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I recently installed a Pmag replacing my right magneto and decided to explore temperatures within the engine compartment a bit before committing to adding a blast tube.
Armed with an infrared thermometer I had previously probed temperatures after shutdown on the magnetos, firewall, engine, and just about anything that I could reach and consistently saw highs around 165 near the engine with temperatures fading rapidly the farther away towards the firewall. The question of what kind of temperatures are there in flight was kicking around for me... with the Pmag installed I decided to find out.
The Dynon SkyView has two auxiliary contacts for thermocouples with the engine module (along with extra CHT and EGT contacts that can be used for a 5th and 6th cylinder).
The SkyView has built in tables to handle type J and K thermocouples. I poked around with Google for a bit and found several companies that specialize in temperature measurement that offered so many different probes it was like shopping for cereal at the grocery store. I ended up selecting a heavier gauge thermocouple wire terminated in a molded silicon end with 2 meter leads to give the most flexibility in moving them around and mounting them.
I used some silicon rescue tape to fasten one to the engine mount below the magneto in the exhaust stream from the oil cooler figuring that this might be the hottest spot and another I attached directly to the top of the Pmag.
The sensor has a foil tape on one side but it did not stick... I used some gorilla tape that was okay for testing but left some residue that needed to be cleaned up afterwards.
I also tried using some RTV to bed the sensor, but it did not setup well so I tested several more locations that were easier to mount to. After I finish exploring the temperature profile a bit more I will mount them more permanently.
What am I seeing for temperatures?
Lower than I expected in flight... at the Pmag the highest that I have seen was 144, with a stabilized modest cruise the temp was just 133. The hottest temp in flight was 165 under extended high cruise after climb at the oil cooler discharge area near the engine underneath the magneto. In the pattern and on final temperatures were down in the 110 range and stayed there by the Pmag during taxi but rose to 165 as a max at the oil cooler discharge (much lower in the engine as well).
Interesting to get this data and nice to have it displayed with my other engine data in flight. All of this testing so far has been with mild outside temperatures around 50 so I do expect to see things heat up quite a bit on our trip across country to sun-n-fun.
Armed with an infrared thermometer I had previously probed temperatures after shutdown on the magnetos, firewall, engine, and just about anything that I could reach and consistently saw highs around 165 near the engine with temperatures fading rapidly the farther away towards the firewall. The question of what kind of temperatures are there in flight was kicking around for me... with the Pmag installed I decided to find out.
The Dynon SkyView has two auxiliary contacts for thermocouples with the engine module (along with extra CHT and EGT contacts that can be used for a 5th and 6th cylinder).
The SkyView has built in tables to handle type J and K thermocouples. I poked around with Google for a bit and found several companies that specialize in temperature measurement that offered so many different probes it was like shopping for cereal at the grocery store. I ended up selecting a heavier gauge thermocouple wire terminated in a molded silicon end with 2 meter leads to give the most flexibility in moving them around and mounting them.
![img1235af.jpg](/proxy.php?image=http%3A%2F%2Fimg696.imageshack.us%2Fimg696%2F1023%2Fimg1235af.jpg&hash=03eeb3bfc26d46c1e438b48a02b97f42)
![img1237e.jpg](/proxy.php?image=http%3A%2F%2Fimg842.imageshack.us%2Fimg842%2F3815%2Fimg1237e.jpg&hash=317738e44ae0e9a85371f88d24ef608e)
I used some silicon rescue tape to fasten one to the engine mount below the magneto in the exhaust stream from the oil cooler figuring that this might be the hottest spot and another I attached directly to the top of the Pmag.
![img1259gn.jpg](/proxy.php?image=http%3A%2F%2Fimg268.imageshack.us%2Fimg268%2F8140%2Fimg1259gn.jpg&hash=1f89ed8fb967b346cd5a45b79b987944)
The sensor has a foil tape on one side but it did not stick... I used some gorilla tape that was okay for testing but left some residue that needed to be cleaned up afterwards.
![img1238qb.jpg](/proxy.php?image=http%3A%2F%2Fimg849.imageshack.us%2Fimg849%2F8590%2Fimg1238qb.jpg&hash=bf22ac2aa0d22d9df1cca8078e61e66f)
I also tried using some RTV to bed the sensor, but it did not setup well so I tested several more locations that were easier to mount to. After I finish exploring the temperature profile a bit more I will mount them more permanently.
What am I seeing for temperatures?
Lower than I expected in flight... at the Pmag the highest that I have seen was 144, with a stabilized modest cruise the temp was just 133. The hottest temp in flight was 165 under extended high cruise after climb at the oil cooler discharge area near the engine underneath the magneto. In the pattern and on final temperatures were down in the 110 range and stayed there by the Pmag during taxi but rose to 165 as a max at the oil cooler discharge (much lower in the engine as well).
Interesting to get this data and nice to have it displayed with my other engine data in flight. All of this testing so far has been with mild outside temperatures around 50 so I do expect to see things heat up quite a bit on our trip across country to sun-n-fun.
![screenshot2012032220321.jpg](/proxy.php?image=http%3A%2F%2Fimg100.imageshack.us%2Fimg100%2F4050%2Fscreenshot2012032220321.jpg&hash=e09c6d110bf95d6d91cc4b4b4d135fcd)
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