Good info! Got it. I will change the load break points to something close to matching my old map (I know it won't be exact but it will be close). Then I'll paste in my old numbers to the rows closest resembling my old load breakpoints. Then I'll project rest. To be honest, I've already set my tune up to project out what AFR's need to be at higher boost levels because I forgot that absolute pressure drops at altitude. I don't think it will take me more than a half hour to get her running good.

 

Well, the relative boost pressure is still what it would be at sea level. Absolute pressure, which is what your manifold and boost gauge read, is lower. So, in a forced induction setup you lose less performance than you would think under boost. I know there's a mathematical calculation for this but I believe that under boost we are over 90% as efficient as you would be at sea level.

So yeah, we lose a little less than 10% (under boost, 15% NA) at 5000 ft BUT there are advantages. Because your dynamic compression ratio drops at altitude we can, theoretically, run more boost safely than you could at sea level. As long as we're not heat soaking because we're over spinning the blower, we should be able to compensate for the lost power by running slightly more aggressive setups. For me, it means I will be tracking a 13 psi setup haaaard without fear of blowing her up.

Granted, I'd rather have that power back at a lower blower rpm to help keep temps down, but it's the best we can do this high up. We do get to ski some bitchin' powder out here, though.