I run 11.5:1 with 92-93 octane, always have, no issues, at sea level. I run lower octane at high altitude of course.
Stock cmopression is 9.7:1 and the manual recommends 92 octane or higher, but we've all been schooled lately that 89 octane produces more hp with no issues.
So what is lowest ocatne for 12.5:1 at seas level?

 

Hightower-I too am in the process of trying to figure out the lowest possible and safe octane level that i can run in my 690 raptor which is 11:1 and i have found very different opinions on this subject.I ran 92 pump premium in my previous raptor motor with a 11:1 compression level with no problems and in fact i noticed decreased performance when i used 110 or a mix so i am probably going to try 92 pump gas with a slight mix of 1 gallon of 110 to four gallons of 92 to try and obtain the most power possible .Sorry to jump in on your post with my situation but i am also confused on this issue and hopefully we can get some expert opinions on this.

 

everybody running 14:1 runs 110 octane, and I've heard that even the new 16:1 that is available runs 110 octane - is that true? cause if 110 is cool for 16:1, then it may not necesary for 14:1. and if that's the case, that's part of my questioning...

 

I think Gottfried at Pami told me 95 for the 12.5:1. I've run VP110 but, lately have tried some of the exotic fuel but, only at altitude.

On the Raptor's from what I understand, the compression for them is typically higher than what is stated on the piston since Trinity would typically take some material out of the head??? So, an 11:1 piston you order that says 10.75:1 is actually higher than 10.75:1???

 

I tried half 110/93 which should be 101.5 when we were at Silver Lake last September and it sounded like a diesel. I cleaned up the combustion chamber for hot spots when I installed the 12.5:1 piston and cams too. I run at least straight 110. I had heard before that at least 100 octane but I wont try it anymore.