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.
Thats my opinion and I could be wrong
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.
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.