Modifications to run at High Altitude
Thread Starter
JK Enthusiast
Joined: Feb 2010
Posts: 394
Likes: 3
From: San Jose, Ca
I've had the JK over 8000 feet several times. Apart from reduced power, everything worked fine. The power loss is due to reduced oxygen because of lower atmospheric pressure. It will run a little rich (or they used to before computers) but it doesn't hurt anything.
When you get to high altitude country, you will probably notice that "regular" gas is only 85 octane. As Ron said: "The higher the altitude, the lower the octane you can run."
When you get to high altitude country, you will probably notice that "regular" gas is only 85 octane. As Ron said: "The higher the altitude, the lower the octane you can run."
JK Junkie
Joined: Jun 2007
Posts: 2,467
Likes: 1
From: 4 Corners
I've tried'em all and think the 87 octane setting works the best up here. I keep 87-88 octane in the tank. That seems to give me the best performance with my Jeep. Be sure to use the crawl setting while on the trails, it's great.
JK Jedi
Joined: Dec 2011
Posts: 5,234
Likes: 4
From: Nevada City California
When I was in Moab this year, I tried the 85 octane gas. I did notice the decrease in performance and switched back to the 87 octane which seemed to give more power. Interesting on the 91 octane, I was thinking about running the 91 octane tune but it sounds like it might not make a difference for the added expense.
JK Enthusiast
Joined: Jan 2010
Posts: 157
Likes: 0
From: Centennial, CO
I regularly wheel and camp at 12k feet+ and live at 5700 ft. I spend the extra to fill with 91 octane and run the 93 tune. As previously pointed out, 91 one is like 93 at altitude. I have found this gives me optimum power here. I am using a TrailDash but ran a standard SuperChips unit previously also with 93 tune.
JK Freak
Joined: Feb 2012
Posts: 748
Likes: 1
From: Colorado Springs, CO
I regularly wheel and camp at 12k feet+ and live at 5700 ft. I spend the extra to fill with 91 octane and run the 93 tune. As previously pointed out, 91 one is like 93 at altitude. I have found this gives me optimum power here. I am using a TrailDash but ran a standard SuperChips unit previously also with 93 tune.
JK Freak
Joined: Jun 2011
Posts: 780
Likes: 0
From: Native to Los Angeles, but migrated to Denver.
I have been running the 87 tune with 85 oct and haven't had any issues. I tried the 91 tune with 91 oct and the only thing I saw was money being wasted. In fact... I lost 1.4 MPG's compared to the 87 tune with 85 oct. I drove the same streets, the same way every day.
I haven't tried the 87 tune with the 87 oct yet... I might just to see what the differences are, but I doubt there will be any.
I haven't tried the 87 tune with the 87 oct yet... I might just to see what the differences are, but I doubt there will be any.