Can anyone help me with information in this regard. I live in Calgary which is fairly high altitude (sorry, don't have exact numbers).

I'm assuming the higher you are the worse your car performs due to a decrease in oxygen content of the air, but how significant is this? Could it make a 2 second differance in your 0-60mph time?

 

I have heard 3% of your engine power per 1000 ft. I live in Denver at 5280 ft and can feel a huge difference from California at 200 ft.

Mark

 

Altitude plays a very big role.

One time, I was crossing the applachaian mountains over Pennsylvanis, I was about 3000-4000 ft above sea level, and my maxima felt like an altima!

I AM NEVER GONNA LIVE IN COLORADO! Or any other place with high altitude. I believe a 2 second difference in 0-60 is very possible.

 

The higher up you are, the less air pressure there is. The smaller the air pressure, the worse it is for a combustion engine. It can make a significant difference if you race at sea-level versus racing in colorado or something.

 

Hmm.. the higher up you are, the less gravity (I kid you, the difference is negligable, and the atmospheric pressure is much more important for a combustion engine)... I don't know nearly enough about how combustion engines work to give you any exact numbers, but in my opinion, 2 seconds sounds a little extreme..

As for racing someone in Colorado, I would assume that the relative results would be the same.. (ie.. the car that wins at sea level woudl still win, cuz the drop in atmospheric pressure should affect your opponents engine roughly the same amount that it affects yours)...

Now a race against an electric/hybrid car on the other hand. . .


-Tom Z.

 

Also noticed huge difference in performance from Dallas where I bought the car, to Denver where I live.

 

Altitude is another reason why I want that damn SC!

Mark

 

If that's true then a stock Maxima should have about 190hp at around 5000 feet altitude.

I'm wondering if this accounts for why my car feels slower than I thought it should be (which I have somewhat verified by highly unscientific stopwatch measurements).

If I get the car dyno'd, would the altitude have an effect on that too or is that somehow compensated for?

 

Yeah that's what I came up with also. That's not even to the wheels. Time for the Y-pipe and S/C. Damn Warranty

 

Yeah, but like tomz17 said above, everyone else in Denver should have the same reduction in horsepower due to altitude so, relatively speaking, it doesn't effect your place on the power hierarchy.

 

Yup... but now here's the thing.... I would assume that Nissan tuned the engine to run optimally at atmospheric pressures closer to sea level... Therefore, if you were able to mess with your ECU, I'm sure you might be able to squeeze out considerably more HP for your given conditions... Like the piggyback ECU site says, cars are tuned for the "lowest common denominator" of situations.. (so that they work, even in more extreme conditions).

Therefore, I blindly assume there's lots of room to optimize those settings based on your particular driving conditions...


-Tom Z.

 

You cannot reprogram the ecu to compensate for higher elevation. The problem is the physical amount of oxygen in the air. The higher you go up, the less oxygen there is.
simple as that.

The only real solution is the supercharger.

Rembember, NOS works by introducing more oxygen to the combustion chamber. Most people have this image of KaBoom!!! NITRO !!Wham Bam!!
but in reality,
The nitro doesn't do anything. It is the oxygen molecules that are attached to the nitro that are responsible for added power.

 

Yep, less pressure at higher altitude that does the opposite of a supercharger. I lived in CO and the air pressure was 11lb/in^2 (PSI). At sea level it is 14lb/in^2 (or PSI). (Temperature also changes these numbers but not nearly as much) A supercharger running at 3PSI of boost is needed to have the same performance as running at sealevel.
Some cars sold in CO has a "high altitude" package. I don't know if this was a different ECU or another dealer scam.

 

I think NOS will be better option of low O2 concentration environment. SC just packs outside air crazy.

 

The situation is similar to combustible engines in airplanes for which I am familiar. As altitude increases air density decreases, making poor engine performance due to too much fuel in less dense air. In airplanes we compensate by leaning out the fuel mixture, i.e., sending less fuel to the engine via a control designed for this purpose, re-creating the right proportion of air to fuel. To the degree that this cannot be done in a Maxima, you’re stuck with poor engine performance.

 

Yeah Tell me about. After driving my car at almost sea level, up here it's seems like driving at 75%.

 

I wonder what my car would feel like at sea level...
7000+ ft here in Colorado Springs-I might just be the slowest one on the board

V

 

Yaay!
I don't Lurk anymore!!!
khmm,sorry.....

V

 

Since altitude directly coorelates to barometric pressure, dyno runs made on a DynoJet have already been corrected for altitude differences. That little "CF" number on the dyno runs is a correction factor which is applied to the raw data to adjust your dyno run back to standard conditions of 60F and 0'elevation.

BTW, you can check out the following site to see exactly how much HP change there is due to altitude and temperature.

http://members.home.net/rabeveridge/html/about_hc2.html

I just put in 222hp at sea level and had it calculate hp at 5000' elevation. Guess what??? It's only 185hp at that altitude!!! This is why your Max seems so friggin' slow.

Also, just a side note: I was playing with some numbers and basically dropping the temperature 20F and decreasing the altitude by 1000ft you'd gain a free Y-pipe upgrade!!! Man you guys in Colorado must feel like you added a SC when you go back down to sea level!

 

Yes internal combustion engines in planes DO work that way, but the problem is, it's just to keep from fouling the plugs and for better fuel consumption. Even by leaning the mixture, you still lose just as much power becuase you are not burning anymore fuel. Fuel + O2 in large amount makes power, if you are missing a considerable amount of either of these, you lose power. That's why a single engine piston aircraft has a VERY hard timing climbing to it's service ceiling....massive loss of HPs.

The only way to compensate is forced induction or NOS.

 

Excellent link, thank you very much. Calgary is at 3440 feet giving me a rating of 200hp. I still don't feel that fully accounts for my lack of power, but I'm hoping that changing my brand of gasoline may help. If problems persist I'll get it dyno'd sometime.