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Thread: Fuel consumption

  1. #61
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    Quote Originally Posted by Traveler View Post
    I have 2 professors at uni looking into this...
    their is an answer... complicated...
    answers tonight or tomorrow.

    here is the question i asked them:
    Hello again.
    here is the problem.
    their are no factors which may influence performance eg: wind, road surface, driver technique, type of fuel used,gear changes,optimum fuel efficiency point, etc.
    point A to B is a flat surface.
    both vehicles are at their given RPM speed constantly and in 4th gear between point A and B.{no acceleration, braking.}
    Car 1 is doing 2000RPM constant throttle speed between A and B
    Car 2 is doing 1750RPM constant throttle speed between A and B
    Car 1 will reach point B in less time than Car 2.
    Which car uses more fuel for the overall trip from A to B?
    Read
    Last edited by Traveler; 2nd October 2007 at 04:41 PM.

  2. #62
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    Quote Originally Posted by Traveler View Post
    No Phil, here is the last question.
    Well taking out all variables, you simply need to calculate the the air used per revolution, and work in the fuel at the 14.7:1 ratio, and they'll both use the same amount of fuel, because both have completed the same amount of revolutions to get to the desired destination, It can't be different as you've taken out all of the real world inclusions that effect fuel economy

  3. #63
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    Oh, don't be like that! Your pursuit of the truth is admirable, but your success in finding the truth is sadly impeded by the vacuum inside your cranium. GET A LIFE! YOU CERTAINLY NEED ONE.

  4. #64
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    Quote Originally Posted by rovercare View Post
    Well taking out all variables, you simply need to calculate the the air used per revolution, and work in the fuel at the 14.7:1 ratio, and they'll both use the same amount of fuel, because both have completed the same amount of revolutions to get to the desired destination, It can't be different as you've taken out all of the real world inclusions that effect fuel economy
    Bingo!
    close this thread
    -----------------------------------------------------

    But the following is where I thought this post took yet another leap backwards

    Quote Originally Posted by PhilipA View Post
    BUT AFAIK, you still have to input some data on economy at speed points
    Quote Originally Posted by Traveler View Post
    Philip you are confused. My question does not include any of your variables.
    Traveler, Please listen to this.
    If you do not take into consideration the above variable put forth by PhillipA then you are wasting your time, cause that will be the main factor in any further calculations.
    If you want to know about a certain vehicle, you need to find out these variables for that vehicle, and as you, and many others know, all vehicles are different.

    So the first thing you need to do is decide on what economy figures you would like to 'simulate' for these two identical vehicles.

    If you do not want to figure/simulate this, then you do not want an answer to your question.
    If you do want to figure this out, a basic answer will be very simple, but a mathematical one will still be slightly complex (but not hard).

    At the end of the day you can simulate what ever you want, it will not help you save fuel in the real world
    I rule!!!

    2.4" of Pure FURY!!!

  5. #65
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    Quote Originally Posted by 001525 View Post
    Oh, don't be like that! Your pursuit of the truth is admirable, but your success in finding the truth is sadly impeded by the vacuum inside your cranium. GET A LIFE! YOU CERTAINLY NEED ONE.
    Ease up mate, you havn't helped this thread at all.
    I rule!!!

    2.4" of Pure FURY!!!

  6. #66
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    I know, but when someone starts a thread which is basically nonsensical, what do you expect? How can one accurately and precisely calculate what Traveler is asking. You would have to have two finitely identical vehicles in every respect and that's where the problem begins. There cannot be two identical vehicles on this planet, even brand new ones coming off the factory floor. Not every bolt will be applied in the precise same manner with the exact same amount of torque etc. No two screws will be installed to the exact same amount of rotations. The vehicles may appear to be the same and will be extremely close in specifications but there are too many variables that have to be considered. Atmospheric conditions, quality control, the distance the car is driven from the assembly line to the transporter and then to a cargo ship etc will alter a vehicle's configuration albeit in a very small way. To accurately measure two cars fuel economy side by side is nigh impossible. One can only arrive at figures that are approximate, not precise. This is just my opinion for what it's worth.

  7. #67
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    IMHO this thread should be terminated by the administrator as it appears to contravene at least 3 rules of the site.
    1) NO PERSONAL ATTACKS ON ANYONE BY ANYONE WILL BE TOLERATED

    2) NO SEXUAL HARASSMENT OF ANY TYPE WILL BE TOLERATED

    3) IF YOU CANNOT BEHAVE WITH CIVILITY THEN THIS IS NOT THE PLACE FOR YOU.

    In addition it is now clear that the thread is not appropriate in this topic area.
    It is not a legitimate enquiry about technical aspects of operating a Land Rover product.
    I urge the administrator to remove the thread.
    Regards Philip A

  8. #68
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    I wish to thank everyone for their patience, sincerity, and objectiveness. I apologise to those who are offended. I also would like to thank Dr R.M at CQU for his time and effort.
    Attached Files Attached Files
    Last edited by Traveler; 3rd October 2007 at 11:43 AM.

  9. #69
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    "the relationship between revs and speed is not linear"

    hmmm, i dont agree, unless its an auto, perhaps a worn out auto. relationship between TPS and speed may be similar to what he mentioned.

    The only way to realistically find out is to drive it.

    Sorry dude, but we just dont have the data to work it out. Other calcs done on this thread assume its at wide open throttle, which also doesnt help.

    The ONLY way to find out on paper is to find the engines efficiency at certain rpm. Fuel has a fixed energy density, and locked in 5th gear, assuming WOT, they will use the same.

    The simple answer is probably the slower one. With a slower stroke it can burn more of the intake charge, and will have proportionally less wind resistance, as its non linear.

    Cheers guys!

  10. #70
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    I agree with PhilipA. There was no need for the personal attacks by Traveler in response to my posts and there should never be any personal attacks by any forum member on another. I wasn't offended by the remarks and I gave back as good as I got but it had to stop at some point. I think Blknight.aus gave the best and most logical response to Traveler's thread.

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