Surefly SIM

I may be installing a Surefly. I went to do some pattern work Sunday and on lap 4 smelled hot electrical. Turning crosswind I noticed a bit of smoke , informed the tower ( no emergency ) and landed . Found a ground wire had gotten hot so I started poking around and found a bare spot on a wire I thought was the culprit
Went out yesterday and on lap one smoke again . Landed and taxied back and started to suspect ignition issues as the engine wanted to die if I applied carb heat .
Felt the Electroaire Controller mounted under the dash and it was very hot . The Electroaire Mag was extremely hot. I think with that much heat it’s done. I will be on the phone this morning but with the controller alone costing 1600 I don’t see myself staying with electroaire.
I will also be on the phone with Surefly
 
So far I’m happy with the SureFly. Have about 5 hours on it. The engine runs smoother than before with the old mags. When I do the mag check on the SureFly, there is a slight hesitation (some other SureFly owners have told me they hear a little “pop”, but I don’t). I will do a fuel burn test soon to see if there is any reduction in G/H compare to the old mags.

Juergen
Pacer N3342Z
 
So far I’m happy with the SureFly. Have about 5 hours on it. The engine runs smoother than before with the old mags. When I do the mag check on the SureFly, there is a slight hesitation (some other SureFly owners have told me they hear a little “pop”, but I don’t). I will do a fuel burn test soon to see if there is any reduction in G/H compare to the old mags.

Juergen
Pacer N3342Z

Juergen,

You kept your original Bendix mag with the impulse coupler, correct? Do you plan to change the dip switches in the future to allow variable timing of the SIM? You'll have to add a Manifold Pressure tap as I understand it, and a CHT system.

If I go the SureFly route, I'm going to go with the variable timing SIM, and I'm strongly considering replacing the fixed timing mag with it. That way both the impulse coupled original mag and SIM would retard on start and I can start with "both" selected on the mag switch.

I was talking to a SureFly rep and another pilot at OSH about this and, when I asked the question about using the variable timing SIM in concert with the impulse coupled (Left) mag, the SureFly rep replied that that was not "typically done". The other pilot standing there at the booth got kind of wry smile and said he had just done that very same setup even though they (SureFly) do not recommend it. He said, "it works great!"

The Rep said the standard setup from them is to configure the dip switches with fixed timing, if you change out the fixed timing (Right) mag, and if you replace the Left mag, they configure the SIM for variable timing which gets you the startup retard function along with more total advance capability (up to 38 degrees, I believe).

I'm curious why they would not recommend the original impulse coupled mag be paired with the variable timing SIM? Maybe Steve knows...I know at least one pilot out there has done it and reported great results. The Rep just sort of shrugged his shoulders like it didn't matter...

Thanks,
-Subsonic
 
I didn’t plan on installing the SureFly right now. When servicing the right mag it turned out it needed to be replaced. So I replaced it with the SureFly. I don’t have an engine monitoring system, so I can’t use the variable timing (plus the PA-22 is not on the STC yet).
I kind of like to have the original left mag with the impulse coupling. In case if the Batterie is dead, I can had prop using the left mag and as soon as the alternator kicks in the SureFly should fire.

Juergen
Pacer N3342Z
 
I have been installing the SureFly in place of the impulse mag to eliminate issues with the impulse coupling. A small 9 volt battery is enough to power the SureFly for start.
 
Be sure to disconnect the nine volt battery after start before you put the alternator or generator on line.
 
So far I’m happy with the SureFly. Have about 5 hours on it. The engine runs smoother than before with the old mags. When I do the mag check on the SureFly, there is a slight hesitation (some other SureFly owners have told me they hear a little “pop”, but I don’t). I will do a fuel burn test soon to see if there is any reduction in G/H compare to the old mags.

Juergen
Pacer N3342Z

My real life technical experience with another electronic system is that the fuel savings are insignificant. The idea was born from a lack of significant benefits other than smoother engine operation less perceived maintenance.

The idea is that with electronic ignition combined with manifold pressure mapping to advance the timing you are converting more chemical energy (fuel) into heat energy (expanding burnt fuel) thus more power. With the increased power of the electronic system you may see a 50 RPM rise in comparison to that of standard mags with fixed timing all with a given throttle valve position. So the idea is you throttle back the 50 rpm to reduce the throttle valve position, thereby less fuel consumed all while making the same power you used with standard mags.

The fault with that thinking or idea is that manifold pressure on a normally aspirated engine is really just the restriction provided by the throttle valve. Low angle of the throttle valve like 1500 rpm, partially open, restriction gives you 10 to 15 inches of vacuum. Go to full throttle, valve is fully open no restrictions, lets say 29 inches or outside barometric pressure. At that full throttle manifold pressure the MP map is going to drive the timing right to the manufactures fixed timing. The only thing that will change the timing on the map is going to an extremely high altitude, dropping the manifold pressure. One of our customers set a lot of high altitude cross country records and saved a little gas in the process. Personally I have logged a lot of time flying with customers with a laptop attached to the ECU and have never seen the timing advance to the ranges 38 degrees BTDC like advertised.

Also if your alternator is not "self exciting" a dead battery will not power the field, leaving the system inop.
 
My real life technical experience with another electronic system is that the fuel savings are insignificant. The idea was born from a lack of significant benefits other than smoother engine operation less perceived maintenance.

The idea is that with electronic ignition combined with manifold pressure mapping to advance the timing you are converting more chemical energy (fuel) into heat energy (expanding burnt fuel) thus more power. With the increased power of the electronic system you may see a 50 RPM rise in comparison to that of standard mags with fixed timing all with a given throttle valve position. So the idea is you throttle back the 50 rpm to reduce the throttle valve position, thereby less fuel consumed all while making the same power you used with standard mags.

The fault with that thinking or idea is that manifold pressure on a normally aspirated engine is really just the restriction provided by the throttle valve. Low angle of the throttle valve like 1500 rpm, partially open, restriction gives you 10 to 15 inches of vacuum. Go to full throttle, valve is fully open no restrictions, lets say 29 inches or outside barometric pressure. At that full throttle manifold pressure the MP map is going to drive the timing right to the manufactures fixed timing. The only thing that will change the timing on the map is going to an extremely high altitude, dropping the manifold pressure. One of our customers set a lot of high altitude cross country records and saved a little gas in the process. Personally I have logged a lot of time flying with customers with a laptop attached to the ECU and have never seen the timing advance to the ranges 38 degrees BTDC like advertised.

Also if your alternator is not "self exciting" a dead battery will not power the field, leaving the system inop.
Todd, do you think the lack of fuel savings and performance gain was the FAA being so conservative with the engine parameters? I remember Harry and I think you relating some of that years ago.
 
Harry was very good at putting a spin on things. As I wasn’t around for the certification process, Harry told me that the addition of the CHT parameter was driven by the airframe manufacturers, specifically Piper and Cessna. Adding the CHT parameters changed the mapping from a simple X and Y plot to a limited authority, closed loop, or whatever you want to call it three dimensional plot or map. The reasoning was that if you advanced the timing the fuel air mixture was burning longer inside of the cylinder. For example you start the burn now at 38 degrees before TDC on the compression stroke and it isn’t expelled until 15 degrees ATDC on the exhaust stroke. That heat will drive up the CHT. Piper says their hottest cylinder, based on cowl design…baffling.. is #3. Cessna #4. How can you control CHT on different aircraft? Give authority to the ECU and add a 3rd dimension to the map. Harry blamed the added CHT loop for limiting the advance and inhibiting fuel economy. In practice I noted that the non CHT and CHT controlled ECUs both advanced the same at normally aspirated absolute Manifold pressures in cruise flight.

Electro air, Surefly are two dimensional maps. That is why you, the pilot have to use a GEM or CHT gauge with the vacuum advance. You are the authority, the human computer, to shut the advance down and manage CHT. Of course only if you elect to use it and turn on the dip switches and your manifold pressure is low enough at cruise altitude to drive the advance.
 
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If you have the hawker battery installed you will need a new battery.

If you have Slick mags you can reuse the harness although they recommend new plugs and harness.

STC says you can tap into existing Manifold pressure lines.

SIM will draw power continuously from the battery in standby mode, so you will need a maintenance charger when not in use sitting in the hangar.

Pinging this old thread because I ordered a SureFly SIM4P earlier this week.

I don't see any reason to replace my Hawker J16 battery. Installation specs say:
2.2. Power Requirements:
The data herein prescribes only requirements for a SIM to operate safely. The requirements below DO NOT constitute authority to connect a SIM to an aircraft electrical system, to install electrical devices or to modify the electrical system of an aircraft.
Operating power requirements @ 2700RPM (w/ safety factor added in): Model: @ 14VDC @ 28VDC
SIM4P
1.0A
0.5A
For engines equipped with a single SIM:
1. The first SIM on an engine must be powered directly from the primary aircraft battery, and
2. The primary aircraft battery must be 10-30V and be able to provide a 10A peak current demand to the SIM.

Odyssey/Hawker/Powersafe specs all say 15Ah, with 25 minutes at 25 Amps reserve capacity. What am I missing?

Also, I'm replacing a Bendix mag, so have to buy half a Slick Harness. What do you guys like/use?

Champion has coiled conductor wire and claims high flexibility and tight turns without breaking even after thousands of heat cycles. They also say their wires reduce RFI so retains high sensitivity of VHF radios. They say other wires may reduce radio sensitivity by 50%.

SureFly has recommendation for Maggies Ignition Systems harness. https://www.newhorizonsmaggieaircraftignitionsystems.com/maggie-ignition

They have a screw-in type Slick cap allowing single HT lead replacement as an option. But they have a 7 strand steel conductor. Maybe not too flexible. And they don't mention RFI. I don't want to noise my radios.

Please comment.

Thx,
-Subsonic
 
I have the SureFly SIM on my Super Cub with a SBJ16 battery. I have had no issues and according to my contact at SureFly I am all good. I have a friend who installed the SureFly on his and his wifes L21 Super Cubs and used the Kelly harness. I like what I read on Maggie's and plan to use them on the next one I install which is here waiting now. I just need to order the harness.
 
Pinging this old thread because I ordered a SureFly SIM4P earlier this week.

I don't see any reason to replace my Hawker J16 battery. Installation specs say:
2.2. Power Requirements:
The data herein prescribes only requirements for a SIM to operate safely. The requirements below DO NOT constitute authority to connect a SIM to an aircraft electrical system, to install electrical devices or to modify the electrical system of an aircraft.
Operating power requirements @ 2700RPM (w/ safety factor added in): Model: @ 14VDC @ 28VDC
SIM4P
1.0A
0.5A
For engines equipped with a single SIM:
1. The first SIM on an engine must be powered directly from the primary aircraft battery, and
2. The primary aircraft battery must be 10-30V and be able to provide a 10A peak current demand to the SIM.

Odyssey/Hawker/Powersafe specs all say 15Ah, with 25 minutes at 25 Amps reserve capacity. What am I missing?

Please comment.

Thx,
-Subsonic

I had looked at using the Surefly on my aircraft with a Hawker battery. If you look at the electrical load on the attached drawing, I was concerned that in an electrical failure, alternator, etc...that a 16 amp hour capacity was not enough for my planned type of flying. When you consider the hawker battery is the primary source of power for the SIM module, now take out 6 amp for a radio transmission, and whatever else you have that you consider essential for safe flight until that runs out, about an hour. You are then running on backup. Nothing in the POH supplement about load shedding, (notice I put a separate bus and avionics switch to shed load) time to land in case of electrical failure. Section 3-4 is for the dual sim application but it does require you to do a electrical load analysis. You should at least consider doing that for your application.

The Hawker battery was designed as backup or reserve battery for transport category aircraft. When used a reserve power source for a backup attitude indicator lets say it could pull 25 minutes of 25 amps to get you back on the ground in case of total electrical failure. Aircraft battery size (and weight) is directly tied to capacity. So if you got the lead acid 35 that is good for pulling 35 amps for and hour. With a sealed battery there is no way to determine battery health other than a capacity test. Can't do the specific gravity test at annual time. A capacity test is nothing more than attaching a 16 amp load to discharge the battery and starting the stopwatch. Did not make it an hour before it went flat, no good, replace before flight. Its not its ability to crank but to hold a charge.

Todd
 

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Thanks Todd,

That's a very conservative analysis with conservative assumptions and illustrative of a worst case scenario. Great schematic. I have a B&C 40 amp alt, too. I don't have the same gauges. No JPI or AV20, but I do have similar demands from EI fuel flow, tach, EGT/CHT instruments, so call that even...

If I take a somewhat less conservative list of assumptions and known power demands for my plane specifically, they would include the following:

1) Much lower power demand for the all the lights. My plane has LED's everywhere. And, I don't run lights typically. They're only on at night. Subtract 18 Amps from your load analysis. If it's night and my lights are really on, add back 5 Amps for all my LED lights.

2) Why do you need an hour to figure out where to land? Fuel requirements dictated by the FAA say 1/2 hour reserve in daylight, 45 minutes at night. I think that's probably a good baseline for reserve electrical power requirements for the same plane. Don't you? So, 30 or 45 minutes, not 60.

3) So, my daytime 30 minute power demand is closer to 14 Amps, not 32, and nighttime 45 minute demand is 19 Amps. I think the 15 to 16 Ahr Hawker can handle it. As you suggest, only a load test would prove it.

Bottom line: I'm retaining one magneto. Plane keeps flying in event of total electrical power failure for as long as I have fuel.

-Subsonic
 
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Thanks Todd,

That's a very conservative analysis with conservative assumptions and illustrative of a worst case scenario. Great schematic. I have a B&C 40 amp alt, too. I don't have the same gauges. No JPI or AV20, but I do have similar demands from EI fuel flow, tach, EGT/CHT instruments, so call that even...

If I take a somewhat less conservative list of assumptions and known power demands for my plane specifically, they would include the following:

1) Much lower power demand for the all the lights. My plane has LED's everywhere. And, I don't run lights typically. They're only on at night. Subtract 18 Amps from your load analysis. If it's night and my lights are really on, add back 5 Amps for all my LED lights.

2) Why do you need an hour to figure out where to land? Fuel requirements dictated by the FAA say 1/2 hour reserve in daylight, 45 minutes at night. I think that's probably a good baseline for reserve electrical power requirements for the same plane. Don't you? So, 30 or 45 minutes, not 60.

3) So, my daytime 30 minute power demand is closer to 14 Amps, not 32, and nighttime 45 minute demand is 19 Amps. I think the 15 to 16 Ahr Hawker can handle it. As you suggest, only a load test would prove it.

Bottom line: I'm retaining one magneto. Plane keeps flying in event of total electrical power failure for as long as I have fuel.

-Subsonic

My A&P/ IA responsibility as the signing installer is to ensure that this modification is compatible with other previous modifications. In this case its the Surefly and the Hawker battery. In consideration of my responsibilities you have to add my 42 years of experience in dealing with regulatory agencies, both certifying and and enforcement. My experiences with signing off FAA 337s, using faulted manufactures instructions that were certified by one branch of the FAA, which were later used by another branch of the FAA to violate my license. I have also worked in a certified parts manufacture environment, so I understand the gap in "white paper" design versus the real world application.
 
I maintain 5 NX Cubs and from time to time X Cubs all have tow SIMs. You can add a back up battery like Cub Crafter's has done and is in process by SureFly on their dual SIM STC. In my Super Cub, on the event of an alternator failure I have at least 45.minites to get on the ground if not longer. I don't fly at night so that is a plus. Even when going to Utah I can land somewhere safely. Definitely something to consider but not a huge concern for me unlike my old Slick/Champion magneto failing prematurely. I have Bendix on the other side of this engine and have found them to be more reliable that the Slick.
 
In consideration of my responsibilities you have to add my 42 years of experience in dealing with regulatory agencies said:
Sorry Todd,

I think you should know the SureFly SIM is not an early white paper design in a development process. I believe a certified aircraft component for certified airplanes is one which meets FAA standards of acceptance on many criteria that you may want to look at (again?) before you proclaim the SureFly ignition module to be some sort of white paper concept, so that you don't continue to misrepresent it.

The SureFly STC does not state how much capacity a battery must have. It only states the power demand requirement to power the SIM.

The Hawker/Odyssey battery specs do not state anything more than its capacity and its demand/load capability in CCA, Ahr, etc.

Engineers understand this language very well. It forces one to do some math on loads and accept or not accept levels of risk.

It leaves that math and the decisions for use to the mechanic/owner/installer/engineer to determine whether all demands, margins of safety and constraints are met, or not. Temperatures cause a lot of variation. Lifespan in months or years, load limit cycles, all matter.

Simply said, I think you have an opinion. I respect that opinion. I do not agree with it. Your math is much too conservative for majority of flying that I will do. And, please don't say I have to manage my risks to some imaginary small number. I know risks. Intuitively.

Side note: I spent some significant time with an ER Doctor today talking about his PA32 with IO540. He was telling me about his top overhaul. Compressions were down in the '60's. Says he doesn't get out to fly as much as he likes. AP suggested he needed a top overhaul, so they pulled two jugs and over-bored them, new pistons, rings, pins...did the valves, and now they have to do all 6 to get the balance right.

He's very limited in his knowledge of that engine and plane in general. when he said they were over-boring it and putting in new pistons...He didn't know the dimensions. .010" we asked? He didn't know. He talked about it like he'd just learned it, and the terminology, like he'd just heard it for the first time in his life.

But he can do a Tracheotomy and shove a tube down into your lungs, and open your chest with really sharp knife to separate cartilage from bone, crack your chest with with a hydraulic spreader that will split your ribs from your sternum, administer the correct meds, and grab your heart and massage it to get it to beat again in less than 1 minute. Different skill set.

I think we all come here to this site to kibitz, talk to our brothers in kind, and SHARE our insights on topics and seek knowledge. We all appreciate that. I appreciate and respect that.

Finally, I do my own risk assessment. As any airman should.

-Subsonic
PS. I flew from COI FL to OSH WI and back in 24.5 hours including six (23 minute average) gas stops (2,150 nautical miles) in my '56 TP last week. I'm headed to Portland ME at the end of the month to see the kids, and out to CO before it starts snowing in mid Sept. for a buddies 60thBD. I typically travel alone. I appreciate all info that helps me travel safely in my cross country flying. How much CC flying do you do?
 
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I've read a few places that the Surefly in the variable timing mode does not perform well at WOT in high DA situations (takeoffs from high strips). Has anyone experienced that? I'm in the process of buying a Tri-Pacer with mags that are 50hrs from OH and I'd be keen on replacing one with an EI for the starting ease and a bit of efficiency. Those that run a Surefly in the fixed timing mode, do you think it was worth it or do you wish you stuck to standard mags?
 
I've read a few places that the Surefly in the variable timing mode does not perform well at WOT in high DA situations (takeoffs from high strips). Has anyone experienced that? I'm in the process of buying a Tri-Pacer with mags that are 50hrs from OH and I'd be keen on replacing one with an EI for the starting ease and a bit of efficiency. Those that run a Surefly in the fixed timing mode, do you think it was worth it or do you wish you stuck to standard mags?

Update: It's installed: So, I've only flown about an hour on my new left-side SureFly. Replaced my starting mag with impulse coupler. Using the variable timing function. Tapped vacuum off existing port on #3 head. So smooth inflight. Engine is smoother. I have only started my plane about 8 or 10 times with the new SureFly. Simply stated: It rotates about 50% to twice as far in angular space to get started. Instead of 300 degrees or so, it goes about one and three quarters of a rev before it lights off. Kind of cool actually. It's very repeatable. That's all I ask. I learn. Different but not concerning. Very definitive light off. An extra 2 seconds. Your starter will not care. I find my engine running smoother everywhere. It's subtle, but smoother. It has a bit more power, too. IMO.
 
I've read a few places that the Surefly in the variable timing mode does not perform well at WOT in high DA situations (takeoffs from high strips). Has anyone experienced that? I'm in the process of buying a Tri-Pacer with mags that are 50hrs from OH and I'd be keen on replacing one with an EI for the starting ease and a bit of efficiency. Those that run a Surefly in the fixed timing mode, do you think it was worth it or do you wish you stuck to standard mags?
I have heard some folks say they had high CHTs in the mountains with variable timing on the SIM. Mine is set in variable timing. I don't have any data with it in set timing. All you have to do is pull the SIM and change the dip switches. I have changed the switches with the SIM installed, will not do that again, working through a small hole, looking in a mirror with a home made 90 degree pick. Easier to just pull it off.
 
I have heard some folks say they had high CHTs in the mountains with variable timing on the SIM. Mine is set in variable timing. I don't have any data with it in set timing. All you have to do is pull the SIM and change the dip switches. I have changed the switches with the SIM installed, will not do that again, working through a small hole, looking in a mirror with a home made 90 degree pick. Easier to just pull it off.
Good to know. I wonder if the high CHT's in the mountains was partially due to being too lean? I read somewhere that the variable timing SIM will not advance beyond 25 degrees until DA gets to above 7,000 feet.
 
I have heard some folks say they had high CHTs in the mountains with variable timing on the SIM. Mine is set in variable timing. I don't have any data with it in set timing. All you have to do is pull the SIM and change the dip switches. I have changed the switches with the SIM installed, will not do that again, working through a small hole, looking in a mirror with a home made 90 degree pick. Easier to just pull it off.

I wish the timing was able to be wired to a switch in the cockpit for this reason. It'd make life easier in the long run.

Good to know. I wonder if the high CHT's in the mountains was partially due to being too lean? I read somewhere that the variable timing SIM will not advance beyond 25 degrees until DA gets to above 7,000 feet.

Consensus seems to be that advancing timing does cause CHT's to rise since the heat from combustion is staying in the cylinder longer before going out the exhaust. On a day with standard pressure, 5000ft elevation, and 75* temp you'd be above the 7000 ft DA so I bet this is why I'm seeing reports of high CHT's on takeoff for higher elevation fields. I kinda wonder if turbo'd engines would be the only way to have your cake and eat it with electronic ignitions and high altitudes.
 
I wish the timing was able to be wired to a switch in the cockpit for this reason. It'd make life easier in the long run.



Consensus seems to be that advancing timing does cause CHT's to rise since the heat from combustion is staying in the cylinder longer before going out the exhaust. On a day with standard pressure, 5000ft elevation, and 75* temp you'd be above the 7000 ft DA so I bet this is why I'm seeing reports of high CHT's on takeoff for higher elevation fields. I kinda wonder if turbo'd engines would be the only way to have your cake and eat it with electronic ignitions and high altitudes.

Its a simple 2D open loop performance map. At this rpm (X plot) and this manifold pressure (Y plot) advance or retard timing. Probably mapped on a water brake dyno for the best settings. If you look at the STC instructions, the pilot is the CHT control. Meaning if you get close to max CHT, shut her down. For these reasons you have to have CHT monitoring system with the advance timing option. Does not say where to put it, like hottest cylinder in a climb, factory position, GEM with multiple tools.

When we certified the LASAR system and I found the RPM/MAP mapping only advanced 1 to 2 degrees close to sea level. 4 to 5 degrees in the higher elevations. We use to compare it to Turbo Normalizing. In other words you advance the timing as manifold pressure decreases in altitude. Electronic ignition is kind of a waste on a turbo engine that has a constant sea level pressure if one of the triggers is manifold pressure.

The smoothness comes from the fact its a waste spark system. Always fires on two cylinders. 1 and 3. 2 and 4. Lycoming firing order LH rotation is 1324. Two coils with two outlets.

Todd
 
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When we certified the LASAR system and I found the RPM/MAP mapping only advanced 1 to 2 degrees close to sea level. 4 to 5 degrees in the higher elevations. Todd
Todd, can you clarify this statement for me? As I understand it, a standard mag advances a fixed 25 degrees once the engine is running.

Do you mean to say that at sea level, the variable timing SureFly SIM advance is a total of 26 or 27 degrees (25 + 1 or 2), near sea level and 29 or 30 degrees total at higher altitudes?

-Thx.
 
A regular magneto is fixed at 25 degrees before top dead center.

My experiences are from real time flying with a laptop attached to a similar electronic ECU all over the US and Canada.

Marketing said it could advance up to 46 BTDC based on MAP (manifold absolute pressure).But I only ever saw 1 or 2 degrees at Sea level. At altitude you can expect higher advances, Surefly claims 38 degrees BTDC. That is 13 degrees earlier than the fixed 25. I only ever saw 4 to 5 degrees. Your milage may vary.
 
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I have one SureFly SIM on my 160 HP O-320, but I’m not using the spark advance since I don’t have a CHT gauge. How much reduction in fuel burn are you getting with the spark advance? Not using the spark advance I haven’t seen a reduction in fuel burn.

Juergen
Pacer N3342Z
 
USAF glider tow aircraft at Colorado Springs 6500’ best power, no CHT control, 4 to 5 degrees advance.
 
I know experimental guys that run variable timing in the cockpit and go way beyond 4-5 degrees. Harry told me the FAA limited the advance on the Lazar system where there wasn't much advantage over fixed timing. They did start nice and run smooth at idle. I like the SureFly SIM for ease of maintenance. I get tired of Champion issuing service bulletins and having to work on mags because the things they changed didn't work out. I don't usually go high enough to see any savings in fuel burn. It also starts on the 3rd blade like clock work. Also from talking to the engineer at SureFlly I can run the gap wider and have less propensity to fouling a plug.
 
I know experimental guys that run variable timing in the cockpit and go way beyond 4-5 degrees. Harry told me the FAA limited the advance on the Lazar system where there wasn't much advantage over fixed timing. They did start nice and run smooth at idle. I like the SureFly SIM for ease of maintenance. I get tired of Champion issuing service bulletins and having to work on mags because the things they changed didn't work out. I don't usually go high enough to see any savings in fuel burn. It also starts on the 3rd blade like clock work. Also from talking to the engineer at SureFly I can run the gap wider and have less propensity to fouling a plug.

Yes.... the experimental electronic ignitions and Surefly are not limited by CHT control or a 3 dimension map. I have been cognizant in all my posts to avoid the closed loop 3D RPM/MAP/CHT mapping as we are talking about 2D mapping. I was not employed by Unison when the mapping was done at Lycon. According to Harry it was open loop 2 dimensional at first. That is only RPM and MAP (manifold absolute pressure). As I understand it Cessna and Piper objected to the open loop 2D function as the CHT varied by CHT probe location and baffling designs across the two manufactures TCDS mandates. i.e. Hottest cylinder in climb # 3? #4? where is it mandated to go? Did the TCDS argument grow and the FAA stepped in during certification? I don't know. I also don't understand how the FAA would mandate it on LASAR and then allow it unchecked on Surefly.

Back then I was a parts changer sent out to fix LASAR units all over the US. Being a problem solver I wanted information, data to see what was going on inside of the box. was it working? what was it advancing? Was it even working without any cockpit interface? Back then only the important people like Harry had laptops. About 97,98 Compaq made one of the first tablets with Microsoft windows. I tried and tried to get it to sync with the box. No assistance from Unison, so I took that as they didn't want me to see what it was doing. Most Customers had laptops and cables with DB9 connectors, so I used theirs. Experimental mostly... Vans RV's so no CHT control 3D map. I remember vividly flying from the spot the Orville and Wilbur first flew from. Which is pretty close to sea level as you can get and thinking 6 million dollars in development cost and this thing only advanced 1 degree. When does the 46 BTDC come in? at what manifold pressure? Again I was not employed when it was mapped.

Yep, for sure Surefly is a good "electronic" magneto. No points, Condenser, to control Egap. Yep... smoother.... starts easier. But without cockpit control, feedback indications what are the effects of advancing the timing? Higher CHT? Fuel economy? Gamblers will always tell you about their winnings and never about their losses.

For me, I see these guys in a new jeep going down the road. Lift kits, oversized tires, winches, spare fuel tanks and tire ramps on a rack. Driving down a paved road!!!! Do they need it? No! Did they want it? of course they did! That's what the marketing guys see in the electronic mags "gotta have it"

In my opinion... it has almost been more than 25 years since electronic ignition came out and the engineers at Lycoming and Continental knew what they were doing back then and made the best compromise.

Call me weird, but I like working on magnetos, challenging my brain, keeping my skills current. In this "set it and forget" it society what will happen to those skills?
 
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Ok, I'm calling you weird. Don't invite what you don't want.

First, you confuse me when you say 1 or 2, or 4 or 5 degrees. Can you simply use ABSOLUTE numbers, please?

What you should have said is : the UNIDENTIFIED ELECTRONIC IGNITION that you were working with about 25 years ago had a 2D map and was only advancing the absolute lead 26 or 27 degrees at SL, or up to 29 to 30 degrees at higher altitudes and lower MAP's.

I think the pertinent information you were attempting to convey is the fact that the SureFly SIM also uses a 2D map. I get that.

Cool. Don't care. Not pertinent to the SureFly SIM. Have you seen their 2D map for total timing as a function of manifold absolute pressure? I have not. Do they publish that data? Have you compared SureFly's 2D map with the unidentified 2D map you worked with 25 years ago?

Third, I'd also appreciate it if you stick to the topic and stop talking about your whining to get a laptop 25 years ago and Jeeps with skyjacks, and keeping your brain working. We're all working on keeping our brains working. That's not the discussion here.

Bottom line: We are talking about the variable timing advance on a SureFly SIM and you are talking about something else. And, if you haven't noticed, Lycoming now sells their new engines with the SureFly SIM's installed.
 
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