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Taken from: http://www.leesracing.com/articles/a1.html

Research Octane Number (RON)

is measured under mild conditions and is more important in controlling part throttle knock.

Motor Octane Number (MON)

is measured under more severe conditions and is most important for octane satisfaction at wide open throttle.

Anti-Knock Index (AKI)

is the average of the RON and MON. This is the number posted on the retail gasoline pumps normally indicating 87, 89, or 92 octane. Racing gasoline have AKI's from 100 to 118

Taken from Wikipedia: http://en.wikipedia.org/wiki/Octane_rating

The most common type of octane rating worldwide is the Research Octane Number (RON).

Edited by MintR33
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It's up to your car to tell you which fuel it's gonna like best.

For example, i run Caltex Vortex 98 and BP Ultimate. The car runs like a dream on BP but its halfway across the city for me to get a tank, so it doesnt see it much.

Caltex Vortex it runs fine on, no complaints, the knock sensor never shows knock when giving it a bootfull.

Shell Optimax however has given me some cases of knock when booting... alot of people say that optimax is good to reduce knock and shit but i guess it all depends on your car, because it didnt reduce knock on mine.

So just try a fresh tank of them all and decide for yourself.

It's up to your car to tell you which fuel it's gonna like best.

For example, i run Caltex Vortex 98 and BP Ultimate. The car runs like a dream on BP but its halfway across the city for me to get a tank, so it doesnt see it much.

Caltex Vortex it runs fine on, no complaints, the knock sensor never shows knock when giving it a bootfull.

Shell Optimax however has given me some cases of knock when booting... alot of people say that optimax is good to reduce knock and shit but i guess it all depends on your car, because it didnt reduce knock on mine.

So just try a fresh tank of them all and decide for yourself.

Hi Justin, where are you located?

:P cheers :dry:

always used bp ultimate around my local, could feel a difference and per tank of gas got further on avg, real numbers

filled in parra @ teh wooly's station as was getting onto empty line thanx to misses picking me up an not gassing up ^^ best tank of fuel ever, best price was packed cuase tehy sell cheaper than everywhere. the fact that shite loads of fuel goes through, "fresher" fuel maybe, less time swishing in tanks with the added station mixers ? eh eitehr way, went the furthest ever, like freakishly better, no a single frigging nock and 200k's to less than half tank, when i get 300k's on avg per tank.

97 s2 stocker with cat back, mod suspension and a quickshift kit

you mean this link??

http://www.skylinesaustralia.com/forums/in...treme&st=20

From SydneyKid

"A/F ratios are based on weight, not volume, hence the need for specific gravity of the fuels.

Moving on...............we have a new project car, an R33GTST that is in need of some TLC. One of the recent upgrades was a Power FC. As most people are aware, the default ignition maps are a little advanced for Optimax, Ultimate or Vortex 98. Not as bad as they used to be for 95 ron fuels, but still a tad. Obviously I will tune it properly eventually , but we have a few mods to go yet and I don’t have the time to tune it multiple times. So the idea was to stick the Power FC in and run it on the default maps for a couple of weeks. On Optimax and Ultimate (didn’t try Vortex) it was reaching knock of 60+ up our usual test hill in 4th gear as logged on the datalogit. The dash warning was also flashing frequently, as it is set for 60, in normal day to day driving around. When the tank was just about empty this week, we filled it up with Optimax Extreme (@ 5 cents a litre more than Optimax). Several runs up the hill and we are not seeing knock over 10. And zero dash warnings in 3 days of normal driving.

Now that is very worthwhile, there is not enough Optimix Extreme around yet for me to tune it exclusively for 100 ron, but it sure will be a useful for the odd track day or run down the ¼.

I will monitor the effects of the ethanol on the fuel lines, o’rings and seals over the next few weeks. The injectors and fuel pump will have to come out shortly so I will check their condition as well. I am not anticipating any problems, but it is still worth checking.

cheers:)"

Hi Justin, where are you located?

;) cheers :happy:

Hey SK,

I'm in Canberra. I havent tried Optimax extreme or whatever the ethanol one is, but the optimax 98RON. I filled up a popular servo in my area so i'm going to assume it was pretty fresh.

I found it strange that i saw knock with it when all i've heard people say is that it will reduce knock.

If your car is stock I see no reason why you cant use any 98 RON fuels. If its modded then probably BP Ultimate is good.

My car is stock I mainly buy Optimax when I have 4 cent discount vouchers from Coles and BI LO or get Ultimate. I run Ultimate every second or third tank anyway.

I also use Mobile 8000 Synergy but very rare.

220-250k's to a FULL tank is doing well on bp ultimate, vortex 98 from popular stations seems the go 400+k's, stuff al back fires and much less overfueling like my car isnt running on the safe map, there are no popular bp servo's in sydneys west, everyone goes the cheaper fuel proly why i can get decent vortex, 4c off aye.

anyways the vortex "seems" to drive better,

thats real odd.......

whats the difference between vortex and ultimate performance wise....anyone tried?

im gonna fill up my next tank with vortex...ill see how it goes

well I tried most high octane fuels in my r33, such as Mobil premium, Optimax, Ultimate, And i felt that when i startyed using Vortex98 my car ran alot better, more perfromance, more km's out of a tank, and alot less backfire(hardly any at all). I would strongly reccommend Vortex, but by the looks alot of different people cars run better on a range of fuels. My advise would be to try them all! see how you go.

Yeh bro just put fawken good old leaded in there she be right. Car might cough and fart bit ay heh but she be right, then just chuck bit of supercheap carby cleaner through intake every 500k's or so car should run sweet. >_<

Todays prices i think our only choices is to use the 98 octane. I havent noticed difference between BP and vortex

Edited by siiick

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