On Gas, are things different?

[Pedro_The_Swift]

My '03 V8 has gas injection which cuts in at the right temp and revs,,
which means it only uses PULP when starting,

Does this mean different considerations with plugs and oils?
(I can only assume the installer changed all this.) It has never missed a beat (until recently) so is it just a matter of replacing what plugs are there?
and are GAS oils a marketing trick?

[Stormie]

Hey Pedro,

Where is your tank fitted?
I have a 04 D2 V8 and would consider putting it on gas if it doesn't take up all my boot space.
Also does injected gas effect the power or torque of the vehicle?

Sorry to answer a question with a question but your opinion would be appreciated.

[Pedro_The_Swift]

PM sent.

[pibby]

Oil – I use an oil for lpg. Better or not than normal oil – don’t know.

Plugs – my disco has a 4.6 in it and when I bought it it had NGK BP5…plugs in it which were in good nick. changed them out for what is recommended is the correct heat setting for lpg plugs in relation to petrol and put in NGK BP6… plugs. instant difference made on gas driving (for the better).

[bee utey]

1. You need different plugs if your injection is set for pure LPG under load. I have successfully programmed a couple of Prado 4.0 engines to run a percentage of petrol under load and this gets rid of the need for special plugs. I recommend Bosch WR7KI33S LPG specific long-life platinum plugs if you can get them but any brand choice is OK so long as you run 1 heat range colder than standard and reduced gap (0.7mm)

2. Gas oils were originally designed to cope with different combustion products. There were some issues with bearing corrosion using ordinary oils but the Penrite rep told me most of these issues have been overcome. So probably not a big deal unless its the same price as the standard prucuct.

3. Hey Stormie, the D2 takes a similar rig to the D1, with two small tanks where the petrol tank was, 70 litres of LPG and an auxiliary petrol tank of around 45 litres under the RHR corner.

4. LPG injection when well set up is indistinguishable from straight petrol. See notes above on tuning.

[INter674]

1. You need different plugs if your injection is set for pure LPG under load. I have successfully programmed a couple of Prado 4.0 engines to run a percentage of petrol under load and this gets rid of the need for special plugs. I recommend Bosch WR7KI33S LPG specific long-life platinum plugs if you can get them but any brand choice is OK so long as you run 1 heat range colder than standard and reduced gap (0.7mm)

2. Gas oils were originally designed to cope with different combustion products. There were some issues with bearing corrosion using ordinary oils but the Penrite rep told me most of these issues have been overcome. So probably not a big deal unless its the same price as the standard prucuct.

3. Hey Stormie, the D2 takes a similar rig to the D1, with two small tanks where the petrol tank was, 70 litres of LPG and an auxiliary petrol tank of around 45 litres under the RHR corner.

4. LPG injection when well set up is indistinguishable from straight petrol. See notes above on tuning.

I have noticed quite a reduction in power especially when heavy towing on LPG. The installer said this is normal as LPG does not produce the same power per unit measured as PULP and the engine uses more of it volume wise. There is a marketing/misconception that converting to LPG will always produce significant savings as this will depend largely on the price of LPG (currently shot up to 86cpl in Tas!!) compared to PULP (@ 130cpl in Tas) and also what LPG system is used (direct injection being the best), state of tune and so on. High LPG prices and unexplained sudden increases naturally dampen the enthusism for LPG conversions in Tas.

Saving 100% of the price difference between LPG and PULP is impossible given the different power characteristic of LPG versus PULP - more like 50-60% savings from my experience for a MP LPG Emer injection system on a 4.0L V8. Still a saving in any event....but not as great as the installers will have you believe and now I nervously watch both PULP and LPG price movements

[DeeJay]

I have noticed quite a reduction in power especially when heavy towing on LPG. The installer said this is normal as LPG does not produce the same power per unit measured as PULP and the engine uses more of it volume wise. There is a marketing/misconception that converting to LPG will always produce significant savings as this will depend largely on the price of LPG (currently shot up to 86cpl in Tas!!) compared to PULP (@ 130cpl in Tas) and also what LPG system is used (direct injection being the best), state of tune and so on. High LPG prices and unexplained sudden increases naturally dampen the enthusism for LPG conversions in Tas.

Saving 100% of the price difference between LPG and PULP is impossible given the different power characteristic of LPG versus PULP - more like 50-60% savings from my experience for a MP LPG Emer injection system on a 4.0L V8. Still a saving in any event....but not as great as the installers will have you believe and now I nervously watch both PULP and LPG price movements

63.9 in Melb & ULP around $1.27. I suppose the distribution network is slanted towards petrol & diesel

Pedro.
Traditionally, your spark plug leads need to be 100%. I've had LPG vehicles for 30 years now & Holden used to replace them around 60,000klm intervals

[400HPONGAS]

These LPG systems , are they Liquid Injection systems or Vapour Sequential Injection ? (or possibly fumigation systems running closed loop control ?)As there is a major difference in the end result in terms of power/control/Tanks etc , as well as initial install costs. Only the DLI system can hope to be as powerful/economical as Petrol , all the others will always suffer loss of Volumetric efficency by at least 10%
When properly set up for LPG , the engine shoild be optomised in terms of CAM/Heads/compression and ignition .When the end result of optomising for LPG is that it "goes" as well as petrol did , it not so much the fuel type change , its the fact that now it doesnt go as well if it was optomised for petrol.
Perhaps bee utey can clarify what these systems actually are , DLI or SVI or Fumigated ?

[scarry]

Pedro,
In the mid 90's we did a lot of work with castrol & their new synthetic oils for refrigeration.We were also using LPG on our work vans & the castrol rep's advised us the "gas " oils from castrol were the same as their normal oils,except for the packaging.
Penrite gas oil is different than it's normal oils,& we use this in our work vans once they are out of warranty.Whether we really need to use the gas oil or not is anyone's guess.
It is also interesting that neither Mitsubishi or Toyota use a gas oil in vehicles that operate on LPG.

[bee utey]

These LPG systems , are they Liquid Injection systems or Vapour Sequential Injection ? (or possibly fumigation systems running closed loop control ?)As there is a major difference in the end result in terms of power/control/Tanks etc , as well as initial install costs. Only the DLI system can hope to be as powerful/economical as Petrol , all the others will always suffer loss of Volumetric efficency by at least 10%
When properly set up for LPG , the engine shoild be optomised in terms of CAM/Heads/compression and ignition .When the end result of optomising for LPG is that it "goes" as well as petrol did , it not so much the fuel type change , its the fact that now it doesnt go as well if it was optomised for petrol.
Perhaps bee utey can clarify what these systems actually are , DLI or SVI or Fumigated ?

Liquid injection gets the best economy as the charge cooling by the incoming liquid is significant and allows good economy strategies. It is still not as flexible to install as the other 2 types because the tanks are specifically built with pumps in them, so limited for choice of sizes. That means no using of recycled old gas tanks! Orbital Autogas HOME - Orbital (who bought Boral Autogas) is building bolt-up kits for liquid injection on late model cars, to remove the errors commonly seen in poorly fitted generic stuff. According to their engineers, twin tanks are not really feasible. I haven't yet fitted one of their kits. Costing wise they are very similar to vapour injection on the vehicles that kits are available for. Orbital intends to be a strong market presence, especially as they are developing OEM kits for both Ford and GMH. There are aftermarket liquid injection kits around but they are much fussier to install I believe so I will wait and see.

Vapour injection gets less economy as it is primarily controlled by the oxygen sensor, no charge cooling. The power output is the same as petrol simply because of the petrol addition strategies available. Not that straight gas running will lose you much, maybe 5 to 10% at the highest revs.

Vapour mixer type systems properly set up won't get noticeably worse economy than vapour injection as they too are controlled by oxygen sensors. Power is down as there is no petrol addition under load. However the changeover switch is a finger flick away. Mid range (towing) torque is often better on gas than petrol because of adaptive ignition timing allowing the engine to take advantage of the higher octane rating.

Most mixer type systems are spoilt by poorly designed mixers. Apart from the mixer, power loss for towing is a function of incorrect plugs and poor ignition timing. The increase in low down torque and excellent mid range on gas in my car has led me to get rid of the petrol system as there was no point in maintaining it for no benefit. I don't hit the revs that I did as a laddie, I know that P76 cranks break when subjected to a frequent 5000rpm +