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Thread: Fuel Temperature

  1. #1
    Join Date
    Dec 2007
    Location
    Lake Macquarie (just south of Newcastle) NSW
    Posts
    1,363

    Fuel Temperature

    I now have a temperature probe inside the fuel hose leading to the IP.
    It gives a digital readout supposedly accurate to +- 1% and I have tested it against a digital multimeter which gives exactly the same readings.

    My findings:
    Regardless of whether I am running on diesel (1 x HE) or veg (2 x HE), when fully warmed up the ingoing fuel varies between 70 degrees and 82 degrees, although I did get one transient reading of 97 degrees. All this with the coolant temp' gauge sitting right in the middle of its range and not varying at all.
    After driving 15kms and then leaving to sit on a hot summer day (27 degrees) for 2 1/2 hours the fuel temp had dropped to 32 degrees - the engine started easily and ran well with veg at this temp.
    First thing in the morning the fuel temp was 20 degrees (diesel). Started easily on diesel and ran well. After 500 metres driving fuel temp was 30 degrees. I wasn't game to switch to veg yet. After 2 km driving fuel temp was 45 degrees and the coolant temp gauge needle just started to move.

    Conclusions:
    I can switch to veg at 2 km from home, or at the point the coolant temp gauge needle just starts to move, I don't need to wait till the coolant warms up completely.
    The 2 HEs supplied and fitted by Fitian are doing an excellent job of heating the veg to the appropriate temp.
    I can leave the engine stopped - on veg - safely for 2 hours (in summer) and still be able to start and run properly on veg.

    Action:
    I will continue to monitor temps for a while - into winter I guess.
    I will switch to veg as soon as the coolant temp gauge needle just starts to move.
    I will try to remember to purge if I am intending to leave the vehicle standing for more than an hour (having another 1.5 hours to get back to it and warm up and/or purge if I get it wrong).
    I will report further as more data is recorded.

  2. #2
    Join Date
    Dec 2005
    Location
    Perth Western Australia
    Posts
    933

    Re: Fuel Temperature

    Well done Paul, it's good to have definitive measurements to go by.

    Your experience concurs with mine and inserting the thermocouple probes into the fuel flow give very accurate readings. I had problems with fuel seeping up the lines, so removed the thermocouple, but as I said your readings and deductions make sense.

    Given my base data, I set the thermocouple sensor on my automated system to switch at 55C measured on the outside of the heat exchanger, and with a single ten plate heat exchanger the valves switch over after about 7 minutes of idling and a bit of running.

    Tim
    Toyota Landcruiser 1988 HJ61 Manual Wagon
    12H-T turbo Direct Injection.
    Twin Tank setup runs on 100% WVO after warm up. 30 plate FPHE with 80C output, 12mm fuel lines
    Start up and shut down electric fuel pump feeds IP direct.
    Front 4WDSytstems Lokka, Rear ARB airlokka for quick escapes up sandhills. Performance GTurbo with 600mm FMIC gives 450nm @ 1700rpm at 20psi boost.

  3. #3
    Join Date
    Sep 2005
    Location
    WA
    Posts
    4,282

    Re: Fuel Temperature

    Paul,
    As the seasons change, the time you can leave the engine (without purging) will drop rapidly for some engines while others may be more tolerant.
    Take care in winter to avoid starting issues if stopped for even a half hour or less if windy.

    Keep up the good work,
    Tony

  4. #4
    Join Date
    Dec 2007
    Location
    Lake Macquarie (just south of Newcastle) NSW
    Posts
    1,363

    Re: Fuel Temperature

    Thanks Tony,
    I will continue to monitor through the coming winter.
    Will report.

  5. #5
    Join Date
    Oct 2006
    Location
    Perth
    Posts
    368

    Re: Fuel Temperature

    Quote Originally Posted by Tony From West Oz View Post
    Paul,
    As the seasons change, the time you can leave the engine (without purging) will drop rapidly for some engines while others may be more tolerant.
    Take care in winter to avoid starting issues if stopped for even a half hour or less if windy.

    Keep up the good work,
    Tony
    Would it be worth insulating the fuel tank to slow the cooling of the fuel?

    Or is there problems with legality/safety?
    Please click below for info on how you can help the victims of spinal injury, or just spread the word.


  6. #6
    Join Date
    Sep 2006
    Location
    Sydney
    Posts
    863

    Re: Fuel Temperature

    I have insulated both heat exchangers on Paul's troopy. I know from experience that I can get away with 45 - 60 min. This also depends on how long the engine was running for before stopping.

    I would insulate the injectors pipes - not sure how much of a difference this will make.

    TroyH, Insulating the tank is a good idea but it won't have any effect on how long the engine can be left with WVO switched on. The WVO is already in the lines all the way to the injectors.

    Cheers,
    Fitian
    <><

  7. #7
    Join Date
    Jan 2008
    Location
    Armidale NSW
    Posts
    53

    Re: Fuel Temperature

    Can anyone recommend a cheap thermometer with remote (or extendable) temperature sensor ? My first winter is coming and I want to be sure of temps.
    Regards
    Geoff.
    1992 Rodeo 2.8 Turbo Diesel SVO, dual tank, 3m copper pipe in pipe HE from vege tank to engine bay, 6 way pollack valve, OEM water separator, OEM fuel filter, 20 F.P.H.E before I.P. Digital thermometer with probe clamped to IP fuel inlet. I switch to vege at 40degC. Runs at 70 to 75 degC. Switch back to diesel 3km before home.

  8. #8
    Join Date
    Dec 2007
    Location
    Lake Macquarie (just south of Newcastle) NSW
    Posts
    1,363

    Re: Fuel Temperature

    Quote Originally Posted by Geoff Bragg View Post
    Can anyone recommend a cheap thermometer with remote (or extendable) temperature sensor ? My first winter is coming and I want to be sure of temps.
    Bought mine from Jaycar for $40, 900mm cable to sensor but should be extendable. They also have a multimeter for $25 with temp' probe. It is shorter but should be extendable too. You could get an auto coolant temp gauge from K-Mart for $14 and plumb it into your fuel system if you don't need a digital readout.

  9. #9
    Join Date
    Apr 2006
    Location
    New Zealand
    Posts
    621

    Re: Fuel Temperature

    I bought the $25 model. It has a small thermocouple style of sensor which can be clipped or tied to the #1 injector line. It works surprisely well even though it's not in direct contact with fuel itself and is quite sensitive to temp movements. It's also cheap and doubles as a multimeter with a good variety of functions. Look at my previous posts where I reported a lot of info re readings.
    Consider rechargeable batteries for it and use it for spot readings rather than continuously on. Since I've ironed the bugs out of my system, I've removed the unit. Awesome for troubleshooting though.

  10. #10
    Join Date
    Nov 2007
    Location
    Victoria
    Posts
    445

    Re: Fuel Temperature

    Hi everyone,

    just back from holidays in the 38deg C heat. The troopy ran fantastic on wvo making our family trip away very cheap.

    The camping trip up to Freeburg[vic] towing our fully loaded offroad campertrailer was the first big wvo test for the troopy.

    The trip up and back was during the day and the temp on both trips reached 38 deg C. My fuel temp gauage showed a solid 80 deg C on both runs. The normal fuel temp that I've been getting up to this trip is about 70 deg C.

    The nights in the mountains were very cool around 10 deg C. The troopy ran a wvo temp of 60 deg C during the night drive.

    It is intresting to see that there was a 20 deg C variation between the min and max temps of the wvo. It just goes to show how much the outside temp influences the fuel and coolent temp of the wvo vehicle.

    Has anyone else had similar results?

    God bless froggo
    HJ45 Landcruiser Troopy
    Home made 2 tank system
    Blending in main diesel tank
    SVO/WVO Converted 18/01/08
    http://www.biofuelsforum.com/svo_users/3667-hj45_troopy_conversion.html

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