That means E10 is also on the table since it's 94 RON. Based on Carsales.com.au fuel specs, most SUVs RON rating is 91, including ASX, CX5, etc.
No engine knocks issue in the foreseeable future, or is this a marketing ploy by these manufacturers to entice fuel efficiency-focused consumers to get a bigger car?
So Most Newer SUVs Can Use 91 ULP, Then What's The Worry about Engine Knocks, Right?
kiwiyonip on 10/03/2023 - 23:07
Last edited 10/03/2023 - 23:20
Last edited 10/03/2023 - 23:20
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Are you sure? My dad's therapist's mother's daughter-in-law's dog said I can get more milage from using higher RON.
His in-law's dog is actually right
Engine ECU adjust timings constantly, resulting in more kms/L for better fuel:"A control loop is permanently monitoring the signal of one or more knock sensors (commonly piezoelectric sensor which are able to translate vibrations into an electric signal). If the characteristic pressure peak of a knocking combustion is detected the ignition timing is retarded by steps of a few degrees. If the signal normalizes indicating a controlled combustion the ignition timing is advanced again in the same fashion keeping the engine at its best possible operating point - the so-called ″knock limit″."
https://en.wikipedia.org/wiki/Engine_knocking#Knock_detectio…
Mod: Removed inflammatory sentence
But for the love of God, don't use E10.
@nuker: If you put premium fuel in a car designed to run on regular you don’t magically get more power. The knock sensor helps prevent knocking by retarding the timing, but the timing won’t advance enough to take advantage of the extra RONs unless it’s designed for it.
And why not use E10?
but the timing won’t advance enough to take advantage of the extra RONs
But it does. And there is no reason why it should not. But ECU advances it very slowly, it’d take few fills to start noticing it. So keep consistent with fuel.
I don't actually remember why E10 is bad, I etched it in my brain when I was convinced of that long time ago. I retract it, until further notice :) I use only 98 anyway.
But it does. And there is no reason why it should not.
But it won’t advance timing ost where the manufacturer says and they don’t build the car with high enough compression to take advantage.
I only use 98 anyway.
And what is your car designed for (or what car)? The fact you can’t remember why E10 is bad indicates you are probably using 98 because of advertising, not rational assessment.
because of advertising, not rational assessment
dude, I have masters degree in Physics
“One of the areas that E10 can have a negative impact is in your fuel systems' seals and gaskets. These are often made of rubber on older vehicles, a material than Ethanol will degrade much faster than petrol.”
https://www.bumper.co/blog/what-is-E10-fuel-will-it-damage-m…@nuker: And yet you don’t seem to understand how fuels work.
As for E10 causing issues with rubber, if your car is designed as suitable for E10, it is suitable for E10. If it isn’t, then you are going to have an issue with seals and gaskets.
@nuker: And has your butt dyno told you 98 gives more power or have you measured accurately the fuel consumption to determine 98 is more better? Or have you been duped into paying upward of 10c more for no measurable benefit?
@Euphemistic: The car running on premium unleaded consumed 9.06 litres/100km, compared with 9.41L/100km for the regular unleaded car and 9.81 litres for the E10 vehicle.
https://www.drive.com.au/news/fuel-efficiency-showdown-20120…Being put back by a random dog, that should hurt :)
@nuker: But it still COST more to use premium.
Still haven’t said what car you drive nor if you’ve actually done the measurements.
@nuker: Save 0.35l over 100km… lol.
That could possibly be the error margin for the test. 0.35 proves nothing.
And E10 is about 3~5% down on energy density, so 0.75l more over 100km is really good for E10.
Let’s consider these based on price… I’ll use my local servo for cost:
E10 = $1.707/l
91 = $1.727/l
98 = $1.927/lTo go 100km on each from your example: (amount used x price)
E10 = $16.75
91 = $16.25
98 = $17.46If you use 98 in your 91 shitbox example, you are literally burning $1.21 every 100km, or about $150+ every year for an average 12,500km/year driver.
So, you’re still wrong. :D
@pegaxs: Get lost lol
Point was that engine ecu takes advantage of 98 petrol, improving mpg. Point was proven.Get lost lol
Childish much?
350ml (less than a can of soft drink) over 100km is nothing. This could easily be written off as a change in test parameters. They even said it was done in 3 seperate cars, and I would assume that also means 3 seperate drivers, and that would absolutely mean 3 different styles of driving, added to this that the 3 cars would have different tolerances enough to make a 350ml difference over 100km.
And the ECU does not “take advantage” of 98. Your car does not know what fuel it has in it and if it has been designed, manufactured and mapped for 91, there is no point putting 98 in it because of the figures you outlined above.
From your example above, you forgot to post the most important part…
The E10-fuelled Camry in the test cost $276.55 to run, while the regular unleaded version cost $271.56 and the premium unleaded fuel version, which cost, on average, 15 cents a litre more than E10, cost $285.54.
98 costs $285.54 on their test compared to $271.56 for regular 91. A price difference of $14. Even E10, a fuel that has less energy density, still out performed 98 in their Camry.
I've crossed check these figures with Carsales to confirm what they've put in their website is accurate, they said it's the manufacturers' recommendation, so what I'm surprised about is these are newer models SUVs, mid-sized, and yet 91 RON? I would expect at least 95 to maximize performance and engine care.
If you can achieve acceptable performance for consumers using regular fuel why wouldn’t you design to use regular fuel? SUVs don’t need race car performance.
performance and engine care.
The stigma about fuels peddled by their manufacturers / sellers dies hard.
Just do what the car's manual says - it is specified by those that designed the car (who actually designed the car around that particular fuel) and know what it actually needs.
"it is specified by those that designed the car (who actually designed the car around that particular fuel) and know what it actually needs."
But are they specified for the best performance and engine longevity or are they specified to meet politically derived 'emissions' standards?
Just because I 'can' use E10 in my car's engine, should I?
I keep my vehicles for a very long time.@Euphemistic: No it's not. But if the car manufacturer says it's ok then it's ok. They are in the business of making sure that the car lasts its warranty period and then performs well enough that you will hopefully be a repeat customer. I am pretty sure they would have considered the ramifications of any of the fuels they specify as part of that business case.
There is possibly also some input from the marketing psychologists - "If you make it work with E10 then more suburban mums and dads will buy this car" or "Listen Kumpel - if vi make ze engin runs on einundneunzig then everyone vill tink its not performance - so make big kompression please and minimum 95. Danke." Who knows? But the engineers will either have the last say, or they'll make it work according to the specs anyway.
WRT to the lower energy density of E10, well that's not the car manufacturers concern. If people are silly enough to buy a fuel that has less energy per dollar that's their own issue.
@fantombloo: If it’s cheap enough that it still costs less to go the same distance doesn’t really matter if it’s lower energy density. But do your own testing.
@dazzawul: 0.008Immortals lives in a world where RON is a political consideration, so I think we can safely say "no"
Modern ICE is complicated and manufacturers employ smart folk to sort all this out and put recommendations in the user manual.
Even monkey gassing, community poisoner VW haven’t been accused of getting their user manuals wrong.
Just go with it.maximize performance and engine care.
Well, you could start by stop swallowing fuel corporation propaganda for a start…
"It gives MoAr PoWaH and cLeAnZ wHiLe YoUsE dRiVe!!11!!!!"
And cross checked with carsales, huh… wow, you really have done your homework… checked in with the most reliable source on the internet… Keeping those car companies honest by cross checking that they have the same info as the ever trusty "carsales".
SUVs, as much or more than any other segment, have been made to meet customer demand for a car that is easy to get in an out of without bending or squatting down.
My 22 year old sports car OTOH, is hell to get in and out of, especially for anyone old or fat.
It adapts to fuel from 91-98 octane within a few hundred kms. But it is best to choose one octane and stick with it, else it will spend time adapting to the new octane level and won't work as efficiently. I choose to run 98 all the time as I want the small amount of extra performance it provides. Because it adapts and works more efficiently with more expensive fuel, the extra cost is offset (a little).
It would be cheaper to use 95- but not 91. This is because the system will not stay clean over time with 91. Contamination of the injectors occurs not because 91 is dirty, but because the fuel molecules are larger and this engine has injectors which are optimised for the more refined fuel mixtures of higher octane fuels. The manufacturer fitted them to make the engine work more efficiently whilst producing less emissions. Combined with contaminants and absorbed water, this can cause these more accurate injectors to foul over time, and affect the quality of the mist they spray in the combustion chambers. This is why it is better to use 95 or 98* for longevity, as even small amounts of fouling cause incomplete combustion, a dirtier burn, foul other parts of the engine, and waste fuel (reducing efficiency). Note this is only the case when the manufacturer recommends higher octane fuels in your exact model.
Given they make most cars for the buyer's perceptions/needs, why would they go to any real trouble to make an SUV perform that little bit better unless the customers or the regulations demand it? Their market research tells them every year that many buyers in the SUV segment will buy a car that works on 91 only, over one that is optimised for 95. And this is simply because the extra cost of 95 and 98 at the bowser is not entirely offset by the additional cost.
not because 91 is dirty, but because the fuel molecules are larger
well, that is indeed a new one.
exactly which compounds within U91 compared U98 result in larger sized molecular structures?I'd be pretty interested to know which car you're driving thats this advanced?
@SBOB: An engineer told me that years ago, so is likely a simplification. You are welcome to look into it and let us know the exact details.
I never did, but it sounds fair to me as I know that injectors from vehicles optimised for 95 octane have their nozzles perforated differently, with lots of small holes instead of a single big one like they had till we adopted 95. This is to maximise atomisation in a more carefully controlled 4 valve combustion chamber, (typ integrated with the addition of knock sensors and dual lambda sensors), but it may also be more to do with how these nozzles foul over time, or how their flow varies given different temp/pressure conditions as the holes are hardly the size of a single molecule…
I have a few cars, all use factory fuel systems made by Bosch- widely copied by others ;-).
@resisting the urge: I mean a quick google (aka using chat gpt which is obviously never flawed or wrong) suggests the complete opposite, higher octane fuels typically contain some more complex hydrocarbon chains.
Regardless, that is 0% an issue
@bhubb18: Maybe it's more about the additives, or how turbulence occurs at the nozzle tip. But I agree it would be good to know.
Everyone should be using 95 unleaded if they care about not spewing heaps of sulphur into the air. (This won't be necessary after December 2024 when sulphur content limits will be standardised)
@pegaxs
Keep it together man.
Dude, I dont know what the (fropanity) OP is talking about… I literally re-read it twice and I'm still trying to work out what the question is…
Where it gets complicated is the turbo engined versions.
Honda CR-V 1.5l turbo and Mazda CX-5 2.5l turbo can use 91 RON, but can get better performance or economy out of higher RON because the ECU supports it*.
Whilst anything VW with a turbo (e.g. most of their models) require 95 RON minimum which is an improvement from pre 2009 when they expected you to use 98 RON as a minimum.
*Allegedly
Honda CR-V 1.5l turbo and Mazda CX-5 2.5l turbo can use 91 RON, but can get better performance or economy out of higher RON because the ECU supports it*
This is because these cars, including my own which is not a turbo, have a knock sensor which detects pre-ignition and backs off the ignition timing to prevent knock if you use fuel below the recommended octane. The car is recommended to use a higher octane, and is most efficient using that. But it will run with reduced efficiency - producing less than the rated amount of power, performance and fuel economy - on a lower octane fuel if you have to or choose to put it in. At least it won't be damaged, but its a poor decision to do so because it costs more in reduced engine efficiency than it saves at the bowser.
You can't get better fuel economy or power by putting higher octane fuel in it than it was designed for. But the manufacturer can get more power or better fuel economy for you by designing the car to run on higher octane fuel. But higher octane fuel costs you more. A higher compression ratio makes an engine more efficient, it uses less fuel to produce the same power, or can produce more power from the same amount of fuel, but it requires a fuel with a high RON number - knock resistance - which costs more to refine from petroleum, and so they have to, and do, charge more for it.
For performance cars manufacturers choose more power, because customers buying them value more performance over paying less every time you fill up with fuel. For economy cars manufacturers choose better fuel economy because customers buying them value less cost at the bowser than less time to 100 km/h.
So buy the car designed and built for what you think is more important, and put the fuel in that it has been designed for. The manufacturer's recommendation tells you what that is.
Why do you think it is a -
marketing ploy by these manufacturers to entice fuel efficiency-focused consumers to get a bigger car?
Your post is not clear.
sigh
Use what the manufacture recommends. Anything with more RON is a waste of money. Anything less RON is not good for your engine.