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High octane fuel and the truth

moose man

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With so many guys on here talking about using 95 RON, 98 RON and higher, and claiming to make up to 30% difference in power output, and so many others asking whether this more expensive fuel is going to benifit them I just thought I'd start a thread to help educate people and dispel some common misconceptions.

1. If your engine is not designed to use premium fuel, it will not benefit.
When I say 'not' I mean in any noticeable way. Sure, you may get a 0.2 or 0.3% change in fuel use or power output, but it is barely measurable, and certainly not noticeable.

2. Premium fuel is not 'better quality' or cleaner than normal unleaded.
Believe it or not, all fuel comes from the same place. It is all refined and then put into storage containers. Chemists then add chemicals to this fuel to determine what it will be called ie. Premium, ultra, regular etc. In fact, premium fuel has more chemicals added to it than regular unleaded.

The deciding factor for which manufacturers designate the engine to use, is DESIGN. The design of the engine (generally the compression ratio of the combustion chamber) decides whether the engine will NEED high octane fuel, or not. Engines wil compression ratios of 8 or 9:1 do not need premium fuel, nor will they benefit. It's not a choice that manufacturers they make, it's a need.

Standard Commodore engines do not need premium fuel, nor will they benefit from it.

I just hear so many stories of people wasting their hard-earned money on premium fuel and not realising that it's no better than regular. Their mate told them that they got an extra 50 km or 100km from a tank, or they think their car 'feels' better with it. One-off anecdotes unfortunately do not make good proof.

There's one main reason fuel companies push it onto consumers (apart from those few that actually need it), because it is more profitable. More $ for the same product. They don't lie, a 0.08% fuel consumption decrease is a decrease, but they happily leave this data out of the marketing dribble.

If you want to know more about it, then I recommend you read some engineering books, or peer reviewed documents (not a forum or manufacturer's website). Please don't waste your money.

I am happy to answer any questions/comments/disagreements that you may have.
 

wraith

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With so many guys on here talking about using 95 RON, 98 RON and higher, and claiming to make up to 30% difference in power output, and so many others asking whether this more expensive fuel is going to benifit them I just thought I'd start a thread to help educate people and dispel some common misconceptions.

1. If your engine is not designed to use premium fuel, it will not benefit.
When I say 'not' I mean in any noticeable way. Sure, you may get a 0.2 or 0.3% change in fuel use or power output, but it is barely measurable, and certainly not noticeable.

2. Premium fuel is not 'better quality' or cleaner than normal unleaded.
Believe it or not, all fuel comes from the same place. It is all refined and then put into storage containers. Chemists then add chemicals to this fuel to determine what it will be called ie. Premium, ultra, regular etc. In fact, premium fuel has more chemicals added to it than regular unleaded.

The deciding factor for which manufacturers designate the engine to use, is DESIGN. The design of the engine (generally the compression ratio of the combustion chamber) decides whether the engine will NEED high octane fuel, or not. Engines wil compression ratios of 8 or 9:1 do not need premium fuel, nor will they benefit. It's not a choice that manufacturers they make, it's a need.

Standard Commodore engines do not need premium fuel, nor will they benefit from it.

I just hear so many stories of people wasting their hard-earned money on premium fuel and not realising that it's no better than regular. Their mate told them that they got an extra 50 km or 100km from a tank, or they think their car 'feels' better with it. One-off anecdotes unfortunately do not make good proof.

There's one main reason fuel companies push it onto consumers (apart from those few that actually need it), because it is more profitable. More $ for the same product. They don't lie, a 0.08% fuel consumption decrease is a decrease, but they happily leave this data out of the marketing dribble.

If you want to know more about it, then I recommend you read some engineering books, or peer reviewed documents (not a forum or manufacturer's website). Please don't waste your money.

I am happy to answer any questions/comments/disagreements that you may have.

Do you have any factual evidence to support these claims?
 

sik_dose

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if you look in the owners book of any 90's commodore it will say its tuned to run on regular UPL so the OP makes perfect sense. I would like to see some evidence to back it up as well.
 

wraith

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I can only go off personal experience which is by no means scientific. But when I run 98 I get 600 km's to a tank on anything else it's 400 km's. Although I suspect my car is tuned for 98 already as it refuses to run properly on anything else.
 

moose man

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hmmm... nothing that I'm allowed to publish online. All too complex and long winded anyway.

I have heaps of books, articles and journals that I studied from, but, being on a forum, this post was more to educate people than to prove or justify my words.

I will, however, answer as best as possible.
 
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mug1000

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not all cars can run on premium fuels I pretty sure it's the first of the fuel injected for a lot of cars all you have to do is ask someone in the buisness that knows from experience not from a book but for the cars that can run on premium fuels the best for around town is the 95ron for a lot cars becuse it gives you a better drive by waking up the engine and improves you fuel ecconomy slightly with it as for the 98ron is only good for cars that need it and only good for long distance driving for the rest
 

Ozzie

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Yeah this is all true.

Basically if you have a standard tune to run 91oct the car will only register the fuel as 91oct weather it be 91 or 98.

Thats why we have smart people like greenfoam out there who re-map our tunes to run the higher octane.
 

wraith

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Yeah this is all true.

Basically if you have a standard tune to run 91oct the car will only register the fuel as 91oct weather it be 91 or 98.

Thats why we have smart people like greenfoam out there who re-map our tunes to run the higher octane.

Not always. Some car's can adjust for the better fuels. The Soarer I used to have used to have an interesting way of calculating on reset. I think it advanced or retarded the timing till it knocked then wound it back one step. So yeah.
 

Ozzie

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Not always. Some car's can adjust for the better fuels. The Soarer I used to have used to have an interesting way of calculating on reset. I think it advanced or retarded the timing till it knocked then wound it back one step. So yeah.

Soarers come standard with a jap custom tune.

Commodores didnt.

I did mention cars that came programmed as stock for 91oct :)
 

wraith

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Soarers come standard with a jap custom tune.

Commodores didnt.

Yeah. I am no expert but I think the later commodores can run better on higher octane fuel as they can adjust on the fly with the knock sensors.
 
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