93 octane vs 91 at altitude

[zbc1969]

so in Utah and other higher altitude places there is no place to buy 93 octane. Something to do with the thinner air compensating for the lower octane. So my question is am I ok to run map 2 on 91 octane being at 4,200 ft elevation

 

[Michael Hespe]

I'm at 5600'-6700' and run map 2 with 91. Over 6000 miles with no issues so far. Do you have access to E85?

 

[zbc1969]

I do but I'm nervous to run it because I know of a guy that ruined his motor running e 85 and a jb4. I don't know the details on it though

 

[Ahawk1968]

I'm at 4000 ft. No trouble with map 2 on 91 octane here. Im also fine running map 3 or 5 with four gallons of E85 to a full tank of 91.

 

[Toddasaurus]

My guess is that you'd be just fine using 91 octane in that elevation. It seems many people are running Map 2 on 91 octane in California, at or close to sea level.

I've used 92 octane pump gas in my area, which is essentially sea level, on Map 2 and it turned out okay, but when it was really hot I could see the ECU pulling a little bit of timing - no knock or anything dangerous though. Right now I'm using Map 6 with some custom boost settings that sit between Maps 1 and 2, seems to be running really well.

The G70/Stinger ECU's are really smart, and able to keep the engine nice and safe even with the JB4 skewing sensor inputs. That said, if you're concerned, put it in Map 2 and log a few pulls and post it either here, or on the N54Tech forum for Terry and others to take a look at. Personally, I put it in third at around 1500 RPM, then floor it (up to the kickdown switch, so it doesn't auto downshift) and drive all the way up to the redline, completely pushing passed the kickdown switch after about 3750 rpm so it's totally floored. This way you get some good resolution across almost the entire rev range so you can validate ignition timing, boost levels, and AFR's.

Either way, let us know how it goes.