E10 Fuel

[Ric001]

flatheadluke thats not different to what i said it the same the reason you can get 98ron is for high comp cars like the high performance holdens fords and all the European stuff now outboards in general don't have enough to get the benefit out

out of it now a prime example of this is diesel very low octane but more energy than avgas but you need 350 plus psi comp to burn it .

the general rule of thumb is low comp low octane high energy fuel and high comp high octane low energy fuel .

Hi tackle. Was the last statement meant to high compression low octane high energy??

Low compression high octane low energy??

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[kingfishbig]

The energy content should be the same regardless of octane rating, all other things being equal. Octane rating is a measure of resistance to pre-ignition or pinging. So a higher octane fuel will have a higher activation energy or resistance to burning but should still have the same energy content. It may be possible though that a premium fuel might be blended to give more power as different chemical bonds release different amounts of energy when burnt. Ethanol has a lower energy content that petrol hence the often reported drop in economy with E10.

Another complicating factor is the use of engine management systems on cars such as knock sensors. If the system has detected knocking on a low octane fuel and adjusted the timing or turbo boost or other factors then performance will probably be boosted with a high octane fuel Outboard motors don't generally have knock sensors apart from a few new models, but if the system is calibrated for low octane fuels than using higher octane fuel won't boost performance.

[Welster]

I just use regular unleaded or sometimes 95. I read that the additives in high octane are not good in two strokes as they can make it difficult for the oil to blend in.

[kingfishbig]

I just use regular unleaded or sometimes 95. I read that the additives in high octane are not good in two strokes as they can make it difficult for the oil to blend in.

I heard that too, but also that the refiners (or maybe it was the oil makers) have adjusted their formulations and it is not such a problem now days. I also heard it's better to use synthetic or semi synthetic oils with premium or high octane fuels.

Edited September 16, 2016 by kingfishbig

[brad_tate]

I have two contributions from personal experience.

1. My prior boat had a 1985 Evinrude outboard. When ethanol fuels first came along I read the advice about water absorption and filled up with premium (then 95 octane I think). The next trip the boat started and then promptly went on strike. My (amateur of course) diagnosis was that the detergent qualities of the premium fuel happily stripped off 15 years of carbon deposits out of the fuel line and deposited them on the final stage fuel filter. In that motor that was a metal screen in the entry port to the carby. When I removed it, it was absolutely full of fine black grit. After cleaning it in petrol I had no more problems. I then used 91 and 95 with no more issues.

So this may be part of your issue if it is the first time in a long while your system had premium petrol introduced. Nowadays I use 91 octane (or 95 premium if I can't get that) in my ETec 60. I haven't tested any difference in range of either, but don't notice a difference in performance.

2. My prior car was a 2008 Toyota Aurion. In that car when towing my boat I got much better performance and range with premium petrol (95 or 98) compared to E10. Considering the extra cost of the petrol it didn't save me money, but it didn't cost more either as the added range/better fuel economy balanced the increased cost. Main benefit was less fill-ups. Without the boat however the improvement was less marked.

I now have a 2012 model Aurion and after testing, this is no longer true. I get pretty much the same range on E10, 95 and 98, and don't notice much difference in performance either.

So I feel the differences can be very much make and model specific.

Regards, Brad.

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[tackleberry]

Hi tackle. Was the last statement meant to high compression low octane high energy??

Low compression high octane low energy??

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nope as i wrote it just talk to any good hi performance engineer

and it bears truth with timed cuts with my chainsaw collection , in the stock saws with just 140 to 160 psi

when you put 98ron in them they cut slower but when you put 98ron in my ported saws with 220 to 240psi

you better be on your guard as they pull like buggery .

and on the premium fuel and 2 stroke just use full synthetic but you better be sitting down when you get the

price for 5 lt .