 07:16 AM
jerry clayton

remember that 100# is the equal of only 12-15 gallons which will get you maybe 100 miles----straight gasolene or diesel is the way to go until we get to natural gas in widespread areas and the MONEY people of the world ain't going to let that happen
04-18-2011, 09:47 AM
1gary

Quote:

Originally Posted by rspears

Gary,
There are a lot of US companies doing Propane/LPG conversions, and I'm sure when you start digging there will be dual fuel, switchable systems, too. In the midwest we've had propane run trucks for years - I remember seeing cars and trucks that had propane tanks back in the 50's. Here's the first listing when googling Propane Conversion Kits, Propane Conversion Kits – Convert Car to Propane – LPG Vehicle Conversion
and there are selections there for kits, DIY kits, and companies that do the deal.

Thanks Roger.I am looking at that link to see what I can learn from that.
04-18-2011, 09:54 AM
1gary

I was parked on Roger's reply when I quoted.Thanks Dave and Jerry for your input.
04-18-2011, 12:18 PM
lotsatoys

Back in the mid 70s I worked for a company in Tampa Florida (Dancy company) that did all things propane. it was the height of the "gas shortage" so we had all the business we could handle. the company did the conversions for all the local phone company trucks, and they survived well over 200,000 miles on straight propane. pull the pan on one of those and it was clean as the day it was built.
the dual fuel conversions were mostly IMPCO and were a simple ring that went between the air filter and carb somewhat like the early nitros kits. I doubt I would even recognize the propane technology today, but the principal would be the same.

Russ
04-18-2011, 05:40 PM
R Pope

I had a 318 Dodge Ram on propane.Watch what you wish for, you might get it!
70 MPH top end, 12 MPG equivalent dollar-wise, and a real hassle to find a station that sold propane on a trip. Plus it didn't run when it got real cold out. Sure, I never had to do anything to the engine, like plugs and such, but I was happy as a clam when I trashed the whole works and put a hi-rise and AFB on it. I wouldn't have another propane setup as a gift!
04-18-2011, 07:36 PM
NTFDAY

LPG was fairly popular here about the time of the gas shortage until some idiot in a pickup went through one of the local car washes. I don't remember the exact particulars except that a part of the car wash equipment got entangled with a hose on the tank or some such thing. The result was a major KA-BOOM which leveled the car wash and killed one, if I remember right, and injured a few more and they had to send out a search party to find parts of the truck. I'll stick with gasoline.
04-18-2011, 08:30 PM
1gary

Quote:

Originally Posted by NTFDAY

LPG was fairly popular here about the time of the gas shortage until some idiot in a pickup went through one of the local car washes. I don't remember the exact particulars except that a part of the car wash equipment got entangled with a hose on the tank or some such thing. The result was a major KA-BOOM which leveled the car wash and killed one, if I remember right, and injured a few more and they had to send out a search party to find parts of the truck. I'll stick with gasoline.

Really not to open a can of worms,but it is for that very reason I have done my level best to discourage the shade tree built hydrogen generator systems.That stuff is nothing to fool around with.The companies trying to sell that are full of haft truths and are just plain out dangerous.

If I did make a move to a dual fuel system,it would be a manufactured system from a company that had a long,long,history installing them.

I am listening to you guys very closely.Seems it would not be a very good move.The question of space for tanks I was thinking because this is a cargo conversion high top van,I could build in one each side high towards the rear a 100lb tank.The slider door is going to get shaved.But then dang,I have just added two hundred lbs to the van which would use more fuel.Sure seems it would be like a dog chasing his tail.
04-18-2011, 09:09 PM
Dave Severson

I'm waiting on some information and don't claim to be an expert, but from the data I've seen, dual fuel systems end up being two systems that are comprimised to allow the other system to work... Lots of places to buy propane, I'm going straight propane with an eye on converting to natural gas in the future.
04-18-2011, 10:36 PM
1gary

Quote:

Originally Posted by Dave Severson

I'm waiting on some information and don't claim to be an expert, but from the data I've seen, dual fuel systems end up being two systems that are comprimised to allow the other system to work... Lots of places to buy propane, I'm going straight propane with an eye on converting to natural gas in the future.

Yeah Dave,

Natural gas is sold per thrum.So I don't know the conversion to gallons would be made to compare mileage.If you knew in advance the distance you where going,maybe you could build a system that with some extra would cover the trip and fill up at home.Around here they let people put in a extension service for a BBQ,so it really would be that hard to have a valve to fill up.But again,you would need to find out what the mileage per fill up.I don't blame you wanting to find a cheaper fuel.The 460's we have had before where great tow rigs,but not too good for gas mileage.
04-19-2011, 03:04 AM
lamin8r

This is an interesting thread...Probably because of the different experiences you guys have had in the past with propane/LPG..
R Pope,,was it dual fuel??and it didnt like running in the cold??Different..mine loves the cold temperatures better than the warm,in fact,its a real hassle when the day is hot..so much so,that I am going to rig up a cold air box and ram air to the carby..Yes,on petrol,my little 302w goes better than LPG,but,I would rather run LPG because of the savings on a trip..so its tuned for LPG..
NTFDAY,,Dont know about you guys,but we have the mother of all inspections,tests down here,,in fact,you can fit your own system,but it has to be tested/checked out by a registered LPG fitter before it can be used..and a yearly warrant of fitness check,[and the tanks are pressure tested every ten years,,just did mine yesterday,,systems all go again.]to make sure everything is hunky dory,,plus,as we have a Warrant of fitness check every 6 months on cars/vans etc over 5 years old,if you dont have a current LPG WOF,you dont get a wof for the vehicle..$150 fine if caught without one..
Dave S..We also ran CNG[compressed natural gas] down here,,has an even higher octane rating,from memory..was dirt cheap,and only did about HALF the distance that LPG or petrol did..in fact,I think it worked better in the tests they did on our aging diesel bus fleet,,although that didnt last long either..:D..Ill stick to what I have got,it works for me..
04-19-2011, 05:51 AM
R Pope

lamin8r, my Dodge was supposed to be dual fuel but the PO never used the gasoline EFI so it was all clogged up and disconnected. At -40, I had to drive something else, the propane wouldn't flow.
Another thing...with any pressurized gas, you can't use underground parking, and they get all hyper when you drive on a closed ferryboat. They make you shut off the tank valve as soon as you stop. And I've been told, but never looked in to it, that if your garage goes up in flames with a propane vehicle in it, there's no insurance. Which all seems strange when you consider how many little forklifts there are in big warehouses that are running on propane so the monoxide doesn't kill everybody!
BTW, you are talking LPG gas, which is a different animal altogether from propane. Thousands of pounds pressure in the tank instead of less that a hundred with propane. Around here, you need a megabuck compresser to use that stuff. A neighbour had a test setup installed for free, and he still said it didn't pay! He ran all his tractors on LPG, as well as his road vehicles. In busy farming seasons, the compresser couldn't keep up with the demand of all the machines needing fuel every night.
No, thanks, I'll stick with gasoline!
04-19-2011, 05:55 AM
R Pope

Rereading posts, I think I have mixed up LNG with LPG a few times.
04-19-2011, 12:55 PM
lamin8r

Quote:

Originally Posted by R Pope

Rereading posts, I think I have mixed up LNG with LPG a few times.

I know where you are coming from,,each to his own,and yes,regarding mix up,,I THINK the LNG is a problem child,,we dont have that down here[I dont think so],but there has been talk of an LNG installation at our little port of Taranaki,and no one wants a bar of it...:eek: because of that reason,,the pressure,and what would happen if it all went tits up..New Plymouth would disappear..[only get mauled a bit with LPG]I think that one of the reasons why the LPG has been a real good deal down here,is the distance we are from oil producing countries,even though we have the oil down here,its the cost of exploration,so the gas side has been put to good use..
04-19-2011, 01:23 PM
lotsatoys

As to hoses being ripped of and the vehicle exploding........ any _proper_ installation will have an excess flow valve in the tank outlet which makes this type of issue almost impossible. much less likely than a gas vehicle having a hose ripped loose and the vehicle bursts into a ball of flame.
Only in Hollywood.

Russ
04-19-2011, 01:53 PM
RestoRod

I visited Las Vegas back in the 70's and, IIRC, the taxi driver we rode with mentioned that his taxi was running on Natural Gas. As a matter of fact, he thanked us as Canadians since the gas came from Alberta and he said he was saving a lot of money using it.:)
04-19-2011, 05:07 PM
Dave Severson

Well you know it's a cinch nothing has been changed or improved since the original stuff came out!!!!!:rolleyes:

Kind of like in the early 1900's when many were sure that automobile thing was just a whim and they'd stick with their horses?????:LOL::LOL::LOL:

40 years ago, before the takeover in agricultural self-powered implements with the diesel engines, many, many farmers were running dual fuel LPG and gasoline as a cost savings measure.... worked fine then! And now, some of these "idiots" running diesels are actually trying bio-diesel!!!!! Then we could go back to my original statement and they could just run a really nice team of Strawberry Roan workhorses and life would be much better, right???? Trying new things is both interesting and educational.....and sometimes they actually work out!
04-19-2011, 05:29 PM
lamin8r

Just think,Dave..if ya tried to hitch up a pair of work horses now,there would be some namby pamby action group would probably try to get you into court for exploiting dumb animals...:LOL::LOL:
04-19-2011, 05:32 PM
Dave Severson

Quote:

Originally Posted by lamin8r

Just think,Dave..if ya tried to hitch up a pair of work horses now,there would be some namby pamby action group would probably try to get you into court for exploiting dumb animals...:LOL::LOL:

Probably....
04-19-2011, 06:15 PM
NTFDAY

Quote:

Originally Posted by lotsatoys

As to hoses being ripped of and the vehicle exploding........ any _proper_ installation will have an excess flow valve in the tank outlet which makes this type of issue almost impossible. much less likely than a gas vehicle having a hose ripped loose and the vehicle bursts into a ball of flame.
Only in Hollywood.

Russ

I hope you're not calling me a liar!
04-19-2011, 07:00 PM
lotsatoys

Quote:

Originally Posted by NTFDAY

I hope you're not calling me a liar!

absolutly not. sorry if you took it that way. just saying a _proper_ installation makes a propane system very very safe, and nearly impossible to make explode. then again.... anything can and does happen under the right set of cercumstances (no matter what the fuel).

Russ
04-19-2011, 07:55 PM
Dave Severson

Found some good information here;

Main Page - Raso Enterprises Auto Parts
04-19-2011, 11:33 PM
Dave Severson

yeah, and now the by product costs more then the product they're refining for......Never have figured out how that works!!!!!
04-20-2011, 05:48 PM
R Pope

Dave..I wonder how many "Strawberry Roans" I'd need to pull my 44 foot air seeder? Or 60' of harrow/packer hitch?
I'd have to seed my whole farm to horse feed to keep 'em alive, and what would keep me alive?
Well, at least this year I'd have lots of water for 'em! 200 acres a couple of feet deep!
04-20-2011, 06:08 PM
Dave Severson

Quote:

Originally Posted by R Pope

Dave..I wonder how many "Strawberry Roans" I'd need to pull my 44 foot air seeder? Or 60' of harrow/packer hitch?
I'd have to seed my whole farm to horse feed to keep 'em alive, and what would keep me alive?
Well, at least this year I'd have lots of water for 'em! 200 acres a couple of feet deep!

Wow!!! You guys have some big time flooding again, huh??? Do they offer "no plant" insurance up there? Brother in law farms all his land and mine, sez he'll be out about 160 acres this year from the water.....
04-21-2011, 02:31 AM
R Pope

Dave... there is a "flooded acres" deal with crop insurance that purports to give you 100 dollars an acre but the last time we got drowned like this, I applied for it and after all the tookage and screwage I got about 500 bucks! I run without that gov't program now. It takes a total failure just to get the premium back.
04-21-2011, 06:42 AM
Dave Severson

Quote:

Originally Posted by R Pope

Dave... there is a "flooded acres" deal with crop insurance that purports to give you 100 dollars an acre but the last time we got drowned like this, I applied for it and after all the tookage and screwage I got about 500 bucks! I run without that gov't program now. It takes a total failure just to get the premium back.

Yeah, it's a bit expensive, going to be glad we had it this year!!! The acres under water are of course the best yielding acres on the whole place!!!
04-22-2011, 03:00 AM
spikeo

Quote:

Originally Posted by Dave Severson

Yeah, it's a bit expensive, going to be glad we had it this year!!! The acres under water are of course the best yielding acres on the whole place!!!

wasnt this about gas?!:LOL:

I think the gas(LPG) story is similar here as it is in NZ as lamin8r said. I have dual fuel on my ute but only really run on gas unless i run out. I know a guy who runs a blown 502 on straight gas and its fine-no need to decompress to boost LPG either!

straight is better than dual you need to compromise with both to make either work ok. you can get propane over here and it supposably works better or more millage but ive only used it once so not enough to compare.

we're payin abou 65c a litre compared to petrol at nearly $1.50 per litre-easter doesnt help fuel prices.That is per LITRE so it sounds cheap to you guys!:LOL: Over here they are running lpg together with diesel to get running costs down on highway trucks but they are combined not one or the other.
04-22-2011, 11:29 AM
HOSS429

1 Attachment(s)

this 429 ford has been powering the emergency generator here at work for 30 years .. runs on LP .. it self starts once every week for about 5 minutes .. ..
04-22-2011, 02:45 PM
spikeo

ill gladly take it off their hands! a guy down here picked up a 460 from a similar gen. only done low hours too
04-22-2011, 06:35 PM
HOSS429

Quote:

Originally Posted by spikeo

ill gladly take it off their hands! a guy down here picked up a 460 from a similar gen. only done low hours too

iv`e been here 22 years and iv`e never seen a gas truck fill the tank for this thang .. :p
04-27-2011, 07:53 AM
fraso

Dual Fuel Systems
To answer the OP's question about dual fuel systems and TBI, the propane system still requires the use of a mixer to supply propane to the engine. The difference between a propane mixer and a propane carburetor is that the carburetor has throttle valves (usually using the throttle body from a gasoline carburetor) in addition to the mixer. Therefore, a straight (mono-fuel) propane system replaces the gasoline carburetor with a propane carburetor. A dual fuel system adds a mixer (typically upstream) of the gasoline carburetor and solenoid valves on the fuel lines determine which system supplies fuel to the engine. As described by lamin8r, you switch back & forth between fuels with a 3-position switch that energizes the appropriate solenoid valves.

Mixers are used with carburetor and TBI engines. Multiport EFI engines are best converted with injection conversions. That is, rather than having a mixer fumigate propane into the intake manifold, an injection conversion adds a parallel injection system to the engine and has propane injector nozzles installed at the intake ports. Although theoretically possible to have propane port-injection with a gasoline TBI system, there are no commercial systems that do this. Technocarb still makes dual fuel TBI conversions.

On an energy basis, a gallon of propane has about 74% of the energy of gasoline. However, open-loop propane mixer systems typically get more like 75-80% of the vehicle's gasoline economy. Feedback systems generally get better fuel economy than open-loop systems. Because of the lower energy content of propane, propane needs to priced much less than 74% of the price of gasoline to have a reasonable payback on the conversion. The lower price should still make up for the slightly lower fuel economy from the additional weight of the propane tank.

The retail price of propane is usually very high compared to gasoline because there is high margin on small volume sales (like 20# BBQ cylinders). To get a much better price on motor fuel, you would have to get an account with a propane supplier. For example, Ferrell Gas in Buffalo, NY is selling propane for $2.35/gallon (winter price), which is their first quantity break (1000-5000 gallons/year). If you would have locked-in the price last summer when the market was low, your price for this year would have been $1.95/gallon. The taxes on motor fuel in NY state amount to $0.2635/gallon so your total price for propane could have been $2.2135/gallon.

Do NOT use a 100# cylinder in an on-road vehicle. It is illegal and will not pass NPFA 58. Only use ASME motor fuel tanks for on-road applications.

Propane burns marginally hotter than gasoline. It has a different flame speed than gasoline so it is very important to use a propane-specific advance curve. This is a bit more challenging to do with dual fuel systems now that Dual Curve is gone but there are alternatives.

Although you can increase your CR to take advantage of propane's 104 octane rating, it is not necessary. For street engines, a 10:1 CR will work well and you keep high-test gasoline in the tank for dual fuel systems. With a dual fuel system, you would primarily be using gasoline to keep it from becoming stale so the added cost of high test would really be negligible.

If you travel long distances, it is a good idea to plan your trips around fuel stops. Propane is plentiful in the USA, but cheap fuel is what you're after. Check the following sites for alternative fuel locations: