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What Octane number do you use inyour gas tank?

  • 91-93, Yea Baby!!

    Votes: 112 36.7%
  • 89, does the job, no complaints.

    Votes: 64 21.0%
  • 87, I'm poor, only wish i could use the high stuff.

    Votes: 129 42.3%

  • Total voters
    305
101 - 120 of 195 Posts

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Audi Fondler
2000 Silverish 2.5rs Sedan
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3,251 Posts
I'm waiting for the place that does 100 octane to open it back up... when they're open again I'll start mixing to around 95 again... n/a doesn't really benefit from too much more unless the engine is rebuilt. Having to resort to crappy octane boosters and 91 octane for now hehe.
 

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i was under the impression the ecu had to learn what octane you used also to sort of adjust timings a little

so question is all you people posting octane rating / miles. are these numbers calculated after you drove around 1000 miles on that octane then averaged with a few tanks after the 1000, or did you just fill up one day with 91 when you were running 87 then the next tank put 89 etc making your ecu go wtf is he doin!

of course i could be wrong i filled up with 91 from 87 for 4 tanks worth i drive 85 miles a day 65~ freeway, and i noticed no power gains and a lose of mpg so i went back to 87 where i avg around 370miles/tank

stock rs btw
 
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I use 87 octane. Its what the n/a engine and ecu ask for and it does the job hands down. Also, I'm in HS and gas is fuggin' expensive and I couldn't afford higher octane even if my GF4 wanted/needed it.
 

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2010 Impreza 2.5i 5-door, 5-sp
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2,124 Posts
DragonRM said:
anyone else's rs car manual ask for 91 octane? Mine does... I use it anyways but I've talked to a couple other people's who don't.
Mine says use at least 87 octane. I use 89, my car runs best with it.
 
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crikey, my UK car has to run 97/98 octane fuel, if we import a jdm version it has to be remapped to run on our lower grade, otherwise its octane boosters to push it upto 100 ron fuel and above!!!!!

i didnt know american grading was so low? RON rating is universal right?

to give you some idea on price normal petrol is 95ron and 80-90 pence a litre (=$1.30) and for 98ron can be as much as £1 per litre! Thats $1.50 per litre and $7 per UK gallon! My car does on average 19 miles to the gallon
 

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2010 Impreza 2.5i 5-door, 5-sp
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25* General Zap Brannigan said:
i didnt know american grading was so low? RON rating is universal right?
Yeah, I think it is universal. I could be wrong though. I think most Americans don't know what the Research Octane Number is so we never say, "89 RON" or "91 RON" we just call it "91 octane." But I think we're talking about the same thing.

25* General Zap Brannigan said:
to give you some idea on price normal petrol is 95ron and 80-90 pence a litre (=$1.30) and for 98ron can be as much as £1 per litre! Thats $1.50 per litre and $7 per UK gallon! My car does on average 19 miles to the gallon
Ok, let's see if I can do this right.
1 UK gallon = 1.20 US liquid gallon.
1 UK Pound = 1.82 USD.
In CA, where I live, 91 octane is about $2.64 / gallon right now.

So, it would take about 1.45 UK Pounds to buy 1 (US) gallon of 91 in the US.
1.45 UK Pounds = about, believe it or not, $2.64 US!

Your 98 octane costs as much as our 91 octane in California!!!
Is that right? If my numbers are correct and the RON and octane ratings mean the same thing, then gas is about the same price or cheaper in the UK. :screwy:
Maybe somebody can check my numbers.
 

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2010 Impreza 2.5i 5-door, 5-sp
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rsowell28 said:
That's better than what I pay out here in Southern California.

$1 (US) = $1.92 (AU)

1 gallon (US) = about 3.79 liters.
So you pay $3.79 (AU) for 1 gallon (US) of gas.
$3.79 (AU) = about $1.98 (US)
I pay about $2.10 - $2.20 for 87 octane while people in Australia get away with $1.98 for 98 octane! Damn...

I guess Australia has better gas prices than California!

(Unless my numbers are wrong, which the very well could be, in which case, please disregard everything I just wrote and pretend I never posted any of this).
:)
:stupid: WOW déjà vu! Looks like I did this already, way back on page 4!!! :lol:. Looks like AU gas prices are comparable to those in the UK.
 

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2010 Impreza 2.5i 5-door, 5-sp
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DragonRM said:
prices in CA are higher than everywhere else too... in CO I pay about $1.90-$2 per gallon for 91... It has its ups and downs but that's about average. When I first moved here a year ago it was $1.70 for 91 :(
Yeah, I prolly should have mentioned that. CA has their own gas that's different from the rest of the country.

Anyway, $2 for 91 is CHEAP foo! :eek:
Hasn't been that cheap in Cali for a LONG time... :(
 

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ok talked to a ASE certified friend (not that it means much he said the certs were written so any redneck idiot could pass em :lol: )

if the car is recommended for 87 you should run 87 or youre just wasting yer money

higher the octane the more it retards detonation aka retards timing. when timing is modified out of its optimized range you lose hp and topend, but could possibly gain a little torque

so basically for octane higher than 87 unless otherwise stated you need to increase fuel consumption (lower mpg) and advance timings to get any sort of real gain otherwise your car just cruises like normal getting the same mpg with lower hp
 

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Audi Fondler
2000 Silverish 2.5rs Sedan
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3,251 Posts
well.... even before I modded my car always ran better on 91 octane... I don't know many rs owners who have said they didn't notice a difference. But I'm modded enough that I notice a much bigger diff :) And I usually fill up when I get below 1/4 tank... and at that point I have at least 330 miles on that tank and that's mostly without much freeway driving. I'm actually getting better gas mileage after I was modded and with advanced timing :)
 

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1990 legacy wagon
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679 Posts
I use 91 octane and add a gallon of tolulene (114 octane) into everytank A gallon of tolulene bought in bulk is about $6 per gallon, so the average price per gallon I am paying is about $2.60 per gallon, and at 15 mph it is getting spendy. However, I don't want to blow ahole in another piston. I am pushing about 7-8 psi on a 1990 NA 2.2 via an Eaton m62 supercharger, walbro pump, MSD rrfpr and an AWIC.
 
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