Brett the other one here (guest)  |
| Fri Aug 13, 2004 6:41 am |
| Re: Here we go AGAIN.... |
Now Ken, I am going to continue to beat the dead horse and here is why.
Running a higher octane fuel in an engine that does not need it will result in less power and more deposits. Why you ask? Because the higher octane fuel has a higher flashpoint so therefore it does not burn as fast. A motor runing less compression using a higher octane fuel will not burn the air/fuel mixture completely resulting in less power and more deposit build up.
Take the same motor and run just enough octane as to not detonate and you will make more power, have better fuel economy and less deposits.
While pondering this, bear in mind that the more compression (which is theoretical in nature) will generate more heat. Using too low of an octane in an engine with higher compression will result in pre-detontation of the air/fuel mixture. This is bad.
Compression (as mentioned previously) is theoretical. What does this mean? There are many variables to take into account regarding "theoretical" compression ratio. One of the biggest factors is overlap in a cam. Take a cam that has a fair degree of overlap and the cylinder pressure will be less than a cam with less overlap. Overlap is the time that the intake and exhaust valves are open at the same moment. Generally a stock cam in a car has very little, if no overlap at all. A race oriented cam has a very good amount of overlap. In order to maintain cylinder pressure, a race motor with a race cam will need a higher compression ratio.
Altitude has an effect on octane rating also. The higher the altitude, the greater the octane needed in general.
This is by far not a complete assessment of octane rating and compression ratio but is meant to provide a high level overview of the process.
Hope this helps!
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Here we go AGAIN.... — Ken, Fri Jun 18, 2004 4:39 am -
Re: Here we go AGAIN.... — Brett the other one here, Fri Aug 13, 2004 6:41 am