LPG consumption Questions

[GURU]

G'day all,

trying to work out why the economy of my RR is so bad. It's on LPG with a P76, has a twin barrel holly on it, and electronic ignistion. It runs smooth and pulls OK but put it on petrol and it screams

what should the timing be for best LPG performace?

what sort of consuption should I be getting. currently it is lucky to get 220kms out of 76L of LPG

[MQ SWB]

G'day DAS Having the same problem with my Rangie, I'm getting about 190km out of 60-65 litres of gas and i'm running a 308, same effects as yours on petrol it screams on gas it's okay.
I'm hoping I can find a decent lpg mechanic so he can have a play with it, i probably should change the spark plugs and leads.
if i find out anything i let you know.

Dixie

[Loanrangie]

Standard consumption should be 5klm's per ltr more if on a highway run.
I would have thought that as the 4.4 doesnt need to work as hard as a 3.5 that you would get about the same or better economy. I was getting 350- 370 k's to 70 ltrs on my 81 4spd rangie with 31" muds.

[GURU]

mine has 4" lift and 35's (but has 4.3 diff gears)

I may be dropping it to 2" lift and 33's (and go back to 4.1 diff gears) as I woill be using it for a tow vehicle soon

if not I will be selling it and buying a run around car (corolla or pulsar)

[grungle99]

LDR 110 with rather loose P76 - out to 4.8 ltr. LT 95 with County transfer gear ratios, Twin Rams horn setup with BRC Positive feed converter and twin donut mixers, runs real well on LPG - prolly about 20% more powerr on Petrol depending on the type - she likes Optimax...

Canberra - Gold Coast - 1100 KM in September for $113 of LPG.

2.5' lift, 33' mudders.

[grungle99]

LDR 110 with rather loose P76 - out to 4.8 ltr. LT 95 with County transfer gear ratios, Twin Rams horn setup with BRC Positive feed converter and twin donut mixers, runs real well on LPG - prolly about 20% more powerr on Petrol depending on the type - she likes Optimax...

Canberra - Gold Coast - 1100 KM in September for $113 of LPG.

2.5' lift, 33' mudders.

[mav]

G'day all,

trying to work out why the economy of my RR is so bad. It's on LPG with a P76, has a twin barrel holly on it, and electronic ignistion. It runs smooth and pulls OK but put it on petrol and it screams

what should the timing be for best LPG performace?

what sort of consuption should I be getting. currently it is lucky to get 220kms out of 76L of LPG

what lpg system are you running if impco is it a 300 you might need a 425, the adjustments might be out at max adjustment on a 300.

[rick130]

Hmm, I used to get an easy 250km out of my old F100 ex-ambo, (2400kg unloaded) loaded to the gunnals with work gear (3/4 tonne) which was powered by a worked over 351C with a C6 behind it.

Two things.
It was built for gas, with 11:1 comp ratio, electronic ignition (bosch dizzy built by Scorcher, advance curve to my specs, Holden spread cap and Commodore HEI coil)
Plugs two heat ranges colder than spec for a 351.

It wouldn't run on petrol unless I used Av-gas from the race car, or octane booster and 98 octane PULP, then it would scream.
The amount of total advance + the comp ratio was too much for petrol.

If you normally only run on gas, with petrol as a backup, try advancing the ignition until you get detonation, then back off a couple of degrees. It should ping like nobodies business on petrol, but performance and milage should be better on gas.

Spark plug gaps need to be closed up a bit on gas. The fuel is harder to ignite, so closing the plugs makes things a whole lot easier on the entire ignition system, even when using an HEI setup, with more reliable ignition and less plug erosion.
If running gas 99% of the time, go colder in the plugs. My plugs were so cold, that I would fuel them up if I tried to start on petrol, but they looked perfect when reading them from running on gas.

Can't think of anything else as we've been exclusively diesel for nearly four years now. Can't beat compression igmition.

[Ralf the RR]

MY 79 4.4 gets 20L/100k.

I have twin sub floor scuba tanks that hold about 70L.
I usually put about 60L in, and from that get about 300km.

Each tankfull varies, but averages out to 20l/100k.
I put the variation down to the amount of gas that "fills" the tank before the shutoff valve works.

My system has an unknown brand converter, and twin SUs (not strombergs).
I have the ignition timing set to 9 degrees.
I tried 12, but that didn't improve anything.

There is not a lot of variation of power between petrol and gas.

[peter r]

G`day DAS , our old 3.5 gave around 4.8 k/pl the 4.0 gives better , most i`ve spoken to , when changed to 4.4 reckon much better economy than 3.5 . ( on road i guess your talking )

I`ve just set ours using a vacuum gauge and also it has True TDC marked , it`s pretty happy at between 14 and 15 degs for gas , seems too much for petrol though but don`t use petrol much .

Pretty sure you`ll know gas likes more initial advance than petrol and not as much later so unless there are 2 curves anything is a compromise .

All the best , peter .

[Ralf the RR]

Pretty sure you`ll know gas likes more initial advance than petrol and not as much later so unless there are 2 curves anything is a compromise .

Anyone running a dual electronic ignition mapping device?

I've seen the one from Silicon Chip, and it's fairly archaic. It only allows about 3 settings, and relies on the HEI kit.

I've heard/read of dedicated dual map devices, but I think they are $300+.
That's alot of gas money to save. Probably takes years to recoup that.