Hi fpolks,

Its me again, trying to get some performance at 6000ft. I have gone to 3 Ford dealers inquiring about the Ford High Alt option. The truck was from Calif. and runs like a bat out of hell there. The first two knew nothing, but were sure it had nothing to do with a comp. re flash. The third dealer Medved Ford in Castle Rock , CO told me the high alt package just has 4.10 gears. I have 3.55 gears now with slightly larger than stock tires. I think they are 265 75 16.

With that said, has anyone gone from 3.55's to say something like 4.56 gears? What is the rpm difference at 75mph? What would the cost be since I am a 4X4? Was the performance that noticable? My other option is a powerdyne supercharger.

Thanks alot
Darren

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97' F150 Lariat S/C long bed 4x4 3:55LS 4.6L auto...SuperChip, 40 series Flowmaster cat back.
Colorado Springs, CO

 

Darren,
I'd be surprised if the differential gears were the ONLY thing that changed in the High Altitude package.
I know that when I lived there I put about 50% of the cost of my vehicle into engine mods to get it to "run" at high altitude. I wasn't satisfied until I could accelerate up I-70 to Eisenhower Pass in 5th gear. Finally made it - never did change differential gears. Back down at sea-level, that vehicle did an honest 140MPH (I drove it from Amarillo, TX to Shreveport, LA in 9 hours flat - had to slow down through Dallas ). Those were the days...

Your biggest problem is Fuel Air mixture. At high altitudes (BTW, Colorado Springs is NOT high altitude, so you must be having troubles elsewhere), your engine has a tendency to run rich due to the thin air (less Oxygen). I think you need to flash your computer to change the mixture.

You might look up Slipstream Automotive in Boulder, CO. Ask for "Bill" - he races the annual Pikes Peak in his 800HP Ch*vy.

 

JC,

Thank you for the response. Thats exactly what I thought , but I went to 3 different ford dealers, they all told me no flash, gears will do it.

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97' F150 Lariat S/C long bed 4x4 3:55LS 4.6L auto...SuperChip, 40 series Flowmaster cat back.
Colorado Springs, CO

 

JC,

What mods did you do to your truck and witch motor did you have? My truck runs excellent at sea level. I was in cali last month and what a difference, my buddies v10 could not pull away from me. Here at 6000ft it feels like im pulling a boat all the time. and my mpg is about 8 around town 11/12 on the highway. my current gear ratio is 3.55 and i have slightly taller tires than stock

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97' F150 Lariat S/C long bed 4x4 3:55LS 4.6L auto...SuperChip, 40 series Flowmaster cat back.
Colorado Springs, CO

 

My truck came with the high alt package.Not sure what is in it.Only listed it on the sticker,but my truck has the 3.55 gears so maybe the dealer you talked to isn't sure either.My computer code is GTL2 not sure if that helps.I live in arizona haven't had time to go to the white mntns and check to see if it works.

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

 

Who the hell can I call at FORD to get to the bottom of this High Alt Package crap. I have been getting the run around for months. You pay 25k for a truck and no one know *****. I went to the ford web site...no contacts there. Called there 800 number for service, no one knows ***** there. aaaaaaaaaaaaaaa

sorry just venting

Darren
maybe chevy or toyota has better service

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97' F150 Lariat S/C long bed 4x4 3:55LS 4.6L auto...SuperChip, Air Raid, 40 series Flowmaster cat back.
Colorado Springs, CO