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For the LPG skeptics

http://franzh.home.t...
and
http://franzh.home.t...

heres some very good info on lpg for any who has doubted the facts
note the power loss figures are of 2 engines the same not one built for lpg and one build for petrol. Also the larger valves, intake runners gives the proper air amount needed to make up for the loss.

http://franzh.home.t...
more info

http://franzh.home.t...

have a look all over the site, its excellent

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Comments

Is LPG really that good?

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setup right (like anything !) yes it is
running a car on avgas is cheeper and better also, can get it local here for $1.00 a litre so go figure.

Tunna Build

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I ran my last V8 on Avgas, when it was around 0.80/litre and plentifull. You can;t buy it here like you used to.

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yea we get it easy here through a trucky who brings us up barrels of the stuff. Helps having a big speedway here, its the main sport ;)

Tunna Build

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Right. I used to buy it from one of two local servo's or from the local light airport. Not any more you can't! Not that I need it, LPG has been a great fuel for the past 9 years for me.

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If you get busted with avgas it costs big fine. So don't brag about it!Also it is leaded so it stuffs your cat if you have one.
If you boost the compression for LPG you pick up a lot of the slack,around 11:1 is good.
But if you don't do big mileages then forking out 2 and a half grand for gas is a big mistake.
I bought a wrecked HQ that already had gas for $450, ripped the gas off, fixed the Q and resold it for what it cost me all up, then got the gas professionally fitted for $160, i did the donkey work the gas fitter just put new lines though and banged a plate on. So it was pretty cheap for me. But before I bumped the compression the power loss and increased consumption meant that if gas was more than half the price of petrol it wasn't worthwhile, but after doing the compression when I converted to injection (the gas was not injection that would have been even better I think) the costs cam much closer.

johnperth

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optimal comp ratio for lpg is 12:1-13:1 even higher for natural gas if u run these comp with right cam specs and right stoichometric mix of 15.7:1 and an advanced timing then gas will perform better than runing premium and with better fuel consumption. basicly when ya all say gas is [Naughty Pottyword] well fuel up ya car on reg unleaded not premium, detune carb and retard timing then she how you car performs and to what fuel consumption you get then. well what have you all done for unleaded dropped comp and set heads up for it and recurved dizzy so fuel ignites and 47deg before top dead centre instead of 18deg for leaded fuels. so if ya take the time to set your engine up for gas it will out perform any pulp any day.
as if you go of the octane rating pulp is 98 but gas has a octane rating of around 105. ask your local servo for the safty data sheet on lpg the octane rating is listed there.

how many of ya actually know what the octane rating stands for?

it would be interesting to know like my little bro was talking about finding 4v 351 heads as 2v heads were [Naughty Pottyword] and i straight out asked him why? whats the difference and what does the 2v and 4v stand for its just funny people talks so much [Naughty Pottyword] about lingo that they dont even understand

THIS COMMENT ABOVE IS NOT POINTED AT ANY1 AT ALL IT JUST MY THOUGHTS AND A QUESTION THAT I WOULD LIKE TO SEE AUCTUALLY IF PEOPLE UNDESTAND ABOUT THE THINGS IN WHICH THEY USE EVERY DAY?

have a nice night and............

long live the hemi

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____________________________________________________
~_~ 4.3 Sucking Through Tripples Mmmmmmm ~_~
____________________________________________________

[:http://gallery.oldho...|link to my shed]
___________________________________

Octane rating relates to the speed of combustion. There are a few ratings actually, Research Octane Rating (RON) that is determined running a "standard test" engine at low tems/load. Motor Octane Rating (MON) is with the same motor at high temps/load. "Pump" rating is somewere between the two. High octane does NOT mean more "volatile", it means it burns slower!

High octane fuel is no good unless it is acompanied by high comp rations and others mods to take advantage of the slower burn. Higher octane fuel generally requires enrichment .vs. "regular" fuel.

The "sensitivity" of a fuel is determined by how much the RON and MON ratings differ. Sensitive fuels (LPG for example) have very high RON's, yet drop significantly at higher temps and loads (MON) so is therefore considered a "sensitive" fuel.

Those that beleive LPG is "high" octane are wrong. LPG has a high RON rating but much lower MON were it counts for power. THis is why LPG engines like plenty of initial and vacuum advance but relatively low total/mechanical advance were you make big power.

Stating an engine can run 10+ to 1 comp on LPG is not being fair. It all depends on the camshaft. Comp and cam go hand in hand. Much better to specify Mean Specific cylinder pressures, this takes is what counts. If you target a specific pressure with LPG, comp would be like 9:1 for a stock cam, moving up to maybe 11:1 for a wild cam.

Anyways, enough from me, most here don;t beleive me anyways. Prepares for the usual oldholden flame-on.

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Gday mate glad to see your posting again, regardless of weather people believe you or not the facts are there mate. Just look at your beast for example, it all speaks for itself.. That statto runs smoother then almost any 308 ive seen, purs like a kitten and roars when the boot goes in. For a car that weighs that much she moves too, were gonna have to catch up soon too for a cleansing ale i reckon.

My Shed

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Ale? Sounds good.

The old girl has had a birthday in the past 3 months while I have been off work. I replaced the carpets, repaired seat runners, new front end (and I mean new!), scored over 2K in NOS parts on eBay and a few rust spots will be fixed int he next month. Can you beleive I picked up a NEW (NOS) drivers side window motor on eBay for $150? Oh, new bailey channels, new bumber rubbers, spare NOS indicator lenses, the list goes on, eBay is a gold mine at the moment! Seen a few sets of good Caprice alloys for between $400 and $800 over the past weeks, bargain!

When is the next cruise BTW?

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sounds good mate, shell be looking and going awesome :D The VH is getting a makeover soon aswell, new paint job and the lot, gonna chuck in power windows, central locking, nice big alarm, new front and rear screens, full performance suspension package and more. Still undecided on the colour :P

My Shed

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And no V8? lol. Sounds good. Carefull with $$$ in stereo/screens, the pricks in Perth are everywere!

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got the screens covered im pretty sure i can get em from work, same as the alarm. Im going for a v8 but thatll have to come a bit later, gotta get some rust fixed first, may aswell do the paint at the same time :)

My Shed

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Yeah rust is a priority!

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octane ratings is the risistance to knock. fuels are tested to determine how they will perform in an engine and they are given a research octane number(ron)to denote their resistance to knocking. higher number less knock and visa-versa, the fuel is a mixture of iso-octane and heptane, and the proportion of iso-octane in the fuel is its octane rating. eg, 93% iso-octane ans 7% heptane, has an octane rating of 93.

lpg on the other hand is defined by the motor octane number(mon)method of rating fuels. this gives numbers different to RON. automotive lpg has a MON of 98 and this can be compaired with pulp which has a MON of 82 but has a rating of 95 ron.
so lpg has a greater resistance to knock than pulp.
the lower the octane rating the easier the fuel is to combust thus causing knock, the higher the rating the harder it is to combust.
during the combustion stage, the spark at the spark plug starts the burning process. a wall of flame spreads rapidly in all directions from the spark and travels through the compressed air-fuel mixture untill the charge is burnt this is called flame propagation.
if the fuel burns to rapidly there will be a sudden increase in pressure and this will cause a knock. low octane will combust before the spark has a chance to start the combustion causing two walls of flame travelling towards each other instead of having a even spread across. the slower burn you were talking about is total different between fuels as ulp burns slower that is why they start the combustion cycle at 47deg btc and super was later same for avgas i have mine on avgas set at 14deg btc. they all have different burning cycles. does kero or desiel burn as easy as petrol no! but at the same time they all are different types of fuels

volatility of fuel is the ease with which a liquid turns to a vapour

long live the hemi

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____________________________________________________
~_~ 4.3 Sucking Through Tripples Mmmmmmm ~_~
____________________________________________________

[:http://gallery.oldho...|link to my shed]
___________________________________

Also you should run on petrol every now and then anyway I found that if I left it too long on gas it sometimes ran a bit scraggy I suspect the gaskets and power pump dried out.

johnperth

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yea i got told if u dont run the petrol much the gaskets in the carby n stuff will dry out and u will get air leaks
-MXR125- old skool rulz

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- Theres no replacement for displacement-

i was told while studying that while using a lpg system on a car built to run petrol using a carburettor, that you should start the car with petrol, run it til you get out of your block or a few mins then switch to lpg. Then before turning the car off or the same distance before home, switch to petrol. The advantage is that because lpg is a gas, when you shut off your car the carburettor is dry & hot & is a heat sink area for the motor. This can really affect your float bowl & gaskets & in extreme cases cause weakening & cracks in your carburettor. By wetting it with fuel before switch off it keeps it cool & lubricated so to speak. Also a little fuel will be in the carb ready to start next time.

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