Question: Why do PT6A-27 engines run so much colder than -20

[Powerplante]

Just trying to find out why the -27/28 runs so much colder than the -20 ? Is there a prime difference in the engine design or are there several integrated features which allow it to thermally run better ? Horsepower can't be the answer; can it ?

Thanks for your replies...

[longjon]

There are LOTS of design improvements in the newer models. Not just 1 or 2 reasons why they run COOLER than the very early models. As you know the reading are all compensated by the trim stick so it can read whatever the engineers decide.

[Gos]

I have the pdf from FreeBee stating all the different PT6 version. Basically there are saying that the -27 is similar to the basic model but with revised engine parts.

Also you get 130 more horsepower on the -27 than -20. Which means that the turbine is really more effective because the design is basically the same but all the important parts to get your power ( compressor, combustion chamber and turbine) are improved.
And getting more power from the turbine means that you gonna have less energy and heat at the exhaust because turbine extract more energy from the gas.

[Bulawrench]

The -27 typically runs cooler than other engines. I have one now that is idling at 500 C while a 114a idle is 595 C.
If the system resistance is within limits and gages are calibrated there must be no issue.

[david_351]

20s run hotter at min flow and idle but not much hotter at max power, maybe 30-50 degrees. More efficient hot section parts on the 27 better ct disc and guide vane, plus the extra horsepower really helps when you add load to the engine like running the generator.