mabelaker wrote:
I hate to burst some bubbles but the the SAE correction factor of 1.22 was almost certainly incorrectly applied. That number sounds correct for a NA engine at 5000', but almost all modern turbocharged engines (even gasoline) maintain sea level output up to 10,000' density altitude (and possibly higher).
It would be foolish to go to the trouble of equiping a modern engine with a turbo that could only produce max boost at sea level and then immed dropped off with altitude. I'm pretty certain the VM 2.8 ECU commands the VGV's to produce max boost(at max throttle, 26psi I think) regardless of altitude. Boost would only be cut back if EGT or some other limit was exceeded. Another limit may be compressor stall(transonic impellor) at extreme altitude/compressor speed.
My point is, if we take CATCRD's numbers and extrapolate the uncorrected data we get:
160 rwhp/1.22= 131 rwhp
340 rwtrq/1.22= 279 rwtrq
These numbers are close to some other posted lower dyno results, and if the factory numbers are correct(or even close), drivetrain loss is almost dead on. ORM, fuel mods/additves and cetain diffs would easily account minor result differences.
Even older diesels with no wastegate generally had some altitude compensation because a diesel can operate with excess air. As boost fell with height gain, power would hardlly change until critical alt was reached, and then a sense line upstream of turbo output to the fuel control would cut back fuel as boost fell to prevent overfueling(one method).
Power in modern diesels prob only varies 1-2% with alt, and can actually increase with alt slightly as system efficiency(induction and exhaust) rises and then falls as height increses.
Air density depends on pressure and temperature(humidity a distant third factor), so power might fall a little with OAT increase, but I suspect in diesel engines, where detonation is the normal mode of combustion, the ECU compensates with a tad extra boost as long as EGTs are in order. Gasoline engines ECUs must avoid knock so they may be more charge air temp sensitive.
Another factor I've noticed in diesel tech papers is fuel temp (and of course fuel cetane) is always stated in output specfics and appears to be the major factor in engine output. I do not completely understand why but I suspect fuel temp affects actual observed cetane number. I seem to get better mileage when the summer weather hits 30+ celsius and the crd is warmed up by the time I'm out of the garage. Warm up is a factor, summer fuel is DEFINITLY a factor and maybe higher fuel temp as well.
OK I'm done. Fire away.
Ha, I knew it, theres always one! Thats a typical correct factor we see here, regardless if it was incorrectly applied we will at least be able to make a comparison between the two PCMs.
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). The 0-60 times are just observations that are subject to Timmaah! error. All I know for sure is that a CRD that has not been castrated will cremate the tire(s). 
