Surefly mags
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
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- Posts: 1421
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Surefly mags
Has any body had any experience with the solid state mag SUREFLY . I can hear the rumblings all ready saying this a constant speed engine [4 cylinders type ] normally . But my response is I run a fixed pitch prop and my RPM is viable while my engine is at 25deg before TDC all the time [except starting ] so maybe advancement could help . They retard themselves on starting . I am asking before purchasing . Is there any fuel saving ? Or smoother running?
- n2582d
- Posts: 2998
- Joined: Mon Apr 29, 2002 4:58 am
Re: Surefly mags
How is it that Surefly has the STC to install a SIM (Surefly Ignition Module) on the C-170 yet apparently doesn’t yet have the unit certified? One can only buy a “pre-certification unit” now for $1550.
Gary
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Re: Surefly mags
A buddy installed one on his C206 and claims he likes it now.
He had a weak battery to start with and when he tried to start the engine, battery voltage dropped below 9 volts, if I remember correctly, and the unit dropped offline. Now he has a good battery and it works ok.
He had a weak battery to start with and when he tried to start the engine, battery voltage dropped below 9 volts, if I remember correctly, and the unit dropped offline. Now he has a good battery and it works ok.
Richard Pulley
2014-2016 TIC170A Past President
1951 170A, N1715D, s/n 20158, O-300D
2023 Best Original 170A at Sault Ste. Marie
Owned from 1973 to 1984.
Bought again in 2006 after 22 years.
It's not for sale!
2014-2016 TIC170A Past President
1951 170A, N1715D, s/n 20158, O-300D
2023 Best Original 170A at Sault Ste. Marie
Owned from 1973 to 1984.
Bought again in 2006 after 22 years.
It's not for sale!
- lowNslow
- Posts: 1535
- Joined: Mon Apr 22, 2002 4:20 pm
Re: Surefly mags
They kind of explain that here.n2582d wrote:How is it that Surefly has the STC to install a SIM (Surefly Ignition Module) on the C-170 yet apparently doesn’t yet have the unit certified? One can only buy a “pre-certification unit” now for $1550.
Karl
'53 170B N3158B SN:25400
ASW-20BL
'53 170B N3158B SN:25400
ASW-20BL
- n2582d
- Posts: 2998
- Joined: Mon Apr 29, 2002 4:58 am
Re: Surefly mags
I guess I'm just slow to understand. Everything else on their website gives me the impression the ignition module is certified. Maybe they just haven't updated this page which refers to "pre-certification units".
Gary
- lowNslow
- Posts: 1535
- Joined: Mon Apr 22, 2002 4:20 pm
Re: Surefly mags
I not sure what they are saying either but it seems before certification you installed them using an STC and afterward they are considered certified replacements. Maybe those mags produced prior to be certification are not considered certified and MUST be installed using an STC???
Karl
'53 170B N3158B SN:25400
ASW-20BL
'53 170B N3158B SN:25400
ASW-20BL
- rupertjl
- Posts: 384
- Joined: Thu Jun 17, 2004 5:29 pm
Re: Surefly mags
They required an engine STC and an airframe STC. So the units have passed certification under FAR 33 rules and that's why SureFly can say its certified. They're having some troubles getting the full features of the EIS with the AML STC. If anyone wants more info you can email me personally.
jrupert@lycoming.com
-Jud
jrupert@lycoming.com
-Jud
1950 170A: N9191A s/n 19366
- cessna170bdriver
- Posts: 4109
- Joined: Mon Apr 22, 2002 5:13 pm
Re: Surefly mags
Electroair here in Howell Michigan also has an electronic ignition certified for the O-300. But, at about 5.5 AMUs (before installation), it would take over a thousand hours to pay for itself, even if it saves as much as 1gph running $5 avgas. I’m not at all certain I have that much flying left in me. My Dad was probably right when he said fuel is one of the cheapest things you can put in an airplane. 

Miles
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
- edbooth
- Posts: 498
- Joined: Wed Nov 24, 2004 3:03 am
Re: Surefly mags
I may have paid for mine, have run an Electroair on my RV-7 for 14 years and 1200 mostly trouble free hours (had to replace the pickup probe) runs very smooth. Use REM37BY plugs in order to gap to .35 .cessna170bdriver wrote:Electroair here in Howell Michigan also has an electronic ignition certified for the O-300. But, at about 5.5 AMUs (before installation), it would take over a thousand hours to pay for itself, even if it saves as much as 1gph running $5 avgas. I’m not at all certain I have that much flying left in me. My Dad was probably right when he said fuel is one of the cheapest things you can put in an airplane.
Ed Booth, 170-B and RV-7 Driver
- lowNslow
- Posts: 1535
- Joined: Mon Apr 22, 2002 4:20 pm
Re: Surefly mags
Just curious how efficient the variable timing feature is when the mechanical mag will always be firing using fixed timing? (I realize that feature is not approved yet)
Karl
'53 170B N3158B SN:25400
ASW-20BL
'53 170B N3158B SN:25400
ASW-20BL
- rupertjl
- Posts: 384
- Joined: Thu Jun 17, 2004 5:29 pm
Re: Surefly mags
the variable timing unit will be firing first when advanced, so its like you're running a single ignition and the regular mag will be there as a wasted spark.
1950 170A: N9191A s/n 19366
- n2582d
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- Joined: Mon Apr 29, 2002 4:58 am
Re: Surefly mags
With a two degree difference in spark advance between our left and right Bendix mags is the right magneto just along for the ride?
Gary
- cessna170bdriver
- Posts: 4109
- Joined: Mon Apr 22, 2002 5:13 pm
Re: Surefly mags
I would say no, since, even in cruise, you get a slight power drop when switching to either mag.n2582d wrote:With a two degree difference in spark advance between our left and right Bendix mags is the right magneto just along for the ride?
Miles
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
- GAHorn
- Posts: 21262
- Joined: Fri Apr 12, 2002 8:45 pm
Re: Surefly mags
Two spark plugs modify the flame propagation pattern and insure the air/fuel mixture is completely consumed. If you have an EGT gauge, if you switch to one mag, you'll observe an INCREASE in EGT because a portion of the combustion is occurring so late (as the gases exit the cylinder.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.

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