horsepower loss vs. elevation

Maybe somebody can offer so insight on the power loss vs elevation experience that I seem to notice more in my Nissan trucks than some of the other ones I own/owed.

First off I live near sea level so I maybe spoiled but often times visit, drive, and wheel up in the mountains from 5k to 9k.

Seems like I lose a larger amount of power with either my 90’ pathfinder or Xterra than say my 94’ Land cruiser 80, 73’ FJ 40, or pervious ’84 Toyota short bed. Yeah I know all about the aftermarket air intakes & exhausts but was wondering if anybody has any specific higher elevation performance recommendations, tips, or things to check for?

I’ve run larger tires on all the trucks and regarded the X and short bed to match the stock ratio. The Nissans are fine on the highway in general and climb grades adequately but I would like to get better higher elevation performance.

Thanxs
Brian

Most drag strips I've been to will list the DA on your time slips. English Town NJ, for example has a very low DA (0-100)which leads to faster times. Colorado on the other hand has a DA of around 5000 which will cause a 12 second car in NJ, to be lucky to see high 13's.

The near sea level air is much more dense and has a higher concentration of oxygen. This leads to better combustion and more power. The higher you go the worse it gets. From what I hear, forced induction vechiles aren't affected as bad as NA ones.

I think that we lose aprroximately 5psi up here on the forced induction stuff.

to truly answer your question: I ahve absolutely no idea why the nissans would lose mroe power than the others. it seems to me that the difference may be FI versus carburetion.