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You'll need to get a tune for 91 octane
 
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Whats with all these people lately putting expensive parts and then wanting to cheap out on the gas ...
 

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You really shouldn't need highe octane unless u up the compression
 

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Don't change the octane unless you get a tune for it. Stock with just upgraded Stage2 is fine at 87. IMO, 89 is trash.
 

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but thanx FocusRacingAustrali...i see rep in your future
I'm still learning as I go but, thanks anyway.


Don't change the octane unless you get a tune for it. Stock with just upgraded Stage2 is fine at 87. IMO, 89 is trash.
You really shouldn't need highe octane unless u up the compression
That's not the case at all
You don't have to up the compression to use higher octane, I've been using 98 octane for 4 years and no problems
In my owners manual it's states for my Euro Aussie Focus I have to use 91 octane and I use 98 octane and I have no tune and I should get 1
The reason I use the higher octane is because you get little bit more Hp like 1% or there abouts and abit more mpg
When fuel price go up to high I use 91.
You will be fine with 87. No need to get 91.Cams dont need a higher octane.
He can run 87 or 91 octane with these cams but, if he want abit extra peroformance in Hp and torque and little bit more mpg then he'll have to get a tune for 87 or 91 octane.
 

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more octane does not mean more hp, more octane is adding a stronger safety factor only. Ur 98 octane is not the same as 98 octane in the states. Do a search on it, I know it is explained. Ask Tom, the only reason you need to run higher octane is if you have higher compression or u advance ur ignition timing. Else, you can start to have carbon build up, or something like that, I know that was explained in a recent forum thread as well, I will see if I can pull it up!
 

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more octane does not mean more hp, more octane is adding a stronger safety factor only. Ur 98 octane is not the same as 98 octane in the states. Do a search on it, I know it is explained. Ask Tom, the only reason you need to run higher octane is if you have higher compression or u advance ur ignition timing. Else, you can start to have carbon build up, or something like that, I know that was explained in a recent forum thread as well, I will see if I can pull it up!
Your 98 octane is race fuel? our 98 octane is street fuel.
if you can find it that would cool.
He doesn't have to use the higher octane but, like Bambooburnr above said adding on performance parts and people still want to use the cheaper gas but, they want max hp. it just kinda doesn't work like that
From what the performance shop have told me you should use the higher octane when getting a tune but, if thats not the case then I'm still willing to listen.
I beleive our fuel over here we have better and cleaner so maybe that could play apart in it as well.
 

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Yes, when you get a tune, you can get it tuned for 91 octane, the way that works is you are advancing ignition timing, so you need to run a higher octane fuel, else you will get predetination. W/O a tune, higher octane fuel is pointless (assuming no higher compression or boost)

There is a way that fuel octane is measuered, I am not familiar w/ it, but am still trying to find the thread. Ur 98 is prolly = to our 89 or 91, I will post the thread when I find it.
 

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here is what i said in the above thread. i really don't feel like typing it again so i will just copy and paste. i do agree, however that the fuel in different countries is different. the gas in other countries outside of north america is actually more dirty than the gas we get here, hince the reason for the higher octane needed to get the same results.

here is what i said.

the only reason you should be running high octane fuel is if you are FI or high NA compression. the higher the octane, the leaner you can run your car without risk of knock and other related lean issues. the leaner the mixture the more power (to an extent obviously). i will give an example.

assuming that you have some way to advance timing and you know how to tune.

say you are running an a/f ratio of 11.3 which is the knock threashold for your car so it is the leanest you can go and make the most power on 87, 91, whatever.

now throw in race gas and your car will still be running your same 11.3 a/f ratio but your car will be running like the a/f ratios are at 10.5. which means what, you can advance your timing, or in a boosted application you can turn up your boost and run an a/f ratio of say 12.0 or something like that and still be safe because of the higher octane.

hope this makes sense and helps a little can't really gather my thoughts right now cause i am busy here at work and got a little down time.
 
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