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  1. #1
    Join Date
    Jan 2005
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    Luton, Bedfordshire
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    Engine temperature v fuel consumption

    Afternoon Guys,

    Hopefully the start of a marginally interesting discussion!

    Engine is a 351W bored and stroked to 394. I took her on a run to Ireland a couple of weeks ago and with the grounding of the nose on the Irish roads and I suspect some long term wear and tear the intercooler let go. Fortunately I spotted it virtually immediately and shut her off while the oil pressure gauge was showing 1 bar still.

    To get back on the road and home I cut the intercooler out of the loop and just connected in and out (on the Mocal thermostatic oil filter housing) together and then took it easy. That worked beautifully and got us home.

    Anyway, and this is the interesting bit, the engine temperature, without the intercooler, was running somewhere between 90 and 100 the whole time. When running on the motorway it would usually run at around 80 if not a little bit lower. It has been said before that we are running a little cool.

    Being sensible we have only ever been able to get 14 or 15 mpg out of her. While running at the higher temperature we were getting about 19mpg under pretty much exactly the same driving conditions.

    I'm not worried about the mpg itself but my concern is that the engine is unhappy / more stressed at the lower temperatures which may be leading to accelerated wear of the internals.

    What do we think?

    Thanks,

    Jon
    www.sounds-legal.com - some have said we\'re mad!!!

  2. #2
    Join Date
    Aug 2011
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    Birmingham
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    Quote Originally Posted by JonnyT View Post
    What do we think?
    I think you probably mean 'oil cooler' not 'intercooler'.

  3. #3
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    Quote Originally Posted by russell_ram2 View Post
    I think you probably mean 'oil cooler' not 'intercooler'.
    I do. Thank you.

    To be fair, in hindsight, I have no idea why I even typed the word 'intercooler'!!
    www.sounds-legal.com - some have said we\'re mad!!!

  4. #4
    Join Date
    Aug 2011
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    No problem LOL.

    As for your question, I don't know about SBFs particularly but I would have said 80C is a bit cold. Your oil won't be boiling off condensates and other bad stuff at that temp. The oil will be much happier at 90-100.

    As for fuel consumption, I assume you are carb fueled - if so you're unlikely to be running on any kind of 'choke' or 'cold' fueling by the time your engines at 80C. Combustion might be 'better' at 90-100 than at 80 but unlikely to be the 25-30% you're claiming I wouldn't think.

  5. #5
    Join Date
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    East Leake, Nottinghamshire, England.
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    The reason it is running cool with the Oil cooler fitted is because the stat in the thermal take off is normally something like 75 deg which is too cool. I have no idea why they fit one this low but all you need to do is fit a higher rated stat. I think the one they sold me was 91 deg from memory as this was just some they had leftover from a project or something. Once I had done this my engine ran at the same temperature it had before I fitted the oil cooler.
    Martin

    351W 416.7 HP and 466.8 ft-lbs

    Running Mega Squirt and Edis 8


  6. #6
    Join Date
    Jul 2012
    Location
    NW England
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    416
    On my Mercedes there is an oil temperature display which comes up as the default display on the dashboard. When cold there is an oil can icon which flashes, presumably telling you no to give it too many bean's. The can stops flashing at 80*C, normally stables out at around 99* no matter what the ambient temperature. I think AMG have put a bit of thought into this and know what they are doing.

  7. #7
    Join Date
    Oct 2005
    Location
    Cape Town, RSA
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    Your engine is designed to have oil viscosity at 10 centistoke. And oil is designed to operate at a "convenient" temperature to give you that. If you are running too cold, your oil is not "stoked" enough and poses restrictions. Try 5W50 oil for 130°C, 5W40 for 115°C and 5W30 for 100°C oil temperature. Drive again, let us know

    Keep it over 90°C, and occasionally 100°C. I have an older Mercedes myself and always wonder if their 80°C is a default reading to keep the operator happy...

    The difference though, from 15 to 19 mpg is quite drastic. I doubt this is all oil / temperature based.
    Nothing is as it seems...

  8. #8
    Join Date
    Feb 2003
    Location
    Devon
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    7,767
    My experience with the sideoiler stroker.......
    Ran too cool with oil cooler connected, even with the thermostatic valve.
    I blanked the front off and also fitted a sump guard which kept the airflow from cooling the Canton sump.
    Before the alterations I got about 11mpg.
    Afterwards I averaged around 13mpg on a decent run without to much hooning.
    It also warmed up quicker.
    In the high temps in southern France in traffic the oil cooler still had an effect when it opened.

    Nothing scientific in the above, just what I noticed as I altered things.
    2003 Dave Brookes Dax 350ci Chevy SB.
    2008 Crendon 462ci Ford Sideoiler No.43
    2012 Crendon 351ci Ford Cleveland No.24
    2019 Crendon 445ci Ford FE No.66

  9. #9
    Join Date
    Jan 2005
    Location
    Luton, Bedfordshire
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    Thanks Guys.

    Looks like I need to get a new thermostatic valve for the oil filter housing. I will let you know what the results are. If I have the time I might do some test runs once I have the new oil cooler before and after the new valve goes in.
    www.sounds-legal.com - some have said we\'re mad!!!

  10. #10
    Join Date
    Feb 2003
    Location
    Devon
    Age
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    7,767
    I think all the thermo valves stay open a little so you still get cooling all the time.
    This is why I blanked off the front of my cooler.
    2003 Dave Brookes Dax 350ci Chevy SB.
    2008 Crendon 462ci Ford Sideoiler No.43
    2012 Crendon 351ci Ford Cleveland No.24
    2019 Crendon 445ci Ford FE No.66

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