LPG sprinter

[craigb]

Contradiction in terms! And I know there are a lot of critics out there of LPG conversion so I hope I am not too offensive for you and of course you can always switch off or change channels. Having said that I probably do respect your views but on this car I have chosen to go this way so please respect my views.

I am happy with the conversion though and it goes much better than it ever did on petrol. That says more about the unsuitable holley carb that was fitted more than anything. The conversion cost me $800 out of my pocket and to fix my carb probs and add in my scarce time it would probably cost more. Added into that is my commuter will cost less to run.

The conversion is straight gas, old tank out - filler in same place. If you have a sharp eye you will be able to see the panel in the boot has moved slightly back. No sign of it inside the car with the guage wired up to the standard needle guage. I was dissapointed it couldn't be hidden better under the bonnet with the standard air cleaner needing to be replaced but there you go. If ever I wanted it standard again, I have all the parts and apart from the odd extra hole that could be filled, you would never know. I did take along a tuned length se manifold that I had hoped he would use if he couldn't make it look standard but you can't have everything!

The guy hasn't touched the state of tune, didn't even replace plugs and said to put 1000k on it first but it is running nicely and now is happy to scream to redline. Having driven Andreas' solex carb manual car on the weekend, it may be missing a little something in the pickup at points but there is not much in it. Also nothing has been touched timing wise and I will get it on a dyno and have the dizzy recurved to suit the gas. Another thing is to replace the thermostat so it runs a bit hotter and this will help in turning the liquid into gas apparently. Will keep you posted on developments and outputs from the dyno.

Fuel economy was about 19l/100km before, so obviously it wasn't right. It will be interesting to see what it gets now but with my foot planted going up through the hills each night I am not expecting much..... but gee its fun! At least I will be paying about a third of the premium when I do fill.

Its looking like I will make the August 17 sprint with just tuning and brakes to look at before then.... which reminds me I must get onto that.

Yes photos! These will follow but I just had a try and I can't get it to upload in gallery again. I can't remember what happened last time. I think I logged off and on again and then it behaved. Run out of time tonight though.

[Big_Richard]

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[Ryan1980]

I converted my 74 450SE to LPG and im really happy with it - runs the same as it did before and i believe i'm getting much better fuel economy from the LPG. Im on straight gas as well, had the tank replaced.

[oscar]

i thought you owned an MB sprinter van,

  The idea of a hillclimbing "sprinter" van popped into my head in my other thread Craig. 

It'll be interesting to see the results of the dyno tune.  No idea what's involved with tuning for LPG unless it's just got to do with adjusting mixture and timing but it'll make good reading to see what difference optimising the engine for it will make.  And of course, ever eager to see those photos

[craigb]

OK finally some pics:



OK, big ugly 75l gas tank replacing the petrol tank but it does fill at the same point and therefore no ugly filler.



And it doesn't look so bad with the panel back in the boot. Those with a sharp eye will notice the panel is back about 2 inches. The original 63l tank (designed for a Toyota Camry) we discussed would have fitted perfectly but there were complications with the fixing to the boot floor and I ended up with a 75l tank (which I may be grateful for one day) but it does take up a bit more space.



You can't tell much from this photo but there is no sign whatsoever from inside the car of the gas. The standard guage works and the priming set up for cold starts is automatic. No gas/petrol switch because it is straight gas.



I am a bit dissapointed that it is not more discreet under the bonnet but that's life and it doesn't matter that much. They couldn't fit everything in and the standard air cleaner as someone did with a lpg 108 i had. That is a standard Oz Ford Falcon air cleaner element in there. Not sure if that has enough flow at 6k revs (certainly I don't think a ford 6 is designed to rev that hard) so when we dyno I will get them to check with and without the filter to see what is happening. With such a common filter no doubt high flow replacements are available.

So there it is and now for some other questions under different threads.

[oscar]

Craig, forget my tacho question in the rotor thread, I can now see you have one.   

This is a really interesting setup.  I think you've gone the right way about it by going full LPG and having it tuned for that alone, not a mix.  Is the gas just plumbed to the carby?  What's under the air cleaner?

I'm pretty glad to see that air cleaner.  I wanted to do something similar as in getting rid of the OEM filter and housing.  It's just too big and heavy, but I didn't know what to look for.  Pretty much anything for a Ford or GM made for a Holley is suitable for a Solex.

[craigb]

Oscar, there is a 'gas carby' under the cleaner, sort of sitting up inside it, and the whole assembly just sits on top of the carby. Theoretically if I run out of gas, I could put a small petrol can under the bonnet, pop the hose in from the fuel pump and the thing should go.

[Takernz]

hi Craigb! I'm bringing this thread back to life! we have the same car as I have but I'm planning to have my car run on straight LPG because in the Philippines, In Cebu City, we have lots of LPG conversion shops around and I haven't visited them but I need some advice from you regarding this set-up; I have questions,
1.) before converting to LPG, did you pull the head and change anything? valves,valve seats, etc...
2.) when running on LPG, did your car overheat? I read somewhere (it's your post) that you're running at constant 100C and you said it was good in the Philippines the summer is on! expect      30-33C heat these days.
3.) how did it perform when driving up the hills, mountains?
4.) what type of mixer did you use on the car?
5.) what plug did you use? and did you change the plug boots or suppressors?

I'm weighing my options here because I found a used but good,straight Solex 4A1 which cost less than converting to LPG. The Solex on my car now is a dead (severe warpping, leaking fuel), this leads to crappy idle, stalling at the lights and 5km/liter consumption).

[craigb]

Sorry Takernz for incredibly slow reply. Was searching for something else and saw it. But for the record:
1. no change and has hardened valve seats anyway
2. Never overheats and I deliberately removed fan for it to run hotter because better combustion/power, just needed to watch in traffic but air con fan would help. If ever a problem I would have put a seperate but adjustable thermostat electric fan. No thermostats I could find were hot enough. But no inherent probs with overheating.
3. No probs on hills, but I suspect you might have some at a bit higher altitude.
4. Not sure, could check but so long you might not even see this - nothing special though and could check if you want.
5. Plugs are different but everything else is the same - I think they are one grade colder?

[Squiggle Dog]

That's really neat! I love alternative fuels. I would probably do the same thing if I had a gasser.

[craigb]

There are environmental benefits but the big plus in running these big old girls here is the lpg price is usually less than half petrol. I think the biggest minus (apart from maintaining originality) is that there are good conversions and not so good. I think most of the negative comments made or bad experiences are in relation to a bad conversion. Mine has been absolutely trouble free and when I did more miles it took some getting used to just how little a fill would cost and I didn't notice the span between fills, theoretically it uses a bit more gas for the same number of miles.

[calvin streeting]

1. no change and has hardened valve seats anyway

How did you know that i have asked merc about these on a 350 lump and they said no..

[Squiggle Dog]

All Mercedes engines built after World War II have hardened valve seats.

[craigb]

Was that 'no they dont have hardened valve seats' or 'no we don't think you should run lpg'? Its an alloy head and therefore must have hardened valve seats, but I have seen a Mercedes bulletin that says the seats are of a standard that unleaded fuel can be run without an issue. Also I wonder about who gives answers within any organisation, I think you need to get stuff in writing sometimes from the right people ie. a factory engineer and not a salesperson or the guy in the parts section. Not saying you haven't done this and only asking to perhaps learn something, not wanting to share with others if I have it wrong. But straight hardened valve seat question, no question they are as Squiggle dog states.

[calvin streeting]

ok this is a copy of the email from merc. so erm.. not sure any more

From: [email protected] On Behalf Of
[email protected]
Sent: 20 August 2010 10:07
To: Calvin Streeting
Subject: WG: A Question about W116 350SE


Dear Sir,

sorry, the have not hardered valve seats.
We recommend unleaded gasoline with oktan rating of 98 (Super Plus) without any
additives.
We recommend that the valve clearance be checked and , if required, adjusted at
shorter intervals (at half the intervals specified in the owners manual).


Kind regards

Daimler AG
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