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IF you are concerned only about power (as opposed to fuel economy) and IF the EMS is able to modify ignition timing to exploit higher octane fuel (probable but would need verified) then you'd want the highest octane you could get.
E20 means it has up to 20% ethanol in it. You don't give (and presumably are not given) the octane rating of this fuel, but a bit of Internyetting suggests its "usually" quite high, in the region of 98 RON, though I suppose it'll depend on the petrol they blend it with.
The water absorption thing might be a concern though, especially if you experience high humidity in Thailand, as seems likely.
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IF you are concerned only about power (as opposed to fuel economy) and IF the EMS is able to modify ignition timing to exploit higher octane fuel (probable but would need verified) then you'd want the highest octane you could get.
E20 means it has up to 20% ethanol in it. You don't give (and presumably are not given) the octane rating of this fuel, but a bit of Internyetting suggests its "usually" quite high, in the region of 98 RON, though I suppose it'll depend on the petrol they blend it with.
The water absorption thing might be a concern though, especially if you experience high humidity in Thailand, as seems likely.
Yes I am interested in power.
I had understood that there is less energy in ethanol than petrol...? Doesn't this translate into LESS engine power from E20 (irrespective of octane rating) and higher fuel consumption?
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"... there is less energy in ethanol than petrol...? Doesn't this translate into LESS engine power from E20 (irrespective of octane rating) and higher fuel consumption?"
I suspect you're right, but as with the other grades of fuel, in the real world there's likely to be little observable difference. Certainly when E10 became the standard unleaded I couldn't tell the difference, even on brim-to-brim MPG calculation. (Less available energy in the fuel should translate into poorer fuel economy.)
It is of course entirely up to the OP if he wishes to pursue the "maximum power" theory, but I can't see that it will make any difference to his driving experience and will instead make his wallet a good deal lighter.
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IF you are concerned only about power (as opposed to fuel economy) and IF the EMS is able to modify ignition timing to exploit higher octane fuel (probable but would need verified) then you'd want the highest octane you could get.
E20 means it has up to 20% ethanol in it. You don't give (and presumably are not given) the octane rating of this fuel, but a bit of Internyetting suggests its "usually" quite high, in the region of 98 RON, though I suppose it'll depend on the petrol they blend it with.
The water absorption thing might be a concern though, especially if you experience high humidity in Thailand, as seems likely.
Yes I am interested in power.
I had understood that there is less energy in ethanol than petrol...? Doesn't this translate into LESS engine power from E20 (irrespective of octane rating) and higher fuel consumption?
Don't think so..
The energy density of E20 is lower, but I THINK the engine will compensate for this by using more fuel. I THINK it does this using feedback from the oxygen sensor, and maybe also by adjusting the mapping. The limit is the amount of oxygen available, and that will hardly be affected at all by the relatively tiny additional volume of fuel.
This of course causes higher fuel consumption, which you have said is not of concern.
Power gains could potentially come from advancing the ignition timing to better exploit the higher octane, and possibly also by applying more turbo boost where this is a factor. Doing this with lower octane fuel would cause detonation
Pretty simple to try it. "Placebo effects" aside, if you can't tell the difference, there either isn't one, or there is one but it doesn't matter.
If you want to be all scientific you could do a blind test by getting someone else to fill your car up and not telling you what they put in it.
Edited by edlithgow on 17/03/2022 at 08:56
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If you want to be all scientific you could do a blind test by getting someone else to fill your car up and not telling you what they put in it.
I like that idea, my tank's nearly empty. Would you like to borrow my car and fill it for me please, save me a wad of cash?
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If you want to be all scientific you could do a blind test by getting someone else to fill your car up and not telling you what they put in it.
I like that idea, my tank's nearly empty. Would you like to borrow my car and fill it for me please, save me a wad of cash?
Not sure what you are on about, or how a wad of cash could be thus saved, but any savings would likely be eroded by you having to pay me having to fly to wherever your car is at, quarantine hotels, and all that.
Don't you have any trusted friends?
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If you want to be all scientific you could do a blind test by getting someone else to fill your car up and not telling you what they put in it.
I like that idea, my tank's nearly empty. Would you like to borrow my car and fill it for me please, save me a wad of cash?
Not sure what you are on about, or how a wad of cash could be thus saved, but any savings would likely be eroded by you having to pay me having to fly to wherever your car is at, quarantine hotels, and all that.
Don't you have any trusted friends?
You save the cash as your friend fills the car up thus you don't have to pay
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You save the cash as your friend fills the car up thus you don't have to pay
I think ed was having a larf, though he didn`t actually say that the friend would pay, only that it would be an idea to get a friend to fill up for you as a blind test, no mention of the friend paying for it, unless I missed it, I don`t think any of my friends would pay for my fill up
Car should run fine on any petrol grade as the ecu would sort engine running, thats what the sensors are for, surprising how many people ask the same question though.
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Car should run fine on any petrol grade as the ecu would sort engine running, thats what the sensors are for, surprising how many people ask the same question though.
As I understood it he wasn't asking if it would run on any available petrol grade, he was asking which would give most power, which was the question I was trying to answer.
I THINK this will be the highest octane available, assuming it can self tune to exploit it.
I suppose it would be easier to design it to use high octane (as suggested by the high CR mentioned by the OP) and then actively de-tune when fed lower octane petrol.
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As I understood it he wasn't asking if it would run on any available petrol grade, he was asking which would give most power, which was the question I was trying to answer.
modern engines are designed to give maximum power given any petrol grade and have been for a long time, and any difference in grades wouldn`t be noticeable on a small engine, and any that has been stated by a driver, is usually a placebo effect, ie been told a specific grade is better than another so think it is, and often state the car runs better when its exactly the same as before
similar to additives help an engine go faster, imo none work but the driver thinks it does, in a lot of cases convinced it works...but thats another story as we know
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modern engines are designed to give maximum power given any petrol grade and have been for a long time...
How do they do that? Sounds impossible.
If you'd said "Modern engines are incapable of exploiting higher octane fuel due to deficiencies in the control system" it would have sounded more plausible.
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modern engines are designed to give maximum power given any petrol grade and have been for a long time...
How do they do that? Sounds impossible.
If you'd said "Modern engines are incapable of exploiting higher octane fuel due to deficiencies in the control system" it would have sounded more plausible.
OTOH maybe I misunderstood and you meant modern cars are capable of fully exploiting the power potential of any given fuel. In that case I would expect the highest octane to give the most power, up to the physical design limit of the engine, which is probably mostly determined by the CR
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I think ed was having a larf, though he didn`t actually say that the friend would pay, only that it would be an idea to get a friend to fill up for you as a blind test, no mention of the friend paying for it, unless I missed it, I don`t think any of my friends would pay for my fill up
That's right, but now I think on't, free car hire for my next UK visit doesn't sound at all bad, so I might accept Badbus's kind offer.
Could show my Taiwanese GF the Highlands.
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Many thanks for all the replies - but TBH I am still none the wiser. I have taken delivery of my new Toyota here in Thailand now and have filled it with a tankful of 95 gasohol. It runs well but the next tank will be E20 for comparison. I am recording consumption etc. Got a month to experiment before we travel to Spain - then I've got to get my Avensis there out of mothballs!
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I'll be interested in your results - but wouldn't expect any Yaris to benefit significantly from using a higher octane fuel - other than a GR2 Yaris of course which I believe is quite a different animal.
Edited by Theophilus on 04/04/2022 at 18:07
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