Fuel efficiency

Discussion in 'Australia' started by GodSilla, Jun 6, 2018.

  1. gavo

    gavo Slacker

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    I think it actually was a car engine and with only a 6500 rpm redline there's part of the answer. High torque,low revs, better fuel economy, Boring.:lol3
    #21
  2. GodSilla

    GodSilla I did that.

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    I don't blame you for thinking those things eh, it does seem unbelievable. This is taken from the Wiki page eh, "Some processes developed for the engine could be used for other engines, such as the Orbital Combustion Process, an air/fuel precompresser for injection.[5]". As others have stated it was used in some marine outboard 2-strokes to keep them legal in California, etc, and it worked. You'd have to ask the car company executives why they bought and buried it. Money will doubtless be the bottom line somewhere.

    My modern common-rail turbo diesel ute returns 24mpg on average, which is about the same as a diesel ute would have returned 40 years ago.

    Most mid-sized sedans return around 28mpg, a small improvement on 40 years ago when they returned maybe 25mpg.

    If you do the research and do the maths, and it is quite shocking that the numbers haven't moved that much at all. The small gains in combustion efficiency soon get wiped out by the extra weight of all the crap everyone expects in a car nowadays, and the required electrickery to drive it all. The end gains are negligible really, with the exception of the small car category for some reason where they are pretty impressive.

    "The Orbital Combustion Process engine took the Orbital Fuel Injection System initially designed for the Sarich orbital engine and adapted it to an easier to implement engine. OFIS used a charge of compressed air to atomise the fuel mixture, allowing a compression ratio as lean as 31.5:1."

    That last sentence says it all. An article that was published in AMCN many years ago went into some detail about how this injection worked, and how it achieved virtually perfect atomisation, and therefore combustion efficiency. The heart of the innovation was switching from compressing the fuel, as in a traditional injection system, to compressing air and using the air to fire the charge into the chamber, and this is where the true gains are made. FYI. :queenie
    #22
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  3. Mouse

    Mouse I'm only smelly

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    Optimax. Belt driven compressor. Compressor wear part/commonly craps out, ~$1500 part.

    Boston whaler run performance data on their boat models, speed economy, really good data where you can compare engines very effectively.

    At the time the 150 otpi used less fuel and went harder than the equivalent Hp Verado (small cap supercharged 4 stroke but ~15% heavier engine)

    But the opti wasn't hugely better, I don't think Mercury went down that path for any other reason than to sell into cali.
    #23
  4. GodSilla

    GodSilla I did that.

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    Why does a 130kg motorcycle with 90kg passenger, weighing say 220Kg all up, use half the fuel that a near-2-tonne car would use?

    This has intrigued me for some time. The lower weight of the motorcycle allows for brisk acceleration compared to the car, but once up to speed the fuel economy equation should be a no-brainer. Except it isn't. :scratch

    Discuss.

    :ear
    #24
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  5. lentil

    lentil All round nice guy Super Moderator

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    I think air efficiency has a fair bit to do with it.

    Lots of rough surfaces shaped like a brick in the air
    #25
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  6. Simosez

    Simosez go ride your bike.

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    This thread will run out of juice before it gets going.:1drink
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  7. Dr AT

    Dr AT Long timer

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    Surely the question is why would the person in the 2 t car burn all that fuel for such little fun?
    #27
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  8. JustAL

    JustAL Armchair Adventurer

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    A 90kilo rider is as effective as driving a brick wall.

    Al
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    Melbourne, Australia
    #28
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  9. madruss

    madruss I'm not disorganied, just flexible

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    I'd love my bike to only be 130kg & rider to lose 20kg to fit the equation :imaposerOnce my 220kg loaded bike plus carrying my 110kg frame, amazed me by doing 4.5L/100k :D Must have been alot of downhill to Bingara :beer
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  10. GodSilla

    GodSilla I did that.

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    4.5/100 is almost in VW Polo territory madruss. A lot of the larger bikes use in excess of 5.0/100. Why such disparity?

    I note that aerodynamics get a mention too. Lots of little bits hanging out makes for lots of little bits of drag, but a lot of modern bikes have aerodynamic fairings too and still suck the fossils. My 2-tonne fourby can get 9.0/100 with the frontal area of a block of toilets.
    #30
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  11. UncleGra

    UncleGra Road Grime

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    My 2005 Kato 625 with the big fat safari tank full gets 24 km /ltr...My 2017 Husky 701 with its pathetic 13 lts gets 24 km / ltr. Kato weighs 132 kg and is carby..Husky weigh 145kg ..much slimmer and is F.I.
    #31
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  12. flinders_72

    flinders_72 Long timer

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    As I posted in the other thread it's mainly kW/tonne. Motorcycle engines are high performance compared with most cars. My K1300 puts out the same HP mas my Honda Accord.
    #32
  13. Mouse

    Mouse I'm only smelly

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    Apples and oranges. Who rides to conserve fuel? A car can constrain/manage a lot of conservation factors without driver intervention.

    I'm sure if you tried you could achieve good economy from a bike, the fact you don't just highlights your lack of self discipline...
    #33
  14. Wodger63

    Wodger63 Long timer

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    The way I see it is the amount of fuel required for KW per CC.
    For example my 1090R puts out 92KW and does on average 5.5 L per 100 Klms. It can do 5 L per 100 klms or better but thats cruising and riding conservative and on the other hand it can do worse if I get heavy handed with the throttle.
    My (sold) XR 6 Falcon put out 195KW and averaged around 9-10 L per 100 Klms, it would drop to 11's running around town but would get anywhere as low as high 7's on a trip.
    So if you use the 1090 as the bench mark for KW per 1000cc the 4.0 litre XR 6 would be putting out in excess of 360 KW, that would be a seriously powerful car and I bet my left knacker it wouldn't be doing 9-10 L per 100 Klms.
    So my point is even some of the bikes we consider to be not overly powerful, when you do KW per 1000cc are still quite powerful engines even before you add in the power to weight ratio.
    Then there is most 1000cc engines do around 4000 rpm +/- @ 100kph, while most mid capacity cars do 2000 RPM or less @ 100 KPH.
    So on average a car engine is spinning at half the revs for any given situation and producing half as much KW's comparative to a motorcycle engine.
    #34
  15. GodSilla

    GodSilla I did that.

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    Well spotted Wodger. Car engines are tuned for economy, driveability, and reliability. Motorbike engines are tuned towards performance over economy.

    An example, a mate of mine's brother builds ASP race cars, and took a V6 Holden motor and easily tweaked the ECU so it produced outputs slightly higher than the 5 litre V8 of the same generation. It didn't suffer any reliability issues either, though it did suck substantially more fossils. But it went pretty good.:-)
    #35
  16. Happy Snapper

    Happy Snapper GOMOB.

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    Cruz.. the secret is engine speed. The Honda doesn't rev like a normal bike!
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  17. Cruz

    Cruz Lost but laughing.

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    Yet it pulls harder than a 18 year old new porn star, gets up to speed pretty quick and makes changing gears rare.
    Great little motor.
    #37
  18. Cruz

    Cruz Lost but laughing.

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    Is your 2 tonne fourby a diesel?
    This is from my 6 litre V8 auto petrol ute 3 weeks ago on the way up the Sunshine Coast in traffic.
    _20180609_163716.JPG
    #38
  19. wrya1

    wrya1 Been here awhile

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    Spot on. Fuel consumption is low for any engine at idle, and as you lift the revs you are increasing the number of times the injector pumps fuel into the engine for any given passage of time. If you can turn that fuel consumption efficiently into speed with conservative gearing and aerodynamics, you get relative fuel efficiency. And a boring machine.

    It’s hard to improve efficiencies at low revs, so not surprising that we get the same kind of consumptions that we got a generation ago, given that engine technology is fundamentally the same. Also, not sure that much fuel passes unburnt any more. Could it be confused with the fact that most engines still produce most of their energy in heat? It was only last year that the Mercedes F1 team cracked 50% thermal efficiency, albeit on a dyno.

    Cruising around Europe on my ZZR1100 with the wife some years back, we would get an easy 7L/100km riding in countries with a limit of 130km/hr. In Germany on the Autobahn when we had somewhere to be, I could double that figure easily if I averaged over 200km/hr. Petrol got expensive and the fuel stops ate into the time savings.
    #39
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  20. diabolik37

    diabolik37 Deadly Gubba

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    Can we put a bucket at the end of the muffler and collect the other half of the fuel tank???
    #40