I've devised the following calculator that will allow you to plug in all the numbers for an LPG conversion, and work out whether you want to go ahead with it.

Its an excel spreadsheet, and you'll need at least Excel XP, or something that can read that format to use it.
All fields marked YELLOW are changeable, to customise it to your own situation.

cheers
PS NOW UPDATED - included KMS until paid off including rebate.

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Last edited by 96ghia on Sat Jul 05, 2008 12:04 pm, edited 1 time in total.

very nice work make a gas conversion look even better thanks where did you get your formulas from

thats cool, nice work.

Manually calculated most of them, and added them over time, gradually improving it.
its actually a few years old, and I thought I'd re-post it, (was lost with FM MkI)

The 30% figure for Gas consumption was something that was fairly well agreed on at the time. if anyone wants to change it or make improvements and re-post, then they're welcome. Just credit my original

good job mate, but still not convinced for Gas conversion...

Thats the idea!
plug in your own numbers, and make your own decision on if its right for you

Haha, as IF gas isnt for everyone.
My 98 model EL gets 550Km's to 68-72Litres of gas if i granny it some of the way, 500Km's normal driving, $32-$35 (worst case) for 500Km's, it works out for me that petrol is three times the price, that is $:Km's

A mechanic told me once "As a rule of thumb a car will use twice as much lpg as petrol for the same mileage"
My car actually uses less lpg the petrol on the freeway. Not to mention that 100km's only costs $5.03

Gasman is this figure mostly freeway driving. I cant better around 20l p 100 around town even when driven very easy and fuel is about 14l p100. If you are getting this around town it works out to be 13l p100. How do you achieve this. Freeway i can get about 17 at best on lpg & 12l p100 fuel. It does vary though but usually worse. Cheers

my mate had the same thing in his EB. One way to acheive this is to adjust the gas ratio's car will run rougher but better economy

Unless it's way overtuned to seem really smooth. Most cars won't run as well on gas

also make sure you run petrol in the engine occasionally as the engine's were built for petrol they need it or go to S**T. My mate found this out the hard way

yeah you need to factor in the cost of petrol some of the time...

often on shot trips i wont run it on gas ill just leave it on petrol... also you should do a long trip maybe once a month..

also gas seems to cost more for maintenance like plugs and leads and convertors that f**k up fairly often.

glad to read that someone else gets the same fuel "economy" as me. i thought it must be someone wrong with me or my car. Even with our tragic figures it still works out about as cheap as running a corolla on petrol.

this will come in handy thanks

gee is someone trying to build up their post count

Fantastic work mate, Great spreadsheet

Some say that if LPG is more than half the price of petrol it isn't worth it. I don't agree with this.

I acknowledge that LPG needs to be less than say 80% of the price of petrol to even get on the table from an economic perspective, considering about 25% more LPG is typically consumed.

However, consider this. About 10 years ago where i lived LPG was about 22c/L and petrol was around 65c/L. When i take into account using 25% more LPG, the equivalent LPG cost becomes 27.5c/L. This leaves 37.5c/L to pay for the installation, maintenance and hopefully give some profit. Then there's higher resale at the end.

Now i live in the country and LPG is around 85c/L and petrol is around $1.50/L (it's passed the 50% mark). When i take into account using 25% more LPG, the equivalent fuel cost becomes 106.25c/L. This leaves 43.75c/L to pay for the installation, maintenance and hopefully give some profit. This is a 17% increase in the kitty over before.

For the sake of keeping this analysis simple i'll say that the 17% covers increases in costs, and let's not forget i'm in the country where LPG is typically much more expensive, which leaves the overall argument for LPG similar to 10 years ago. However, this means the Government grant is pure premium.

So i think the case for LPG is better now than what it was before. And, personally, i think it was good enough before for many more people than utilised it.

Taking that figure, if we say the average installation after rebate costs $1000, it takes around 2300L of (adjusted) fuel consumed to pay for the installation, being around 34 falcon tankfuls. About a year for many.

i just had my EB converted cost me $2600 with the $2000 rebate i out of pocket $600 i did a trip today that normally cost $35 in petrol cost $14.03 in gas and car runs exactly the same i actually kept checking i had it running on gas it was running so good

I have a 4 cyl magna on gas and she costs me about 60 dollars a month to run me and the missus to work and do shopping runs. Its the best money I ever spent my new xr8 is on gas too so well have to see how that goes..... I dont think I would convert a car to gas tho its much easier and more ecconomical to buy a car with gas already installed.....

Well I used the calculator, I averaged it on 15L of petrol per 100k's which is about what I get.

Petrol price 155.9
Gas price 66.9

$23.39 to do 100k's on petrol
$13.05 to do 100k's on gas

Been on gas for 18 months now, after the $2000 rebate I was $200 out of pocket, I think I have more than made up for that by now with savings of almost $2k since I had it done.

hey if you don't like gas, that's ok by me i'll have it all!!