One thing that will happen the more the spark is advanced is that the CHTs will climb. 25 BTC on Lycomings is on the older 360s. Lycoming has revised their recommendations on the later ones, as much as down to 20 BTC. Mine is an older model, but I persuaded my IA to change the timing to 20 BTC. I know this sounds like heresy, but I can't feel any difference in power at 20 BTC vs. 25 BTC, but my CHTs are cooler according to my Insight G1.

I have considered the Electroair, which replaces one mag, at $3570 plus whatever it would cost to be installed (I'm not skilled enough to do it, even with my IA breathing on my neck). They claim a 10% improvement in gas burn. Since I now burn 9.8 gph, presumably I would burn 8.8 approximately. Right now, a thousand mile trip theoretically takes 85.2 gallons (1000 nautical miles / 115 knots x 9.8 gph = 85.2 gallons). At $4.52/gallon that I paid today, that would cost $385. But if I burned 8.8 gph, it would be 76.5 gallons, or $345, a savings of $40. I would have to fly 89,250 nautical miles, or 776 hours, to just pay for the parts in fuel savings. Since they don't offer a representative time for installation, I don't know what that would add to the cost.

Electroair also claims more power and higher altitude capabilities, but doesn't say how much of either. With its draggy airframe, I doubt that there would be any noticeable speed increase, but of course, the best use of more power would be better climb.

In any event, while I seem to have had no hesitancy to spend beau coup bucks on items that seem to provide benefits that I can use, I'm not yet persuaded that Electroair offers that much.

Cary

Cary wrote:One thing that will happen the more the spark is advanced is that the CHTs will climb. 25 BTC on Lycomings is on the older 360s. Lycoming has revised their recommendations on the later ones, as much as down to 20 BTC. Mine is an older model, but I persuaded my IA to change the timing to 20 BTC. I know this sounds like heresy, but I can't feel any difference in power at 20 BTC vs. 25 BTC, but my CHTs are cooler according to my Insight G1.

That sounds right - at 20 BTDC you'll be making less power, as more burning fuel goes out the exhaust. So the result is lower CHTs.

Whereas at 23 squared with an electronic ignition, the engine would retard the spark to maybe 33 or 38 degrees (or somewhere in between), making more power and more heat, so CHTs go up.

Battson wrote:

Cary wrote:One thing that will happen the more the spark is advanced is that the CHTs will climb. 25 BTC on Lycomings is on the older 360s. Lycoming has revised their recommendations on the later ones, as much as down to 20 BTC. Mine is an older model, but I persuaded my IA to change the timing to 20 BTC. I know this sounds like heresy, but I can't feel any difference in power at 20 BTC vs. 25 BTC, but my CHTs are cooler according to my Insight G1.

That sounds right - at 20 BTDC you'll be making less power, as more burning fuel goes out the exhaust. So the result is lower CHTs.

Whereas at 23 squared with an electronic ignition, the engine would retard the spark to maybe 33 or 38 degrees (or somewhere in between), making more power and more heat, so CHTs go up.

Yup!

Battson wrote: ...That sounds right - at 20 BTDC you'll be making less power, as more burning fuel goes out the exhaust. So the result is lower CHTs. Whereas at 23 squared with an electronic ignition, the engine would retard the spark to maybe 33 or 38 degrees (or somewhere in between), making more power and more heat, so CHTs go up.

I think you mean advance the spark (sooner before TDC)?

Anyone been in contact with Surefly? I sent a email several days ago and haven't heard back.

hotrod180 wrote:

Battson wrote: ...That sounds right - at 20 BTDC you'll be making less power, as more burning fuel goes out the exhaust. So the result is lower CHTs. Whereas at 23 squared with an electronic ignition, the engine would retard the spark to maybe 33 or 38 degrees (or somewhere in between), making more power and more heat, so CHTs go up.

I think you mean advance the spark (sooner before TDC)?

Yeah, can't decide if I am advancing or retarding as I age either.

whee wrote:Anyone been in contact with Surefly? I sent a email several days ago and haven't heard back.

Same deal here, no response yet.

If you decide to call them, let me know what they say please

Battson wrote:

hotrod180 wrote:

Battson wrote: ...That sounds right - at 20 BTDC you'll be making less power, as more burning fuel goes out the exhaust. So the result is lower CHTs. Whereas at 23 squared with an electronic ignition, the engine would retard the spark to maybe 33 or 38 degrees (or somewhere in between), making more power and more heat, so CHTs go up.

I think you mean advance the spark (sooner before TDC)?

Yeah, can't decide if I am advancing or retarding as I age either.

Haha, apparently me too - I completely missed the typo you wrote and read what I wanted to see!

whee wrote:Anyone been in contact with Surefly? I sent a email several days ago and haven't heard back.

I used their contact form and they responded.

They are so busy with certification, they are not really responding to customer emails.

They obviously want to crack the GA market more than they want to service their experimental customer base. Probably a wise business decision too.

All the same, I want to buy a pair... I hope they respond some more!

Edit: I just went ahead and called them. All sorted, some kind of problem with their email server or something. Very helpful bunch there at Surefly, I spoke to Jason for at least 30 minutes and he explained everything I wanted to know and more.

I'll report back once I fly the SIM mags.

Glad you heard back. I've decided to go a different direction. Surefly seems like it will be a great option though.

I've been flying jets for 20 years so I'm out of touch and am trying to relearn this stuff.

Surefly makes it sound like their unit will replace one magneto while the other remains. Am I reading that correctly? If that is the case will you have a primary and secondary then?

GuppyWN wrote:I've been flying jets for 20 years so I'm out of touch and am trying to relearn this stuff.

Surefly makes it sound like their unit will replace one magneto while the other remains. Am I reading that correctly? If that is the case will you have a primary and secondary then?

Yes you're right. That is what they recommend and that is what their certified setup will be. One mag, one EI. All the benefits of EI, with all the redundancy of magnetos in case of total electrical failure plus loss of ships battery power.

I am going to install two Surefly SIM mags, which means I need a small backup battery (about 1lb) in case of total electrical failure including ships battery. That keeps me flying for a few hours in case of that exceptionally rare emergency.

A buddy who's on the lengthy waiting list for the Emag (Pmag?) 200 series (6 cylinder version) units tells me the company are currently hand delivering the 6 cylinder versions to customers in TX. They are watching the customers install them, and using the lessons to write a better install manual, I am told. This sounds like hopeful news for anyone waiting on the Emag-200 (6 cyl), maybe they aren't too far from mass manufacturing after all! Personally, I am tired of waiting and will go a different direction.

I'm currently having the Emag from Electroair installed on my Scout. Should be done the end of the week. Cost was around $4,800 with labor. This is my mechanic's first install, so I'm sure I'm paying a little extra for the learning curve. Probably doesn't make financial sense, but life is short and you can't take it with you. My main reasons for doing this are: 1. More power in the high altitude flying I do in Wyoming. 2. Hoping it is more dependable than two sets of mags. 3. Hopefully it helps for starting. My Scout is a fuel injected IO-390 and it is hard to start when it is hot. I will fly it next week and we will see I guess!

I had the experimental 6 cylinder Electroair in my O-540 Bearhawk for about 600 hrs, and overall found it to be a good system. Spark plug wear was greatly decreased and there were performance gains. Two things that weren't obvious from the literature were (1) on hot days, especially running Mogas, it was necessary to shut off the advance to keep CHT in check, and (2) the firewall-mounted ignition coils really messed with the mag compass, such that I had to strategically secure with adhesive a magnet on the boot cowl when I swung the compass.

Here's a picture of the coils and the magnet:





Hopefully, the certified version has less of a magnetic footprint. The CHT issue was easily operationally monitored and corrected.