Okay, so my new engine has "increased" compression over a stock, let's say GT40P engine. Stock spec I could find was 9.1:1. How much more? I'm not sure, but both the pistons and head milling are altered vs. stock. Let's say it's 9.5:1 for a guess.

At what point do I want to start running increased octane fuel? The only chart I could find that didn't relate to boost or have numbers that seemed to be way off said that you want 89 octane at 9.0:1. I don't know what you guys do, but I never ran 89 in my old stock engine (but admittedly it never ran very well--there was a number of reason for that I'm sure though). But that same chart said you want 93 octane at 10:1. So, if I were to run 91 in mine, that would sound about right? Or not? I really know NOTHING about this stuff.

Then that brings us to setting timing. Do I do that differently given the different octane and compression?

Thanks