I live here in Arizona where elevation is aprox 1500-2000. I can tell a big difference in available power when climbing to elevations especially 7-10k. I figure its the thinner air, but right now in the valley the weather is nasty, humid and HOT. Cooler air up there I thought would mean more power. I do have the airaid I just installed. Can anyone shed some light? thanks!!

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J Randall
elktag1az@aol.com
Arizona F150 4x4 SC '97

 

Your engine will lose rougly 3% of your total engine output per every 1000' of elevation. This is due to loss of air density. For example, you will lose 21% of the HP you had at sea level at 7000'. Turbo engines won't lose as much because the turbo can be overspeeded to equal the sea level boost. For a normally asperated engine you can gain some performance back by rasing cylinder pressure. You can advance the timing (not on most late FI engines). Or, you can raise the compression ratio ( 3-4% HP gain per point of compression (again not easy). Your vehicle needs less octane at altitude, because the low cylinder pressure the low density air causes. I have been in some high altitude towns that had 89 as the highest octane available.

Temperature has the same effect though not to the same degree. Hot damp air is the least dense and will make less HP than cold dry air.

[This message has been edited by Bent6 (edited 08-23-1999).]

 

Bent6, Thanks much for the info!! I had no idea the loss was so great in hp.. Also I wondered why I couldnt find anything higher than 90 octane... Answers a few questions I had. Can you order a truck with a 'high elevation' package on it? Thanks again!

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J Randall
elktag1az@aol.com
Arizona F150 4x4 SC '97


[This message has been edited by ELKTAGAZ (edited 08-23-1999).]

 

I have a 99 4.2 that came with "high altitude principal use" on the options.I'm not sure what its supposed to do didnt order it,but it's available. From another Arizonan

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------------------------- 99 SILVER XLT/REG.CAB/4.2/5SPD/3.55/K&N Airbox Mod/Rhino muffler/Westin Black nerfs and now SuperChiped

 

Speaking of high altitudes, i will be driving through Colorado in the higher elevations in my 4.2 5 speed. Will i run into any problems?

 

Being that these engines are computer controlled, wouldn't the computer adjust the air/fuel ratios for higher altitudes? Wouldn't the power pretty much stay the same? I've towed in the mountains of AZ and CO and really haven't noticed any difference.

Elktag, did you luck out and get drawn this year?? After a 4yr dry spell, I got drawn for unit 6A for the general Elk hunt.

 

V10, the computer probably does a good job of maintaining the proper fuel to air proportion, but this is just a guess. At 10,000', both V8s start right up and run smooth. However, at 10,000', the air is darned thin and there's no way you'll get the same amount of air into a non-blown engine.

 

V10. I drove up the white mountains, res lake, the truck ran smooth and nice but the power was way down. I did just install an airaid but I wouldnt think this would have that effect??
As far as an elk tag, I was tired of not getting drawn so second choice was archery cow elk! Course I got that. Man what a sweet tag in 6a you got! Good luck with it. A buddy of mine took a nice bull last year in that unit..make sure and let me know how it turns out!
elktag1az@aol.com

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J Randall
elktag1az@aol.com
Arizona F150 4x4 SC '97

 

Air density calculations are very important when it comes to drag racing, and is often used. When ever someone posts a 1/4 mile time, I'm always curious to know what altitude the track is at. Just to show an example, I own a '71 F-100 that runs 14.69 at 3300' altitude. To figure out what it would do at sea level, the calculation would be: 14.69x0.9601(NHRA elapsed time factor)=14.10seconds. Good enough to compete with a lightning, depending on where it was tested.

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'98 F-150 XLT Reg. Cab Flareside 4x4, Black, 5.4l, 3.55LS, tow package, K&N, GTS headlight covers, Alpine changer w/FM mod, Clifford alarm system w/keyless entry & starter disable // Future considerations: 285/75/r16 Mud Terrain BFG's, bed mat, tonneau cover, suspension lift.