i only pump 93, occassionally 94 when i can find it. I don't want the knock sensor to kick in and retard my timing cause that would just mean i wasted $40 to have it advanced in the first place.even if you did get pinging...there is a knock sensor that would retard the timing if that occured so even if you didn't use high octane..
Thank you!pvick said:Ignition timing is the process whereby a voltage is delivered to a spark plug at some predetermined time (in crankshaft degrees) to ignite the fuel/air mix within a cylinder, and begin the burn.
If the mix were to be ignited when the piston reaches the top of its compression stroke (know as Top Dead Center or TDC or zero degrees), a lot of the mix would not complete its burn before the exhaust valve(s) opened to purge the engine and allow the 4-stroke process to begin all over again.
For this reason, its is much more desirable to deliver a voltage to the spark plug BEFORE the piston reaches the top of its stroke (Before Top Dead Center or BTDC or X number of degrees BTDC). This will start the burn while the piston is still compressing the mixture which also results in a multiple compression effect: (1) from mechanical compression (the piston), and (2) from the rapidly expanding and burning gases. Consequently, more of the fuel/air mix will be burned, resulting in more power, better economy, and fewer emissions.
There is a trade-off here. If the spark occurs too soon (too many degrees BTDC), pre-ignition (also called ping) will occur, and in the worse case, detonation which is an explosion instead of a controlled burn in your cylinders... VERY bad for your engine.
Most engine manufacturers call for the timing to be set between 8 and 14 degrees BTDC (obviously varies from company to company). When you advance the time further than the OEM setting, you can generally expect better performance. As long as you don't get carried away, the cost will only be the fact that you will absolutely need to always use high-octane fuel.
Hope this helps.