Hi,

I have a turbo 5.3 running an 0411 pcm with the 3 bar SD OS. With the timing tables maxing out at 1.2 g I'm exceeding the limit at 10 psi boost, seeing a max of about 1.35 g.
I scaled the tune to 75% and ran it under the same conditions with 10 lbs of boost and the reported cylinder fill values I'm getting are not 75% of the prior reported values, they are significantly lower. I expected to see a peak of around 1.0 g (75% of 1.35) but they are around 0.75 g. The engine is running about the same as with the unscaled tune and the AFR values reported by the wideband are very close to prior as well. The reported timing values indicate that the pcm is using the corresponding values in the table for the calculated cylinder air mass that is reported.

It runs well and I can make adjustments in the timing table to account for this but I'd like to know why I'm getting this discrepancy and if there is a way of calculating for it.

It would be great to hear from anyone who has experience with a scaled tune on this one.

Thanks