Thread: Dual fuel-propane and gasoline

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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

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..The 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..I 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...

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.

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.

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....

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

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.

I was parked on Roger's reply when I quoted.Thanks Dave and Jerry for your input.

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

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!

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.

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.

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.

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.

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....Ill stick to what I have got,it works for me..