I wrote:
> >These, as do most "economy gauges" use a pressure sensor on the
> >vacuum line of the engine. The harder the engine work the higher the
> >vacuum. Very imperic.

 -Oyvind replied
 >
> Do you mean "less pressure" when you say "higher vacuum"?
> If so, you are mistaken.
>
> If the engine works harder you get MORE pressure in the intake
> manifold.
>
> Just think of it, when you step on the loud pedal you open the air
> intake valve to allow more air into the engine. More air -> Higher pressure.

Faster airflow -> lower pressure ! In the manifold that is.

> On a regular suction engine this pressure will be approx 1 bar, equal to
> the pressure of the outside air.
>
> The above is not true when it comes to turbo or compressor charged engines.
y