Difference at altitude?

[jphilipson]

Is there a general rule of thumb for power loss (HP/Torque) based on altitude? My bike was dyno'd in Denver (5500 FT), just curious about how much that would translate to at sea level. Not that it's a power monster, stock except PC3, Yosh TRC pipes and BMC filter.

 

[Mr Bogus]

not sure on stockers but on our race motors, we were down about 5% per 1000' of density altitude..

 

[Aquaman]

I dont know what the actual formula is, but absolutely your motor will run different at an altitude that you had mapped your bike at. A gas powered cessna style airplane motor has an enrichener just for that purpose.

 

[jphilipson]

not sure on stockers but on our race motors, we were down about 5% per 1000' of density altitude..

So if my bike dyno'd at 180 HP and 106 Torque at 5500 FT, what would you figure it would run at Sea Level?

 

[jphilipson]

So if my bike dyno'd at 180 HP and 106 Torque at 5500 FT, what would you figure it would run at Sea Level?

NM.. figured it out.. new to Dynos here. The first readout is the "actual" and the second is the "corrected" if I am not mistaken.

 

[Busashot]

not sure on stockers but on our race motors, we were down about 5% per 1000' of density altitude..

That's about right. I am up here in Albuquerque, NM where it is on average 5200'. Just get the dyno operator to give you the uncorrected dyno #'s instead of the SAE #s they put out. Because the Density Altitude is usually very crappy during the Summer, you could see upwards of 23% difference from a perfect SAE correction.