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Boost Control at Altitude

Boost Control

Discussion and questions related to the course Boost Control


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2004 Subaru STI on a Cobb AP.

I recently moved from sea level to 5500ft. My boost control was tuned at sea level.

Now that I'm at altitude, my turbo is no longer hitting target boost as I expected. I checked local weather and I was shocked to see the barometric pressure was extremely close to sea level pressure. About 30inhg. If the atmospheric pressure is the same here, my barometric pressure comp tables never come into play.

I feel like I need a physics lesson. I figured I'd just need to double check the comp tables and modify them for this higher altitude, but it seems as if i'll have to modify my regular wastegate tables?

School me.

I figured it out. It has to do with the type of data provided by local weather forecasts. The number commonly found in those forecasts is "altimeter setting pressure". Once I found "station pressure" for my region my observed boost behavior made sense. I confirmed this by looking at the readout of my map sensor and comparing it to "station pressure".