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  #1  
Old 06-30-2021, 08:30 AM
mc607 mc607 is offline
 
Join Date: Apr 2014
Location: Canada
Posts: 63
Default PMags

I will be ordering my new engine to avoid price increase. Canít decide on Pmags. Can anyone tell me their experience. Pros and cons. What is minimum rpm to generate their own power? Iíll be going with the standard io390 210 h.p.
Fuel savings? Reliability?
Thanks
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  #2  
Old 06-30-2021, 09:23 AM
bkervaski's Avatar
bkervaski bkervaski is offline
 
Join Date: Mar 2017
Location: Birmingham, Alabama
Posts: 1,853
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There are dozens (hundreds?) of threads on this with as many opinions.

Suffice to say that at this point any EI is a worthwhile upgrade from traditional mags and there are a lot of RVs with PMags.

Per the manual:

" ... the internal alternator will be unable to support the ignition somewhere below 900 rpm"

Reliable: Yes
Fuel Savings: Some
Easy: Yes
Worth It: Definitely

I started out with traditional mags and at 150 hours upgraded to dual PMags and have been very happy with them, easy starts and a smooth idle. Fair to say, there are other systems out there, each with their own pros and cons.

Note that unless something has changed, Lycoming will only ship with a single PMag and one traditional mag.

Edit: Regardless of how you order you can sell the traditional mag(s) (or the PMag if you want to use another system), they will move pretty quick if priced reasonably.
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Last edited by bkervaski : 06-30-2021 at 09:38 AM.
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  #3  
Old 06-30-2021, 10:00 AM
mc607 mc607 is offline
 
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Location: Canada
Posts: 63
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Thanks for the reply. Have you tested yours to see what the rpm actually is when they stop producing power? What is your rpm setting on final?
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  #4  
Old 06-30-2021, 10:07 AM
bkervaski's Avatar
bkervaski bkervaski is offline
 
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Quote:
Originally Posted by mc607 View Post
Thanks for the reply. Have you tested yours to see what the rpm actually is when they stop producing power? What is your rpm setting on final?
Not scientifically, however, I understand that they can vary, 900 is the official safe spot. It's just not an issue, they don't draw much, so idling around the airport isn't really a factor or problem.

You aren't going to get below 900 rpm on final, even if you try.

While my power setting on final is "whatever it needs based on all the factors" I'm typically at 18 on downwind and 13 after I turn final then idle over the threshold (shooting for 70-75kts), but even at idle on final the wind through the prop still turns it north of 1000rpm, so the PMag generators are still running.
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Last edited by bkervaski : 06-30-2021 at 10:17 AM.
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  #5  
Old 06-30-2021, 10:17 AM
mc607 mc607 is offline
 
Join Date: Apr 2014
Location: Canada
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Quote:
Originally Posted by bkervaski View Post
Not scientifically, but mine is around 850, however, I understand that they can vary, 900 is the safe spot. It's just not an issue, they don't draw much, so idling around the airport isn't really a factor or problem.

You aren't going to get below 900 rpm on final, even if you try.

While my power setting on final is "whatever it needs based on all the factors" I'm typically at 18 on downwind and 13 after I turn final then idle over the threshold (shooting for 70-75kts), but even at idle on final the wind through the prop still turns it north of 1000rpm, so the PMag generators are still running.
Thanks. An EI that produces its own power, makes the most sense.
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  #6  
Old 06-30-2021, 10:20 AM
bkervaski's Avatar
bkervaski bkervaski is offline
 
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Quote:
Originally Posted by mc607 View Post
Thanks. An EI that produces its own power, makes the most sense.
I think the PMags are popular because they are the most "plug and play" install/retrofit with good general settings that suite most people.

However, if you want the ability to tweak and tune, there are lots of options.

Edit: When researching, note the dates of the threads. Some have formed (understandable) opinions on some of these systems based on problems that are ancient history.
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Last edited by bkervaski : 06-30-2021 at 11:50 AM.
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  #7  
Old 06-30-2021, 11:34 AM
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Walt Walt is offline
 
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Personally not a fan of pmags on the angle valve engines, which includes the 390, due to the aggressive advance.
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  #8  
Old 06-30-2021, 11:47 AM
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Carl Froehlich Carl Froehlich is offline
 
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Location: Dogwood Airpark (VA42)
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Quote:
Originally Posted by Walt View Post
Personally not a fan of pmags on the angle valve engines, which includes the 390, due to the aggressive advance.
I do not agree. For either the parallel or angle head engines I recommend a maximum of 9 degrees advance. For the parallel valve engine this is 25 - 34 degree BTDC, for the angle head engines this is 20-29 degrees BTDC.

I installed dual pMags on an RV-14A with the IO-390 a few years ago. It is performing well.

Carl
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  #9  
Old 06-30-2021, 12:50 PM
Bevan Bevan is offline
 
Join Date: Sep 2007
Location: BC
Posts: 1,710
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Quote:
Originally Posted by mc607 View Post
I will be ordering my new engine to avoid price increase. Can’t decide on Pmags. Can anyone tell me their experience. Pros and cons. What is minimum rpm to generate their own power? I’ll be going with the standard io390 210 h.p.
Fuel savings? Reliability?
Thanks
Min RPM, ~900 rpm, tough to do in flight and ship’s power is the backup anyway.
Fuel savings? yes. I typically burn 7.3gph at 60-65% = 160KTAS cruise (RV7A 180hp parallel valve).
Reliability? Excellent. Two sources of independantly controlled ignition, each with two sources of electrical power, and only one moving part each. If you take the time to understand their operation, including how to properly setup, test, control, and identify their failure modes, there’s nothing better in my opinion except for turbine power. I fly over Coastal and Rocky Mountains ranges and large bodies of water. I would be more concerned with magnetos but that’s just me.
Customer service? Excellent!

Do you own research, make informed choices and move forward.

Bevan
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O-360-A1F6 (parallel valve) 180HP
Dual P-mags
Precision F.I. with AP purge valve
Vinyl Wrapped Exterior
Grand Rapids EFIS
Located in western Canada
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  #10  
Old 06-30-2021, 01:04 PM
Dave12 Dave12 is offline
 
Join Date: Oct 2010
Location: Elkton, Md.
Posts: 1,725
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A few years ago I bought the first airplane Iíve had in 30 years that I didnít build. The smart guy that built my current mount had previously installed dual pmags after trying a combination of light speed and Slick ignitions, which he ultimately abandoned. Being a believer in mags, I procured a set of mags, harnesses, spacers, etc. in anticipation of just knowing that these pmags were not going to cut the mustard. Long story shortened, the pmags are staying, they are excellent. Starts quick and they help my little 165 hp io 320 run like a scalded rat. Btw, I have a set of mags for sale.
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