Can anyone tell me what the difference is between a high-altitude principle use truck and a "regular" truck? I live in the Salt Lake City area where the altitude is about 4,250ft and the surrounding canyons and mountains range from 8,000-11,000ft. My truck, however, did not come with the high-altitude option (I bought it in Idaho). I was wondering what it would take to "tune" my truck for high-altitude use.

------------------
'99 F-250 Super Duty XLT Crew Cab XLT 4x4, prairie tan, V-10, cab steps
Mods - K&N filter, spray-in bedliner, tinted windows, Ford hood deflector, Ford mud guards, Donnelly ECT mirror is on the way
Soon to be Mods - Hard tonneau, Airaid, Superchip

 

It makes no difference with a fuel injected engins.

------------------
TRUCKBLACK 97 F150 XLT FlareSide SC.
4.6 MODS: Lowered 5 inches, SnugLid
Hard Tanneau,K&N plus air mods,
Plat+4/8mm wires,Prolong engin
treatment,Amsoil Syenthetic oil
and Filter,Bug&Rain guards.
SUPERCHIPED,No Step Under door nurf,
Interior Visor Shelf. My truck looks
like Ford used it as a model
for the Lightning but mines LOWER!
JACKS ANTENNA HEAD The easiest MOD

 

Because of loss in air density, any normally asperated internal combustion engine will lose about 3% of the total HP per 1000'. In a normally asperated engine you can gain some HP back by rasing combustion pressure. This can be done by advancing the ignition timing or raising the comperssion ratio (3-4% gain per point, for example a 10:1 CR engine will make 3-4% more HP than a 9:1 engine). I think that the high altitude option simply features more igniton advance and perhaps a open loop fuel map witch is optimized fot high altitude operation.

I spent a year in Laramie, WY, elevation 6000', and the highest octane available was 89 octane. This was because the altitude effectively lowers the compression ratio and decreases the need for fuel octane.
Andrei

[This message has been edited by Bent6 (edited 07-11-1999).]

 

Thanks for you reply, Gary. If it doesn't make a difference with FI engines, then can you tell me why there is a high altitude principle use option (albeit a zero cost option)? The option number for my SD is listed as option number 428. Is this a SD option only? If so, should I repost this question in the superduty message area?

------------------
'99 F-250 Super Duty XLT Crew Cab XLT 4x4, prairie tan, V-10, cab steps
Mods - K&N filter, spray-in bedliner, tinted windows, Ford hood deflector, Ford mud guards, Donnelly ECT mirror is on the way
Soon to be Mods - Hard tonneau, Airaid, Superchip