Using an ideal thermodynamic cycle, backward engineering the engine efficiency using factory specs, and adjusting for 5000ft., I got a hp shift from 92 hp to 83 hp.
Assumptions made were standard temperature & pressure, no manifold vacuum, engine efficiency of 45% (admittedly high) and a constant peak HP rpm of 5600 (factory specs) for changes in altitude. I believe engine efficiency is off due to manifold vacuum assumptions, but the change is still relevant
If anyone wants the theoretical method for their own calculations, just ask. If not...an easier approximation is HP = (altitude density / sea level density)^1/2, but I'm not 100% sure on that one. In any case, good night.
- LostCause