EGT & TIT

[Sageair]

While reading the pilots operating handbook for a turbocharged piston engine in a light aircraft, I noticed a recommended turbine inlet temperature of 1450 degrees F. Correct me If I'm wrong but wouldn,t turbine inlet and exhaust gas temp be one in the same? If so why is the aircraft engine able to handle the higher temps. Diesel vs gas? Different materials? Whats the deal?

 

[pepecat]

tit

I see your point. I looked it up in my A&P textbook and I found this "The turbine inlet temp (refering to the turbocharger turbine on a recip- as in NOT a gas turbine-engine turbine wheel) may get as high as 1600 deg F , and the large flow of oil is needed to keep the bearings within a safe operating temp. " Looks to me like it is ok to run that high of an EGT on aircraft, otherwise that would not be the acceptable limits. 1450 or 1600 sustained egt seems very high, but we are talking about air cooled engines as well and engines that are designed to be run at full power for their rated tbo. Aircraft engines and parts are also extremely expensive. A rebuilt IO320 is probably more expensive than most of our whole trucks too!

Nick

FAA certified "P" mechanic

soon to be an "A&P"

 

[Sageair]

Thank you for looking into it! Steve.

 

[klenger]

Interesting. I would think that a CTD is more forgiving than an aluminum air cooled aircraft engine. I wonder where the recommended max EGT that the pre-turbo guys use came from. Since Cummins recommends post turbo, have they ever posted a max pre-turbo temp? Maybe the high EGT's of the 600's isn't as bad as we are lead to believe.

 

[pepecat]

good point but what about that fact oabout aluminum alloy melting at 1350 deg f? Maybe aluminum alloys have a higher melting point

 

[klenger]

Caution, I don't know squat about what I am to present here. Take it for what it's worth.



1) Is 1350 the melting point of pure aluminum? If so, an aluminum alloy could have a higher melting point.



2) Just beause the EGT (G=gas) temperature is 1500 deg. does not mean that the piston temp is that high. The combustion temp is high for only a fraction of a full cycle, and also the piston is connected to a massive oil and water cooled heat sink (the block), which is operating in the 250 deg. range.



3) The only piston failures I have read about here are either caused by an oil related failure or a heavily bombed engine. If 1350 was really the max EGT before meltdown, we'd be reading about it happening every day.



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