LPG Info

Bubba · Post by **Bubba** » Fri Jul 20, 2007 11:16 am

Took my Cruiser to the LPG Mechanic and was told some interesting information.

The Standard LPG Mixer system is only made for 2.5L max motor and starves the fuel at full noise.

With a bigger system (can't remember name of it) it would run the motor at 120 Octane off standard LPG (mmmm drool), giving more power and fuel economy than petrol. he said that it was like fitting a Holly 600 Carby for the petrol

Can anybody tell me in more detail what system he was referring to, how much $$ should I be looking at, was he just trying to sell me something coz he could spot a mug (I don't think so though).

What are the pro's and con's

This is a long long term option for me but may help others getting more ponies under there hoods etc

Goose · Post by **Goose** » Fri Jul 20, 2007 11:50 am

Ahhhh, LPG, where do I begin

For a start, Al from summit (ad at top :wink:

)would give you some good info, he's done a few!!
As for the octane thing, as far as I know, the only way to get the octane that high out of LPG is compression. I have a video of a 4.1 falcon with a turbo and LPG, and the write up for it said (from my rather hazey memory) that with the turbo he was getting 11.5:1 which gave him 103 octane. The only other thing I've heard is that if you "wind open the feed valve" you get more fuel therefore more power...... (and use more $$)
I have a factory LPG falcon, it has a compression ratio of 10:1, a standard motor is 9.5:1. It goes goodly :twisted:

It also uses more fuel litre for litre than petrol by about 10%, so I'd think that if you're talking about feeding the chev("edit" oh, were you the chev 40 or a stadard 6cyl 40? I've seen heaps of LPG's done to toyota 6's, they go great)craploads of LPG, you might find it's not so cheap. That said, I've seen a few 350's running LPG, and the seem to go real good, while still being reasonably efficient.

The 120 octane thing I've never heard of, but I could well be wrong :lol:

Maybe others could shed some light.......

Bubba · Post by **Bubba** » Fri Jul 20, 2007 2:16 pm

Thanks Bud,

Just as a side bar; I was reading up and they say that a cubic litre of LPG is used faster than a cubic lutre of petrol and therefore you have to add about 15-20% extra cost than the pump price. Still the cheapest fuel about I reckon.

As for the mechanic's advice, he seemed to fairly knowledgeable and was very old school and has worked on heaps of Cruisers so he says. Certainly sounded like her knew what he was talking about. Just can't remember what the name of the system bugger it

I didn't pick up much on the the "Bullshit-Meter" from him but the "Give-a-Fuck-Meter" was giving off a low reading at the time and may have interfered with the signal, and that was because the Cash-Meter was recording 4/5 of sweet FA.

muddy · Post by **muddy** » Fri Jul 20, 2007 2:50 pm

I'm no expert, but I've asked a few questions cos I'm running LPF in a 2F FJ40... LPG is around 110 octane. That doesn't mean it has more energy in the fuel - it's a measure of the resistance to detonation, or "pinging". It actually has less energy than petrol for the same volume, which is why it uses about 10-15% more fuel. That extra fuel also means it gives slightly less power than petrol in a standard engine becuase it has less volumetric efficiency - the extra LPG reduces the amount of air that goes in - therefore there is less energy in the air/fuel mixture on each power stroke. That's not the full story though - the higher octane rating means you can run it at higher compression without detonation, so you can get power gains if you turbo or supercharge, or shave the head to increase compression. You have do one of those things though if you want to get power gains, since thats the only way you increase the volumetric efficiency - you have to get more air & fuel into the cylinders. There are other issues with ignition timing - LPG is slower burning than petrol so needs to be advanced a bit further, & ideally you would have to alter the whole ignition timing/rpm curve to get the best out of it.

In the end - I just run on LPG to save cash - & if there's a big hill & I think I'm going to need all the horses I can squeeze out, then I swith to petrol, but most of the time there's bugger all noticeable difference.

Bubba · Post by **Bubba** » Fri Jul 20, 2007 2:55 pm

Bloody hell you fellows are smart alright! This site always amazes me with the knowledge thats on here and the willingness to share it.

Sniff sniff I luvt you guys (hic)

Serous though, mmmm maybe the BS meter wasn't working well that day

Sadam_Husain · Post by **Sadam_Husain** » Fri Jul 20, 2007 3:06 pm

if you want more pony's bubba..... you know what to do :wink:

if its any consolation I had LPG on a cruiser 10 years ago and that also ran like shit

, I just took it all off in the end coz the tank was way too big and took up 1/3 of the tray

, I've still got the fuel gauge if its any use to ya?

Bubba · Post by **Bubba** » Fri Jul 20, 2007 3:10 pm

Sadam_Husain wrote:if you want more pony's bubba..... you know what to do

if its any consolation I had LPG on a cruiser 10 years ago and that also ran like shit , I just took it all off in the end coz the tank was way too big and took up 1/3 of the tray , I've still got the fuel gauge if its any use to ya?

As much as I would like to Sadam, there's a mighty long list of things to do and get before the Chev goes in, but it will happen. As long as i can keep it straight and in one piece long enough, knock on wood.

Steve_t647 · Post by **Steve_t647** » Fri Jul 20, 2007 3:14 pm

the mixers also can start to freeze when flowing large quantities of gas, this may be what he is talking about.

as a side note Rotaries can be setup to go better on gas than on petrol, but at their thirst and using more gas not many are setup this way there is a very fast drag racing rotary in aussie running gas, but who is planning on putting a rotary in a 4x4?

The other thing to know is the engine run's cooler on gas and on some viehicles this is noticeable on the temperature gauge

Goose · Post by **Goose** » Fri Jul 20, 2007 3:34 pm

Steve_t647 wrote:the mixers also can start to freeze when flowing large quantities of gas, this may be what he is talking about.

as a side note Rotaries can be setup to go better on gas than on petrol, but at their thirst and using more gas not many are setup this way there is a very fast drag racing rotary in aussie running gas, but who is planning on putting a rotary in a 4x4?

The other thing to know is the engine run's cooler on gas and on some viehicles this is noticeable on the temperature gauge

Oh hell yeah!! On a hot day, towing the lux through rush hr traffic, I'm lucky if the coon gets to about 20% of the temperature guage....

The other thing is (especially if it's dedicated) the oil stays clean. Ford suggest an oil change in their dedicated LPG vehicles every 25000 k's!! (Try telling that to the mechanical insurance provider :roll:

They want it done every 10000, who knows more about engines, an insurance company or the people who make them!!?? Tossers)

Rotazuk · Post by **Rotazuk** » Fri Jul 20, 2007 5:43 pm

Hi
My 2 cents worth . What I think the guy may have been trying to say is that the mixer is too small for the engine . Should only be on something up to 2.5 litres .
Its just like having a carb on there thats two small , it can only flow so much air and fuel . It may not be that much to just change out the mixer for a bigger one , I have know idea thou . never got around to installing LPG in the rangie ( wish i did when I got it now

)

See if you can read any numbers off the mixer and see what size it is .

Chris

Jerry · Post by **Jerry** » Fri Jul 20, 2007 6:28 pm

http://www.trademe.co.nz/Trade-Me-Motor ... 08.htm?p=1

ramon · Post by **ramon** » Fri Jul 20, 2007 6:57 pm

Give Ian Ruscoe a call, he is the guy all the others in wellington turn to when they cant fix something. he has been working with lpg for 30 odd years and there is nothing he does not know about the stuff.

Mr Ian Ruscoe
Ruscoe Auto Services Ltd
1 Brown Street
Upper Hutt
WELLINGTON
04 9396406

rowinz · Post by **rowinz** » Fri Jul 20, 2007 8:58 pm

Petrol engines use 10-20% more LPG depending on tuning but also because the energy density (ie joules per litre) is less.

LPG does burn slower, thats why you should advance the timing a couple of degrees, so the full detonation is at TDC. Also it pays to run a slightly hotter plug, as the ignition energy for LPG is slightly higher (ie its slightly harder to ignite), so any residual heat in the cylinder helps. Need to maximise energy the plugs, so ignition system is important.
It does run the engine cleaner as there is no other crap that lines cylinders to be washed away by oil.

Engines run cooler because the vaporiser/regulator uses hot water to vaporise the LPG to feed into the engine. New generation kits have liquid injection, which also means cylinder temps are cooler.

Starting engine on LPG can be harder as they need some heat to initially vaporiser the LPG, this is why the clever electronic systems start on petrol.

I had a dual fuel FJ40 2F motor. I don't understand why, but i reckon the torque band shifted down by about 500rpm. That had a vaporiser/reg that was undersized, but that just meant there was little point in ringing its guts out.

here is a good link I just found.
http://www.propanecarbs.com/propane.html

Note in NZ our LPG mix varies from about 60/40 propane/butane to 100% propane.

My job deals mainly with industrial applications of LPG, but I know a bit about automotive. Goose seems to know a shit load of good stuff.

R
Industrial LPG Engineer

mercutio · Post by **mercutio** » Fri Jul 20, 2007 9:16 pm

rowinz wrote:here is a good link I just found.
http://www.propanecarbs.com/propane.html

Note in NZ our LPG mix varies from about 60/40 propane/butane to 100% propane.

My job deals mainly with industrial applications of LPG, but I know a bit about automotive. Goose seems to know a shit load of good stuff.

R
Industrial LPG Engineer

you would be a good person to talk to about diesel LPG fumigation maybe :lol:

Goose · Post by **Goose** » Fri Jul 20, 2007 10:58 pm

rowinz wrote:
Starting engine on LPG can be harder as they need some heat to initially vaporiser the LPG, this is why the clever electronic systems start on petrol.
'My factory dedicated starts good, even the middle of winter outside, I dont know why, perhaps some sort of pre-heat?'
My job deals mainly with industrial applications of LPG, but I know a bit about automotive. Goose seems to know a shit load of good stuff.

Flattery will get you everywhere!! You've got 3 days to stop that!! :lol:

Most of what I know is (like muddy) asking the pro's lots of annoying questions

or from the web, I've had LPG for years, and found craploads about turbo's and compression and how that effects the engine. Oh, and I really like watching the litres go up faster than the dollars at the pump :twisted:

hehe, the vid I mentioned earlier, I posted it on youtube a while back after I found it on an old cd I burned (I was looking for it and couldn't find it, and damn was it annoying!!) so I put it on youtube so I wouldn't loose it again......enjoy :twisted:

http://www.youtube.com/watch?v=HeQO89l8ohU

Madaz · Post by **Madaz** » Sat Jul 21, 2007 12:02 am

Try looking on the Impco web site or a austrailian company called gas research for information.
Theres so much information but the best advice i found was in tracking down Impco instlation manuals from the mid 1980s , they explain in great detail how to set up lpg on any engine be it turbo , supercharge or NA
I set my supercharged lpg engine up from these manuals an it ran sweet as and never missed a beat, this was incontary to the local experts who reconed that the system would never work and that i was wasting my time.
Good luck

Goose · Post by **Goose** » Sat Jul 21, 2007 9:21 am

The place in Aussie that madaz is talking about is Gas Research Australia, based in melbourne. They seem to be the "uber-geeks" when it comes to LPG, they had lots of cool stuff from standard gas-only carbs to systems for supercharged bigblocks :twisted:

I got quite a bit of my info from there, and the old man dealt with them when he converted to LPG (he lives about 3 minutes from them!!) and rekons they're the shit!!

Here's their website: http://www.gasresearch.com.au/

Looks like they've changed their website since I last looked at it, it's got craploads of good info on it.

rowinz · Post by **rowinz** » Sat Jul 21, 2007 2:13 pm

'My factory dedicated starts good, even the middle of winter outside, I dont know why, perhaps some sort of pre-heat?'

I too have dedicated LPG falcon. It cranks a second or so longer on really frosty days, but very little difference between summer and winter. I was thinking it might have an electric preheater too.

muddy · Post by **muddy** » Sat Jul 21, 2007 2:22 pm

I find it starts & runs heaps better on LPG when cold. I think it's to do with the old straight 6 with long passages on the inlet manifold - LPG is always vapourised (it's a gas), but when cold, the petrol condenses on the way to the cylinders & runs really rough till it warms up. Like rowinz says - I think the secret is a good coil & strong spark. Probably not that much difference if you're comparing to injected petrol..

Another advantage - LPG doesn't care what angle it's on - petrol can flood the carb bowl on steep angles.

Bubba · Post by **Bubba** » Mon Jul 23, 2007 9:38 am

The Impco System is the one that the guy was telling me to get.

Got called yesterday by an old fellow who had been referred by the original Mechanic :?:

he's retired and said that he sometimes does a few perk jobs. He said he could tell me exactly what needed doing just by listening to the motor running. I like that talk, the other guy wanted the Cruiser for two days, this one he said he will be able to tell me whats needed in a few minutes :lol:

and should be finished in a few hours, depending if parts are needed