Elevation/Horsepower Question
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 944
Likes: 9
From: Southwest CO
Elevation/Horsepower Question
I have read that for every 1000' of elevation gain you lose approximately 3% horsepower. Is that true? Even with the computers and fuel injection in our cars? Does a dyno show that much loss?
Just silly Saturday morning questions.......still too much salt on the road to go for a spin
Just silly Saturday morning questions.......still too much salt on the road to go for a spin
Last edited by b0xm0ns73r; Mar 5, 2011 at 11:45 AM.
Drifting
Joined: Oct 2006
Posts: 1,340
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From: Redmond WA
Yes, that is true, because that is how much air density decreases as you increase altitude. There's practically nothing you can do about it unless you are forced induction, and this is why if you're running a quarter mile on a day with a high DA, you can't make your naturally aspirated car run any faster. A high DA is like going up in altitude.
Team Owner
Joined: Apr 2008
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From: Middle TN by way of KY, OH, VA, IL, CA, FL, NY, SC, HI
And that is why all the old piston driven fighter planes ceilings were limited - by thin air - and why they used superchargers or turbochargers, or both.
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 944
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From: Southwest CO
Thanks for the responses.
I am sitting at 7500'-7600' so 7500/1000=7.5 7.5x3=22.5
So I am basically losing 22.5%....dang.....that is a lot of horsepower.
And if you factor in the 15% or so you lose from flywheel to rear wheels, that is quite a big loss. I am going to have to get out of these mountains
I am sitting at 7500'-7600' so 7500/1000=7.5 7.5x3=22.5
So I am basically losing 22.5%....dang.....that is a lot of horsepower.
And if you factor in the 15% or so you lose from flywheel to rear wheels, that is quite a big loss. I am going to have to get out of these mountains
Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 944
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From: Southwest CO
I know the air here at 7500' is a lot thinner than the air in the South where I grew up. There it was very thick feeling(and really humid). The summers here are so much nicer.
Le Mans Master
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From: Greater Detroit Metro MI, when I'm not travelling.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Thanks for the responses.
I am sitting at 7500'-7600' so 7500/1000=7.5 7.5x3=22.5
So I am basically losing 22.5%....dang.....that is a lot of horsepower.
And if you factor in the 15% or so you lose from flywheel to rear wheels, that is quite a big loss. I am going to have to get out of these mountains
I am sitting at 7500'-7600' so 7500/1000=7.5 7.5x3=22.5
So I am basically losing 22.5%....dang.....that is a lot of horsepower.
And if you factor in the 15% or so you lose from flywheel to rear wheels, that is quite a big loss. I am going to have to get out of these mountains
Nitrous isnt affected by elevation so a 100 shot is 100 more uncorrected HP or about 130 for you added to corrected.
There are still LS cars hitting 9.3's here with a typical DA of 7000 at Bandimere raceway (5500 feet or so). Pueblo is a bit less maintained but its cheap and available everyday. Friday night at the races is a fun family thing with food and low humidity.
Youre cranking compression falls by the correction factor so an engine that does about 205 CC will measure about 152 or so.
Cylinder pressure is way lower since there is less to compress and as a result you compensate by running higher compression. E85 is everywhere here so you build 11:1 for static compression with 20psi on E85. This makes the car dedicated to the higher elevation. I wouldnt take a 1000rwhp car on a road trip anyway.
As far as moving, I'll drive a prius before I give up the mountain views I have from all the rooms on the front of my house. Pikes peak 14k feet, is dead center of my living room windows.
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Thread Starter
Burning Brakes
Joined: Sep 2010
Posts: 944
Likes: 9
From: Southwest CO
Actually at 7500 feet, you're at a correction factor closer to 28%. With a twin turbo kit and 22psi, you hit 1100HP corrected and about 800rwhp uncorrected (actual).
Nitrous isnt affected by elevation so a 100 shot is 100 more uncorrected HP or about 130 for you added to corrected.
There are still LS cars hitting 9.3's here with a typical DA of 7000 at Bandimere raceway (5500 feet or so). Pueblo is a bit less maintained but its cheap and available everyday. Friday night at the races is a fun family thing with food and low humidity.
Youre cranking compression falls by the correction factor so an engine that does about 205 CC will measure about 152 or so.
Cylinder pressure is way lower since there is less to compress and as a result you compensate by running higher compression. E85 is everywhere here so you build 11:1 for static compression with 20psi on E85. This makes the car dedicated to the higher elevation. I wouldnt take a 1000rwhp car on a road trip anyway.
As far as moving, I'll drive a prius before I give up the mountain views I have from all the rooms on the front of my house. Pikes peak 14k feet, is dead center of my living room windows.
Nitrous isnt affected by elevation so a 100 shot is 100 more uncorrected HP or about 130 for you added to corrected.
There are still LS cars hitting 9.3's here with a typical DA of 7000 at Bandimere raceway (5500 feet or so). Pueblo is a bit less maintained but its cheap and available everyday. Friday night at the races is a fun family thing with food and low humidity.
Youre cranking compression falls by the correction factor so an engine that does about 205 CC will measure about 152 or so.
Cylinder pressure is way lower since there is less to compress and as a result you compensate by running higher compression. E85 is everywhere here so you build 11:1 for static compression with 20psi on E85. This makes the car dedicated to the higher elevation. I wouldnt take a 1000rwhp car on a road trip anyway.
As far as moving, I'll drive a prius before I give up the mountain views I have from all the rooms on the front of my house. Pikes peak 14k feet, is dead center of my living room windows.
And I am like you, I would drive a Yugo or a bicycle before I would move out of these mountains. The view from my deck is priceless.
Racer
Joined: Apr 2007
Posts: 336
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From: Pine Colorado
Hello neighbor, I live at 8600 feet in the mountains above Denver and do not want to leave the mountains. I, too, have a great view from my decks. However, I would not drive a Yugo, but would ride my bike. My 3 vettes love living in the altitude as they get to hibernate 6 months out of the year. When they sleep, I drive 4X4s.
Racer
Joined: Oct 2008
Posts: 423
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From: winchester Virginia
Yeah, you lose significant power living up here but the beautiful scenery and well-maintained twisty roads make up for it. Favorite drives include 67 south to Cripple Creek or 67 north to Deckers. Can't beat it!!
E-fish
E-fish
Racer
Joined: Apr 2007
Posts: 336
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From: Pine Colorado
i agree, I drive from Pine Junction to Deckers to Woodland Park to Colorado Springs at least once/month to attend the CS Corvette Club meeting [most recent last Thursday night]. That's enough said, as I have hijacked this thread about horsepower and altitude with my comments.
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From: Cape Cod, Mass.
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Back in 2000 I drove a newer fuel injected Corvette across country from Mass to California. When I got into the New Mexico area I could not believe how anemic the car felt. It was a dramatic loss in power. When I went for a jog after staying in Grants New Mexico I couldn't believe how weak I felt The lack of oxygen at those high elevations had the same effect on me as the Corvette.
The lack of oxygen at those high elevations had the same effect on me as the Corvette.
Thread Starter
Burning Brakes
Joined: Sep 2010
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From: Southwest CO
Go Canes!
Joined: Dec 2009
Posts: 5,975
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From: Boca Raton FL
St. Jude Donor '11-'12-'13-'14-'15-'16-'17-'18-'19-'20-'21
The elevation here is about 1" above sea level or less! I guess we only lose the HP due to the heat!!
We do have the ocean view, though!
We do have the ocean view, though!
