Propane 4.0ho

[UKJeeper1]

UKjep1, how many litres does that petrol tank hold may I ask? Never seen a setup like that here in Oz but run a bigger rear LPG tank.
Here at the moment, LPG is not allowed to be sold for more than 1/2 the cost of petrol.
I would love a shot of the donut tank in place of the spare if you can get one too. How many litres does it hold as well?

Gojeep, IIRC its about a 45 liter tank. As i hardly fill it up anymore, i don't really remember. It pretty much starts and runs on LPG with no warm up, i just keep the petrol as a "reserve" in case i can't find an LPG station at the time i need it. The LPG tank is good for about 180 miles (150 when towing), and the petrol got me about another 150 miles last time i ran just petrol to see what distance i could get.

One issue with the dual fuel is that you can't let the perol tank run dry then switch to LPG. The petrol pump will still run (as the engine is going) and burn itself out, apparently)


Found this pic of a donut tank when googling:

More pics here

 

[dan89XJ]

UKJeeper1, nice pics.. looks good

Are those the original gas tank straps ? if so.. that must mean that ground clearance was not lost in the upgrade ?

 

[Gojeep]

Thanks for the info mate. I have never seen a donut tank mounted like that before as here they lay them flat inside of a spare wheel in the boot of cars. Strange that your filler is mounted next to the petrol flap as all gas fillers here on XJ's have it mounted behind the flap next to the petrol filler. You just have to move the petrol one over a bit first and is a much cleaner install. They say for the donut tanks that they are 10-12 gallons which I take to be UK ones? So that would mean 45 to 55 litres then.

 

[UKJeeper1]

Found the installation docs today as i was cleaning up the garage. The LPG tank is 70 litres. We don't really have a default location for fillers. Can be found all over. I think 10-12 gallons is about 45 liters or so. As i think said elsewhere, a friend of mine has the underfloor AND the donut tank.

 

[calvin andrus]

My main concern/problem right now is figuring out what exactly I need to do and get to do this conversion, the motor that I have is a 95' 4.0 HO and its going into a suzuki buggy but it doesn't sound like anyone on this forum has actually done a homebuilt (using forklift parts) straight propane conversion on a 4 liter. Like I said earlier, my buddy did a homebuilt conversion on a carburated toyota 4 cylinder for like under 300 dollars and thats what I'm looking to do to my 4 liter, although it will be a little more involved with a fuel injected motor. Thanks everyone for your ideas and experience.
- cal

 

[UKJeeper1]

As i mentioned before, go poke around on Pirate4x4.com. Theres tech articles and a huge forum.

 

[calvin andrus]

Yeah I have already been doing some research over on pirate, still haven't come up with exactly what I'm looking for but you know how searching a database as large as that can go, a little overwhelming sometimes.
thanks
-cal

 

[ECU88XJ]

My main concern/problem right now is figuring out what exactly I need to do and get to do this conversion, the motor that I have is a 95' 4.0 HO and its going into a suzuki buggy but it doesn't sound like anyone on this forum has actually done a homebuilt (using forklift parts) straight propane conversion on a 4 liter. Like I said earlier, my buddy did a homebuilt conversion on a carburated toyota 4 cylinder for like under 300 dollars and thats what I'm looking to do to my 4 liter, although it will be a little more involved with a fuel injected motor. Thanks everyone for your ideas and experience.
- cal

I have not done it but have done a fair amount of reading on it.


You should need a mixer (most likely with an adapter), regulator and a lockoff. Hoses to connect them and tank(s).

The most common setup i've read about is an impco 425 mixer, model e reg and vff30 lockoff

You could either locate this stuff in a forklift junkyard or http://www.propaneguy.com has good prices on rebuilt pieces.

For simplicity's sake it would probably be easiest to use a 4.2(carb'ed) manifold and distributor.

so you could probably search for 4.2 propane setups too.

 

[calvin andrus]

great, that is exactly what I'm looking for, I was also thinking the 4.2 manifold and distributor, now I just need to figure out some of the specifics, thanks for the info.
-cal

 

[bajacalal]

Just remember that certain forklift parts, stuff designed for a small motor may not work with the 4.0. If you use a carb thats too small, its going to be restrictive like putting a single barrel carb on a Chev. 454. Either way, yes looks like the most popular items for conversion are Impco 425 or 300 mixers (carbs) and Impco model E or J convertors (regulators) depends on the engine size plus the appropriate lockoff valve and other plumbings, do research, decide what you want then go look for it. Yes, you can find these used at Ebay and other sources. You will need to attach the carb to something with a throttle butterfly in order for it to work.

The plans I have drawn up include mounting propane carb horizontally and attaching it with a flanged tube (something I can build with the tools I have access to) to a bored RENIX throttle body and then adapting that to the later model manifolds which are a better design, again fabricate stuff as needed. Reason? The Renix has an adjustable throttle stop which would be helpful I think.

Also, yes, an older vac-advance 4.2 distributor but preferrably hook it up to an programmable aftermarket ignition controller.

I would also like to make the most efficient use possible of the propane motor so I am thinking 4.6 stroker (higher compression ratio more suited to propane) and set up the ignition timing to advance sooner for propane and maybe a different cam. I might be able to change the timing a little using an adjustable CPS (used on high altitude models).

I am even thinking of having dual system for emergencies, but gerared toward propane. The computer has to be fooled so it will regulate the ignition under propane carbureation right? How is this accomplished? Interrupt the injector grounds or a lockoff on the fuel line (gasoline) so that the pump runs but cycles fuel back into the tank (normal function of the pressure regulator) or switching off the pump entirely?

This is of course all a pipe dream but I would like to do this with a pickup like a Comanche so I can use a large tank and have lots of range, there are no places to fill LPG nearby so I would have to make a special trip for it. Yep, its illegal here to put the tank inside vehicles or even in a trunk unless the trunk is vented (portable tanks are an exception). Have you ever seen a propane tank fire, I have, I wouldn't want one in my Jeep but if it were outside it I could run away.

 

[Chancer]

there are no places to fill LPG nearby so I would have to make a special trip for it.

You could always get yourself a transfer pump - that way you can use bottled propane and put it into your jeep at home. Highly illegal here in Blighty, of course...

Have you ever seen a propane tank fire, I have, I wouldn't want one in my Jeep but if it were outside it I could run away.

I just don't get this - what's under the bottom of any normal car? A bloody great pressed steel bomb - 20 gallons of highly volatile hydrocarbons in the form of gasoline! Personally I'd rate my chances better with an LPG tank that's an extremely strong pressure vessel, certified to a standard and a damn sight tougher than any gas tank out there. Unless you own a Volvo.

Elliot's setup is really nice - I'm actually going down that route, using an auxiliary tank I got from a scrapyard. At the mo my 70 litre tank takes up a third of my trunk. One bit of info I got off the guy that installed mine is that he uses a 6cm thick chunk of steel in the trunk to bolt up and onto, so that both underbody tanks are securely mounted in the event of a shunt. Not many installers do that, but it's worth bearing in mind.

My setup is one of simple ones that mixes at the throttle body. Probably the easiest DIY route. My fuel consumption's about 17-22 per gallon (Imperial).

 

[Gojeep]

LPG is way safer that petrol! When I did my fitting course they had 4 cars with dual fuel lined up and put a tray under them with a fuel in it and lit it. All the petrol tanks exploded where as the fitted LPG tanks vented when the pressure got too high and then shut down again when it dropped. They did this a number of times until the fire burned out. None of the LPG tanks exploded!

 

[UKJeeper1]

I agree with these two, I much prefer the VERY thick stainless steel tank which replaced the plastic stock tank and tin foil tank guard. And thats just the petrol tank. In front of that is the propane tank, which is even thicker. I think the fuel (and the occupants) are in a much safer place after the conversion. Of course it IS possible to hit the car hard enough to cause damage to the propane tank, which is 3 feet away from the rear bumper, but i think to have any chance of doing enough damage to make it explode would have to involve AmTrak!

I've seen propane tanks on fire too. There was one alight in Brentwood, CA when i lived there. The heat from the fire pressurised the tank, opening the relief valve, which then released the contents as a column of fire straight up into the air.

 

[bajacalal]

You could always get yourself a transfer pump - that way you can use bottled propane and put it into your jeep at home. Highly illegal here in Blighty, of course...

It would be a good idea and I have heard of people doing this. However, here if you live in urbanized areas your gas is piped into the house like water (in this city its billed by the electric company) and its natural gas (mostly methane) not propane. There is a place about 5 min. away that is selling LP for US$ 2.50/gal. but I can buy unleaded for $2.65/gal. I could maybe get it cheaper if I go to where they have the big LPG tank about 15 miles away or even to Mexico where LPG conversions are popular. Here it would be very unique to have a LPG coversion so thats why I really want a bigger tank. But in order to take full advantage of the conversion cost I would need to get the cheapest LPG possible and longest range possible due to the conveinence factor, so I would prefer a 50 gal (190 L I think) tank which wouldn't fit in XJs.

I just don't get this - what's under the bottom of any normal car? A bloody great pressed steel bomb - 20 gallons of highly volatile hydrocarbons in the form of gasoline! Personally I'd rate my chances better with an LPG tank that's an extremely strong pressure vessel, certified to a standard and a damn sight tougher than any gas tank out there. Unless you own a Volvo.

Don't mean to be rude you guys all missed the point. I'm fine with having the fuel tanks outside the vehicle and recognize the lower flammability of LPG. I (and the government) consider underneath the Jeep "outside" the vehicle so thats fine. You can't anymore put a permanently connected (to the motor) fuel tank inside the passenger compartment doesn't matter if contains petrol, diesel LPG or CNG. Maybe I'm unreasonably leery of vehicle fires because my Jeep already caught on fire once (dashboard electrics, I stopped it though). No point in arguing about it, it would be illegal and even though its unlikely I'll be caught, I don't want to loose my cargo space plus where would I get the donut that isin't legal here?

Anyway its something I am very interested in so thanks for your help guys esp. if youre still getting 17-22 MPG in a Jeep on propane. Too bad its not common here, it would solve a lot of problems.

 

[Chancer]

Don't mean to be rude you guys all missed the point. I'm fine with having the fuel tanks outside the vehicle and recognize the lower flammability of LPG. I (and the government) consider underneath the Jeep "outside" the vehicle so thats fine. You can't anymore put a permanently connected (to the motor) fuel tank inside the passenger compartment doesn't matter if contains petrol, diesel LPG or CNG. Maybe I'm unreasonably leery of vehicle fires because my Jeep already caught on fire once (dashboard electrics, I stopped it though). No point in arguing about it, it would be illegal and even though its unlikely I'll be caught, I don't want to loose my cargo space plus where would I get the donut that isin't legal here? QUOTE]

I wasn't having a go at you at all - it sounds like the legislation you speak of is quite sensible. In the UK we don't go quite as far, in that an LPG tank can be fitted inside: however they draw the line at, say, putting a donut tank in place of the spare on the back door of Discoveries and the like. I was simply having a general rant based on a few ill thought out comments I've seen on these boards saying things like "I'd never want a bomb under my jeep".

Is there much difference in propane and gas costs where you are? It's the one reason why people convert over here, as we're currently paying 92p per litre for gas (95 petrol) and 39-41p for LPG. I worked out that it would be worth paying for a conversion if you were keeping your car for more than 15,000 miles. I know that in Canada propane's also about half the price of gas, which is making me think that I'll just shove my jeep into the container when we emigrate there!