Size of LPG Tank / Mileage

Quote:

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Originally Posted by bee utey

Your "tune up" was probably done on a typical urban propane/butane mix and the gas you bought in Mortlake was pure propane as typically sold to country towns that also do bottled gas. You would have been running quite lean and could have just popped the bonnet and screwed out the power valve to compensate. This is why smart installers fitted LPG processors connected to an oxygen sensor just for the gas. Keeps better tune with different gas mixtures.

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Wow.. The idea I purchased 100% propane (ie: THE GOOD STUFF) didn't even occur to me. So you need more propane mixed in to get it to run .. Not less. That is backwards to what I was expecting :)

I'm glad I didn't ring the Mortlake fuel station and complain now!

seeya,
Shane L.

Quote:

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Originally Posted by DoubleChevron

Wow.. The idea I purchased 100% propane (ie: THE GOOD STUFF) didn't even occur to me. So you need more propane mixed in to get it to run .. Not less. That is backwards to what I was expecting :)

I'm glad I didn't ring the Mortlake fuel station and complain now!

seeya,
Shane L.

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Simple chemistry. Propane is C3H8 and requires 5 molecules of O2 to fully burn to CO2 and H2O. Butane is C4H10 and requires 6.5 molecules of O2 to fully burn. A mixture adjuster set for a substantially butane mixture will result in too much excess air to burn pure propane well. There are other heavier molecules added to auto LPG that also cause mixture problems in simple LPG systems. Pure propane is essential if it is to be burnt indoors, e.g. in forklifts.

Quote:

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Originally Posted by bee utey

Simple chemistry. Propane is C3H8 and requires 5 molecules of O2 to fully burn to CO2 and H2O. Butane is C4H10 and requires 6.5 molecules of O2 to fully burn. A mixture adjuster set for a substantially butane mixture will result in too much excess air to burn pure propane well. There are other heavier molecules added to auto LPG that also cause mixture problems in simple LPG systems. Pure propane is essential if it is to be burnt indoors, e.g. in forklifts.

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I didn't even consider mixture ... as low speed running was severely affected... using hardly any throttle as well, it was missing, carrying on... barely running. It's like the gas couldn't be ignited. Surely the power screw doen't effect it to the point where it will barely run with an almost closed throttle ...

Simply put ...whatever I put in the tanks at Mortlake .... doesn't want to burn! The tank float also doesn't float on it .... I'd imagine if it was 100% propane the tank float should float !

seeya,
Shane L.

Hi All,

Just an update to this post .... I've been logging my milage, litres used, cents per litre LPG and cost to fill tank every week for last 11 months.
From my records I'm averaging around 3.5 Klms per litre of LPG x 72 litres gives me approx 250 Klms total range to empty.

Most of my driving is done around the city and I usually keep an eye on the milage I've done before refilling and have never pushed it close to empty.
Bee utey (as usual) was spot on with his thoughts on what the average LPG consumption should be early in this thread.

I replaced spark plugs in August 2017 to WR7DC+ gapped to 0.7mm as recommended again by bee utey (thank you) and the engine is noticably smoother at idle
and has that distinctive V8 burble and purr which is just magic

Overall this 92 Vogue with 3.9L 14 CUX for a 25 year old vehicle gets a big :thumbsup:

Cheers

Baggy

I love a happy ending[biggrin]

I was asking in a different topic about fuel efficiency. I have dual fuel and the Gas tank only takes 30l from the bowser, from empty to the point where it won't pump in anymore. but the tank is stamped WAT CAP 60L.
also the LED gauge doesn't stay on the Full (top led) mark for long, maybe 10km's max, but the rest run through longer.

Is there a problem with my tank? can it fill with water over time, or is the pick-up from the bottom of the tank? and why does gauge go to empty, but only takes 50% of what the tank should hold?

A picture is worth a thousand words.

Ok so my gauge lied to me. got 230km out of the tank before it conked out. took 54L to fill. that sounds better... still rubbish economy.