ah, you lucky Evo-addicts living at sea-level areas...I am currently visiting the Baltimore/DC area and I brought my Evo from Colorado. I made a few passes with my G-Tech Pro-Comp and the results were devastating I really don't want to go back to the idilic Rockies when I'm done here. On top of that, I can get 93 gas over here (cheaper!) instead of the Colorado only-available **** 91. Check the facts:

_______________________6000 ft. / Sea-level (>>>seconds)

50-75 mph in 3rd gear: ______3.64 / 2.91

50-75 mph in 4th gear: ______4.65 / 3.82

50-75 mph in 5th gear: ______9.45 / 6.05

The turbo spools sooooooooo much faster... I will post some more numbers after I get the "PD" treatment this weekend.



(sorry,no acceleration pulls...too much traffic and plenty of cops around here )

 

I would venture to guess that the air is somewhat less dense at 6000 feet.

 

higher = less air = less 02 = less combustion. sorry friend. on the bright side i've heard training at high altitudes can really make you quite the endurance athlete.

 

I'll be finding out when I move to the Springs in a month or two. I don't think it's possible to be 3 seconds off from 50-75, since the 1/4-mile times (0-110) are no more than a second off, but it definitely does make a difference.

 

How did you conduct this test, from net zero acceleration at 50mph (traveling at 50 for several seconds and stomping) or is 50 -75 mph a section of an allready accelerating car?

The reason I ask is that your times seem unusually fast for an otherwise stock car being about 0.2 seconds faster than mine, and my car is modded more heavily and tuned to it's maximum safe potential.

 

Those are some big differences. Yea, the air is less dense at higher altitudes so you car gets less air.

 

Once you have full boost the power is the same. It is the slow spool and off-boost perfomance that suffers at altitude...

 

Not true. Full boost at altitude is not the same as full boost at sea level. I had my modded car dyno'd in Denver and Philly, the difference in power is substantial. We really didn't even need to dyno as the car was a different animal on the road in Philly as compared to Denver.

 

i had my car in wyoming last time i was here (6300ft), it was slower but not that bad. I was more worried about this **** gasoline

 

I'll have to agree 50%, decrease in combustion at altitude is caused by the amt oxygen per volume of air because the atmospheric psi is less than sea level. At 6000 ft 0 psig = 12.5 psia and at sea level 0 psig = 14.5 psia depending on weather. Thats a 2 psi difference.

So if your at sea level and want to roughly see what you would run at 6000ft, just boost 2 psi lower. There are many different variables like knock at higher psi, humidity, etc, etc, but above is pretty much the bottom line.

However, despite the fact that Efunk is now running 93 octane instead of 91, and that combustion is seeing 2 psi more/unit of O2, his time differences seem to be more than you would think: 9.45 / 6.05

 

I have never ran my EVO at sea level, but I did run my 01 GTI up here and down in Chicago. I was able to lose almost 7 tenths of a second and pick up 6 mph in my trap speed, this was a GT28RS equpped GTI. I must say I am very jealous of you sea level dwellers I don't know if what he is claiming is that drastic, but who knows. My best trap speed up here on my stock turbo with cams, tbe, mbc, walbro, flash, fuel pump and intake was 108. Warrtlon did that almost stock on his MR so........

 

Oh and gas plays a role.

 

My house is at 6500'. Atmospheric pressure is usually under 12psi as opposed to the 14.7 you'd see at sea level. That's an 8% loss in boost pressure at 20psi. The delay in spool is much more noticable as the atmosphere is about 20% thinner.

My car feels slow as hell.

EDIT: and while I'm thinking about it, my gas mileage is significantly worse here than it was in chicago. I could get 24-26 mpg around town on the 93 in illinois. Out here, the best I've seen is 20-22 while _trying_ to maximize mileage. To put it into perspective, my car has stock cams and can only get about 10 in.hg of vacuum at warm idle. Outside of town, there's a parking lot at 11000'. Vacuum drops to 6-8 in.hg there.

d

 

I performed the same tests with my late Mini Cooper S with a Stage-2 (220 bhp) and the car was 0.2-0.3 secs slower in Colorado than when it was stock (163 bhp) at sea level. Believe me, it is that bad. My best friend Carlos brought once his highly modified 02 WRX (now he drives a MR ) and the car was almost one second slower in the 1/4 mile.
Rule of thumb is for each 1000 ft. you go up, your car will loose about 3%

 

Yes, that is exactly the way I did it. I started slow and then I stomped the gas at about 40 mph. There are many cops on this area and I didn't want to take any chances. I made 2 runs on each gear (6 total) and I posted the average of those runs. It was cold though, about 43 degrees, but on my behalf I can say that it was raining (93% humidity) and my tank was 80% full.