LPG Conversion and swap into watercooled Suby

Discussion in 'Modified Shizzle' started by pgtips, Sep 20, 2018.

  1. Hi,
    this thread sort of comes in 2 parts, one is my posts back in 2011 before I had a major engine change (subaru) just after I had LPG fitted in my old aircooled engine and then afterwards. It's mainly to provide some info on converting buses like the cost and practicality. It also gives me a before and after.

    All this Brexit crap going on we're all looking the other way, petrol prices have been creeping up again so its possibly on a few peoples minds.

    In a nutshell yes its possible and will cost about £895 + vat to pay someone to do it all in supply and fit. Carbs or FI it doesn't matter. I originally had mine installed in my aircooled auto 1.8l 1975 FI bay. I think I save ball park £26 per tank (equiv) so only worth it if you want to keep the bus.

    My tank goes under ther R&R bed so I lose that storage space but I've managed just fine on camping trips with kids, tents, holidays etc. Its holds 70l and they are bullet proof. I wanted the biggest possible.

    lpg tank.jpg

    Why did I look into converting?, if you think your bus is a bit juicy try running an auto 1800 . 17mpg isn't wallet friendly and I planned on keeping it. (auto torque converters were developed back in the day before they figured (or could afford to develop) lockup converters so you lose loads of energy .

    Why a Subaru engine fit? En route to main summer holiday, me and the kids camping, the engine blew. I figured I could spend a lot rebuilding a 75hp engine or a lot less fitting a subaru in it ... so I chose subaru and sold the old engine complete with all the FI kit.
    (In between while initially looking for an auto engine I 'accidentally' bought a 1302LS bug convertible and restored that too)

    So fast forward to today (Sept 2018) Ive finally got the LPG system up and running again with the Subaru so in another couple of months I'll know what my MPG (it all sounds so easy)

    Having had the exact same LPG setup in both aircooled and watercooled I know they are the same so these pics and everything else I figured might help if you're thinking about it.

    Air or watercooled you need a temp sensor. An exhaust probe is used for air cooled..
    water temp sensor.jpg
    On the aircooled engine this equivalent temp sensor would be hooked back into the exhaust with a probe.

    Mines a Stag 300-4 system and here you can see where it is positioned in the engine bay (aircooled or watercooled its the same, in fact for everything this point on, aircooled or water, its the same bar the sensor above)
    ecu and injectors.jpg

    lpg ecu close up.jpg

    These (below pic) are new/added injectors (red tops) that run the LPG.
    Basically you start the van on petrol and when its warm enough it switches over to LPG and so your new injectors and ECU (brain) run the show. You will also have new nozzles into your manifold that provide the seperate fuel supply (LPG). If you can get your head round it, its 2 seperate fuel supplies, your exisitng one then an LPG one on top.

    injectors left.jpg
    The silver bit by my thumb is a LPG filter, like a petrol filter but for LPG so it needs changing at service time same as you would your fuel filter. They're about £8.

    This next picture shows the reducer, on the left in my van in front of the leisure battery, gas comes into this and is vapourised and fed to your cylinders. Air cooled your exhaust 'dongle' will also have capability to preheat the gas, watercooled you use coolant.

    lpg reducer.jpg
    And here's the button on the dash, its also supposed to be an LPG level gauge but they are all pants, when you run out of LPG it switches to petrol. I work out how many miles I can do and use that to tell me when to fill up, if you've got a trip meter thats a result :)

    front dash button.jpg

    So long before i swapped (or even thought about) engines i posted up this thread below (in 2011) in another forum.

    "I've got a 1975 bay window 1.8L FI westy automatic.

    I had a 84L LPG tank fitted (so holds 70 litres of LPG because you can only appx 80% fill them), its tight but it does go in under my R&R bed, maybe a tad too big but it fits. I had to bring my R&R bed front panel forward an inch.
    Stock petrol tank is 60 litres btw.

    Cost to fill up
    petrol 60L at £1.309 = £78.54 (that was in 2011)
    LPG 70L at 0.749 = £52.43

    I know tank sizes are different but I can use this to compare miles I get from a full tank and cost per tank to give me calculations. Size difference accommodates/makes up for lost mpg using LPG as well as LPG doesn't give as good mpg as petrol.

    Est I save £26.11 per tank.

    Cost to install - £895

    You can buy a kit for £650 ish + P&P, I looked into it (self install) and spoke to people who have done it, but really I didn't think it was worth it i.e being onsite during the whole install I can honestly say its not worth you trying to save £200 vs. to pay someone else. It took the garage a day to install, a long day but a day all the same.

    Based on £26.11 per fill up saving, divide the cost to install (£895) by this saving gives me number of fills to achieve payback which is in 32 fill ups time, so I'll be quids in/paid for and save thereon.

    How does it drive, virtually no difference, the LPG ECU is mapped to match the engine, drove home 200 miles and it was absolutely fine. 2018 Update with Subaru engine it's the same, you barely notice any change.
    It switches between petrol and gas if necessary.
    My range based on both tanks filled up is now at least 400 miles between stops.

    My miles per tank. I drove 200 miles to get it installed and used just over a 60l tank of petrol (had to top up so possibly more than 60L but 60 is a stick in the mud. I drove 200 miles back home on a tank of LPG (70l) and had some left over. My petrol gauges aren't super accurate but its as near as dammit.
    Guesstimate I'm losing 2 mpg (running on LPG). Don't forget my bus is an auto so MPG is dreadful, on a pound for pound basis to petrol I'm now about 1/3 mpg better off based on cost.

    I.e if you accommodate 10L difference in tank size, that trip home was 1/3 less in cost coming home than to get there.

    Runs well. Bar refixing my R&R seat which I altered because I wanted a mother sized tank it is brilliant, I am genuinely impressed and slightly surprised as how little difference it makes in driving.

    I had concerns over this LPG conversion which included "is it safe?", "where will it (the tank) go", "how do you fill up", "will it affect my engine", "is it really cheaper etc". After 18 months + of restoring my bus I was cautious but the pics above will give you an idea of whats what.

    I'll update this with Subaru engine mpg numbers in a few months once I've done some good mileage.

    Last edited: Sep 20, 2018
    art b, scrooge95, bernjb56 and 3 others like this.
  2. Haha, never again. I remember the honeymoon period with our lpg. The savings were total justification for the install costs and we got through the 'payback' period...just.
    Before the blanks blew off the regulator in southern Spain, flooded the engine bay with gas which was ignited by the alternator, which turned onto a ball of flame, which burned out all the wiring and set the engine lid on fire. :eek::eek::mad:
    The resulting 130km recovery truck to Seville, 3 days repair and 1700 euro bill took the joy out of lpg for us.
    I had the kit removed and now live with the mpg.
    Unlucky I guess...;)
    art b, Dicky, pkrboo and 1 other person like this.
  3. Scariest 130km you ever did!!!!!!!
    art b and theBusmonkey like this.

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