Boost Pressure

[911TT_STEVO]

That's a big jump! I know that it can jump .2/.3 (i.e 1.8 to say 1.6) due to warmer/cooler/humidity conditions.

[DavidT]

Do anybody knows why when I go up in altitude (2,250 mts above sea level) my boost goes down to 1.38 bar from the 1.8 I'm getting at sea level

Altitude is one of the things the ECU measures. The boost pressure is reduced at altitude to prevent the turbo's from over-spinning.

[zeke]

Strange, because it should be the other way around, more boost at a higher altitude to compensate the lack of oxygen. Thats why the normal aspirated engine lose around 30% at this altitude.

[robobeastt]

Hi zeke ... you just have to think of a column of air right above of your car ... and air also weights, specially when you have 2kms of it over your head .... this column will be somewhat taller/thicker when you are at sea level than when you are above 2400 mts at Mexico´s City .. that is why .... also air is thicker at sea level so it´s easier for turbos to condense intaking charges.... hope you get the idea ....

I don´t know if your engines can have manual boost controllers on your engines (maybe twin controllers so as to connect each turbo) but i know that on 1.8T they work great .... in that way you can push up your boost at Mexico City but then need to readjust the valves when going down to the coast ....

Cheers & see you around ....