A very interesting theory - something I never really put together until I read this.
Here are some thoughts. First, a computer controlled engine can only do so much, yet it can do a heck of a lot more than nothing. We've all driven non-controlled carb equipped cars (or at least us old farts). The change with air density, esp altitude, is dramatic with those cars.
Think about this though - one thing a modern FI engine can't do is increase compression ratio - which, all else being equal, is a huge factor in hp output. Ok, so the engine gets cold, dense air. The computer can detect this with the MAF and adjust A/F and timing. But it's goal is still to maintain 14.7:1 given the O2 sensor feedback. If the conditions persist long enough, it may affect WOT output a bit as the long term trim values are used in open loop calculations.
But it's fleeting. A really hot day does the opposite - even worse because the air density is less AND the air temp is up. So the PCM pulls fuel and timing back out.
Now back to the theory. If the engine was baselined for programming at the same conditions as the SAE correction factor table, then all is well as neither makes a correction. Beyond that - I'm not sure we can know. If I were to design a very high output engine (e.g. high compression, high rpm) I might take even greater steps to protect that engine under extreme conditions - I may pull more timing back and watch air temps and knock sensors like a hawk. In most cases like this, detonation is the enemy. I'll let the feedback system take car of the mixture (and hence emissions), but I'll cut power back much farther than the SAE correction. So I'll net even LESS corrected hp - as there is effectively double correction.
A less powerful engine may have enough inherent margin such that I don't need to reduce output as much. So it's corrected numbers, as you suggested, may be higher. But it's all relative, as this engine would produce less hp anyway - hence you couldn't tell just by the results.
Bottom line: the PCM cares most about emissions (as mentioned) - but primarily during closed loop. In doing so, it corrects for the conditions at hand. We can't know what impact a set of conditions would have on the output, unless a Ford PCM expert wants to chime in, or someone takes a Mod motor and slaps a carb on it. (ugh)
How's that for a long winded, verbose, non-answer?
Heck, I was just typing as I was thinking, and it's late. So take this all with a grain of salt, or a bit of memory.
- Dave (SCOA #1474)
'01 Cobra Coupe (Laser Red, Charcoal), no wing
- #812 of 3867, born 5/7/01
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