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Fuel economy?

Discussion in 'Performance' started by Jenny Frappell, Oct 7, 2016.

  1. bern

    bern Well-Known Member

    Messages:
    1,075
    Location:
    Fernvale, Qld
    Lots of posts here
    did not read all but the
    little or big fancy roof racks are fuel costly even if not loaded
    did anyone mention small price for electronic ignition but up to 10% more pwr and less fuel..,plus wet weather reliability...and NO POINTS to set and buy !
     
    chris taylor likes this.
  2. chris taylor

    chris taylor Well-Known Member

    Messages:
    2,354
    Location:
    adelaide sth aust

    Berrn you got it Bud.
    Unless you use it turf the Pack Rack ,and the same for the so called roo bar which will do nothing in a prang{ Could get an argument on this one}. since installing : elec ignition : some 10 years ago have had no issues regards timing , but did fit a new u beaut coil , did the Adelaide to Stanthorpe run there and back without missing a beat and averaging 8.2 kls per ltr, or 460 kls per tank working on a 56 ltr tank. Oil can also help, i switch from mineral to semi synthetic {Nulon} and noticed a difference immediately, Light truck tyres also help with stability when driving and i think with fuel economy less drag on the road BUT still has the grip and handling aspects as well as making the steering easier ,bearing in mind of course that these are after all a heavy vehicle and do require a more sturdy tyre,
    I believe that fuel economy is not always any one thing but a whole series of things and when these are put right your economy gets better.
     
  3. cbus

    cbus Well-Known Member

    Messages:
    12,359
    Location:
    sunshine coast
    Yeah.
    I'll argue over the bull bar. :)

    But totally agree that economy results from attention to all details.

    Nulon 'appears' to give an advantage because its thinner. This can be deceptive. Would be cautious on an older engine.
    But attention to oil pressure and temps is a first check.
    Unsure re its zinc content.?

    Definitely ditch the roof racks.

    Tyre pressures rather than a blanket tyre type division.
    Fuel Economy type choices avail in Lt and passenger.
    A lot of people running very old unsafe tyres. Often mismatched.
     
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  4. bern

    bern Well-Known Member

    Messages:
    1,075
    Location:
    Fernvale, Qld
    ditto Chris,
    tyre pressure AND size ...makes a big difference
    small tyres g00d acceleration but lower top speed
    bigger tyres on std rims = less fuel on trips as the diameter means longer rolling surface per nr of engine revs and fuel squirts lol.
    DRAG
    1.Read about an economy run in the USA once, the winner and others had also loosened the rear brake shoes so less or NO drag...52 mpg in a KG sounded amazing but US gallons are more than Imperial lol..
    2. spare wheel drag on bull bars are my gripe...protection is value too, a young KCer lost a leg due to no B/bar a few yrs back! but the wheel...arghhh
    3. low tyre pressure is a big drag and costs fuel and tyres due to uneven wear....same as mismatching ones.
    4. roof rack...loaded or not....noise is an indicator of drag!

    enjoy the ride, stay safe and maintain all the moving parts - the Kombi ones too...r. o. f. l. :confused::oops:;)
     
    David H likes this.
  5. Alpal

    Alpal Moderator Staff Member

    Messages:
    8,674
    Location:
    Melbourne Bend of Islands
    SO where do I put my spare? The navigator will be really pissed if it goes on the bed!
     
    David H likes this.
  6. Barry

    Barry Well-Known Member

    Messages:
    4,330
    Location:
    Abbotsford NSW
    Other way
    Imperial gallon = ~4.5L
    US gallon = ~3.8L
     
  7. cbus

    cbus Well-Known Member

    Messages:
    12,359
    Location:
    sunshine coast
    My call is the spare on front being an improvement over just bull bar.

    Especially if we are camping near Al and he's bitching about it being cold outside all night :eek:
     
    chris taylor and David H like this.
  8. Maxa1967

    Maxa1967 Member

    Messages:
    48
    Location:
    Western Queensland
    Just came home from drive to Emerald for a familiarisation for our next job via the Barcaldine drags. Had an impressive headwind on the way down ( raising dust - about 15-20kts). Averaged 7.1km/l, I put a set of 205 70 15’s on the back in place of the 14’s , they stand about 40mm taller than the 14,s. Averaged8.1 on the run home, had the sun visor and roof rack on. 8.1 is about my average without the rack and visor on 14’s. Be interesting to see how it goes minus rack and visor next trip. Driving average was 90kmh and about including 60km of dirt.3250@ 100. Premium fuel in Barcaldine is 12c cheaper than Emerald no gouging there just the good old “mineing tax”.
     
    cbus likes this.
  9. bern

    bern Well-Known Member

    Messages:
    1,075
    Location:
    Fernvale, Qld
    way to go, bigger wheels; Mercedes fit straight on but watch ET from the bigger Benz models.

    thanks Barry = a kind of dyslexia...or senior mowmeant. lol no excuse when talking specs aye..

    now one more consideration for economy is what Maxa mentios...(nice one for safety and mech-longevity also);
    10% lower speed at top cruise means lots less fuel...dyno it if you doubt!

    cheers all. B
     
    chris taylor likes this.
  10. bern

    bern Well-Known Member

    Messages:
    1,075
    Location:
    Fernvale, Qld
    maybe time for a new thread on that Alpal, under bed, rear hinged rack (rear protection) !
    dual cab style is nice i.e.; under the seat...if no walkthrough model...or make a sock like cover and use as a pillow with snack storage for looooong nights,
     
  11. chris taylor

    chris taylor Well-Known Member

    Messages:
    2,354
    Location:
    adelaide sth aust
    Can understand your question re spare wheel , i put mine where it was designed to go BUT i am the only one to sleep in it so there is not an issue.
    Alpal, i am suggesting that we do tend to carry more than we need to ,so , what ever we do not use get rid of it ,if you require a bull bar then it stays ,same with roof rack , i turned my bull bar into a nudge bar ,thereby getting rid of say 10 kg , the same with the roof rack say another 15kg , so bit by bit got rid of stuff that was never used which can add up to the weight of a small person .
     
    Last edited: May 9, 2018
  12. cbus

    cbus Well-Known Member

    Messages:
    12,359
    Location:
    sunshine coast
    I would question that on a couple of points.
    But obviously interested in alternate info.
    My thought would be that for a stock ( often less than new) motor that close to stock gearing would be a best balance of keeping motor cool under all conditions and balance of available power for ' comfortable' cruise speed and hill attack.

    Higher revs with the smaller wheels, guessing a variation between both options about 150 rpm max ) can also mean lighter foot on throttle.
    Obviously a worked motor can push taller gearing within its ideal torque range.
    Changing 185R14 to 195R14 = 650/668 mm respectively and is just noticeable on stock 2l. = 2% change.

    Running 215/60.15 now from 235/45.17
    No confirmed numbers yet but seems same fuel consumption per speedo miles so maybe a 3% gain ?
    Yet to be shown under comparative conditions.

    Are the dyno numbers adjusted to reflect the actual road conditions?
    Air drag being the biggest factor at 100km.hr
     
  13. cbus

    cbus Well-Known Member

    Messages:
    12,359
    Location:
    sunshine coast
    Agree weight also a significant factor Chris.
    One thing I like about the wheel on front is it lowers front thus reducing amount of air getting under slightly.

    Small things but they add up if there's not a counterproductive factor involved.
     
  14. chris taylor

    chris taylor Well-Known Member

    Messages:
    2,354
    Location:
    adelaide sth aust
    Hi Col, i do not doubt your saying for a moment at all, but I think i am missing something here , how does a lower front benefit the performance of the van, i would have thought more air underneath would be beneficial for cooling and so on, or is it a handling , steering problem. curios.
     
  15. cbus

    cbus Well-Known Member

    Messages:
    12,359
    Location:
    sunshine coast
    Hi Chris.
    Having the front down slightly in relation to rear means less air flow underneath which is beneficial re drag and stability.
    Less affected by sidewinds.
    Normal stance for the old rally car was also 3/4 inch higher at rear axle.
    Again makes for good balance and stability.

    Have tried different heights ( front /rear balance ) on a stock height kombi and definitely more chuckable with bum up.

    Lowering benefits from same factors as well as lowering roll centres.

    Normal kombi sits a bit nose up when empty.
    Factory settings are based on spring plate angles and then with 1/2 ? load fuel and driver.

    Care but be taken when checking old ( hence all) kombis as often the front suspension is worn and binds so affecting where bus settles.
    Rear bars are often sagged.
    Should be checked with shocks disconnected , especially if running gas shocks.
    Tyre pressures correct.

    My preferred stance is likely different from factof setting.

    Cooling for engine is from upper engine air intakes.
    Opening side windows affects such by allowing air flow to separate from sides.
    Medium lowering shouldn't affect any venturi effect from engine cooling air exiting at lower rear of engine.
    push rod cover plates should always be fitted if running Heater boxes.

    I recon tinware should be in place between body and bumper.
    Belly pans are something I want to fit.
    Sheeting under battery trays would be included.
    Air flow around gearbox retained.
    One day :rolleyes:
     
    Last edited: May 9, 2018
  16. cbus

    cbus Well-Known Member

    Messages:
    12,359
    Location:
    sunshine coast
    177366.pdf

    Google this thesis Chris.
    Some bedtime reading and intro.:D
    Don worry about the tricky bits but follow the gist and see how it could be applied to a kombi.
    Another on flow indicated improvements down ti 4 inches but you might have to compromise on that if you want to do real camping ;)
     
  17. bern

    bern Well-Known Member

    Messages:
    1,075
    Location:
    Fernvale, Qld
    this is getting good
    juss tha spellin is a bitt wirehay.. lol
    1. A,,, Arr... Aerodynamics from

      Chalmers University of Technology
      Private University
      [​IMG]
      Chalmers University of Technology is a Swedish university located in Gothenburg that focuses on research and education in technology, natural science, architecture, maritime and other management areas.
     
  18. chris taylor

    chris taylor Well-Known Member

    Messages:
    2,354
    Location:
    adelaide sth aust
    Hi col been reading up on that thesis and i have to admit it is a bit beyond my level of understanding, but correct me if i am wrong , in a nutshell , the lower the rear end the greater the drag ,ie wind speed over the top and underneath at same speed creates drag effect, lower front end fractionally and raise the rear means a reduced air flow from underside while air speed over top remains the same , result is airflow over top will have less drag effect at rear due to reduced air flow from underneath.
    Less drag means a more fuel efficient vehicle , i think .o_OAm i somewhere near the mark ???. would a diffuser {or spoiler } mounted on the Bumper Bar underside have the same effect, ie dispersing the air flow at the lower front end there by leaving a cleaner air flow over the top at the rear.
     
  19. chris taylor

    chris taylor Well-Known Member

    Messages:
    2,354
    Location:
    adelaide sth aust
     
  20. Barry

    Barry Well-Known Member

    Messages:
    4,330
    Location:
    Abbotsford NSW

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