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LPG timing.

Discussion in 'Performance' started by cbus, Feb 1, 2019.

  1. cbus

    cbus Well-Known Member

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    11,263
    Location:
    sunshine coast
    Last edited: Feb 1, 2019
  2. cbus

    cbus Well-Known Member

    Messages:
    11,263
    Location:
    sunshine coast
    I remain cautious about interpreting data from a different engine and will eventually do a dyno run but so far things are very positive.
    Caveat utilitor.
     
  3. saabman

    saabman Well-Known Member

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    4,770
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    Goulburn
    youve lost me col,

    whats the title of the article you were trying to link to ?
     
  4. cbus

    cbus Well-Known Member

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    "An investigation into the burning rate of LPG in a multi cylinder engine. "

    "MG Burne."

    Pdf file


    Damn thing won't copy correctly.
     
  5. Grantus

    Grantus Well-Known Member

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    15,044
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    Southern ACT
    Clever copyright software warning on that site......... print once, but no sharing. ;)

    Google Col’s Quotes Bernie, and it will come up.
     
  6. cbus

    cbus Well-Known Member

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    11,263
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    Ahhh ,;)
     
  7. AC-T3

    AC-T3 Well-Known Member

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    Interesting, very interesting. Exported, downloaded from the UoW site and saved as a .pdf for further relaxed reading.
     
  8. AC-T3

    AC-T3 Well-Known Member

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    Was a nice read thanks cbus. Gotta say 1974 was way back when???? The results remain relevant and were used by my gas fitter say back when. Are you planning a single fuel LPG set up?

    Me? I'm still sitting back thinking duel fuel LPG liquid injection managed by a Haltech ECU that can load maps that maximise performance from both LPG or petrol - at a flick of a switch. Then again, maybe not.

    PS. The article can be shared, emailed or what ever. Just gotta get the file first.
     
    cbus likes this.
  9. cbus

    cbus Well-Known Member

    Messages:
    11,263
    Location:
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    Hi Rob.
    Finally getting something backed by hard numbers was good.

    Both my kombis are currently LPG only

    Both 2l air cooled. Mild cam. Type unknown. One supposedly ceramic coatings head, piston, valves.??
    Cone filter into vw EFI throttle body and manifolds.
    Lpg spares H420 vaporiser. Oil heated thru sandwich plate takeoff.
    Impco 125 mixer.
    Non feedback mixer setup.
    Run slightly rich to avoid issues with variable fuel qualities.
    Home made narrow band O2 says 0.74 to 0.85 mainly. Can go lower.
    Richens slightly on full throttle and idle. Plus stays rich as speed.
    I would say mix is closer to correct than O2 suggests.
    Indicator only till I get a wideband.

    The t3 was / can be reverted to dual fuel.

    009 dissy.
    RPM....was...now..ideal LPG? .. Prop.*
    900...... 8.........16.......,....21............12
    1000.... 10....................... 26............25
    1500.... 20.......23.............28............27
    2k........ 24........29............28............28
    2.5k .... 30........................29............30
    3k/max.33.......32...........29............ 31
    *(Prop. Is what I'm aiming for.)

    A lot more punch do far .
    Only touching pedal 1/8-1/4 and it goes same as prev 1/4-1/2 throttle around town.
    Still bit flat up to maybe 1500+ so needs advancing there.

    16 initial has starting resistance.
    14 Is fine but better lower in case of low power in battery.
    Happy to have a degree or two up on test results at top end given test engine ran higher compression and only slow dropoff after peak power.
    I don't use full throttle either and 1/4 throttle usualy means vac advance comes in on petrol engines.

    Stuff you will already know but part of my reasoning.
    Temp doesn't increase much with lean or advance on LPG as with petrol.
    One danger is LPG preignition is hard to pick initially.
    Retarded combustion gives worse pressure conditions whereas advance seems pretty safe past normal excesses. Not that I would risk it.


    Given the cost of fitting LPG I wouldn't bother now due to insufficient cost margin difference and thus crap payback period.

    Would be interested to see what was possible tho
    I would be interested to see what you can achieve in your injected bus if you were able to do a hwy test at legal speeds without putting boot into it :D

    I'll see how mileage is affected in a few weeks once I have the curve where I want it.

    Up hills is better.
    Local one I hit at 100 and usualy drop by 10-12 km at min I hit yesterday and dropped 8 -9km.
    Off from lights is stronger on half throttle and runs higher in gear quicker.
     
    Last edited: Feb 3, 2019
  10. tillis

    tillis Active Member

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    Location:
    gold coast
    Col I did up my sons 253 holden V8 running LPG only and supercharged. I used a programable MSD ignition and it works great...LPG needs lots of early advance. However the MSD can't be used with fuel injection
     
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  11. AC-T3

    AC-T3 Well-Known Member

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    Location:
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    [QUOTE="cbus, post: 650531, member: 513"I would be interested to see what you can achieve in your injected bus if you were able to do a hwy test at legal speeds without putting boot into it :D[/QUOTE]
    Like your work Col. Always found the vapour systems a bit light on performance and hard/impossible to tune between low mid and high revs, throw in dual fuel, life down here in the higher latitudes and yeah, you gotta be mad or chasing something. But hey, life is full of challenges. Will try and find time to lift the lid on my ECU and download some ignition data that you might find useful. And what pisses me off? Liquid injection wasn't available when Kev O Sev offered all those fiscal incentives to chase alternative energy. Add in the excise bonus' and it was an opportunity to good to pass up and certainly paid it's way when bus was an F3 high speed commuter. Still reckon liquid injection has potential, it's just if and when.

    Until then very happy with my Haltech inspired 5 speed 1970cc Type 4 that puts out around 120+BHP and gets driven much much more sedately these days. Must be getting old.
     
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  12. cbus

    cbus Well-Known Member

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    11,263
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    I have no issues with the vapour system other than installers that do bad fitments and can't tune.
    Gas leaks in joins, oil lines blowing off from wrong fitting, wrong sized mixers that can't be tuned and freeze up in winter.

    With that sorted its pretty trouble free.
    I just drive off in summer. A few km under 80 to let oil warm up for engines sake.
    In winter that's about 8 km for engine plus gas benefit.
    As said before, run slightly rich to accommodate fuel variations.
    BP should be avoided.
    Only thing that causes occasional check is draining heavy ends or split diaphragms.
    First check if there's any issues.

    Power on both kombis is up on a stock 2l .
    With the extra advance that I should have sorted years ago its much stronger again.
    Also sorted an occasional stumble down low.

    Next thing should be an engine built to use LPG' s characteristics.
    I wouldn't trust the extra octane rating too much due to lack of fuel standards compliance.
    A well known problem in the industry.

    Direct injection in a dedicated engine is certainly something that needs to be tried :D

    Dual fuel is problematic due to the ignorance of installers who gave the dissy a couple of degrees advance.
    This destroys heads at hwy speeds and isn't enough down low.
    Plus the issue of mix not helped by the flow meter.

    I can definitely recommend just running single fuel.
    And regraphing dissy.
    ( for vapour/carb type setup anyway)

    But with your 120bhp to play with I doubt you will be tempted with LPG for a while.
     
    Last edited: Feb 6, 2019
  13. cbus

    cbus Well-Known Member

    Messages:
    11,263
    Location:
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  14. AC-T3

    AC-T3 Well-Known Member

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