Calculating crank horsepower at elevation

[88kawi]

How do we apply simple maths to guesstimate horsepower at elevation?

I have a MPI kit with the high flow exhaust, EABC and prologger turned up to 7.8 lbs from what ive seen.

How much power is this at 10,000 ft elevation?

10,000 ft * 0.03/1000 ft = 0.3 or a 30% power loss.

I am guessing horsepower * 0.7 + (9hp*0.7*LbsBoost) ?

so 135*0.7+(9*0.7*7.8) = 144.6 hp?

or is it 135*0.7+(9*7.8) where we omit the 30% loss in the turbo, so it = 164.7 hp

 

[rallikuski]

Doesnt MPI kit have elevate compensation? At least MCX kit has it. It puts more boost at hing altitude and it keeps horsepower up, like in MCX190 kit it has 190hp at any altitude and same with 270hp kit.
MCX ecu has baro sensor in it and it controls wastegate operation to keep boost up to make that 190/270hp.

Look this link: http://viper.mountainperformance.com/Viper-Turbocharger-Complete-190HP-Yamaha-Kit_p_83.html

It says what i was quessing: "Makes 190HP at all elevations (Capable up to 270HP with upgrades)"

 

[88kawi]

Mine makes 7.8 max psi. Mostly runs at 7.4 lbs.

How much hp is that at 10,500 feet? 20F degrees.