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Discussion Starter · #1 ·
Maybe I'm crazy but I put 91 octane gas on my car yesterday and the engine makes a better sound at high RPM .

Try it and we'll see if I'm crazy ! :)
 

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i doubt it was the gas... lol
could be the weather?
and you dont need to put 91 octane gas in your car. they come tuned from the factory for 87 octane so anything higher will not make a difference youre just wasting your money.
 

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2021 Forte GT w/GT2, Currant Red, SXTH Element Intercooler Kit, Evilla Exhaust, Takeda S2 Intake
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Seriously...I ran 91 octane in my Koup SX since I bought it:eek: -- I have gone back to 87 octane as it didn't help:rolleyes:. My wife's Forte SX sedan has only been fed 87 octane since we bought it and it outruns my Koup SX...:mad: They are actually closer with both of them using 87 octane in each...but the sedan still gets ahead of the Koup...DAMMIT!!!

Stick with 87 IMO!
 

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all your doing is making your car run rich by putting a higher octane rating that it doesnt need in it. factory tuned for 87? use 87
if you get it tuned for 91 octane, THEN it will perform better on 91
 

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all your doing is making your car run rich by putting a higher octane rating that it doesnt need in it. factory tuned for 87? use 87
if you get it tuned for 91 octane, THEN it will perform better on 91
it wont necessarily run rich but hes just adding more octane which would be useless if he doesnt tune for it. with 91 octane he could run more timing but the fact that its still on factory tune it will only run the amount of timing that the factory tuned for.
 

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Aussie Forte's must be tuned for 91 octane then, as it's our standard gas. Premium gas is 95-97 octane and about 8cents a litre dearer
 

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Aussie Forte's must be tuned for 91 octane then, as it's our standard gas. Premium gas is 95-97 octane and about 8cents a litre dearer
Australia uses a different formula to calcualte octane ratings. Your 95 is equal to our 91 IIRC.
 

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2021 Forte GT w/GT2, Currant Red, SXTH Element Intercooler Kit, Evilla Exhaust, Takeda S2 Intake
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Try some 100LL avgas...if money is no problem get the best gas out there.
 

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I did a MPG and "feeling" test. If I go down to regular pump gas (87) I noticce about a 20-25% drop in MPG and a definite performance drop.
thats somewhat inaccurate as you do not drive EXACTLY the same everyday.
Also, there would be no increase in performance due to your car not being tuned to the higher octance.
Even if there was a performance increase it would not be significant enough to notice the power gains.
 

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thats somewhat inaccurate as you do not drive EXACTLY the same everyday.
Also, there would be no increase in performance due to your car not being tuned to the higher octance.
Even if there was a performance increase it would not be significant enough to notice the power gains.
Same gas station
Same distance to and from work
same drive times

and I tested it to and from Ohio from DC on two seperate occasions. Yeah I can say that I have a MPG idea down very well, and a "feeling" down as well. You dont to agree but I have a marked drop in MPG per tank on 87 opposed to 93.
 

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The Low-Down on High Octane Gasoline

read that. now im not trying to sidebust or be an asshole im just trying to get some facts across.
My car when i was stock with just an intake felt very similar to my car on a full exhaust, intake, 2.8 in. pulley, 60# injectors and other mods it, in fact, still felt somewhat the same as stock but i can assure you there was a huge difference in power.
you will not feel 5-10 hp added to your car and im positive you would get no where close to that by using higher octane gas, untuned.
 
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