Race fuels vs octane & AFR

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   I've been reading much about how higher octane fuels cause a drop in performance because of the slower burn rate of the fuel. In my part of the world the lowest octane pump fuel available is 95 octane...already much higher than the recommended octane in your parts.  Race fuels available is the 24/7 race fuels. 102 unleaded mildly oxygenated and 109 unleadedhighly oxygenated.  Oxygen content is 3,6 and 3,8. Since our pump gas is slow burning already i keep entertaining the thought of the oxygenated race fuel...the oxygenates in the fuel should make it a better fuel than our 95 pump gas in my mind...am I wrong?

Was also wondering, how does AFR relates to octane.  If you get a best performance on 87 octane running say a 13,1 AFR...then running 95 octane would mean that 13,1 AFR would be useless, would i not want an AFR with an higher air ratio with the higher octane fuel?
Similarly...if my best performance come from say a given AFR of 13,1 on pump gas...will it be 13,1 for oxygenated race fuels too or will it become something like a 12,8.

Was just thinking, if AFR is octane sensitive then the Brock's maps wont do much for us in my part of the world?

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Frederick Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: July/30/2019 Location: RSA Status: Offline Points: 30	Post Options Post Reply Quote Frederick Report Post Thanks(0) Quote Reply Topic: Race fuels vs octane & AFR Posted: October/04/2019 at 7:25am
	I've been reading much about how higher octane fuels cause a drop in performance because of the slower burn rate of the fuel. In my part of the world the lowest octane pump fuel available is 95 octane...already much higher than the recommended octane in your parts. Race fuels available is the 24/7 race fuels. 102 unleaded mildly oxygenated and 109 unleadedhighly oxygenated. Oxygen content is 3,6 and 3,8. Since our pump gas is slow burning already i keep entertaining the thought of the oxygenated race fuel...the oxygenates in the fuel should make it a better fuel than our 95 pump gas in my mind...am I wrong? Was also wondering, how does AFR relates to octane. If you get a best performance on 87 octane running say a 13,1 AFR...then running 95 octane would mean that 13,1 AFR would be useless, would i not want an AFR with an higher air ratio with the higher octane fuel? Similarly...if my best performance come from say a given AFR of 13,1 on pump gas...will it be 13,1 for oxygenated race fuels too or will it become something like a 12,8. Was just thinking, if AFR is octane sensitive then the Brock's maps wont do much for us in my part of the world?

Steve6 Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Joined: February/01/2013 Location: Ohio Status: Offline Points: 870	Post Options Post Reply Quote Steve6 Report Post Thanks(0) Quote Reply Posted: October/04/2019 at 9:00am
	Frederick, I would stick with the 95. Just remember you are using the RON scale, we use the RON + MON/2. And 95 RON is approximately 91 on our scale, and on the ZX14s we run 89, so that is very close.