"Jim Macklin" wrote in message
...
Not exactly. It depends on whether the gauge is calibrated
to an exact temperature or whether the gauge is used only to
find relative peak and degrees above and below. It also
depends on where the probe(s) are installed. EGT has the
probes about 4 inches past the exhaust valves,

On single-probe EGT systems such as on John's Cessna 340 the probe is
located toward the tail end of the exhaust riser, well ahead of the turbo
but past the 4" point. This was determined (by Cessna) to be the point
where the exhaust gas is hottest. Cessna POH for the 340 recommends running
at peak for many power settings below about 62%. Cessna designed their own
exhaust systems on their twins, Beechcraft had TCM design their exhaust as a
unit with the engine.

Allen