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LPG timing.

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

  1. rstucke

    rstucke Well-Known Member

    Messages:
    1,112
    Location:
    Wamberal NSW AUS
    Don't see it that way
    Liquid petroleum gas has to be a gas before entering the mixer
    In so doing it absorbs a large amount of heat
    normally the hot side of the cooling system (water cooled) takes care of this to eliminate freezing up.
    Running the lpg through a tx valve in an evaporator under the dash is a brilliant way of achieving the liquid to gas conversion without icing the whole thing up.
    Might be a problem in winter though.
     
  2. cbus

    cbus Well-Known Member

    Messages:
    11,954
    Location:
    sunshine coast
    Yep.
    The air con unit is in line before the engine supply vapouriser.
    Tx valve controls the pressure.
    The air con can be used as such as in those experiments but my purpose is to chill the intake air for engine to make it denser.
    The vapouriser still controls final gas delivery for mixer and is oil heated as is the current setup.
    Lpg being a slightly more efficient gas than R12 in refrigeration/ air con units.

    Hopefuly this can give further efficiency at no cost of load on engine.

    Stimulus for looking at this is the loss of volumic efficiency due to lpg entering intake as a gas and displacing intake air.

    My lpg delivery temp has been too high in my view.
    Delivery hose measures at 58C.
    Was planning to reduce this temp.
    Although the high value temp fluid( engine oil temp 90-100C) does ensure vapouriser of heavy ends which saves me having to clean it out regularly.
    And this muck probably assists in some slight way as an upper cyl lube ??:D

    Have just stripped the other lpg engine that developed a loose drive plate and cleaning g up the heads.
    Considerable carbon deposits in inlet ports from vapour of heavy ends in lpg.
    To solve this I will fit a catch can and copper tubing to drop gas vapour temps.

    An alternative may be use water as the heating fluid in the vapouriser and run that thru a small radiator mounted in base of air Feed ducts .
    Sort of heat exchanger setup.
    One possible issue would be balancing for enough warming capacity for vapouriser.
    Winter temps may limit its function also.
    The air being drawn in by normal engine needs of intake and cooling fan.
    The chilling effect from vapouriser supying cold air via the radiator to reduce air temps into engine bay.
    An easier setup but think colder ambient temperature may be the limiting factor.
     
    Last edited: May 29, 2019
  3. rstucke

    rstucke Well-Known Member

    Messages:
    1,112
    Location:
    Wamberal NSW AUS
    Considering the volume of air going into the engine (even at idle) I'm not sure you can bring the air temp down compared to the amount of liquid converted to gas(not a lot) at any throttle setting.
     
  4. cbus

    cbus Well-Known Member

    Messages:
    11,954
    Location:
    sunshine coast
    I'll have to do the numbers re volume vs cooling value.
    Will recheck the papers.
     
  5. cbus

    cbus Well-Known Member

    Messages:
    11,954
    Location:
    sunshine coast
  6. David H

    David H Well-Known Member

    Messages:
    5,159
    Location:
    newcastle
    Damn glad I can afford to run stock F/I:).
    How much does this experimentation/actual cost?:rolleyes: & what is the gain for the miles done:confused:.
    Cost/benefit analysis. Money spent..."opportunity cost" of money (how it may have been better served somewhere else!).
    Can you talk about the advantages of this on the average 20,k/yr pls.
    Cheers
     
  7. cbus

    cbus Well-Known Member

    Messages:
    11,954
    Location:
    sunshine coast
    E xperimemtation cost is stuff all as it has so far just been regraphing dissy, checking mixtures, necessary repairs to original sub standard fitment by a 'qualified' installer.
    I have heaps of spares if needed.
    The install paid for itself over 10 yrs ago and within 4 months when lpg was cheap.
    Extra items I scrounge from old cars or make.
    Improvement over original installation is reduction from 16 l/100 to 12.59.
    Average petrol consumption on a bay is 12-12.5.
    On this T3 was as per bay on 95 as it didn't like 91.
    Current cost lpg 90C/ Lt.
    91 is 1.46
    95 is about 1.57 last time I checked.
    I average 30k km a yr.

    Someone using 91 pays X 1.6 what it costs me on gas.
    On 95. X 1.74.

    I expect further improvements when I build an equall length exhaust system, add ceramic coatings on next engine build, add belly pans for less drag, add electronic ignition to enable leaner mixes, then tune on dyno.

    Pissing with efficiencies in many forms is my hobby:D
     
  8. Barry

    Barry Well-Known Member

    Messages:
    3,825
    Location:
    Abbotsford NSW
    Coming in halfway here but where do you getR12 from now?

    Been banned for a while
     
  9. cbus

    cbus Well-Known Member

    Messages:
    11,954
    Location:
    sunshine coast
    Just comparison used in a number of papers .
     
  10. rstucke

    rstucke Well-Known Member

    Messages:
    1,112
    Location:
    Wamberal NSW AUS
    HyChill is used in refrigeration and vehicle air con. It's a highly refined lpg and has very similar properties to R12 (controversially used in vehicles because its flammable)
    So the whole idea that Col is looking into looks promising.
     
  11. saabman

    saabman Well-Known Member

    Messages:
    4,803
    Location:
    Goulburn
    I have been doing a lot of reading about direct injection petrol engines lately and in Homogenous lean mode they make use of the evaporating fuel to during the intake stroke to reduce the combustion temperature.

    Not haveing much to do with Gas systems I had forgotten about the need for the heater in the gassifier.

    Using the cooling effect of the expanding gas to cool the cabin down is a very neat idea though like cbus mentioned wouldnt be great in ythe winter - but I guess you could always use the conventional system.

    I thought it was interesting in that article that the cooling effect didnt vary much once the flow rate got to 3g/s and above - Im guessing that was a limiting factor of the air flow through the evaporator.
     
  12. Ninga

    Ninga Well-Known Member

    Messages:
    1,006
    Location:
    Tumut
    You’re a nerd Col. :D
    But I still love ya.
     
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  13. cbus

    cbus Well-Known Member

    Messages:
    11,954
    Location:
    sunshine coast
    I deny it.
    But am pleased you still love me .:D
     
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  14. cbus

    cbus Well-Known Member

    Messages:
    11,954
    Location:
    sunshine coast
    Bernie.
    Martin said that you were getting sub 10l/100km numbers on the nullabour trip at same time others and he were as usual. Think he said he was 12-13 at same fills. Heavily loaded.
    Any mods that you think account for the good mileage or just everything done right?
    A number of stock builds with reco carbs and dissy regularly sit at the 10.7 mark and are my benchmark for comparisons.

    Would be interested what Rob @AC_T3 manages with the new injection if he ever say at hwy speeds :D
     
  15. oldman

    oldman Super Moderator Staff Member

    Messages:
    8,701
    Location:
    Avalon Beach NSW
    Sub 10’s.........woah, that’d be an achievement in a travelling kombi with two people plus gear.....
    I smell hay.:p
    Cheers,
    Mark
     
  16. cbus

    cbus Well-Known Member

    Messages:
    11,954
    Location:
    sunshine coast
    Don't you get mid/ high 10s Mark?
     
  17. AC-T3

    AC-T3 Well-Known Member

    Messages:
    970
    Location:
    Woy Woy
    Hi Col, been following your work with interest - seems like you got too much free time!!!!!! (but like the direction and results so far). You building an inter-cooler to improve LPG's inherently low VE? Should help without having to go forced induction. Fuel consumption on my Haltech setup is around 12 - 12.5 around town with freeways giving 11 - 11.5. Remember bus puts out around 120bhp at he flywheel and is set up for driving pleasure, not economy so I don't mind spending an extra $1.70 or so per 100km to get what I get. Another factor is final drive is different between the 091 and 094 gearboxes meaning bus has to rev an extra 300-400 rpm higher than a stock '82 or Bay. Will fix this at rebuild by putting taller legs on 5th gear. Hope this helps.
     
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  18. cbus

    cbus Well-Known Member

    Messages:
    11,954
    Location:
    sunshine coast
    Thanks Rob.
    Not so much too much spare time but finally completing what I should have done 10 yrs ago.
    Amazed at the extra low/ mid grunt and extended red line from having close to correct advance for the fuel.
    And yep. Aim is to improve VE and accordingly see what economy is realistic on a conservatively tuned unit.
    If there is energy at no cost ,might as well use it.
    Or in this case ,recover energy of liquifying the fuel for storage.
    If numbers stay as is I will be happy as it represents the wishful target already.
    20-25% more fuel than best on petrol but with considerably more punch.

    More to come ?
    Eventualy.
     
    Last edited: Jun 2, 2019
  19. saabman

    saabman Well-Known Member

    Messages:
    4,803
    Location:
    Goulburn
    Yes mid to high 9’s were common on flat roads at sea level. I was also running whatever fuel was cheapest at the pump BTW. I think everyone one else on the trip was running premium and I’d just pull up look at the pump and put in 91 or E10.

    Carbies has been redone at CBB a couple of years earlier.

    The engine was an 1800 with unleaded heads and the original domed pistons replaced with dished ones . It was also running a freshly rebuilt 2litre gear box.
    I had spent a lot of time getting the carbs balanced and adjusted right but it paid off.

    I should never have sold it - no rust as well !
     
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