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280SE LPG conversion

Started by Bandolero, 15 August 2006, 03:10 AM

Bandolero

Hi all,
reading the post below on 450 (& 6.9) LPG conversions, makes me ask if anyone has had experience with LPG on the 280? (1979)
I have heard that it is a lot of drama to go dual fuel on the mechanical injection systems (K-Jetronic), I was told I am better off making it LPG only.
Also, I was hoping to put a "donut" tank in the wheel-well and remove the fuel tank to give me more room in the boot. (Trunk in the US)
Anyone had a conversion done???
Russell Bond - (Adelaide, South Australia)
1978 450SEL 6.9 .... #5166 .... 12/78 (Sold.) [url="//www.ezycoat.com.au"]www.ezycoat.com.au[/url]

olliparr

As you can see from the previous thread mine is 280se 77 K-jet. No probs. Go ahead.

oscar

Bandolero,

The donut tank, is that for petrol or LPG?
1973 350SE, my first & fave

AMG69

In Australia its very common to place an LPG tank in the spare wheel well - usually its three small cylinders horizontally aligned (I think!).  Ford Australia pioneered this with their Falcon.
sigh....sitting back contemplating the next purchase..!

Bandolero

I have seen the latest tanks LPG and they are shaped like a donut, sure hope one will fit in my wheel well.
Russell Bond - (Adelaide, South Australia)
1978 450SEL 6.9 .... #5166 .... 12/78 (Sold.) [url="//www.ezycoat.com.au"]www.ezycoat.com.au[/url]

olliparr

Out of interest - it is a legal requirment in the Netherlands to carry a spare wheel - is this not the case in Australia?

Bandolero

I think it is here as well.
But if I put the gas tank in the wheel well, I can move the spare tyre to any place in the boot.
Also, If I make it gas only, I will remove the fuel tank and have more boot (trunk) space.
Russell Bond - (Adelaide, South Australia)
1978 450SEL 6.9 .... #5166 .... 12/78 (Sold.) [url="//www.ezycoat.com.au"]www.ezycoat.com.au[/url]

olliparr

Can you run it on gas only? I understood that it was necessary to start the engine on petrol and warm it up before switching.

OzBenzHead

Quote from: olliparr on 20 August 2006, 12:58 AM
Can you run it on gas only? I understood that it was necessary to start the engine on petrol and warm it up before switching.

That's the common 'gospel' that I've laways heard spouted, too. However, check this post (third from top of page) from John Green, MB Spares & Service, Canberra, at http://forum.mbspares.com.au/viewtopic.php?t=1179:

Quote... straight gas is the only go if you want to do a gas conversion.

- First of all if it is injected the injection system dies very quickly if the engine is run without fuel to cool it. They when you switch back to petrol it runs like s$%t. This is especially the case with k-jet. Some later fully electronic systems dont suffer quite as bad.

- If it is a carb model, even worse the fuel in the carb dries up and then the gaskets dry up and when you eventually put fuel back in it they leak all over the place.

- Gas is 104 octane, so if you want to tune it you need to take that into account. So what happens when you switch back to you 96 octane petrol....
[img width=340 height=138][url="http://i12.photobucket.com/albums/a215/OzBenzHead/10%20M-B%20Miscellany/OBH_LOGO-2a-1.png"]http://i12.photobucket.com/albums/a215/OzBenzHead/10%20M-B%20Miscellany/OBH_LOGO-2a-1.png[/url][/img]

oscar

I had no idea gas was 104 octane!! So what's with the "loss of power" myth with LPG?  Sounds like perhaps tuning isn't tuned properly for some gas conversions I hear of. (not Mercs, other makes).

As far as warming up on fuel, from what I've read it's for allowing the LPG to enter the plenum chamber as a gas not a liquid. ie, once the motor's warm, it heats the LPG before it reaches the plenum chamber. That GTI link in one of those threads on LPG also mentions how its system has a warm-up regulator or something to that effect whereby the LPG is converted to a gaseous state before it goes to the injectors, thus not requiring petrol to warm up the motor and the LPG.

There's been dedicated LPG cars in Aus for some years now, but I've got no idea what type of system they are or how pre-heating of the LPG is achieved.  I've also got a sneaking suspicion that warmer climates don't need to heat the LPG.  But I have nothing to back that up.
1973 350SE, my first & fave

OzBenzHead

Quote from: oscar on 20 August 2006, 08:23 AM
I had no idea gas was 104 octane!! So what's with the "loss of power" myth with LPG?  ...

My (very limited) understanding is that octane rating is unrelated to a fuel's thermal efficiency - i.e. the amount of realisable energy in the fuel. Octane rating relates merely to the fuel's ability to resist knocking when burned under compression in a confined space.
[img width=340 height=138][url="http://i12.photobucket.com/albums/a215/OzBenzHead/10%20M-B%20Miscellany/OBH_LOGO-2a-1.png"]http://i12.photobucket.com/albums/a215/OzBenzHead/10%20M-B%20Miscellany/OBH_LOGO-2a-1.png[/url][/img]

Bandolero

octane rating is unrelated to a fuel's thermal efficiency - i.e. the amount of realisable energy in the fuel. Octane rating relates merely to the fuel's ability to resist knocking when burned under compression in a confined space.

Sounds like this could be right as I heard that LPG burns slower, therefore you can advance the ignition timing more.

My 6 cylinder Holden was on gas, it started on gas and rarely ran on petrol. Of course this was not fuel injected. The ignition timing was advanced for gas and when it ran on petrol, it "pinged." It had no trouble starting it in the morning and also when I drove cabs in 1978, they only ran on gas, never any problem starting cold.
Russell Bond - (Adelaide, South Australia)
1978 450SEL 6.9 .... #5166 .... 12/78 (Sold.) [url="//www.ezycoat.com.au"]www.ezycoat.com.au[/url]

OzBenzHead

Quote from: Bandolero on 20 August 2006, 06:27 PM... when I drove cabs in 1978, they only ran on gas, never any problem starting cold.

You mean the cabs in Adelaide actually have a chance to get cold?   :o

Whenever I hacked cabs (Melbourne, 1970s) they ran 24/7 - which is why I figured they went 'forever': they never got cold (which is where a hell of a lot of engine wear happens).
[img width=340 height=138][url="http://i12.photobucket.com/albums/a215/OzBenzHead/10%20M-B%20Miscellany/OBH_LOGO-2a-1.png"]http://i12.photobucket.com/albums/a215/OzBenzHead/10%20M-B%20Miscellany/OBH_LOGO-2a-1.png[/url][/img]

Bandolero

Ha Ha....I was a slack "cabbie".
Used to start late...8pm and knock off early 6am.
I drove the night shift.
The boss always wanted me to start at 6pm, but I was slack!!!!
He couldn't sack me as I looked after the car and cabdriving jobs were easy to get as there were not enough drivers.
What an a**hole I was!!!!!!!.. ;D
Russell Bond - (Adelaide, South Australia)
1978 450SEL 6.9 .... #5166 .... 12/78 (Sold.) [url="//www.ezycoat.com.au"]www.ezycoat.com.au[/url]