Web www.M3Forum.net

View Full Version : 20% power gain?


VailM3
Sun, Jan-30-2005, 02:19:29 AM
Finally moving from the mountains 7000+ feet down to Texas. (Dallas) Due to the change in air density I should have a 19-20% power increase since NA engine lose close to 3% power per 1000ft.

Mendoan
Sun, Jan-30-2005, 02:57:12 AM
I think it is not an increase but getting back of what has been decreased...
I dont know...I am confused too :)

Mash3
Sun, Jan-30-2005, 03:13:27 AM
I wouldn't worry about the numbers too much. Just enjoy the extra power you now have. I've run the drags up in Palmdale (3500 ft.) and it felt like driving under water it was sooo sloooww (best of 13.84 @ 100.??mph up ther in the mtns).

I've driven to Denver and really felt the power sap you've lived with as I came over the pass on I-70.

GHOSTRIDER
Sun, Jan-30-2005, 03:18:05 AM
Welcome to Dallas VailM3! Please let us know when you get settled in and come join us for a get together.

flybigjet
Sun, Jan-30-2005, 04:54:05 AM
I've driven to Denver and really felt the power sap you've lived with as I came over the pass on I-70.

Yup. Pretty much works that way with your lungs, too. I got educated the first time I tried carrying furniture up a flight of stairs when I moved to Denver (pant, pant, pant). Taking lowland friends up to the top of the chair at Copper or Winter Park (about 10,000') is always a fun experience.

Although not quite as fun as skiing their ass off. There's a reason that the Olympic teams train in Colorado! R.

whitee46m3
Sun, Jan-30-2005, 05:38:05 AM
U will definetely gained the power lost back....i had the same issue, was living in Vegas which is about 2000 ft elevation and once i moved to Bay Area I hardly used Sports which I had to turn it on every time I drive back in Vegas!!!

Blackspeed
Sun, Jan-30-2005, 07:54:26 AM
It's more like 4-5% per every 1000 feet for NA cars 1.5-2% for FI. A good example is a friend of mines 360 Modena with Tubi and some custom exhaust work losing to a stock EVO in a straight drag in Boulder.
http://forums.evolutionm.net/showthread.php?s=&threadid=69370&highlight=360+modena

Altitude is a *****!!!

Rob's Archive
Sun, Jan-30-2005, 02:31:19 PM
Dallas is still in the 1000 ft range but yes you will regain a good chunk of power due to the decrease in density alititude.

Teso
Sun, Jan-30-2005, 02:44:36 PM
Here's a good example for you. The altitude where I live is ~ 8,800 ft and with the S/C I boost at 5.0 psi, but when I drive down to sea level, my boost increments to 6.5 psi.

withaJ
Mon, Jan-31-2005, 01:38:07 AM
It's not just the altitude, but the temperature plays a big part, too. A 10-ded F hotter change in temperature reduces air density almost as much as 1000-ft increase in altitude...about 1.5-2.5% depending on where you start.

Mash3, were you driving in Palmdale in the summertime?


Anyway, all else being equal, the air at 1000ft is about 16% more dense that at 7000 ft. At 1000 ft, the air is at about 97% of its sea level density compared to 81% at 7000 ft.

--yeah, I'm a geek. :)

VailM3
Wed, Feb-02-2005, 11:12:29 PM
Welcome to Dallas VailM3! Please let us know when you get settled in and come join us for a get together.


Finally got into Dallas, almost settled in. All I have to say is that I have missed a good chunk of this cars power. Its night and day from Vail to Dallas. As for GtG, cant wait, too bad i missed the big one this last Sat then again the weather has been far from amazingto say the least but hec its warm to me. Maybe i can make my tires chirp for once down here.

Mike00
Thu, Feb-03-2005, 12:17:45 AM
You clowns need to just stop guessing and do the math. :soapbox:


All things being equal, going from 7000ft to 1000ft will yield a 24.8% recapture of his HP.


http://www.csgnetwork.com/relhumhpcalc.html

Enter Current Air Temperature (OAT) Degrees F 75
Enter Ambient Barometric Pressure Inches Hg 29.95
Enter Ambient Relative Humidity % 35
Enter Physical Or Pressure Altitude Feet 7000


Calculated Relative Horsepower To Rated % 75.2 :thumbsup:
Calculated Dynamometer Correction Factor 1.330
Calculated Air Pressure Inches Hg 23.11
Calculated Vapor Pressure Inches Hg 0.306


**EDIT: Mods, make this calculator a sticky, it will save us from another 500 threads about the altitude, the weather, why does my car pull so hard in the winter, my tires are chirping and its -10deg outside, my car sucks in the summer, etc... and give me 100 reputation points while your at it. kk thx.