Severe Engine Power Loss at Altitude?
02-28-2015, 07:48 AM
#11
I have a formula somewhere. I'll need to look it up. If I recall correctly, the 3.6 at sea level is 285 HP. at 5500' it is somewhere around 240 hp and at 10,000 it's somewhere around 200. I need to confirm, I calculated this about 2 years ago, memory is a little fuzzy.
Last edited by Jeepstin12; 02-28-2015 at 08:00 AM.
02-28-2015, 07:53 AM
#12
02-28-2015, 07:59 AM
#13
Elevation x .03 x HP @Sea level / 1000 = Hp lost Or Elevation x .00003 x HP @ Sea level = HP Lost The 3.6 loses 47 HP at 5500' And it loses 85 HP at 10000' This is a general conversion that will give close approximates for all engines. Nothing is immune from elevation. 
Last edited by Jeepstin12; 02-28-2015 at 10:08 AM.
02-28-2015, 08:05 AM
#14
JK Jedi Master
Your ".0003" in the second formula should be .00003, correct? And the with the 1000', you meant 10,000'?
Last edited by ronjenx; 02-28-2015 at 08:09 AM.
02-28-2015, 10:09 AM
#15
02-28-2015, 10:15 PM
#16
The thin air above 8,000 feet can have a significant effect on your motor's ability to generate power. Last Summer we took our jeep to Ouray and Silverton, CO. We live at about 200 feet above sea level and regularly travel to areas in the 4-5,000 feet above sea level, without issue. At the time we were still running stock size Jeep tires and when we hit areas like California Pass I noticed a very profound drop in power in our Jeep. So much so I began to question our upcoming tire purchase (we were looking at 35'"s, which everyone here at JKF would be, "just fine" with our 3.73 gear set. Maybe at sea level but if I couldn't adequately turn 32"s at 11,000 feet, 35"s were going to be a problem. Not in a hurry to re-gear, we ended up going with 33"s, which so far, are doing fine but I have yet to get the Jeep up above 11,000 feet like last Summer.
03-01-2015, 06:40 AM
#17
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I was not debating a loss of horsepower at altitude. My drag bike can't pull nearly the dyno numbers around here as it does near sea level. I was just saying when not loaded down, my basically stock (3.6L, 6-speed) JKUR has no problem maintaining the speed limit or greater up any mountain. Which in this area amounts to around 10,000 ft. Now you load that pig down with gear and it's a different story.
03-01-2015, 02:43 PM
#18
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OP are you talking about pulling grades at 6000 feet or level ground at 6000ft? What size tires are you running and what gears are you running in the diffs? The 3.8 will never throw you back in your seat but you shouldnt be struggling that bad if you are set up correctly.
03-01-2015, 02:49 PM
#19
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I was not debating a loss of horsepower at altitude. My drag bike can't pull nearly the dyno numbers around here as it does near sea level. I was just saying when not loaded down, my basically stock (3.6L, 6-speed) JKUR has no problem maintaining the speed limit or greater up any mountain. Which in this area amounts to around 10,000 ft. Now you load that pig down with gear and it's a different story.
03-03-2015, 06:09 AM
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I am not talking about my daily commute which is a 4,000 ft elevation change. I have been through the sierra's and cascades and have always been able to maintain atleast the speed limit on paved roads. Maybe because I started with 80 more HP then you and have a 6 speed.