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  #1  
Old 08-22-2017, 09:36 AM
FLY6 FLY6 is offline
 
Join Date: May 2010
Location: Stoney Creek On. Ca
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Default SDS CDI vs Pmag

I currently am flying behind two magnetos with a carburetor and am starting to investigate electronic ignitions. I have tried to keep up on any post regarding this subject. I am trying to determine the difference between SDS CDI and Pmag or if there are any significant differences as I would like to eventually change one mag to EI.

Any comments from people with either experience or knowledge in this field would be greatly appreciated.
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  #2  
Old 08-22-2017, 09:57 AM
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Toobuilder Toobuilder is offline
 
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This is a good place to start:

http://www.vansairforce.com/communit...d.php?t=140263

I started out with Pmags and they provided good service. They did exactly as promised. However, I gave the CPI a shot on my latest airplane and soon discovered just how limited the advance curve was on the Pmags. For my mission, the ability to tune the advance curve is the discriminator which strongly favors the CPI.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

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  #3  
Old 08-22-2017, 10:14 AM
FLY6 FLY6 is offline
 
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Default Chart Correction

Thanks for directing me to the chart.
I believe date in A&B 22 should be yes. From reading SDS's site, it states they are weather proof
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  #4  
Old 08-22-2017, 10:20 AM
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Brantel Brantel is offline
 
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Like Michael my original Pmag has worked exactly as advertised. I am currently in the process of installing a second one.

That being said, if I were not already in bed with the Pmag, I may have gone a different direction if I were starting out fresh today.

The SDS CPI would be very high on my list....

Pros: Complete monitoring and control of the ignition from cockpit (without any 3rd party add on box) including completely customizable and user selectable curves, no moving parts, electronics out of the heat and vibration, great quality components etc. are what would push me that way. Bonus are they are less expensive as well.

Cons: They are harder to install and the user must provide some sort of backup power scheme.

This list is not complete, just what would be important to me at this time.
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  #5  
Old 08-22-2017, 10:42 AM
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Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by Brantel View Post
Like Michael my original Pmag has worked exactly as advertised. I am currently in the process of installing a second one.

That being said, if I were not already in bed with the Pmag, I may have gone a different direction if I were starting out fresh today.

The SDS CPI would be very high on my list....

The Pmag is almost plug and play, no doubt. However, after doing several installations of each type, I dont find the CPI is much harder. The flywheel magnets are really the only items which require a bit of consideration.

I'm completely "pregnant" with dual Pmags on the -8 and I'm probably going to switch to CPI before too long.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
______________
Harmon Rocket II -SDS EFI instalation in work
RV-8 - Flying
1940 Taylorcraft BL-65 -flying

Last edited by Toobuilder : 08-22-2017 at 10:45 AM.
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  #6  
Old 08-22-2017, 10:49 AM
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DanH DanH is offline
 
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Minor note...the OP wrote "SDS CDI", and of course that should be "SDS CPI".

Capacitive Discharge Ignition (CDI) would describe a Lightspeed system. Very different operating principle.
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  #7  
Old 08-22-2017, 10:58 AM
Canadian_JOY Canadian_JOY is offline
 
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Location: Ontario, Canada
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Al - if buying Canadian means anything to you then SDS is the only choice! :-)

I have a P-Mag and a Slick impulse-coupled mag. The engine starts and runs very nicely on the P-Mag alone. Installation is easy. For me the discriminating factor was the self-powered aspect of the P-Mag. If I were to replace the Slick I would give serious consideration to using the CPI system, powering it from the Essential bus which has its own backup battery.

Ross Farnham has proven himself to be a real stand up guy and his products are well tested. The installation kit appears to provide top-quality components. I just wish the CPI controller wasn't quite so gaudy in its colour scheme... LoL
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  #8  
Old 08-22-2017, 01:08 PM
FLY6 FLY6 is offline
 
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Location: Stoney Creek On. Ca
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Default CPI, Correct

Dan is correct, I did mean CPI. Is my thinking correct to see the only big difference in the two unit would be that the SDS can be programmed for more advanced curves? If I am of the school where I lean using my tach as an indicator, would either unit be an advantage? If I am just putting one EI on, would I still need to put a separate power source for the SDS or would I count on my mag with an impulse coupler to start the engine?

As stated earlier, I am in the beginning stage of research so forgive me if some of the answers to my questions are simple.
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  #9  
Old 08-22-2017, 01:10 PM
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rv6ejguy rv6ejguy is offline
 
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Preliminary design work on the next gen CPI will begin on Sept. 1 after we finish some additional engine running on our test stand this week.

All I can say so far is that it will be completely repackaged to take up about 1/4 the panel space of two of the current CPIs and there will be a single head to access optional dual boards, all integral. Also, the much hated green will be gone.

Pretty much all the proven software and basic hardware will remain as is.

Planned release is early 2018 but that's dependent on how busy we are with filling our regular orders and how long it takes to get it all developed and properly tested.

Looking for customer feedback on any additional features people might want.

We'll offer 4, 6 and 8 cylinder systems as we do now. They will all be released simultaneously so no waiting for a 6 cylinder system...
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Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 426.1 hrs. on the Hobbs,
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http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


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  #10  
Old 08-22-2017, 01:33 PM
tspear tspear is offline
 
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Location: Boston Area
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I still think it funny how Ross's poor green color gets maligned on multiple boards.

Good luck on the next release.

Tim
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