Turbo problems...where does this pipe go?

[Nighthawk]

as we are now the atmosphere pressure is 1 bar so if a gauge reads 1 bar when the engine is switched off then it is reading correctly- most gauges will read 0 bar at atmosphere - when the engine is switched off. this is deliberate to make it easier to understand when you are only talking in terms of pressure increase on atmosphere
ie. 0.7 bar is the same as 1.7 bar

confusing tell me about it!!

Yup, most gauges fitted to vehicles and specs quoted to users are adjusted or relative measurements to ambient pressure. I've seen the eyes of some Technicians glaze over when you tell them that they're subject to 1bar pressure as they breathe, so your not alone with the confusion m8

A diagnostic gauge worth it's salt will have a true 0 point and a bar or so below that, a defective turbo can be quickly diagnosed with that gauge because of the negertive pressure reading the engine will create as it tries to draw more air than the inlet system can flow if the compressor fan is stationary.

[stevew]

Pressure is a relative measurement, you only compare the pressure at point A with that at point B. Most guages are just open to th atmosphere on one side hence you get a reading above or below atomspheric pressure.
Anyway we are saying the th pressure across the turbo at maximum boost should be around 0.7 bar?
Steve