Fuel efficiency

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

  1. Cruz

    Cruz Lost but laughing.

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    Compare two same kind of bikes like the Honda CB500X, well known for good mpg in the mid to high 60's, and the Kawasaki Versys 300, which weighs about 30 kg less than the Honda but averages considerably less at around the mid 50's.
    One you don't rev past 6,500 very often, the other you rev past 11,000 RPM a lot.
    #41
  2. Phil_Fong

    Phil_Fong Over Regulated

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    Petrol fuel injection is a marvellous conception for economy (and power when you need it), but has anyone noticed how all this goes out the window when you tow something ?

    Interesting reading in the Sidecar thread where an inmate with a fuel injected Suzuki 1400 and chair suffers.
    #42
  3. abhibeckert

    abhibeckert Long timer

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    Most petrol engines are around 20% efficient (convert 20% of energy in the fuel into actual motion). Diesel engines are usually around 40%. Electric motors are around 90% efficient and zero emission, so that's where we need to go in my opinion.

    The big car manufacturers are working on petrol engines that burn fuel similar to a diesel engine (using compression instead of sparks) however it's difficult... I don't fully understand this stuff but I think temperature/altitude/humidity are the main problems. Easy to make a 40% efficient petrol engine work in controlled conditions, but very difficult in variable weather.

    If your goal is to be better on the environment, diesels produce more pollution than gas engines... both CO2 contributing to global warming and NOX which is harmful to humans (there's a trend to ban diesel in large/densely populated European cities because NOX levels are getting too high). It's not actually clear how much pollution diesels produce, since so many manufacturers have been caught lying on their emission reports, or at least being unrealistic. They might be doing the same with petrol engines...

    The other problem with diesels is they're a lot heavier, and they only produce good power in a small engine RPM range... no thanks!

    It's worse than you think.

    A typical modern car has a drag coefficient of around 0.3. The best ones are 0.2 (a lot of these cars are quite ugly to improve aero, the Toyota Prius for example).

    Your "block of toilets" fourby is probably around 0.4 (worse with a roof rack).

    The best bikes, like a MotoGP bike designed to do 350kmh down the main straight, will be around 0.6... and that's with a skinny 5 foot tall rider jamming whole body behind the windscreen and wearing those ridiculous hump back jackets.

    An adventure bike's drag with an upright rider can be as bad as 1.0... which nearly as bad as a B-Double truck.

    Sure, bikes are smaller, but because there's 3x more drag the size benefit is lost. On average, a bike has more drag than a passenger car. If you put a VW Polo engine in a motorbike, it will get worse fuel efficiency than it does in the car.
    #43
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  4. UncleGra

    UncleGra Road Grime

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    My old 82 falcon wagon gave its best economy at 90kmh..same for my o3 Commodore wagon....put a box trailer on the back..even empty and the consumption goes up to buggery
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  5. Mouse

    Mouse I'm only smelly

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    Good post abhi

    Not sure I follow your diesel heavy limited rpm range argument though, I've found (especially turbo) diesels mostly better to drive than turbo petrol for lag etc but the gap is closing.

    Question.... What has Toyota dove to the hilux and lc gearing and why? Feedback I'm getting is they're crap on the farm but good on hwy.
    #45
  6. GodSilla

    GodSilla I did that.

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    Petrol will fire in much the same way as diesel when compressed, but compressing petrol to that pressure appears to be a bit harder to do.

    Compressing stuff makes it heat up, and above a threshold that heat will initiate combustion. This is why intercoolers are fitted to turbo engines to reduce the temperature (thus increasing the density) of the charge.
    #46
  7. Clay-doh

    Clay-doh Adventurer

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    Godsilla's post reminded me of this from a few years ago:

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  8. Vertical C

    Vertical C Long timer

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    A lot is about speed. I have seen under 2L per 100km on a couple of 125cc
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  9. Gone Troppo

    Gone Troppo Somewhat bemused observer

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    Fascinating. I remember in the 80s, manufacturers used to trumpet fuel economy figures....fast forward 30 years and all is quiet.

    Meanwhile....petrol is just a bit more expensive...:D

    Interesting.
    #49
  10. gunnabuild1

    gunnabuild1 Long timer

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    The other part of 'efficiency' is our expectations and safety minimums.
    How many of us drive a vehicle without power steering, air con, ABS, traction control, air bags and all the electronic hoopla that is considered minimal equipment nowadays, not even that many manual vehicles being sold nowadays in comparison to just 2 decades past.
    70's efficiency was produced with light weight and generally low powered small engines, manual gearbox and an am radio for equipment.
    That extra weight has to be pulled along.
    I remember the Sarich orbital engines were going to change the world, from memory Aprilia ran the tech in some scooters that were miracles of efficiency in both economy and power produced.
    I guess that didn't actually live up to the noise.
    #50
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  11. Reduke

    Reduke Red Rider

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    We have 2 of the new LC tray backs. Only thing Toyota have done to the gearing is change 5th gear ratio. The rest of the ratios are the same so no difference around the farm but about 2L/hundred better fuel economy and rev about 600rpm less on the hwy @110. They are suppose to have a different tune to have the torque lower in the rev range too. A lot nicer to drive @ 110.
    #51
  12. diabolik37

    diabolik37 Deadly Gubba

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    So much wisdom and true facts in this thread.... :imaposer You gotta love Internet...
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  13. DeLewis

    DeLewis Been here awhile

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    Ok, this makes a lot of sense. If those drag coefficients are as bad as those figures suggest, that alone would account for all most/all the “excess” consumption of bikes vs cars. It reminds me of the pedal powered vehicle top speed competitions - current record is around 136km/hr! All down to exceptionally “slippery” aero designs (and powerful thighs!).
    #53
  14. Bounty1

    Bounty1 Been here awhile

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    A couple of observations, the Orbital combustion process is a low pressure air assisted, spray guided, direct injection system that enables a highly stratified charge to be managed in the combustion process. Put very simply this means you can have a stoicheometric charge at the spark plug so it still goes bang and a very lean charge in the rest of the combustion chamber. Hence you could get very good fuel economy compared to a carburettor or port injected petrol engine. Testing indicated in the range of a 20-25 % improvement in fuel economy over the standard port injected system for an Australian made 6 cylinder engine. There are some good SAE technical papers available on the net on this technology, Dr Geoff Cathcart was the lead author for many of these papers.

    In respect of a lot of unburnt fuel exiting the exhaust pipe this was true for the older carburettor technology but emissions limits for total hydrocarbon (THC) in the exhaust for new petrol vehicles were restricted to 0.2 g/km from about 2007 onwards.

    http://www.environment.gov.au/archive/transport/publications/pubs/nise2-technical-summary.pdf

    The above link should take you to the technical summary for the National In Service Emissions (NISE2) study completed in 2009 for the Australian government. It looked at the real world emissions from from a representative sample of petrol passenger vehicles sold in the Australian market from 1996 to 2007. The emissions testing was conducted at the Orbital test facility in Ballcatta Perth. It was commissioned to see if the real world emissions were consistent with the certified emission limits when first sold. It is easy to see where real gains have been made in reducing air quality emissions, NOx, Co and THC over that period. Fuel economy (CO2) for passenger vehicles by and large had not changed over that period. The full report is also available at that site and is a good read if your are interested. If the link does not work just type "second national in-service emissions study" into your favourite search engine. As far as I am aware there is nothing published more recently in Australia on real world emissions performance and nothing on motorcycle emissions performance.

    Homogenous charged compression ignition (HCCI) is/was the holy grail for fuel efficiency and good air quality outcomes and I understand that there are some issues with combustion stability still to be solved. This is diesel like ignition but with petrol as the fuel. This is what I think @GodSilla was referring to in his post earlier today.
    #54
  15. Warin

    Warin Retired

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    There is a lot more to consider in the electric question.
    While it may be 90% efficient form battery to electric motor and on to propulsion. The efficiency of charging the battery may be 60%, could be worse than that especially for older or cheaper batteries. And then the 'transport' of electrical energy to your home, say 20% loss ?
    so 90% then 60% of that 90 is 54%
    54% then 80% of that 43%.
    And then there is the question of the conversion from some source to the electrical power? Comes down a long way with that battery charging efficiency .. they are working on it.

    I suppose that the liquid/gas driven vehicle should include the losses along the way too .. transport of the fuel is probably a large cost as we have to get it from over seas now...

    For the consumer .. it all comes down to costs .. that is much easier to determine rather than efficiencies.
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  16. Cruz

    Cruz Lost but laughing.

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    We have 5 new auto Hilux dual cabs at work and all use more diesel on the highway and around town when carrying a full load than the previous auto gearbox 3 litre diesel. Using Toyotas crap cruise control makes it even worse with the gearbox hunting up and down constantly when it really doesn't need to change gears. Far better to drive without it for economy unfortunately. Wonder when they will produce a better cruise control with more user friendly controls?
    The new auto and motor are a lot smoother than the old model though.
    #56
  17. Reduke

    Reduke Red Rider

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    Are you talking about the 200series with the auto box or the 70series with the manual box?
    I reckon the 70 series are a lot better with the new box in them.
    As for the 200 series we have 3 of them and the auto box is a heap of shit for hunting through the gears but there is a free easy fix for that. Different box when you play with it a bit.
    #57
  18. Cruz

    Cruz Lost but laughing.

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    Sorry, the Hilux twin cab chassis.
    We have 2 x 200 series as well which are really heavy on fuel once you load them up or drive them hard. Only the base model, so a bit like sailing an old sloop in a swell.
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  19. troy safari carpente

    troy safari carpente #501 Team f5oolery

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    I've just patented the "Re-cyclo-phone" trademark on our behalf diabolik... :1drink:D

    It'll basically just be a length of nylex garden hose and a bunnings funnel... but if we do them in karbon-fibre look-alike hose cheep n' nasty and anodized fittings...

    [​IMG]
    and knock em out in Taiwan for 63 cents a piece, flog 'em on E-bay for AUD 89.00 per unit... we'll clean up... :norton
    #59
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  20. diabolik37

    diabolik37 Deadly Gubba

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    Excellent.. :clap:clap

    It remind me a lot of the last tool they used on me at the hospital...:hmmmmm Never mind...

    Now all we need it to find a way to make the engine push even more fuel down the exhaust instead of making more power and burning it, and the saving will be even bigger... :clap:clap

    Tell you what... we are gonna be rich... :imaposer
    #60