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07-17-2012, 04:09 PM
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Join Date: Jun 2011
Location: Mansfield Australia
Posts: 19
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One P-mag or one Light Speed CDI ignition?
I am thinking of either one P-mag or one Light Speed CDI ignition on my IO 360 in my RV 7a. Can you please give me the benefit of your experience? Do I put the single EI source on the right side? Bard ample
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07-17-2012, 05:32 PM
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Join Date: Oct 2005
Posts: 1,516
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LSE Plasma
Why the angry face? 
Making these decisions and many others were the most enjoyable parts of
building my airplane.
Can't tell you about Pmags but I have had great success with one LS ignition
and one magneto.
Electronic ignition for the top plugs and magneto for the bottom plugs.
Benefits are: easy starting, variable timing for maximum efficiency and
no moving parts.
__________________
Ernst Freitag
RV-8 finished (sold)
RV-10 Flyer 600 plus hours
Running on E10 mogas
Don't believe everything you know.
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07-17-2012, 05:42 PM
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Join Date: Jan 2008
Location: Ashland, OR
Posts: 2,574
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EI on the left
One of the advantages of the electronic ignition is the strong spark for starting, so I put mine on the left, in place of an impulse-coupled magneto.
And yes, it fires the top plugs.
The one small down-side risk is kick-back. If you have too low a voltage from a low battery and the starter doesn't quite get it cranking, the ignition may also loose its retarded spark feature and fire early. This (at least this is my understanding of the phenomenon -- others may correct me) can cause kick-back that can damage the starter.
So, just don't let the battery get so low 
__________________
Steve Smith
Aeronautical Engineer
RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet"
Hobbs 625
LS6-15/18W sailplane SOLD
bought my old LS6-A back!! 
VAF donation Jan 2020
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07-17-2012, 06:45 PM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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Both are good ignitions. The P-mag is much easier to install.
You can search to find the pro's and con's of both.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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07-17-2012, 09:59 PM
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Join Date: Aug 2009
Location: Redding,Ca
Posts: 633
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Whatchit!
Steve if you removed the impulse mag, you need to make sure you can't or don't ever start on the non impulse mag. You'll bust a starter or ring gear almost guaranteed.
I believe most leave the impulse mag and remove the non impulse so if needed you can still start on the mag or just use both without concern.
Tim
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07-18-2012, 07:40 AM
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Join Date: Jan 2005
Location: Boise, ID
Posts: 1,007
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Why Mix Ignitions?
The life-cycle cost of mags exceeds the initial higher cost of an EI: inspections, parts, expensive plugs and harness. Why are you retaining one mag? If it's fear that EI's are failure prone, why are you installing even one? Mags fail, too.
Then, you have increased your parts count, inventory needs, and skill set to service two ignitions types. Since the mag doesn't contribute much to the engine's operation with the EI lighting the fire sooner and hotter, why keep it?
John Siebold
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07-18-2012, 07:58 AM
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Join Date: May 2005
Location: Tuttle, Oklahoma
Posts: 2,563
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Quote:
Originally Posted by RV7ator
. . . why keep it?
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Old ways die hard. Old men hang on to old ways. Old men convince young men that old ways are better. Young men take up old man's ways. Young men become old men. New old men hang on to old ways. Old ways live on! 
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07-18-2012, 09:06 AM
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Join Date: Oct 2006
Location: Garden City, Tx
Posts: 5,145
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Quote:
Originally Posted by RVbySDI
Old ways die hard. Old men hang on to old ways. Old men convince young men that old ways are better. Young men take up old man's ways. Young men become old men. New old men hang on to old ways. Old ways live on! 
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That's largely true, we see it time and again. I'm in the same boat with ignition choice and I'll put in one impulse mag and one EI - but I'll tell you why and it has nothing to do with gray hair. I've modified my fuel system to eliminate the engine-driven pump and go with dual electrics pulling cool fuel directly from the wing (as a few others have done) and pushing forward under pressure to eliminate vapor lock issues on our tightly-cowled engines. That makes my airplane electron-dependent for continued flight - which means I have to take that into account. All my panel EFIS have internal backup batteries good for at least an hour, I will have a backup alternator, and an emergency bus that can shed almost all load if needed to keep the fuel pumps turning as long as possible if for some reason both alternators go Tango-Uniform. If I can shut off the EI and keep going on the mag, that's more load shed available to me in an emergency, and that's worth having it for me.
__________________
Greg Niehues - SEL, IFR, Repairman Cert.
Garden City, TX VAF 2020 dues paid 
N16GN flying 700 hrs and counting; IO360, SDS, WWRV200, Dynon HDX, 430W
Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
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07-20-2012, 11:01 AM
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Join Date: Oct 2011
Location: Atlanta
Posts: 878
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Quote:
Originally Posted by RVbySDI
Old ways die hard. Old men hang on to old ways. Old men convince young men that old ways are better. Young men take up old man's ways. Young men become old men. New old men hang on to old ways. Old ways live on! 
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Yeah, we'll, maybe. But there are other considerations, particularly if you are modifying and already flying airplane rather than building.
In my case the single most important factor is safety/redundancy. Removing a bendix d3000 dual mag that has many failure modes than can take out both ignitions with an electronic version that also has failure modes that can take out both ignitions is fruitless. So, that implies dual circuits, dual batteries, additional annunciation etc etc. doing only one side is a significantly easy install to achieve the same goal.
__________________
RV-8 IO-360 (Bought)
RV-6 O-360 C/S (Sold)
Walkman aka Flame Out
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