Ooops! Typo. High octane fuel burns slower than low octane fuel. Thanks 420...too much "high, low...this that" discussion. Should have proof read better. That should also answer your second question.
Your third question: If the car is set up properly, ignition already should be occuring at TDC. Using too low an Octane will cause early ignition. So if ignition is already at TDC, then there is no benefit with using higher octane.
Keep in mind that there are many variables that affect pressure in the cyclinder. Not the least of which are atmospheric conditions. We have no control over things like humidy, temp, and altitude. As a result, engine computers are really quite sophisticated in order to take into account all of these factors.
There are instances when you are getting early ignition due to these factors as well as high engine load (full throttle, up hill, towing, ...) when using the recomended octane rating. This is what causes ping. In these cases, going to a higher octane fuel helps address this problem in the EXACT way that you described in your post.
I have an '02 Suburban. When I am towing my boat on a long trip, I always go with 89 octane instead of 87. If I don't, I get a small amount of ping when going up hills and we have a lot of them in Eastern PA.
Please, there are no stupid questions. If I don't know the answer, I know where to find them.
Blake
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