LPG Systems

Submitted: Thursday, Jul 07, 2005 at 11:19
ThreadID: 24519 Views:9648 Replies:6 FollowUps:7
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I just came across a post dated in May which stated that Sprint Gas equipment was crap and Impco was great. Well I don't have any experience of Impco but I do wonder where American technology comes from as they are still trying to run cars on propane over there.
I bought a complete conversion kit from Sprint Gas (OMVL) three years ago and fitted it myself to my ED Falcon wagon and after 100,000 kms, including towing a caravan from Melbourne to Perth and back, I can say I have not had a moments trouble with it. And this is a sophisticated system with it's own ECU which is wired into the cars ECU to take advantage of the oxygen sensor and other sensors to always give the optimum mixture for the conditions. There is no smell of unburnt LPG which is usually noticeable with other systems. Any loss of power compared to petrol is undetectable and it runs smoother on gas than on petrol. Additionally, the engine oil remains clear and light coloured for the full 20000km between changes.
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Reply By: gqpat - Thursday, Jul 07, 2005 at 11:53

Thursday, Jul 07, 2005 at 11:53
try putting it on a 80-100 series and compare dyno figures to petrol i beleive these are the vehicles people were talking about..
AnswerID: 119266

Reply By: theshadows - Thursday, Jul 07, 2005 at 12:30

Thursday, Jul 07, 2005 at 12:30
I had an Impco system in my 60 series. All I can say is it was an old XC taxi sytem with 500000 miles on it and cost me less than $105 to buy. There was nothing i could not fix on it that didnt require 2 screw drivers and a can of aero start to clean the units.

tune up where done by ear after paying for 3 expensive dyno tunes ,I had a old mechanic show me how to tune by ear and that was the best that old motor ever run. For 3 months out bush I used to push start it and it would run all day.

Now I'm not stateing that SPRINT is better but I will say in my opinion the old style IMPCO system was one of the hardest running systems I eversaw. I recommend Them anyday.

AnswerID: 119271

Follow Up By: winnjimmer - Thursday, Jul 07, 2005 at 16:12

Thursday, Jul 07, 2005 at 16:12
Old LPG systems were very simple and apart from a bit of sludging up or freezing you couldn't kill them with an axe.
It's a bit different on EFI vehicles. The system has to start the engine on petrol using the injectors and then switch over to gas and switch off the injectors. Then using its own computer connected through the car's ECU, it computes the correct gas/air ratio using information from the sensors on the engine. To atually change the mixture the Sprint Gas system uses a stepper motor on the gas line just before the mixer. I believe IMPCO use variable apertures in the mixer. Me; I prefer the stepper motor. I tuned my setup myself by ear and it's a breeze.
If a Sprint system doesn't deliver the expected power, I'm sure Sprint would be happy to reprogram the gas computer. They were very helpful with me.
FollowupID: 374398

Reply By: awill4x4 - Thursday, Jul 07, 2005 at 19:50

Thursday, Jul 07, 2005 at 19:50
Winnjimmer, what makes you think that the ECU on the sprint gas system is any more sophisticated than any modern gas system currently available. All fuel injected cars running an oxy sensor have to have a closed loop system just as you describe.
I've got an Impco closed loop system on my EFI GQ and I'm happy with it.
Regards Andrew.
ps: If you want sophisticated gas systems, the way of the future is gas vapour injection where gas is injected into each inlet port just like petrol with its own dedicated gas injectors.
AnswerID: 119319

Follow Up By: gqpat - Thursday, Jul 07, 2005 at 20:22

Thursday, Jul 07, 2005 at 20:22
The main reason i prefer Impco is it has a varible venturie compared to a fixed size venturie of the simple mixer stuff.The benefits of a varible venturie are that at low engine speed the venturie is small which increases air speed though it improving throttle responce and economy and as engine speed increases so does the venturie allow more as required no other system does this except for the predator petrolcarbie .

On a closed loop efi system the mixture is NOT controlled by the cone in the mixer but a computer connected to the oxy sensor like all off them and tps and revs .which operates a valve putting vacuum agaisnt the converter diapham reducing gas flow. The benefit of this system is it has no steeper motor to jam which does happen sometimes closing all gas to engine and if the vavle happens to fail it allows the converter to breathe as normal causing it to run richer than normal but funchion quite ok .
Simplicity is the key word in Impco...
FollowupID: 374432

Reply By: Cabbage - Thursday, Jul 07, 2005 at 21:31

Thursday, Jul 07, 2005 at 21:31
""any experience of Impco but I do wonder where American technology comes from as they are still trying to run cars on propane over there.""

I was just wondering what you think LPG is????
The stuff you put in your car is called autogas which is normally a blend of propane and butane, supposed to be 50/50 but is more likely to be 60% butane & 40% propane.
At least the yanks use propane and not the bleep we get here.
If you want to use wog-gas stuff on your car go for it, but personally I prefer Impco.
Look at this way, Impco was designed to run big engines [ala yankmobiles]
all the Italian and Dutch gear was designed for small engines.
BTW there is a servo in Broadmeadows near Ford that sells autogas or propane[2cents a litre dearer]

Leave nothing but footprints, take nothing but photos!
AnswerID: 119341

Follow Up By: winnjimmer - Friday, Jul 08, 2005 at 10:31

Friday, Jul 08, 2005 at 10:31
I'm an Industrial chemist and I can assure you I have a damned good idea what LPG is. If you want to run your car on barbeque gas that's your prerogative.
You have all missed the point though. All I wanted to do was pull up those people who think they can just say something is crap and get away with it.
However, I have obviously touched a nerve and brought out some nasty aggression. Some of my best friends are what you would call wogs.
That being the case I will now retire from this site and never visit it again. There are nicer places on the net, particularly in the motorcycle areas.
FollowupID: 374482

Follow Up By: Clan - Tuesday, Jul 12, 2005 at 23:14

Tuesday, Jul 12, 2005 at 23:14
"cabbage" - hospital slang used by doctors to describe a patient who has suffered severe brain damage or brain death.


wake up mate.
FollowupID: 375105

Reply By: winnjimmer - Saturday, Jul 09, 2005 at 11:08

Saturday, Jul 09, 2005 at 11:08
I decided to come back once more after doing a bit of research and I submit the following.
1. I don't know if IMPCO gear is better than OMVL or vice versa. I do know OMVL works fine and you advise that IMPCO does too.
2. According to Hawley's Condensed Chemical Dictionary LPG is a by-product in petroleum refining and would contain variable proportions of butane,isobutane,propane, propylene,butylenes and their mixtures. The butylene mixture for example would be butene-1,cis-butene-2,trans-butene-2, and isobutene. So LPG is not just a mixture of propane and butane.
3. BP would not divulge what they thought was in their LPG but said that they assume that it is 50:50 propane butane so that they have a formula to set the price in Australia according to the daily prices for propane and butane in the Singapore World Market. We seem to have construed that to mean that LPG is actually 50% propane and 50% butane and we are not correct.
4. There are 1.5 million vehicles running on LPG in Italy ( the home of OMVL) compared with 350,000 in USA and 350,000 in Australia. 350,000 is such a small proportion of the USA motoring population that garages have not put in Autogas pumps and until they do, the situation is unlikely to change.
5. It is important that the recipe for LPG remains consistant, because variations in components require different air/gas ratios. For example if you were to use some of that straight propane from Broadmeadows your mixture would be way out.
6. Little Johnny may have been thinking ahead of all of us when he introduced the excise on LPG, because LPG represents 5% of the oil refining process and we LPG users already account for 3% in Australia. The last thing anybody wants is for the stuff to become scarce.
7. IMPCO have factories all over the world. The biggest seem to be in China, India and Italy. Their main focus seems to be on gas equipment for fork trucks as that may be the biggest market.
8. The dedicated LPG BA Falcon does not use a seperate gas computer but has an ECU designed by them to work with LPG. They wont say who makes the condensor and mixer. THe BA would undoubtedly have much more power than my ED but its LPG consumption is 6.5litres per km which is not much better than my long term average of 6.2.
9. Ideally we would be running on LNG but the problem of the high pressure required to keep LNG liquid at room temperature seems insurmountable at present.
AnswerID: 119539

Follow Up By: Member - Jimbo (VIC) - Tuesday, Jul 12, 2005 at 23:47

Tuesday, Jul 12, 2005 at 23:47

Don't bail out mate.

All forums have people who make statements that may be unsuitable. This forum is no different. Don't judge the rest of us by someome who offends your principles.

Your contribution is valid and well appreciated.

Stick around.


FollowupID: 375109

Reply By: Mad Dog (Australia) - Wednesday, Jul 13, 2005 at 00:49

Wednesday, Jul 13, 2005 at 00:49
I've had 5 vehicles over the last 10 years on gas using both systems and haven't had one bit of trouble. The omvl system on my ED was a great performer, the system on my present AU, factory system whatever it is, is simply stunning. Did 300,000 k in my VL Commodore on impco, not one problem, converter never cleaned. I love the stuff, it's been great to me.
AnswerID: 120081

Follow Up By: winnjimmer - Wednesday, Jul 13, 2005 at 11:11

Wednesday, Jul 13, 2005 at 11:11
Hi Mad Dog,
When I first got my ED wagon about 11 years ago it overheated when I towed anything so I fitted a three row radiator for a 50% increase in cooling capacity and also a fan clutch which cut in earlier than standard.
It already had a transmission oil cooler. It didn't give any trouble after that. I've kept it so long because of all these mods and the gas conversion, but I've been thinking of updating to a dedicated gas AU or a bit later and I'd welcome your comments about what you find so good about yours. How far can you go on a tank full? And do you have an overheating problem when towing a caravan?
Thanks Jim.
FollowupID: 375156

Follow Up By: Mad Dog (Australia) - Wednesday, Jul 13, 2005 at 12:22

Wednesday, Jul 13, 2005 at 12:22
Hi Jim, The usual cause of overheating in older Falcons when towing is casting sand blocking the radiator. The old block wash wasn't really up to the task but that problem was now been rectified with the recent installation of new plant that always leaves the block squeaky clean, I'm directly involved with the Falcon engine manufacture. It's impossible to tell the difference between the two fuels on the AU and the fuel consumption, well I've only checked it once and that was on petrol with the cruise set on the highway 9.2L/100K. There will be a big difference between highway and town running, once that big vehicle gets moving on the highway with the engine revs at only 1800 it's very frugal but stopping and starting around town is a different story.

I don't tow Jim but as I implied any overheating with a Falcon have the radiator and block flushed, same with any vehicle really.
FollowupID: 375169

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