[SROC3]

Does this help any? I put 2 gallons in my car today and gunned it around.....runs smoother? or am I imagining this? Does the stock computer adjust automatically? Some say yes and some say no.....I figured in this area of the forum I would get a more directed answer.

[SoCal335i]

Originally Posted by SROC3

Does this help any? I put 2 gallons in my car today and gunned it around.....runs smoother? or am I imagining this? Does the stock computer adjust automatically? Some say yes and some say no.....I figured in this area of the forum I would get a more directed answer.

You'll always get more power from better octane! Even stock.

[Railgun]

Not if you're tuned for 93. Gains, if any will be marginal at best and any feeling of more power will most likely be a placebo effect.

[scalbert]

It depends on what the timing limit is. I suspect that in the summer you would benefit more from higher octane than in the winter. In cooler weather the car can run more timing on a given octane. But at some point there will be a maximum amount of timing the ECU will allow.

For instance, assume 25 degrees timing was the maximum and you could hit that on 93 octane in 20 degree weather without knock. At this point higher octane fuels will provide no benefit. In fact, the lower BTU content could cause a power reduction. Now, in 100 weather on 93 octane the best you manage is getting to 20 degrees timing before inducing knock. Add some 100 octane during the summer and you may get back to hitting that 25 degree maximum timing limit.

This is just an analogy and the numbers are not correct but possibly not too far off. It should also be noted that even if the advance was the same at 25 degrees, the vehicle in the 20 degree F temps would still be pulling faster even though it is on lower octane.

[SROC3]

interesting answers. Definitely better insight. thanks guys!!!!!

[Ryan(e92)]

U live in Cali so adding 100 octane to our 91 octane is beneficial. I wouldnt add more than 4 gallons a tank tho.