Page 1 of 3 123 LastLast
Results 1 to 10 of 24

Thread: Tight arse Fuel Efficiency

  1. #1
    Join Date
    Jul 2020
    Location
    gippsland
    Posts
    21
    Total Downloaded
    0

    Tight arse Fuel Efficiency

    What is considered the optiminal speed on the flat etc. to achieve maximum fuel efficiency from 300tdi Deefer.

  2. #2
    Join Date
    Apr 2012
    Location
    Whyalla, SA
    Posts
    7,064
    Total Downloaded
    0
    Parked

  3. #3
    Join Date
    Apr 2019
    Location
    Brisbane
    Posts
    1,675
    Total Downloaded
    0
    90

  4. #4
    Join Date
    Jul 2020
    Location
    gippsland
    Posts
    21
    Total Downloaded
    0
    Not more like 70 or 80?
    Quote Originally Posted by W&KO View Post
    90

  5. #5
    Join Date
    Jun 2013
    Location
    Warner Area - SEQ
    Posts
    1,855
    Total Downloaded
    0
    Quote Originally Posted by W&KO View Post
    90
    x2 agreed...

    but I guess it also depends on your vehicle setup as in accessories fitted; tyres fitted; vehicle weight and gearing.

    The best I've got out of mine (recently too) is 9.5ltrs/100kms ripping down the Hwy but on average I get 11.7kms/100kms since ownership which also includes all offroad driving & Touring Trips which I think is not too bad and when out on the Hwy, I tend to try and sit on the speed limit (ie: 100 or 110)

  6. #6
    Join Date
    Jul 2020
    Location
    gippsland
    Posts
    21
    Total Downloaded
    0
    That's good . I'm not unhappy with the fuel economy on my 300tdi def, in fact the opposite. I try to keep it lightish, ie no roof rack, I'm just wondering how slow does one go before it becomes law of diminishing returns. In 5th on a flat road no wind to speak of and not laden. Goodrich AllTerrain.
    Quote Originally Posted by Robmacca View Post
    x2 agreed...

    but I guess it also depends on your vehicle setup as in accessories fitted; tyres fitted; vehicle weight and gearing.

    The best I've got out of mine (recently too) is 9.5ltrs/100kms ripping down the Hwy but on average I get 11.7kms/100kms since ownership which also includes all offroad driving & Touring Trips which I think is not too bad and when out on the Hwy, I tend to try and sit on the speed limit (ie: 100 or 110)

  7. #7
    Join Date
    Jan 2010
    Location
    Perth S/W
    Posts
    369
    Total Downloaded
    0
    90 works for me too .

  8. #8
    JDNSW's Avatar
    JDNSW is offline RoverLord Silver Subscriber
    Join Date
    Jan 1970
    Location
    Central West NSW
    Posts
    28,804
    Total Downloaded
    0
    I don't have a 300Tdi (Isuzu), but none of these diesel engines have much change in specific fuel consumption with engine speed, so the main variable is the drag from various sources on the vehicle.

    For a relatively un-aerodynamic vehicle like this, the major source of drag over about 60kph is aerodynamic drag. This is proportional to the square of airspeed, so increases pretty rapidly above this speed. Accessories etc such as roof racks, oversize tyres etc increase the amount of drag, but not the way in which it varies with speed.

    At first glance, this suggests that around 60 would be the best economy speed, but remember that this is the speed at which aerodynamics become most important - at that speed other factors are still important. Perhaps the most important is that travelling at that speed you tend to use the brakes and acceleration a lot more, and can't use momentum to go over even slight rises without putting the foot down. What this means is that the advantages of driving slower diminish as you drop back towards about 60.

    In light of this, 90 is probably a reasonable compromise for most people. Certainly, this is what I have found.
    John

    JDNSW
    1986 110 County 3.9 diesel
    1970 2a 109 2.25 petrol

  9. #9
    DiscoMick Guest
    We found about 90 was best in our four-speed auto 300Tdi D1.

  10. #10
    Join Date
    Sep 2007
    Posts
    577
    Total Downloaded
    0

    long range cruise fuel consumption.

    for max range don't exceed 100 km/hr. fuel burn goes up exponentially to sit on 110 kmh expect at least 2 litres /100 more on a tray back.

    best long range cruise I find is 90 to 95 on 7.50 tyres. can come down to just under 9 litres 100km on a freeway type road but usually sits around 10.

Page 1 of 3 123 LastLast

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Search AULRO.com ONLY!
Search All the Web!