Manifold Pressure Gauge

A manifold pressure gauge is the cockpit instrument that displays the absolute pressure in the intake manifold of a reciprocating engine. On aircraft with constant-speed propellers or turbocharging, it is the primary power-setting instrument. On fixed-pitch propeller aircraft, the tachometer is the primary power reference.

Overboost Prevention

On turbocharged engines, the manifold pressure gauge must be monitored to prevent overboosting — exceeding the maximum allowable manifold pressure. Overboost can cause engine damage through detonation. The maximum MAP is marked on the gauge and published in the POH. Turbocharger wastegate operation should keep MAP within limits automatically; monitor the gauge regardless.

Related Terms

See also: Manifold Pressure, Critical Altitude.