Thread: dual fuel question

Hi, we had a '77 Range Rover classic on gas for about 7 years of the 11 years we owned it, it was only a 3.5 litre but it still went ok, the gas never effected the durability of the engine, it cured a lot of starting problems, as well as the massive cost of petrol fuel consumption the car did 300,000 klm of lots of off and on road stuff on gas before we sold it on to a friend, that was 12 years ago and I believe it is still used as someones daily driver.
My mate put his 84 Rangie on gas based on our success with it and his old car still lives on within his family, so no need to think a "gassed" Land Rover V8 is a problem. Gaz

What is gas like performance wise?

The pro's of LPG are:
1. It doesn't evaporate so even after a year or two the fuel is there and ready to start.
2. It doesn't dilute the oil on cold running so an engine used on mainly short runs will last longer. Your oil will stay clean longer.
3. Power delivery down low is smoother, well tuned you can increase your torque output noticeably at low revs.
4. Saves you some money on running costs, around 30% at current prices.


the cons of LPG are
1. You need to have the tanks inspected every 10 years, filling out of date tanks is illegal. Having tanks tested can be quite expensive.
2. Your range on LPG will be about 1/2 of that if you replace the LPG tanks with a long range petrol tank.
3. You may have power loss especially at high revs with a poorly set up LPG system, Impco being one of the worst for that.
4. Your tuning needs to be different to stock to get optimum performance out of LPG, stock settings don't work well.
5. Auxiliary petrol tanks tend to collect water and destroy petrol pumps if the fuel isn't used up regularly. Starting without petrol may take a little longer than dual fuel starting with petrol assistance.

Your choice basically, if the LPG runs well leave it in, if it needs major work, chuck it. There are many brands and types of LPG system, they aren't all the same and performance varies. Oh, and there is no such thing as LPG "scuba" tanks. SCUBA stands for "self contained underwater breathing apparatus". Don't confuse the two.

Originally Posted by bee utey

The pro's of LPG are:
1. It doesn't evaporate so even after a year or two the fuel is there and ready to start.
2. It doesn't dilute the oil on cold running so an engine used on mainly short runs will last longer. Your oil will stay clean longer.
3. Power delivery down low is smoother, well tuned you can increase your torque output noticeably at low revs.
4. Saves you some money on running costs, around 30% at current prices.


the cons of LPG are
1. You need to have the tanks inspected every 10 years, filling out of date tanks is illegal. Having tanks tested can be quite expensive.
2. Your range on LPG will be about 1/2 of that if you replace the LPG tanks with a long range petrol tank.
3. You may have power loss especially at high revs with a poorly set up LPG system, Impco being one of the worst for that.
4. Your tuning needs to be different to stock to get optimum performance out of LPG, stock settings don't work well.
5. Auxiliary petrol tanks tend to collect water and destroy petrol pumps if the fuel isn't used up regularly. Starting without petrol may take a little longer than dual fuel starting with petrol assistance.

Your choice basically, if the LPG runs well leave it in, if it needs major work, chuck it. There are many brands and types of LPG system, they aren't all the same and performance varies. Oh, and there is no such thing as LPG "scuba" tanks. SCUBA stands for "self contained underwater breathing apparatus". Don't confuse the two.

tanks have just been inspected. seller said it started using oil but I'm guessing its just rings. he said it ran well on gas.


I THINK its impco. I will double check.

From my experience and I think I could say for my mate with the '84 Rangie that there were certainly more positives than negatives with the gas.
The difference of course today is that whereas we started off in a time, (1995), when gas was 14 cents/litre, so the gas installation in my case was repaid in savings in less than 2 years. You now are buying gas in an artificially inflated market that keeps the price up to about more than 66% of the petrol price, ( I'm referring to up in the North where I live), you may have reasonable gas prices and because you did not have to pay for the gas installation at todays stupid prices you should be laughing.
I agree with some of what bee utey says but found our Rangie started fist button every time on gas, cold or hot, the power was slightly down on petrol, particularly at higher speeds but I still managed to get booked a few times through the years in it.
We both had the Impco systems and had no issues with them over a long period, I have heard of gas into coolant leaks in the converters, but had not had any worries.
The biggest bonus I felt was that had we not converted to gas I would not have been able to keep a vehicle that I really loved for so long, on petrol we were struggling to get 15 mpg out of that old low compression engine, so gas made it so affordable to run, from memory we used to get about the equivalent of 12 mpg on gas, still cheap running as gas was only a fraction of petrol/litre.
Both my mates and our Rangies were fitted with the 100 useable litre gas tanks so fuel range was ok, the down side of that was loss of useable luggage space in the back.
Eventually we both never ever ran the cars on petrol, and as both were carburettor models we had no issues that can plague injected models, but the dashpot diaphragms did occasionally fail which meant VERY poor performance with only one carb/gas injector working.
But all up I would say not a bad way to go. Gaz