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Thread: E10 and our NSX

  1. #11


    So, how much more E10 than E5 does anyone use for the same mileage? I read on other car forums that owners are using more. Anyone got an idea how much more an NSX uses? (no, I haven't tried it myself).

    If you have to use 5% more fuel, does it amount to producing 5% more carbon? Is the equation that simple? If so where's the advantage? Use more than 5% means it's worse for the environment!!! I suspect E10 fuel just ticks a box for the Green Party. Also much more tax for the government.

    E5 (Super unleaded) is about 5% more expensive (at my local Sainsburys), so on the basis of using more than 5% of E10, it's cheaper for me to run E5!


  2. #12
    Join Date
    Jan 2018
    Near Stuttgart, Germany
    Blog Entries


    From my personal experience, the difference in fuel usage varies way too much to detect any meaningful changes when all you have is a number of petrol bills. I tried this with my Honda Jazz on the same way to and back from work - only to answer the question if winter tires need more fuel - It already failed after recognizing that the tyre diameter change caused the distance to jump so much that all comparison was useless.

    Ethanol certainly has a lower energy content than petrol but it's not zero. It's therefore unlikely that 5 % more Ethanol causes 5 % more consumption and would compensate a 5 % price increase.
    The COČ reduction btw. is accounted for by the usage of plant generated Ethanol.
    Last edited by Heineken; 21-11-2021 at 12:59 PM. Reason: typo
    1997 JDM Custom Order AT VIN 1400005 - Stock
    Heineken's Garage

  3. #13


    The energy density of gasoline is variable depending on the refinery (its a blend or stuff) and season (cold weather usually gets more volatiles than hot weather in the blend). The commonly referred to energy density is around 34.2 MJ/l. The number for ethanol is 24 MJ/l. I don't know whether those are higher or lower heating values. I expect LHV because that would be the appropriate comparison for internal combustion use.

    You can calculate the raw energy content purely on the ratio of ethanol to gasoline. A 5% ethanol mix has an energy content of 33.6 MJ/l and 10% ethanol has an energy content of 33.18 MJ/l. So, as a first approximation your E10 has 1.25 % less energy in it per litre than your E5. Unless you have an engine dyno I think you are going to have to do a couple of years of checking your petrol bills before you spot that change. Driving in cold damp weather is going to have a bigger effect on your fuel economy than E5 versus E10.

    The stoichiometric ratio of pure ethanol is different; but, not that different for the blends so I expect that the ECU should have no problem correcting to a lambda of 1 when operating in closed loop. Out of closed loop your AFR may change slightly; but, if you are regularly driving out of closed loop you shouldn't be beaking about deteriorating fuel economy. Ethanol does burn differently than gasoline. High ethanol engine will run with remarkably clean combustion chambers. I really don't know whether the flame speeds for the E blends are materially different than unblended gasoline which might alter fuel economy on an engine designed for unblended gasoline.
    Last edited by Old guy; 21-11-2021 at 07:35 PM.

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