ALtitude and Horsepower

[OB_DanaT]

At 6000 ft you have roughly a 25% hp loss. By 10000ft it is about 50%.

-Dana

 

[OB_boneman]

Hence the need for a turbo, great excuse to get one, Altitude compensator.

 

[OB_terra1]

I shipped my bike to Utah and rode it between 6000 and 9000 feet of altitude. The power dropped off significantly. I have dyno'ed at 165.5 rear wheel [Akro pipe, sealed airbox], and it felt like it might have lost as much as 30 HP or more. Is this possible?

I've been told fuel injection has no lambda sensor [O2 detection], although I can't see what difference that would make since, whether you detect it or nothing, the oxygen ain't there.

Anybody know how to calculate altitude effects on horsepower?

 

[OB_SlowHand]

The books I've read said to calculate the power loss as roughly 3 1/2% per 1000 feet for most engines. Above 10000 feet it can go beyond that.