Temperature Readings

[killtrassy]

Since I have had my Gazelle I have had trouble finding out what temperature readings I should be seeing in summer for CHT and oil. As the green line on the gauges go very high before getting to the red , I am interested to know what the considered acceptable temperature readings should be. In the cooler months I generally cruise at 100C for CHT and 90C for oil but summer tends to be 115C CHT and 100C oil. Interested to hear what others get.

 

Regards Tony

 

 

[cscotthendry]

Tony:

 

You didn't say what kind of engine you have or what type of coolant you use. If you're using a propylene glycol coolant like Evans NPG+ the allowable temps are a bit higher than for ethylene glycol/water like car coolant. In any case, the temps you posted look reasonable for a Rotax engine running Evans coolant.

 

I forgot to add that my Nynja 912uls runs evans and in summer I'm grtting temps up to 120 for both oil and CHT. This is the top of the green arc on the Aviasport gauges supplied by Rotax. Also, the temps I mention are maximums seen on long climbs or high RPM cruise at low level on hot days. Other conditions give lower temps. Sometimes my oil temp goes as low as 70 on descent.

 

 

[killtrassy]

Hi Scott

 

Thanks for your reply. My motor is the 80HP Rotax and I have an 80% ethylene glycol coolant.The top of the green arc on my gauges ( original Skyfox gauges ) are 150c which I can't understand why they would mark them that high. The problem I see is the radiator in Skyfox's is mounted in the centre of the motor instead of out the front and the oil cooler is attached to the firewall which is OK in cool weather but in summer !!!

 

Regards Tony

 

 

[cscotthendry]

Tony:

 

Yes 150C does seem rather high even for Evans coolant. For ethylene glycol that's in the territory where you can get steam bubbles forming in hot spots, I believe. Rotax recommends that the oil temp exceed 100C every flight at least once to boil off condensation. So having the oil cooler mounted to the firewall may be Gazelle's design to achieve that.