Revving at high altitudes


#1

I have a 2008 Subaru Foreser that I bought used. It has 37,000 miles on it. When I drive at high altitudes, the rpms rev up, the car slows down, sounds terrible. Why is this and what can be done?


#2

How high? At high altitude the engine can’t put out a lot of power, so you’ll push the gas, causing it to downshift and rev. Any warning lights? Is the air filter clean/new?


#3

The higher you go, the more the engine has to work to do anything. It’ll happen to any vehicle. A few years back going up the Pikes Peak road in a V8 van, the thing just crawled when I got near the summit. If you’re really upset about it, you can install forced induction (turbo/supercharger) which will give you power in the mountains, but at the cost of longevity and reliability. Boost is not cheap to own.


#4

You bought a Subaru, and are just now complaining about it being slow, and sounding terrible? That’s a good one.

Trade your Forester in for something better, is the best advice I can give you.

For every 1k feet in altitude you go up, your engine loses about 4% of its horsepower.

So, if you are sea level with a 170 hp Forester, and you drive to Denver (~5k feet), you then have a 136 hp Forester. If you then decide to drive up to Crested Butte (~9k feet), you then have a 109 hp Forester.

So, at altitude, because your engine has way less power, you have to rev it much higher to get to that little bit of power, and it sounds terrible, because Subaru Foresters are just not very good sounding cars.

You want a car that sounds good, and is an SUV, get yourself a Porsche Cayenne Turbo. Lots more power, turbocharged to not lose power at altitude, and sounds WAY better.

BC.