P-Mag Operating Temperatures

[eddieseve]

Originally Posted by jakej

Eddie

I have a shipment about ready to go to OZ, we can share the shipping cost if you want.

Jake J

Running 2 P-Mags with 200+ hrs so far, all's good !!

Thanks Jake, but I'm not quite ready at present

Cheers

[WAM120RV]

Hi

I am about to order a commander, but noticed on the Spruce website that the display appears to be connected to the brain box by a 6 inch ribbon. This would not be long enough for my set up. Is it possible to get a longer ribbon?

[N941WR]

Originally Posted by WAM120RV

Hi

I am about to order a commander, but noticed on the Spruce website that the display appears to be connected to the brain box by a 6 inch ribbon. This would not be long enough for my set up. Is it possible to get a longer ribbon?

That is for the old rectangular EIC, which we no longer manufacture due to issues with getting parts. The only one currently available is the round EIC, which is completely self contained and does not require any kind of external brain box.

Sorry about the confusion.

[Bavafa]

Looks like I am getting a second Pmag and if I can find a space on my panel, I would also get a EIC. I would hate to lose any of my current instrument to replace it with this.

[FasGlas]

Now that I had a chance to get some flights in and get the data the OP asked for to begin with... Here's two pics of the pmag temps on a tightly cowled 360 engine. One is inflight and the other is right after landing and refueling, giving the pmags some time to soak up some heat. By the data shown it looks like the pmags are well within the operating temps prescribed by Emag. Granted, this wasn't a 110 deg OAT day but it's also not a 50 deg OAT either. Adding 30 ~ 40 more degs OAT would take the pmags to their published limit but there has been no indication of my pmags not firing on a hot summer day in SoCal.

[lr172]

Originally Posted by Walt

Not really a good answer IMO, if this is really important then perhaps this "restrictor" should be supplied with each Pmag?

Obviously timing is adjusted using MP as an input, perhaps some of the problems being talked about here might have been caused by fluctuations at the MP line?

Or maybe business is slow and now everyone with a Pmag needs run out and buy an EIC

Walt,

Restrictors can be a critical piece depending upon how the software smooths out the jumpy MAP readings. When I installed my Dynon 120 on my O-320, the MAP was jumping around with a good 5" variability. A .040" restrictor smoothed it out nicely. When I put a custom EFII on my Porsche, I had a lot of issues that were solved by installing a large vacuum accumulator another method of smoothing). The software in that particular EFI didn't do a good job smoothing out the fluctuating vacuum signal and it needed to be done mechanically.

I can't speak to the Pmag, but ignition systems do need stable MAP/vacuum readings to perform properly.

Larry

[nigelspeedy]

So my engine has dual Mags. Originally I installed a vertical card standby compass on the right hand side of the instrument panel but it turns out if the two back up batteries for the EFIS that are always charging in flight are close by the heading indications are not that reliable. Kind of like the watch with a flat battery that is right twice a day. So what to do with a 2 odd inch hole in the instrument panel? Well putting in an EI commander seemed like the most sensible and useful answer.

My engine has 140 hours on it since new. I have had air blast tubes off the back of the plenum since new as per the PMag instructions. I also installed some temperature sensitive tape on installation to keep an eye on temperatures. With a new engine that started flying in the SOCAL summer my oil temperatures have not exceeded 190F. Coincidentally the temperature tape on the body of the Mags also shows 190F.

Using the EICommander I see that the maximum temperature recorded to date is 255C. I think this may violate a few laws of thermodynamics as this equites to 491F. Today with an OAT of 18C the pre start current PMag temp was 6 & 3C. After taxi and runup was complete with engine oil temp of 124F the EI Commander showed PMag temps as 20C and 10C. After a climb from 4,000' to 10,000' where the OAT was 4C and with an engine oil T of 174F the PMag showed 34C and 23C. After 20 minutes of cruise with engine oil T of 175F the Mags showed 48C and 34C.

Based on the above I consider the PMag temperature sensors to be inaccurate and of no practical value. It seems to me that a large metal object bolted to the back of the engine accessory case will likely be same temperature as the engine oil that is splashed around inside said case.

Given the instructions were to install blast tubes and there is anecdotal evidence that high temps may not be good for the PMags it does not meet my risk/reward level to repeat the experiment without the blast tubes.

Sorry for mixing units but I think the discrepancies are pretty clear.

For your consideration

Nige

[N941WR]

You are correct, the temperature sensors on the P-mags are not calibrated and occasionally record the maximum temperature you observed.

Unfortunately, the only way to reset the Max Temp is to send them back to Emag.

[FasGlas]

This is why I added my own temp sensors to the pmags. I've posted the inflight and after flight temp readings. They are will within emag's published parameters. Emag says not to use the pmag temp readings.

[RhinoDrvr]

I just noticed that my temp stickers on my PMAG?s were both black. Odd since they went through a summer in the mojave desert without turning black, but sometime recently they went black (since the last oil change).

My oil has never been above 210 ever, and is normally 190 in flight. CHT?s are 320-350 with a max of 380. I?ve ordered some new temp stickers with a range of indicators so I can tell exactly how hot the PMAGs are getting.

Think this is cause for concern? I have blast tubes and my cooling to all other engine components seems nominal. My guess is that a heat soak during a quick turn in 90-100 degree OAT?s is the cause.

I?ve never had an issue with the ignitions, but am wondering if I?m setting myself up for an issue?