Of course most modern vehicles, (if not all of them) would have 2 timing tables, Hi and Lo, it's needed for people who think is good to pump 85 octane at 7000ft elevatation and swear by internet stories of the air been less dense at elevation and having less air in the cylinder means you can run less octane. While this portion is true, this stories never talk about the fact that you can run more timing with less cyl airmass because the engine is not operating at full efficiency at higher elevations.
If the manufacturers left the timing static, like they did back in the 70's where timing was vaccum advanced 4-5* from startup to part throttle, and mechanically advanced at WOT, but no retarded based on bag gas, or 85 octane gas, then moving to Colorado and using 85 would probably work good depending on how much static timing was set in the distributor, most engines ran what, 18* timing when not using WOT ? now days, manufacturers can use an engine more efficiently increasing timing where the engine is less efficient, and will in fact increase the timing, the higher the elevation is, making this 85 octane theories useless.
If they wanted you to run 85 octane in Colorado, they'll do put a big sticker in red in the first page of the manual, and advertise how their 6.0 cars can run with ****ty 85 octane, Lol, do your engine a favor and run the highest octane you can, This cars are not Honda Civics, you paid for a 6.0L or 6.2L engine, the 6.0L runs 10:4 compression, and the 6.2 is bigger than the 6.0, why in the heck you want to run 87 octane in it ?Luckily for you, the factory timing/KR removal strategy allows you to run 85, "somewhat safely", and "somewhat optimally", at 7000ft, but not because the car was tuned for the lower octane gas.
Now, if you really wanted to take a look at some engine vitals, log Knock retard and knock learn factor, the last tells the pcm the % of the timing it should use from the Lo octane table, to make the engine operates at safer power levels with the most ****ty gas you can pump, to a point of course.
2012 Mustang GT, M6, 3.73's, Base/Brembo Package
3" H Pipe/Stock cats, Res!/3" pipes, Magnaflow 14419's AB, UPR Catch Can
HPTuners Pro v2.25 | Street Tuned
2010 Silverado 1500 LT Crew 5.3L
Magnaflow 14619, K&N Drop Filter, Airraid MIT, UPR Catch Can, American Outlaw Deputy 17x9, BFG 285/70/17 TKO, Bilstein 5100's
Hptuners 2.24 Pro / Street Tuned
Last edited by bluegoat06; 12-09-2012 at 10:03 PM.