"Denny" wrote in message
oups.com...

At full throttle you cut in an extra X% of fuel flow, beyond 'max
rich'... It is for cooling the exhaust valves at take-off power...
Pull the throttle back, even a small amount, from full forward and you
lose that extra X% of cooling... It is the same for carburetor and
injected engines...

On our Turbo Saratoga's TIO540S1AD, the throttle is nowhere near full
forward at takeoff when we set max manifold pressure. Full forward will
significantly overboost. The throttle has to be continually moved forward
as altitude increases, reaching full forward at critical altitude.
Throttle-linked wastegate, no turbocharger governor.

Stan