Boost gauge

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Boost gauge on a Ford Focus RS

A boost gauge is an instrument that indicates turbocharger or supercharger boost pressure in an internal combustion engine. They are commonly mounted on the dashboard, on the driver's side pillar, or in a radio slot.

Turbo- and superchargers are both engine driven air compressors and provide varying levels of boost according to engine rpm, load etc. Quite often there is a power band within a given range of available boost pressure and it is an aid to performance driving to be aware of when that power band is being approached, in the same way a driver wants to be aware of engine rpm.

A boost gauge is mandatory when boost pressure is being modified to levels higher than OEM standard on a production turbocharged car. Simple methods can be employed to increase factory boost levels, such as bleeding air off the wastegate diaphragm to 'fool' it into staying open longer, or installing a boost controller. To avoid excessive leaning out of the engine (caused by increasing the boost beyond the fuel systems capacity) care must be taken to monitor boost pressure levels, along with O2 sensor levels.

A boost gauge will measure pressure in either psi or bar and many also measure manifold vacuum pressure also in inches of mercury (in. Hg).

Boost gauge

See also