91-93 octane when at lower altitude

[reconbygod12]

so i was wondering on this..i leave colorado in less then 8 months and my car is tuned for 91oct... no tuner in colorado can tune my car for 93.... only e85, which ive never heard of a mazdaspeed doing...but what my point is how bad will it effect my engine if i go from 91-93 without the proper tuning when i return to sea level and find a solid tuner back home which their isnt to many...i do have my ap, but with my car it seems to make my car run wicked lean with it..so any advice would be amazing

[chickenwafer]

You're increasing the octane rating by 2 points. If anything this will give you a SAFER tune. I've always said, an engine runs BEST on the lowest octane fuel it can safely burn.

But an increase of 2 octane points isn't significant enough you'll notice a difference, or will even really require a re-tune unless you want to squeeze every last once of performance out of your car.

[tbot]

The lower octane rating w have here is because of the altitude. Going back to sea level and using 93 is essentially the same thing.

[RichB]

Agreed. You basically have a sea level 93 octane tune already.