Does anybody have ageneral idea of what jetting changes should be made when switching from 110 oct. to 91 oct. I have an 02 800 setup to run 91 octane but i noticed it has a hard to read wash pattern and tuning is pretty well limited to plug reading which is not my first choice. I realized that w 110 octane it produced a very pronounced easy to read wash pattern( partially due to the color it left on piston domes). SO if an engine is jetted using 110 octane how much would u need to jet up when running premium. I was guessing about 3 sizes. Anyone have experience with this?

What kind of race fuel and did you do any head changes to accomodate for lower octane or is it stock? Not exactly sure as to what you are trying to do.

What kind of race fuel and did you do any head changes to accomodate for lower octane or is it stock? Not exactly sure as to what you are trying to do.
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I use sunoco standard(110)I have a different head than factory but it only requires 91 octane. I just found that by using the race gas it creates a good wash pattern that u could actually jet to. So if it was jetted using the race gas how much jet size increase when switching to 91 octane?