wont make much of a dif but it will make a dif. all i can say is get more power mods and get your car re-tuned as soon as you get there haha

 

It depends on how far up you go. There's a map in the ecu that starts to cut boost as you go up in altitude. I live in Denver and it's about a 20 hp difference. You'll notice about a 3-4 lb decrease in boost. You can either get a boost controller or I can fix it with a reflash.

 

Im moving to Colorado Springs/Ft.Carson area. But whats a reflash??

 

Power output is proportional to the number of air molecules that you can force or suck into the combustion chamber. Since the air density in Colorado Springs (~6000 ft) is about 20% lower than at sea level, an aspo engine will lose 20% in power. You will be down 30-40% on the higher passes (11,000-12,000ft). A turbo will compensate some since it will spin faster in the thinner air. However, the complex engine management in most modern turbo cars can play tricks. I'm not expert on the WRX engine management; maybe T_rex can help. By reflash he means re-programming the flash memory in your ECU. Cobb Stage 1 will almost compensate at 6000ft. Stage 2 will give you ~sea level performance steaming up Loveland Pass. A good custom tuner can optimize the ECU map for your mods and elevation. Welcome to town!

 

Bingo, +1.
The oxygen density drops as you go up in elevation, remember the "A" in A/F is actually oxygen.
On average here in ABQ ( 5300ft ) we get a -0.5 second compensation to our 1/4 mile times ( NA is -1.0 ). Custom tuning is the best way optimize your ride but don't be too bummed when the car feels slower than in WA.
One good thing about going up is that you will run richer at first, waaaay better than running lean. The computer does a decent job at adjusting but definitely keep a low altitude map handy if traveling or moving.

 

I wouldn't call a WRX at any altitude "slow". Plus the good news is that everybody's car slows down at altitude but turbos less so. Some sort of ECU mod is the best way to go (actually the best way to go is to just not worry about it, IMO).

 

Hmmm... this is something I've never really thought about too much. I thought todays modern e.m. compensated pretty well for a/f ratio changes? I remember it used to be a problem w/carb'd cars. I drive from 5500 ft down to 2200 ft. and then back up nearly everyday.

 

Hmmm... this is something I've never really thought about too much. I thought todays modern e.m. compensated pretty well for a/f ratio changes? I remember it used to be a problem w/carb'd cars. I drive from 5500 ft down to 2200 ft. and hen back up nearly everyday.

I am curious on this subject, mainly since by last vehicle chunked 5 pistons due to my poor tuning choices and no active A/F compensation on a trip from ABQ to sea level.
Timber, do you have a wideband or OBD monitor? I would be curious how your A/F looks when you get to the lower altitude.
FWIW my WB should be installed and running by Sunday. I am planning a trip the following week to Las Cruces, 2500ft altitude. I will keep an eye on how quickly the STFT adjust going both directions and report back.

 

Will do. We have the same pee quality 91 octane here in NM as the Cali folks do so that won't influence the test.
One thing that will negate the results is that we have ethanol in our ABQ fuel at this time ( blended 10% from Nov 1st to end of Feb ) where my destination does not. Also another test!

 

... We have Cali gas? News to me. Should I be running the damn Cali map on my AP?

 

Yea. I'm up here in the Ft.Carson/Colorado Springs area, and I'm driving my husband's car [06' Acura Rsx Type-S] and it seems very slow to me. Slower then what it use to. It doesn't have that "kick" it use to.
I'll be driving down my Sti in a couple weeks. I'll be pretty bummed it my baby runs slower...LoL But thank you for all the scientific answers guys!

 

bleh I drove Loveland pass / Denver for a couple months / and drove to Portland. I never really noticed a difference.

 

Got everything installed b4 my trip. The AEM UEGO puts on quite a neat light show!!!
Anywho, the WB stayed right at 15:1 for most/all the trip. After digging into the ECU compensation for air and fuel I found that the corrections are almost instantaneous. The STFT is good for monitoring how much fuel the ECU is adding/pulling at a particular moment in time but not a barometer for actual performance.
The best monitor is the injector duty cycle percentage. Going up/down in elevation would cause a problem only if you were maxed out ( higher than 90% ) on injector pulse at high elevation and could not compensate for the increase in O2 as you drop down towards sea level. Any good tuner worth his/her salt will check the DC and add bigger injectors if above 85%.