Surefly Dual SIM

[NickG]

Would you do a single install instead?

[kortopates]

On the initial flight I climbed to 8k, leveled off and leaned to 50 ROP. CHT's went nutz  hitting 420 degrees in minutes.

50F ROP is maximum CHTs, about the worst place to operate an engine.
Richer would have brought the CHTs down on the ROP side.
But LOP is coolest.


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[takair]

As I recall, on the Ovation, the number two battery is trickle charged. I wonder if this might not be enough to run the Surefly in flight AND keep the battery charged. 

[FlyingDude]

On 7/12/2024 at 10:34 AM, N442PT said:

Just Finished the install of my dual Surefly SIM last night. The first start and ground run up was a noticeably smoother running engine and much faster start up. I will be test flying this weekend and will post some updates. 

Is this configuration robust against an alternator fail at take-off?  That's when the battery is at its lowest.

[Will.iam]

How did the A&P isolate the second battery and keep it charging? The surefly run off the alternator which is also charging the battery only when you have an alternator failure would the surefly then run off the battery. Maybe the second surefly wasn’t running off the alternator and only the battery, don’t see how that would be legal. Some one had a chart from surefly that showed when the surefly starts advancing the timing based on MP i can find that chart anywhere now but iirc the advance starts at 25” and advances farther as the MP goes down. Point being for takeoff or when you can get above 25” there is no advancing and the surefly fires at the fixed timing setting. Course as you climb, the MP will reduce to below 25 and you will see that in rising cht’s. 

[philiplane]

[KSMooniac]

I've installed the dual Electroair on my J with the IO-360-A3B6D (siamese/dual mag).  It was the first application AFAIK to get dual electronic ignitions approved, and since I have a single battery and electrical system, it required the installation of a dedicated backup battery (TCW unit, STC'd for this application) with a status panel to monitor its voltage.  This battery charges off the main system, and it only powers my #1 EIS and nothing else, so presumably it will keep the prop turning if everything else takes a dump at any time.  The status panel has LED indicators for EIS #1, EIS #2, and battery in-use as well as the voltage of the battery and a switch to turn on the battery circuit.  I like the design very much despite the extensive installation effort, but haven't flown it yet.  Hopefully we'll get my annual finished in the week or two and then off to test.  If you cannot be sure the Ovation dual system can be made to work like intended, this TCW system might be a good backup plan.

Electroair has a similar timing advance curve to what Phillip posted, except starting at 25° BTDC in my case.  I'm a LOP cruiser 100% of the time and am looking forward to more power/efficiency and am curious to see how difficult it will be to keep CHT's in check.  Our hot weather is pretty much over now so it might be 2025 before I get a final judgment.

[hais]

On 10/14/2024 at 2:41 AM, N442PT said:

Ok so I have 20 hrs on the dual Sim install. My Ovation has a second battery so my A&P wired them independently to each battery. Most of my flying is 8-10k and I always run ROP. On the initial flight I climbed to 8k, leveled off and leaned to 50 ROP. CHT's went nutz  hitting 420 degrees in minutes. After contacting Surefly I was told that the variable timing did not really work well with ROP flying. Decided to switch to fixed and everything went back to normal. Saturday on a long cross country flight Battery #2 failed. The result was exactly the same as the magneto that failed which is why I decided to go with the Surefly.  It was a hard bump followed by normal power and than about every 3 min another had bump. Not knowing what was wrong in air, I diverted to the closest airport to check it out. When I did a mag check Sim #2 shut down immediately. To get back home I transferred Sim#2 to Battery 1 and made it home with know issues. Looking back on my decision I would not do it again. I will send my mags off for overhaul and keep handy just in case.  

So here is my takeaway pros & cons 

• Very smooth engine performance
• Will be looking for a standby battery power gauge to monitor both battery voltages 
• No performance difference seen at this point 
• Hot starts are much better
• Faster cold start  

Did you perceive any reduction in fatigue after a long flight due to increased smoothness? That would be valuable. 

First time I flew a Continental, I was confident my teeth would fall off before I complete one pattern