hp at 5,500 ft.
hp at 5,500 ft. Just wondering I have an 02 firehawk with the basic stuff, lid and free mods. I know the factory rating of 345 is at the crank. The car dynoed at 288 rwhp and 298 tq. I live in Colorado at about 5,500 ft does the altitude make any more diff. vs being at sea level. Thanks for any input.
Tech Resident
Joined: Jan 2006
Posts: 5,117
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From: Philly
yes it does. the higher the altitude, the less power you will make. reason being is an engine is a big air pump: the more air that goes in and out, the more power it makes. air at higher altitudes is thinner than air at lower altitudes. the thinner the air, the less power you will make. ideally, you want cool, humid air. i feel my car runs strongest when it's a very humid day with the temps hovering at around 50 degrees. my car seriously feels 20 horsepower stronger on a very cool autumn night than it does in the middle of a 90 degree summer day.
Originally Posted by ChocoTaco369
yes it does. the higher the altitude, the less power you will make. reason being is an engine is a big air pump: the more air that goes in and out, the more power it makes. air at higher altitudes is thinner than air at lower altitudes. the thinner the air, the less power you will make. ideally, you want cool, humid air. i feel my car runs strongest when it's a very humid day with the temps hovering at around 50 degrees. my car seriously feels 20 horsepower stronger on a very cool autumn night than it does in the middle of a 90 degree summer day.
Humidity is not better for a car than dry air. The same car will make more hp on a cool/dry night as compared to a cool/humid night. Humidity is water vapor. In a given amount of air, it displaces oxygen content, making the air less dense. As a result, the engine ingests less oxygen, and its output is reduced. For example, on a hot day at sea level, high humidity would cause a carbureted motor to run rich. Same with an injected motor, however, the EFI motor would adapt much better than the carbureted. But a lack of oxygen is still a lack of oxygen.
Last edited by 98RedBird; Jun 12, 2007 at 08:56 PM.
Welcome to elevation where FI rules all. I'm going to be getting my car dyno'd soon after I get my intake on and I hope it produces decent numbers although I won't be holding my breath.
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Verdad Gallardo Tech Resident
Joined: Jan 2006
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From: Philly
Originally Posted by 98RedBird
Humidity is not better for a car than dry air. The same car will make more hp on a cool/dry night as compared to a cool/humid night. Humidity is water vapor. In a given amount of air, it displaces oxygen content, making the air less dense. As a result, the engine ingests less oxygen, and its output is reduced. For example, on a hot day at sea level, high humidity would cause a carbureted motor to run rich. Same with an injected motor, however, the EFI motor would adapt much better than the carbureted. But a lack of oxygen is still a lack of oxygen.
pretty much what has been said....higher altitude means less dense air, meaning less air in....meaning less power....
cold dry air is your best option.....in florida we dont have that much and humidity isnt the best thing when it gets into the block
cold dry air is your best option.....in florida we dont have that much and humidity isnt the best thing when it gets into the block
TECH Enthusiast
Joined: Jun 2004
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From: Fredericksburg, VA
Here are my numbers for your comparison:
At sea level, I dyno about 400 HP.
In NM, at 5,000 ft., I dyno about 330 HP. Trust me, it's a difference you can FEEL.
For anyone that doubts the accuracy of SAE correction on a properly calibrated dyno- my SAE corrected numbers at 5,000 ft. normalize the 330 HP right back up to my sea level 400 HP.
Are your numbers uncorrected, or SAE corrected?
At sea level, I dyno about 400 HP.
In NM, at 5,000 ft., I dyno about 330 HP. Trust me, it's a difference you can FEEL.
For anyone that doubts the accuracy of SAE correction on a properly calibrated dyno- my SAE corrected numbers at 5,000 ft. normalize the 330 HP right back up to my sea level 400 HP.
Are your numbers uncorrected, or SAE corrected?
Here in SLC at about 4500' my car put down 325 Corrected. Just for kicks I asked to see the uncorrected graph. 270 something. A loss of about 15%. Same thing goes for the track. Most LS1s run low 14s or really high 13s.
Forced induction can of course help but you still loose about the same percentage as an NA car.
Forced induction can of course help but you still loose about the same percentage as an NA car.
Teching In
Joined: Mar 2007
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From: Lumberton
Originally Posted by sportsaddict_21
does ur car run faster times tho in the high alltitudes because there isnt as much gravitation pull on it??? idk just a thought. if there is then would that make up for the lost horses.
Ummm, no---probably not much loss over the gravitational pull thingy because he has a flux capacitor powered by dylithium crystals for the warp drive 
Originally Posted by sportsaddict_21
does ur car run faster times tho in the high alltitudes because there isnt as much gravitation pull on it??? idk just a thought. if there is then would that make up for the lost horses.
A higher elevation would not make your car weigh less.
All kidding aside, I did have professor tell me that you would weigh less if the moon was directly overhead, but I don't think it would help you quarter mile times. 