Ok my question is this.. when boost is raised when do you need more octane to compesate?

couldnt you add a larger intercooler or a intercooler sprayer to keep temps down so you dont need higher octane?

or is it a set pressure you should use higher octane fuel.

pretty much is it boost dependant or heat dependant for use of higher octane fuels?

hope this makes sense!

 

if its temperature dependant.. at what air temp going into your motor should you want more than 93 octane of fuel?

 

well it is temp but also how much pressure, basic rule of thumb is over 18psi need higher octane gas, some people run up to 22psi but they are over the edge.

If you want to run higher boost and not increase the octane is run a water/meth injection, the meth increases the octane some.

 

yeah i heard that but i also heard that the meth water inejction can hurt your overall power numbers too..

 

if you really want to split haris, it's completely dependent on what octane you are starting with, your intercooler setup, EGT's, etc. Ask 5 good tuners they'll give you 5 different answers.

 

yeah i understand i was pretty much just askin a rule of thumb on it if there is one.. so i can have a half way guess what im allowed to do with pump 93 octane? and how to make the most of it without going race fuel.. or meth water injection.

 

This is so true, there are many ways to skin a cat

 

I'll throw some numbers out there... from what I can see, most people with a medium sized single turbo (60-1, GT35, etc) won't go over say 14-15psi, and probably 13-17 degrees of leading advance with 8-12 split. That's on 93, AFR's between 11-11.5 at full boost. This is without any other type of water/meth injection.

 

understood.. so if i run over 14 on the stock twins i should then be lookin at higher octane or water/meth injection huh?