octane question

[zpactfc]

Saw the best gas thread. Never thought about the gas problem before. After some research, I found out this thread is very interesting.

However, can someone tell me, is octane important?

I usually use Shell or Shevon #91. I guess I need use something better?

http://www.nagtroc.org/forums/index....-the-bay-area/

http://www.nagtroc.org/forums/index....3845&hl=octane

http://forums.rennlist.com/rennforum...-bay-area.html

[LarThaL]

Originally Posted by zpactfc

Saw the best gas thread. Never thought about the gas problem before. After some research, I found out this thread is very interesting.

However, can someone tell me, is octane important?

I usually use Shell or Shevon #91. I guess I need use something better?

http://www.nagtroc.org/forums/index....-the-bay-area/

http://www.nagtroc.org/forums/index....3845&hl=octane

http://forums.rennlist.com/rennforum...-bay-area.html

From what I have heard, the S65 motor will advance timing up to about 94-95 octane, other input variables being favorable. I can tell you with reasonable certainty that the motor will not produce the rated 414hp running 91 octane when it is 90 degrees outside, for example.

[burnsniper]

The octane rating is simply a measurement of the gasoline's resistance to detonation under compression. Thus a higher octane rating allows a car to safely be designed with a higher the engine compression ratio (or boost in forced induction applications). Higher compression (or higher boost) equates to more power as more oxygen molecules are present during combustion.

Since higher octane gas takes more energy to combust, using a higher octane gas than your car is designed for reduces power. Conversely, using a lower octane gas than your car is designed for increases the chance of compression induced detonation (knock) and thus most modern cars will retard timing to compensate. This in turn also results in less power.