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pwnd
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3,455 Posts
Well depends on what kind of gas you want to use. I have mine at 15 and run 89, at 15 you probaly could use 87. If you go higher you better use 92 octane. Many run 17. I just opted for 15 since my car rarely does much more than spirited driving, highway crusing, and I dont feel I need the shot in the pocket for 93. So Ive always put 89 in mine so kept it that way. My timing was orignaly around 13 according to Eric, and that made driveability horrible. I would floor it and it would be like a carberator loading up with fuel or something, then it would take off a second or two later. 15 degrees fixed that totaly. So its up to you and what kind of driving you do.

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Thats my opinion and I could be wrong

93 classic
Aztec Red, Automatic, POP, STB, OEC battery tie down, AD22VF's, Pirelli P4000's

 
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This is going to sound like a stupid question, but do America use the same fuel octane rating system as over here in the UK?

The reason I ask is because from what I can gather, the "standard" petrol over in the US is 89 octane, and the "performance" petrol is 92 octane.

Over here in the UK, the "standard" petrol is 95 octane, and the "performance" petrol is either 97 or 98 octane.

I believe that there are two different octane scales in use - RON and MON. The UK use the RON scale.

I just wanted to make sure before I up the timing on my car to 17 or 18 degrees (on 95 octane fuel) as I don't want the thing to detonate and die a slow horrid death on me...
 

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pwnd
Joined
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3,455 Posts
Well general rule of thumb, if you go past 15 use the highest octane. We do have different scales, ours will be lower than what yours is. I just use midgrade cause I have always done it, figure I better treat this car better than my old one. People run 17 and more and run midgrade, but IMHO thats just taking the life of your engine in your own hands. Stock is 13-15, so going to the highside of 15 should be safe with low grade, possibly get away with 16 on low grade but i would go to midgrade myself. Past stock timing you run the risk of detonation in the 4500-5500 rpm range I think. Something like that and the upper end could do it....probaly just talking out of my ass tho.
 
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Right, thanks for that. That has probably just saved me a detonating, and therefore soon to be sick, engine...

If I'm correct, detonation will stick out like a sore thumb on a dyno won't it? Maybe I'll take the car to somewhere that has a dyno and get them to do the timing instead... a little extra money, but probably worth it if it saves me having to shell out for a new engine in 6 months time.
 
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