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Pmag internal temps.

N941WR

Legacy Member
On this morning's flight I used the EICommander to check the internal Pmag temps.

They averaged 180*F with 190*F oil temps and 94*F OATs. Also, I have blast tubes on both Pmaga.
 
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Brad has mentioned to me that the internal temp sensors are not calibrated and therefore can't be trusted for actual temps....
 
Brad has mentioned to me that the internal temp sensors are not calibrated and therefore can't be trusted for actual temps....

Pay no attention to the numbers our machine is giving you. Really?
 
Yes, he said the temp sensor is intended for their use only and that to attempt to use it for real time accurate temp is most likely futile.

Keep in mind that EmagAir does not market internal temp readings as a feature.
 
Indeed, the absolute values may not be accurate, but the value will be relative . I think the most important issue is whether the worst case situation is in flight or in a heat soaked situation on the ground.
 
I'm most interested in the temps 15 minutes after shut-down on a blistering hot day.

I spoke to Brad this morning and will check the temps after the flight home. A 104 degree day should be a worst case scenario.

As for the temps being calibrated, Brad mentioned the max temp was buggy but didn't say a word about the operational temps we discussed. He also said the 180*F I was seeing is right in the middle of their expected operating range.
 
OK, on the hotest day of the year, I managed to do some flying and grabbed a bunch of numbers after landing.

Here is my setup:
O-360,
113 P-mag bodies (no cooling fins) with 114 boards
Blast tubes
And of course the EICommander

OAT’s of 92 to 104*F with oil temps of 190*F +/-.

Prior to engine startup: 110F & 123F (left & right) The airplane sat out on the ramp, in the sun, for 11 hours. Yes it was hot today!

During level cruise flight the P-mags averaged right around 180*F, as I said above.

Immediately after landing I pulled off the runway and checked the temps with the engine running, 186F & 199F.
It did not surprise me to see the temps go up because I have found that when I slow down to land, my carb temp goes up. Probably because there is less air going through the cowling.

I taxied in and left the airplane on the hot ramp, with the oil door closed.

After taxing in and shutting down: 179F & 192F (Call it a half mile taxi with 96F OAT’s on the ground. Yep, the temps were cooling down.)
5 minutes after engine shutdown: 192F & 199F
10 minutes after engine shutdown: 192F & 204F
15 minutes after engine shutdown: 199F & 204F
20 minutes after engine shutdown: 186F & 210F

I didn’t stick around for a 25 minute check but based on the left P-mag temp, I suspect they are both on the way down.
 
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Why would you suspect that they're both dropping when the right PMag appears to be increasing in temp? Did you mistype the temps, or was it rising from heat soak? Also, why only the left side getting cooler?
 
Why would you suspect that they're both dropping when the right PMag appears to be increasing in temp? Did you mistype the temps, or was it rising from heat soak? Also, why only the left side getting cooler?

Is the glass half full or half empty?

With the engine cooling down and no heat source, the P-mags temp will rise and then fall. Once one started falling, the other would follow shortly.

It is possible that I missed the absolute high temp and the number I saw was on the way down, not up. Then again, it could go up a few more degrees before heading down but probably not a significant additional rise.

As to why there is a difference between the left and right P-mags, it could the temp sensors are not calibrated the same, the blast tubes are miss-directed on the right P-mag, there is something about the design of the engine that keeps the right side hotter, or some other reason.

One additional thing that I didn't note, until now, my 113 P-mag bodies do NOT have cooling fins in their necks like the 114's do. Thus, the 114 internal temps may be lower than what I observed.
 
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OK, it was hot again today. Like 111F when I taxied out hot. What a great time to test the P-mags again for heat soaking.

Same setup as listed above, same test, only this time I waited longer. Each sample was taken at five minute intervals, after shutdown.

OAT upon landing: 105F
Temps immediately after exiting the runway: 186F & 192F (Left & Right)
At shutdown: 186F & 192F
5 Minutes after shutdown: 192F & 192F
10 Minutes after shutdown: 179F & 204F
(No idea why the left P-mag reported 179 and then jumped back up 192F.)
15 Minutes after shutdown: 192F & 204F
20 Minutes after shutdown: 186F & 204F
25 Minutes after shutdown: 192F & 199F

BTW, I've been sharing these numbers with Brad and Tom at Emag.
 
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Good info

Hi Bill,
This is good info. I know the values are not necessarily absolute or completely accurate, but I think you are collecting some good trend data. I have dual PMags and want to keep them cool as possible.
I know your previous tests were done with the oil door closed. Next time you fly, can you take some data with the door open after shutdown? I am curious how much it will help getting the hot air out and preventing the PMags from overheating.

I used a block of wood with a #2 phillips bit epoxied in the bottom to open and keep the door open! A small piece of velcro helps keep it secure in the cockpit.

Oilblock.jpg


Dan
 
You read my mind Dan. Maybe next time I go flying I'll have a chance to perform another test.

You door screwdriver is a good idea. Only I used the hidden hinge and Hartwell latches so no tool is required and my door stays open on its own.

(Note, Aircraft Spruce seems to have a type-o on the price of the latches. I’ve sent my contact there a note and I suspect that will be corrected soon as the going price is around $8.)
 
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Temp data with oil-door open?

Hello Bill

Thanks for print your results, this is really interesting!

Do you have any temp data from a shutdown with the oil door open?

Dominik
 
What is the issue with Pmag temps? Why different to old style mags?
Thanks.
Johan

Because of the electronics inside the Pmag, they have a maximum temperature recommendation. The installation instructions suggest installing a blast tube for cooling.

That's fine for in-flight cooling, but won't help post shut-down, which is where I suspect the highest temperatures are experienced.
 
Thanks

Bill, thanks for posting this info! In the NW we are still waiting for Summer heat so mine are good still!
 
Reducing P-mag temps

Howdy
Sent in my pmags for repair/inspection recently and Brad was concerned that I had experienced high temps, apparently over 200F. My CHTs are fine, about 265 in cruise on a warm day. My oil temp tends to be high on a warm day, 216F the other day, but thats not above the acceptable range. I do have blast tubes to the neck of each pmag, which are 113 bodies with 114 boards.

Im considering replacing the corrugated vinyl blast tubes with some smooth-walled rubber ones to get a little better air flow in them and possibly increasing their size slightly - I think they are currently around 3/4 inch diameter.

Im also considering replacing my oil cooler for a more efficient model that will likely lower oil temps around 10 degrees. Oil coolers aint cheap. Do you suppose slightly cooler oil will make have any significant differance in my pmag temps?

I currently do not have any way of monitoring the pmag temps, but could get some of the color coded temp indcating labels I suppose. If I cant get the temps down I may have to bite the bullet and switch to a Lightspeed ignition.

Any suggestions/comments?
regards,
erich
 
Howdy
Sent in my pmags for repair/inspection recently and Brad was concerned that I had experienced high temps, apparently over 200F. My CHTs are fine, about 265 in cruise on a warm day. My oil temp tends to be high on a warm day, 216F the other day, but thats not above the acceptable range. I do have blast tubes to the neck of each pmag, which are 113 bodies with 114 boards.

Im considering replacing the corrugated vinyl blast tubes with some smooth-walled rubber ones to get a little better air flow in them and possibly increasing their size slightly - I think they are currently around 3/4 inch diameter.

Im also considering replacing my oil cooler for a more efficient model that will likely lower oil temps around 10 degrees. Oil coolers aint cheap. Do you suppose slightly cooler oil will make have any significant differance in my pmag temps?

I currently do not have any way of monitoring the pmag temps, but could get some of the color coded temp indcating labels I suppose. If I cant get the temps down I may have to bite the bullet and switch to a Lightspeed ignition.

Any suggestions/comments?
regards,
erich


My CHT's almost always go to 400 during climbout. Normally the oil temp is 190-200.

I have a 3/4" corrugated plastic tube blowing on the neck.

My temp dot/tattle tale label on the 114 Pmag has never turned black.
 
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Erich,
It seems the heat is the culprit for ELECTRONIC failures. OUR recent failures are mechanical in nature. I suppose heat could be a contributing factor but I suspect the magnet attach method. Cooling the p-mag will help preserve the electronics but will have little effect on the magnet issue, IMO.

I haven't heard of any electronic type failures in quite awhile. What is your opinion?
 
Well, lots I dont know here. Doesnt seem out of the question that heat could be weakening the magnet and/or the attaching material, and just trying to do what I can, within reason. Brad at emagair was concerned about the temps and suggested I install louvers on my cowl. WHAT? Seems to me that an ignition system that gets installed inside the cowling should be able to handle temperatures that normally occur inside the cowling. Since my EGTs/CHTs/oil temps are all within the acceptable range, I have reason to believe that the temperatures inside my cowling are not out of the ordinary either. Should my ignition system really be the weak-link in terms of temperature tolerance? I had a good streak where it was working fine, but this last failure has given me some concerns.

erich
 
Brad at emagair was concerned about the temps and suggested I install louvers on my cowl. WHAT?
erich

HA!!! No, really, did he really say that? (I personally believe you :). )

I'm intrigued with the ongoing saga here. If you aren't careful, you guys just might make me go unearth my story (not quite yet). Not that I haven't told it to anybody that will listen.
 
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If you aren't careful, you guys just might make me go unearth my story (not quite yet).

Ah, yes, I remember this story and it's a good one. Tony, with your latest problems, you should get Scott to tell you about it.
 
How many have you had? All magnet related?

I have returned mine for some problem or recommended update 3-4 times now, although until the recent magnet failure I had a good streak of several years going and thought the problems were behind me. While I have always found them to be very responsive, Emagair often does not care to know what the problem is. Once they simply exchanged units with me, and another time they changed out the board and never went to the trouble to diagnose exactly what went wrong. Others have also had this experience - check the archives.

Dont know how to include multiple quotes in my message, but yes, Scott, he really did ask me to consider louvers. Kind of left a sour taste with me..

erich
 
HA!!! No, really, did he really say that? (I personally believe you :). )

I'm intrigued with the ongoing saga here. If you aren't careful, you guys just might make me go unearth my story (not quite yet). Not that I haven't told it to anybody that will listen.


Yes, do tell! I'm about to order my engine and dual pmags is topping the list at present.
 
Yes, do tell! I'm about to order my engine and dual pmags is topping the list at present.

Add another interested party to wanting to hear it. I have been contemplating to replace my slick with PMAG. Still gather info.
 
Add another interested party to wanting to hear it. I have been contemplating to replace my slick with PMAG. Still gather info.

Scott may be reluctant to post because his bad experience with the P-mags and the company were about five or six years ago, and things do change.

I personally am flying dual P-Mags on two airplanes, and having very good luck, both with the equipment and the company. YMMV

Paul
 
My CHT's almost always go to 400 during climbout. Normally the oil temp is 190-200.
I have a 3/4" corrugated plastic tube blowing on the neck.
My temp dot/tattle tale label on the 114 Pmag has never turned black.

My label has just turned black- probably due to heat soaked taxi and shut down in PHX AZ. 65 hours on a new 114 model. Anyone think of putting a fan on(with timer) for these PMags while taxiing to cool down after shutdown?
 
Oil Door

Brad,
What I would do before I installed a fan, is to put a small servo on the oil door. A small switch in the cockpit and you can open and close the oil door on the ground. You would be amazed at how much this would aid in cooling the compartment. (Don't forget to put "Oil Door - Closed" on your pre-takeoff checks though)

Dan
 
Tony,
Is that how you con Vlad into paying for lunch, beta test? Haha. Oh wait, he never pays right?

The mod is quite simple, a hangar mate in CA when I was there did it. He found out how much the oil door helps cool temps by 'accident' when he forgot to latch it on pre-flight. I will see if I can get some pictures and post here. I had planned to do the mod this last condition inspection, but ran out of time.

Dan
 
OK, it was hot again today. Like 111F when I taxied out hot. What a great time to test the P-mags again for heat soaking.

Same setup as listed above, same test, only this time I waited longer. Each sample was taken at five minute intervals, after shutdown.

OAT upon landing: 105F
Temps immediately after exiting the runway: 186F & 192F (Left & Right)
At shutdown: 186F & 192F
5 Minutes after shutdown: 192F & 192F
10 Minutes after shutdown: 179F & 204F
(No idea why the left P-mag reported 179 and then jumped back up 192F.)
15 Minutes after shutdown: 192F & 204F
20 Minutes after shutdown: 186F & 204F
25 Minutes after shutdown: 192F & 199F

BTW, I've been sharing these numbers with Brad and Tom at Emag.

I was asked if I could do these tests with the oil filler door open.

Since I haven't seen 104*F temperatures this entire year and fall has hit us, I still pulled the number this evening, just to see the trends.

OAT upon landing: 63F
At shutdown: 154F & 161F
05 Minutes after shutdown: 167F & 179F
10 Minutes after shutdown: 174F & 186F
15 Minutes after shutdown: 174F & 192F
20 Minutes after shutdown: 167F & 186F
25 Minutes after shutdown: 167F & 179F
30 Minutes after shutdown: 167F & 179F

The only way this will mean anything is if I have a chance to run the same numbers on a similarly cool day with the oil filler door closed. However, you can see that the numbers rise and then fall after 15 minutes. I wonder if the steady state temperatures are a result of the engine block heat soaking the P-mags.
 
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I was asked if I could do these tests with the oil filler door open.

Since I haven't seen 104*F temperatures this entire year and fall has hit us, I still pulled the number this evening, just to see the trends.

OAT upon landing: 63F
At shutdown: 154F & 161F
05 Minutes after shutdown: 167F & 179F
10 Minutes after shutdown: 174F & 186F
15 Minutes after shutdown: 174F & 192F
20 Minutes after shutdown: 167F & 186F
25 Minutes after shutdown: 167F & 179F
30 Minutes after shutdown: 167F & 179F

The only way this will mean anything is if I have a chance to run the same numbers on a similarly cool day with the oil filler door closed. However, you can see that the number rise and then fall after 15 minutes. I wonder if the steady state temperatures are a result of the engine block heat soaking the P-mags.
INTERESTING data set. It looks like with everything else being equal, max temperature (whatever the max is) will be around 15min after shutdown. A few more tests runs should verify/de-bunk this 15min idea but 3 runs with the same basic trend looks good.

THANKS for doing this and posting the results.

:cool:
 
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I wonder if the steady state temperatures are a result of the engine block heat soaking the P-mags.
Bill; Do you have a way of recording your oil temp after shutdown? If so, it would be interesting to correlate this with the P-mag temps you have recorded.

:cool:
 
Bill; Do you have a way of recording your oil temp after shutdown? If so, it would be interesting to correlate this with the P-mag temps you have recorded.

:cool:

Duh! Why didn't I think of that.

Yes, the SkyView continues to update the temperatures. Let me see if I can grab the data and correlate it to the P-mag temperatures. It will be close but not exact.
 
Duh! Why didn't I think of that.

Yes, the SkyView continues to update the temperatures. Let me see if I can grab the data and correlate it to the P-mag temperatures. It will be close but not exact.

Bummer, It looks like when I shut the plane down, I also powered down the SkyView. The log data doesn't exist, Oh well, I guess I'll have to do another flight.
 
Duh! Why didn't I think of that.

Yes, the SkyView continues to update the temperatures. Let me see if I can grab the data and correlate it to the P-mag temperatures. It will be close but not exact.
Cool. We don't need exact numbers only the trend. It would be very interesting if the oil temps also showed the same 15min trend.
Bummer, It looks like when I shut the plane down, I also powered down the SkyView. The log data doesn't exist, Oh well, I guess I'll have to do another flight.
That is why I asked if you could record the temps "After Shutdown". ;)
 
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FWIW: I flew today and kept my SkyView display on for 30min after engine shutdown. This is what the oil temps were:

Cruise Flight 208
Shutdown 196
5 Min 191
10 Min 187
15 Min 187
20 Min 186
25 Min 182
30 Min 179

At least with my airplane (Lycoming O360-A4M) there was no 15 Min peak of oil temp. I have no way of recording P-mag temps.

:cool:
 
FWIW:
At least with my airplane (Lycoming O360-A4M) there was no 15 Min peak of oil temp. I have no way of recording P-mag temps.

:cool:

The oil temp in the sump is at peak when the engine is running. The 15 min "Peak" discussed earlier in the thread is how long it takes for the higher engine temps to propagate into the P-mag. You have 350 degree cylinders and heads that are going to give off their hear to the surrounding engine components and the air inside the cowl. I am sure the oil inside the valve covers peaks well above 250 some time after shutdown.
 
In simple terms, when the cooling air stops, all component temperatures begin to equalize.
 
Yup, but we were looking to see if there was an equivalent temp trend between the P-Mags and Oil Temp once cooling air stopped flowing. At least with this one data point there doesn't seem to be one.

:cool:
 
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