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Old 12-05-2009, 11:25 PM   #1
2Fast2Furious
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Default Octane Level

I use 95 RON from my convenient petrol station.

99 RON is currently available from Maxol = E5 unleaded which I could start using but at greater hassle

or

I could use Octane Booster.

Is there any reason to and what do you all use?
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Old 12-06-2009, 03:38 AM   #2
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Well, the octane number that I run won't be of much help as the octane standard used here is the average of research octane and motor octane. I run the mid grade available in my car. Octane is a balancing act.... but I'm not going to get into that.

95RON is what Toyota recommends for the MKIII GTE at sea level. 97RON is the recommendation for the GE at sea level. Higher octane fuels allow the ECU to increase the timing advance resulting in more power; However, you may notice worse mileage as higher octane fuels contain less kinetic energy.

At higher altitudes and in colder climates you may run lower octane rated fuels as the potential for detonation deminishes in proportion to these.



This is from the MKIII owner's manual:
Quote:
Originally Posted by UK Toyota Supra MKIII Owner's manual
7M-GTE engine:
For optimum engine performance. Toyota recommends using premium type gasoline with an
octane number of 95 or higher (Research Octane Number).
However, if such premium type cannot be obtained, you may use gasoline with an octane number as
low as 91.

7M-GE engine:
Select the octane number of 97 or higher (Research Octane Number).
NOTE: The numbers above are RON only! The US and other markets use different methods of determining octane rating: Motor Octane Number and/or Research Octane Number. The US uses (MON+RON)/2... this number is almost always lower than RON by itself.
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Old 12-06-2009, 05:20 PM   #3
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Thanks for reply. Since the higher the octane level the better I will fill-up on Super Unleaded when I can.

I know this topic has probably been discussed before but I am new so could you elaborate on the balancing act debate you touched on, if you don't mind.

I just bought some Octane Booster today which will increase octane level by 1.5 points.
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Old 12-06-2009, 05:33 PM   #4
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Not to p1ss on your bonfire, but that octane booster stuff is a total waste of money IMO. If you read into the ratios actually needed to boost the RON by a certain amount you'll realise that you may as well just go buy 100 race fuel for the amount you'd be spending to get any noticeable benefits. FWIW just do like you said & stick super in the tank.
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Old 12-06-2009, 05:51 PM   #5
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Guess I'm wrong, burning higher octane fuel than the engine was built for won't make a blind bit of difference. 95 RON/8586 MON/9091 AKI it is then.


http://en.wikipedia.org/wiki/Octane_rating

Many high-performance engines are designed to operate with a high maximum compression, and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.

However, burning fuel with a lower octane rating than required by the engine often reduces power output and efficiency one way or another. If the engine begins to detonate (knock), that reduces power and efficiency for the reasons stated above. Many modern car engines feature a knock sensor a small piezoelectric microphone which detects knock, and then sends a signal to the engine control unit to retard the ignition timing. Retarding the ignition timing reduces the tendency to detonate, but also reduces power output and fuel efficiency.
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Old 12-07-2009, 06:25 AM   #6
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Thanks for looking it up.

See the balance?

If you want cheap octane booster go buy a couple gallons of toulene or xylene or alcohol... Look around on the net and you can find a lot of recipes for mixing your own octane booster; But, I doubt you need it.
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