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Surefly electronic ignition

XLS+PAT

Active Member
Has anybody had any experience with this product. It looks easy to install and the price is quite reasonable. They have a product description on Youtube.


Pat

RV7
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0-360
KHAF
 
I have talked to a mechanic who has heard good things about them, he is a DAR as well and said he had seen a couple on planes he expected, going to check them out at S n F. That?s all I can add .
 
Surefly

I installed one in place of the impulse mag on my 10 and have been very pleased,
quicker starts hot or cold and super simple install as you said. No complaints so far.
 
Surefly

I installed one in my RV-10 and found it not to perform as well as my existing Light Speed EI. I sent it back and got my money back.
Subsequently I installed a SDS CPI from Racetech and it is performing perfectly.
http://sdsefi.com/cpi.htm
 
Excellent product! I've been running one unit on my RV6 with a high compression IO-360 for two years, and I can't wait to put on the second unit.

This is by far the most tested aircraft electronic ignition ever made. The unit was subjected to much more testing than their certified competitor (by a factor of 7!), tested thoroughly by Lycoming, and has passed with flying colors. The development of this system is a great example of how the FAA bureaucracy can ruin a company, but they persevered.

What it is: This is an easy to install, magneto replacement, that provides altitude compensated ignition advance within the detonation safe zone. In a low altitude, high manifold pressure, high power climb you are going to get 25 degree advance (base timing) just like a magneto. However, it will advance up to 38 degrees once your are in the detonation safe zone below 25" manifold pressure. Installation is just like a magneto with the addition of fused power directly from the battery, and a manifold pressure connection. You use the magneto gear, and the existing spark plug harness. It will last the life of the engine, with no maintenance. Only moving part is the geared shaft on a 50,000 hour bearing that only acts as a trigger. No external boxes or electronics, using existing ignition switch.

What it is not: This is not an electronic ignition for the "hotrodder" that wants to tweak the ignition curve and push the boundaries of detonation with their high dollar engine. Automotive engines have a "knock" sensor that advances the timing until is detonation is sensed and then backs it off. Piston aviation engines have no such system. So the philosophy was to build a KISS principled unit that is easy to install. You cannot adjust the timing curve, which also made the FAA happy during certification.

What it does: No 500 hours inspections, no impulse couplers destroying themselves and falling into the engine, no AD's, plug and play installation. I have easier starts, hot and cold. I can easily run lean of peak, seeing 7.5gph at 10,000' 165knots TAS. It runs so smooth that your mixture essentially becomes a throttle. I even know of carbureted O-360's easily running LOP with this ignition.

What to expect: Any electronic ignition system that burns the mixture more efficiently is going to highlight any deficiencies within your powerplant system. The CHT's will run slightly higher (10 degrees, below 25" MP) as you are extracting more BTU's from the fuel. In my case I found inefficiencies in my baffle that I corrected. I also needed to re-tune my GAMI's as I'd never been able to run this far LOP with mags. Finally, I discovered I had some tired spark plugs that needed replacement.

Bottom line is that I have a engine life span ignition system that costs just a little more than a magneto overhaul, makes my engine happy, and allows me to run more efficiently. I'm going to install my second Surefly SIM as soon as my RV6 comes back from the paint shop. I think you will see further product development from Surefly in the near future.

Who am I: I've been in the homebuilt game since the early 90's. My first project was a Thorp, and I've owned or flown just about every RV. I'm an A&P and an airline pilot. Full disclosure, I live in Granbury and have followed the development of this unit from the start. They are the same group that brought us Skytech and Plane Power, and are well funded. They will be around for a long time. I have no financial connection with them, and had to buy my units just like everyone else. I'm not an ignition expert, and I'm sure that those individuals can pick away at my comments.......but you get the jist.

Fly safe!
Jimmy
 
I took a quick look at the docs on their website. It appeared to me that it's like most other EIs in that it would require a redundant power source? Or is something built into it like the PMag?
 
I took a quick look at the docs on their website. It appeared to me that it's like most other EIs in that it would require a redundant power source? Or is something built into it like the PMag?

I spoke with Les Staples at SnF. The sim requires around 8 vdc to fire. If you only put one on then your mag is the redundancy. It uses the same wires and cap from Slick so it is a very simple install. I will likely add one when my mags need overhauled just for the efficiency and reliability.
 
I spoke with Les Staples at SnF. The sim requires around 8 vdc to fire. If you only put one on then your mag is the redundancy. It uses the same wires and cap from Slick so it is a very simple install. I will likely add one when my mags need overhauled just for the efficiency and reliability.

OK, so if you had two of them, you'd need some sort of redundant external power supply?
 
Yes, but what would be the gain in performance over just having one? Again, the KISS principle comes into play...:)

In the case of an angle valve, I suspect one Surefly would be just about right.

The stated advance is base plus 13. In the case of a dual Surefly install with base 20 timing, 33 BTDC would be too much. However, one mag at 20 and one Surefly would probably put effective timing in the sweet spot.
 
Yes, but what would be the gain in performance over just having one?

Again, the KISS principle comes into play...:)

I'm not advocating anything. I'm perfectly happy with my PMags. I was just trying to figure out what the differences were.
 
In the case of an angle valve, I suspect one Surefly would be just about right.

The stated advance is base plus 13. In the case of a dual Surefly install with base 20 timing, 33 BTDC would be too much. However, one mag at 20 and one Surefly would probably put effective timing in the sweet spot.

Maybe, but the mission, environment, and engine build also throw in variables.

Illustrating yet again the fallacy of a "one size fits all" curve.
 
Illustrating yet again the fallacy of a "one size fits all" curve.

Agreed.

Jimmy mentioned FAA approval. The FAA's sole interest is ensuring it won't fail the engine. They do not address optimum settings.

Any electronic ignition system that burns the mixture more efficiently is going to highlight any deficiencies within your powerplant system. The CHT's will run slightly higher (10 degrees, below 25" MP) as you are extracting more BTU's from the fuel.

EI's tend to reduce cycle to cycle variation, i.e. they light less than optimum mixtures more consistently. Although consistency certainly contributes to overall efficiency, there is no combustion difference beyond the initial flame kernel, nor can increased spark energy extract more BTU's. The CHT increase is a function of spark timing and resulting point of peak pressure, not energy.

Flying a parallel valve engine, Nigel Speedy measured the CHT increase as 2.5 degrees F per degree of ignition advance when 100 ROP, and a little less than 1.6 degrees F per advance degree when 25 LOP. Given 13 degrees of advance (38-25), that would be a little over 30 F when ROP, and 20 F when LOP. The tests were flown with Pmags and an EI commander to vary the timing. At the same advance setting, the Surfly would deliver the same result. See the May 2017 issue of Kitplanes.

With the author's permission: https://www.danhorton.net/Misc/Nigel Speedy - Ignition Advance .pdf

Conceptually, I like the Surefly. Simple, self contained, with easy installation. That said, I could not accept the locked timing advance...not due to an inability to hot rod, as Jimmy put it, but rather because it's already too hot-rodded for my taste.
 
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Yes, "hot rod" gets thrown about a bunch in these threads. It's generally used as a disparaging term meant to scare builders away from developing a curve for their particular engine. Not sure I understand that. If you have spent several thousand hours building your dream airplane, why not spend 2 hours of flight test to make the ignition perfect?

But point taken- the Surefly fixed curve is "too aggressive" in some areas of the curve and "sub optimal" in others. That said, I'm sure that it can be mechanically "spoofed" like the Pmag to at least buy you some detonation margin. Of course, by the time you go through the testing to figure out how much to move it to keep the engine alive you could have developed your own curve.
 
I had been considering going to one of these when my next mag overhaul is due. I am also concerned that it may be a bit too aggressive though.

That being said, I am not bothered by the fact that it is not “optimal”. It is still far and away superior to the old way, and not all of us have the inclination or desire to tinker for hours until we find the absolutely perfect setup for our engine. I would imagine gains from further optimization will be marginal compared to the initial gains from the stock system, at least as compared to traditional mags. I want plug and play, that will give improved economy and reliability compared to mags, with enough safety margin to not have to worry about reducing engine life.

I think I am more of the target audience than those who want complete control.

Chris
 
I think I am more of the target audience than those who want complete control.

I think you're right...for every owner who wants optimization there has to be ten who just want reliable plug and play.

Please note that Mike and I are coming at this from two different directions. Mike would be an optimizer; best performance above all. If "best" includes a lot of advance, then "all" includes higher CHT and higher mechanical stress. It's a choice, and I'm not knocking it. I simply prefer low CHT and reduced mechanical stress, even if I accept slightly less power to get it.

Here's the thing; spark energy and spark timing are two different issues. They tend to get balled together, which is a shame. I really think the average owner would be better served with a fixed timing EI...all the energy, but no advance. It would provide the starting and lean operation advantages, but would not cripple climb due to CHT and oil temp concerns. If it's down a few knots, just climb an extra 2000 feet. Easy to do when your CHTs are low.
 
I really think the average owner would be better served with a fixed timing EI...all the energy, but no advance. It would provide the starting and lean operation advantages, but would not cripple climb due to CHT and oil temp concerns. If it's down a few knots, just climb an extra 2000 feet. Easy to do when your CHTs are low.

I think Surefly has a fixed timing mode. The installation instructions says (I cut and pasted below from the Surefly 4P installation instructions.)

To operate the SIM in advance timing mode, the engine onto which the SIM is installed must comply with the following requirements:
1. Normally aspirated,
2. Have Cylinder Head Temperature (CHT) monitoring capability,
3. Use minimum of 100-octane low lead aviation fuel.
If the installation does not have equipment to monitor cylinder head temperatures, if the engine is equipped with a turbo or super charger, or if the engine operates on any fuel other than 100LL, you must configure the SIM for fixed timing mode.
 
...Mike would be an optimizer; best performance above all. If "best" includes a lot of advance, then "all" includes higher CHT and higher mechanical stress. It's a choice, and I'm not knocking it. I simply prefer low CHT and reduced mechanical stress, even if I accept slightly less power to get it...

Not so fast. The engine is capable of 100% power indefinitely. It has the required strength, oiling and cooling capacity. At any altitude above sea level, the maximum power we can extract from "optimized" timing will be LESS than the engine is designed for. At altitude, an optimized advance is certainly going to result in higher temps than a magneto but it is well within the capability of the engine architecture. ALL of our NA engines give up power with altitude - an optimized ignition curve simply gives up the least.

Where people get in trouble is figuring if a "little is good, more is better". At high altitude and lean, the "optimum" advance is a very sharp peak, and one degree either side will make a difference in airspeed. And while the airspeed peak is easy to track, the temps keep going up with more advance, which leads some people to think that their higher CHT's of their newly installed EI are a sign of more power. Not necessarily. Often, the high CHT is the destructive byproduct of an overly aggressive "canned" advance curve.



....Here's the thing; spark energy and spark timing are two different issues. They tend to get balled together, which is a shame. I really think the average owner would be better served with a fixed timing EI...all the energy, but no advance. It would provide the starting and lean operation advantages, but would not cripple climb due to CHT and oil temp concerns...

If we all flew below 1000 feet MSL I might be inclined to agree, but we don't, so I cant.

Fixed timing is a huge compromise. The data plate value HAS to accommodate the needs of lean, high altitude flight while also addressing the opposing requirements of low, rich, high power ops. So the fixed data plate value is as far advanced as the engineers can go for high altitude flight without grenading the engine at takeoff.

In other words, any fixed timing that provides acceptable flight when high and lean is going to be TOO advanced down low. Conversely, fix it so it works perfectly down low and the airplane will be a dog at altitude because the advance is not far enough. There is no way around this fact.

And contrary to your comments above, part of "my optimization" strategy includes a significant REDUCTION in timing at high power. I recognize the compromise of the data plate value and run LESS at takeoff power. I've done the testing and I know the power output is relatively insensitive to timing, but detonation sure isn't. I use the variable timing to "buy back" detonation margin to levels even Lycoming can't do. Do the timing right and you can have more detonation margin and cooler CHTs on takeoff and climb, as well as optimum performance when high and lean.

Easy to do, but it doesn't come in ANY canned curve from the EI manufacturer's.
 
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I think Surefly has a fixed timing mode.

It does indeed. See page 8:

https://docs.wixstatic.com/ugd/712b87_09a39f76a483436986ecaa3a67acf708.pdf

I think it's a marvelous development.

Noted a few other details. The system uses a Slick harness, thus massive aviation plugs...but apparently they can operate with much larger gaps.

Operating temperature range up to 250F; no need for blast tubes.

One suggestion; the Surfly unit is externally powered and grounds through the engine case. So, if installed dual (no magneto) the wise builder will run two braided ground straps, from separate points on the engine, to separate points on the airframe.
 
Not so fast.

Those are the optimizer's arguments, and I understand them very well.

Now put yourself in the shoes of the average Joe...the guy without any deep knowledge of engines, and no desire to be a test pilot.

He doesn't care if he squeezes out three more knots, and he sure doesn't want higher temperatures; they're scary. He just wants his Bendix-injected engine to hot-start easier and cruise real lean...which a fixed timing EI will do.
 
I think I?m near to Dan?s camp. Running Plasma III and a Pmag. I could get a fairly non advanced spark if I disconnect the manifold tube from these systems, correct?
 
Now put yourself in the shoes of the average Joe...

...He doesn't care if he squeezes out three more knots...

Since this is VAF and not the "Cessna 172 Renter" forum, I'm guessing the "average Joe" spent several thousand hours crafting an airplane because he wanted to learn some stuff and expected an efficient, high performance aircraft at the end. The average Joe buys a Cessna or Cirrus because they are "good enough". VAFers want performance, and they brag about it at every opportunity.

Anyway, I believe you missed the boat concerning my comments about temps. "Fixed timing" will result in HIGHER CHT on takeoff and initial climb than "optimized" timing because it is TOO FAR ADVANCED. You have seen my 100% power test data. My 25 degree PV engine returned the same speed at 20 degrees as it did at 30. Therefore, the factory setting of 25 is more advanced than required for that power setting and results in higher CHT and reduced detonation margin. Period. Dot.

At the other end of the spectrum (high and lean) yes, compared to fixed timing an optimized timing value will run somewhat higher temps. But they are still going to be far lower than the 100% power figure the engine is designed around. And certainly you can't suggest that the low temps observed with the combustion process hobbled by (the now) retarded fixed timing is "normal"?

The bottom line (as always) remains that the timing is either "right" or "not right", and IMHO, is a lot more important for engine performance than the "energy" of the spark.

As a final comment, your speed estimation "three more knots" is understated. I get three more knots just going from my "optimized" ROP setting and my LOP setting. That's just a small jump in an already significant advance. Making the same leap all the way from the data plate (fixed) setting would be huge - like 10 knots.

10 knots at the same fuel flow over the life of the engine is a LOT of time... Seems like the "average Joe" VAFer would gladly trade a few hours of some some tuning in exchange, don't you think?
 
I think I?m near to Dan?s camp. Running Plasma III and a Pmag. I could get a fairly non advanced spark if I disconnect the manifold tube from these systems, correct?

Nope. You would need to reliably seal it somehow so it always reported ~29.92. That has risks.
 
Seems like the "average Joe" VAFer would gladly trade a few hours of some some tuning in exchange, don't you think?

I think the fact that the majority of us RVers still run mags is a testament to the contrary.

I built my plane, and I have a master's degree in engineering. I am confident that if I wanted to become an expert in engine timing and tweak every single ounce of performance out of my ignition, I could, eventually. But I also wouldn't half-@$$ it, because my engine is too important to me. And since I don't have the time or desire to go all-in on ignition systems, I just want what I stated previously: better performance and better reliability than a mag, which it sounds like the Surefly, maybe even with a fixed curve, could deliver. Also, I am (gasp) carbureted, so max efficiency is already out of the question.

Maybe it is either "right" or "not right", but if so, 99.99% of planes have been flying around "not right" since the dawn of reciprocating engines, so I won't feel too bad about it.

Don't get me wrong, I love the fact that there are smart, passionate people like you guys leading the way for us, and one day I'd love to have the time to join you, but until then it's all about simplicity and reliability for me. I don't need to brag about performance, I can barely get in the air with my 150 horses :D

Chris
 
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I think the fact that the majority of us RVers still run mags is a testament to the contrary.

I built my plane, and I have a master's degree in engineering. I am confident that if I wanted to become an expert in engine timing and tweak every single ounce of performance out of my ignition, I could, eventually. But I also wouldn't half-@$$ it, because my engine is too important to me. And since I don't have the time or desire to go all-in on ignition systems, I just want what I stated previously: better performance and better reliability than a mag, which it sounds like the Surefly, maybe even with a fixed curve, could deliver. Also, I am (gasp) carbureted, so max efficiency is already out of the question.

Maybe it is either "right" or "not right", but if so, 99.99% of planes have been flying around "not right" since the dawn of reciprocating engines, so I won't feel too bad about it.

Don't get me wrong, I love the fact that there are smart, passionate people like you guys leading the way for us, and one day I'd love to have the time to join you, but until then it's all about simplicity and reliability for me. I don't need to brag about performance, I can barely get in the air with my 150 horses :D

Chris

Copy all. The advantages of EI and variable advance have been well proven in pretty much every single other spark ignition engine in existence for the last several decades. Even model airplanes have them now. There is a reason for that:. It's simple and effective. Qualities near and dear to any engineer.

That said, if one is in the market for an ignition, why not pick one that has the capability to grow along with you? Why limit yourself to some randomly developed fixed curve on the word of the manufacturer? We KNOW there are different requirements from engine to engine... Buy one that will do exactly what YOU want. Want it fixed? Fine. But you cant tell me the capability to later change your mind and set a custom curve is a deterrent, can you? After all, pilots have had control of the red knob since the beginning of time, and that is a lot more destructive to engine life than the ignition.
 
I think the fact that the majority of us RVers still run mags is a testament to the contrary.

Maybe it is either "right" or "not right", but if so, 99.99% of planes have been flying around "not right" since the dawn of reciprocating engines, so I won't feel too bad about it.

Don't get me wrong, I love the fact that there are smart, passionate people like you guys leading the way for us, and one day I'd love to have the time to join you, but until then it's all about simplicity and reliability for me. I don't need to brag about performance, I can barely get in the air with my 150 horses :D

Chris

Have owned and worked on most every type of EI out there....
My new IO370 was delivered with Bendix Mags! :eek:
 
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What is the advance curve of the LSE Plasma III?

Thx.

This is from the Lightspeed install manual - available on Klaus?s web page.

?During start, the system will fire at TDC for standard compression engines with ratios less than 8.7:1. At idle the strobe light should indicate 21? ? 2? when the manifold pressure hose is disconnected and 40? ? 2? when connected.

If you are using a compression ratio of 8.7:1 or higher, the timing must be retarded another 5?. If you are using the Hall effect sensor module in place of the magneto, reposition it to show idle strobe light readings of 16? ? 2? when the manifold pressure hose is disconnected and 35? ? 2? when connected.

Note that these numbers are for sea level. You can add 1 degree for each 1,000 ft of density altitude. The low number (MP hose disconnected) is the most important.?
 
You guys have been busy beavers! I thought I had subscribed to the thread, and was surprised at how quiet it was.....surprise!

The Surefly is not competing with Pmag and other user adjustable EI's. There is definitely a place in the experimental market for those that want to take the time, fuel, and risk to tweak their engine to a measurable optimum. Sorry I used the term "hotrodders," as I saw it as a compliment.....even aviators are sensitive these days......SAFE SPACE!

Surefly is going to make their impact felt in the certified market, as magneto technology is rotting on the vine. Surefly is marketed as a magneto replacement that can be used in fixed or advanced timing mode. You are going to get magneto "plus" performance in a simple and reliable system. You are not going to experience huge gains in performance, as that was not the design goal. You will gain reliability and a unit that doesn't crumble out of its case at a 500 hours inspection, or have its impulse coupler self destruct into your accessory case. Have you looked inside a magneto lately? Actually, there are no inspections required on the Surefly.

I would argue that the curve is not aggressive, as the FAA required extensive testing to show that it performs safely in all fight modes. If you were able to make it user adjustable, every imaginable mode would have to be thoroughly tested to insure safe operation. Not feasible if you want to sell a unit for only $1250.

There may be future developments as the company is finally starting to generate income from the certified market. They understand that there is a desire for a backup battery when using two Surefly SIMs. They also understand the desire to have auto sparkplugs. However, like the Greek king Sisyphus, they have been pushing the FAA ball up the hill, only to watch it roll back down, for the last 3 years. Experimental products have been a low priority until now.

So, if you want an EI that you can be loaded with a curve that worked for someone else, and then test fly it to its optimum, PMag is the system for you. Great guys and a great product.

But, if you want a plug and play, reliable mag replacement that is certified, safe, simple, and reliable..........consider the Surefly.
 
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Pecanflyboy,

Anything in the works for a certified Surefly replacement for the Bendix D2000 / 3000 dual mags? Is the market large enough to even consider?
 
...The Surefly is not competing with Pmag and other user adjustable EI's...

...I would argue that the curve is not aggressive...

...So, if you want an EI that you can be loaded with a curve that worked for someone else, and then test fly it to its optimum, PMag is the system for you. Great guys and a great product...

Just as a point of clarity, I don't consider the Pmag product to be "adjustable". You can shift the entire curve a bit, but you are still stuck with the slope that Brad and company locked down years ago. And there are some points on the Pmag curve that are more advanced than required for correct engine opperation. Surefly is similar in this respect. If the curve is more advanced than required, then the characterisation of " too aggressive" is accurate. The fact that Lycomings are not grenading as a result is good, but hardly lets either company off the hook. Too much advance adds heat and stress and reduces detonation margin, all for no benefit. And the degree of advance "required" varies significantly with engine configuration and basic architecture. Using a curve optimized for a low compression PV engine would be a disaster on a high compression AV - yet the locked down curve of the Pmag does not differentiate. This is exactly why there are 3rd party controllers available and the requirement to mechanically "spoof" the ignition to reduce the advance.

The reality is that when it comes to aircraft engines, one size does not fit all (ESPECIALLY in the EAB world) - and that includes magnetos. I will conceed that in context of a direct magneto replacement, Surefly might be a slight step up in some circumstances, but that will require analysis and test.
 
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I think you may be overestimating the scope of the FAA's testing. They will ensure that the Surefly will "do no harm" across a range of TC'd engines. I doubt very much they are going to explore the edge cases of the EAB world where we live. It would be foolish accept the testing on a 150 HP Skyhawk as applicable to a big bore, high compression Angle Valve that an RVer is going to hang on his new pride and joy.

FAA testing is worth something, but it's not the whole picture.
 
Allow me to illustrate the "too aggressive" claim with some real world data.

I documented a series of flight test profiles with a timing sweep to determine "optimum". The flight was at 8500 and 23 inches MP. If I read the Surefly advance chart correctly I would have seen 35 degrees advance if using that product. Let's take a look at how the 35 degree value chosen by the Surefly developers stacks up in the real world:

My 50LOP optimum speed was 194 KTAS @ 33 degrees, but at 35 degrees the speed fell 4 knots to 190. Not the end of the world, but this speed loss came with additional CHT, oil temp and engine stress. None good things.

My peak EGT optimum speed was 199 @ 30 degrees. By 33 degrees the speed was down to 196, CHT, oil and stress was up. Didn't go to 35, but the trend is clear more advance woul be "no good"

Best power mixture is even worse. Highest speed was 201 @ only 27 degrees. (Keep in mind the Surefly would be forcing 35 down my throat). By 31 degrees my speed was down to 198. Clearly, the 35 degrees of the Surefly would be significantly over advanced here. Would it be destructive? Not in my low compression PV engine, but would CERTAINLY do no good. In this case, I'd be better off with a fixed magneto at the data plate value of 25. Would still be a bit slower than optimum, but would still be FASTER than the Surefly at a lot less heat and stress.

So without the benefit of comparative testing, the Surefly owner would likely accept the higher temps as "more power" and motor happily on.

...but now you know better. Hope you understand that my constant wailing about "correct" timing and "too aggressive" canned curves is based on real world test, not product bias.
 
Most folks in the airplane world have failed to note a great divergence. On one hand we have the LOP operating mantra promoted by GAMI/APS. It assumes fixed timing, typically magneto based. Going LOP with fixed timing pushes the point of peak pressure further after TDC. The result is lower CHT and a slight power loss. With a turbo, add another inch of MP to regain the power. With an NA engine, adding 100 RPM pretty much does the same.

On the other hand we have the mantra of LOP with ignition advance. The advance compensates for the slower combustion rate of the lean mixture (see charts, links below), returning peak pressure to a point closer to TDC. Early adopters tended to be the performance-at-any-cost type; Klaus would be a fair example with his hotrod EZs. As we've seen (refer to Nigel Speedy's recent data, for example), at altitude, the parallel valve engines respond to more and more advance with more and more speed, and no one seems to have found an absolute performance limit (the practical limit is CHT rise). The practical result was a trend toward more advance being incorporated into electronic ignitions.

Among consumers, the resulting CHT increases during ROP climb have become synonymous with EI, when in fact it is not EI, but the advance schedule dialed into that EI. It is entirely possible to run an EI with fixed timing, just like the GAMI/APS case. Or, one may select an EI with dual maps, and select less advance for ROP climb. Note the engine control computer in your automobile shifts the advance map in lockstep with fuel mixture; it's invisible to the operator. Unfortunately, none of the currently available ignitions for aircraft have that capability. The advance schedules are biased toward LOP operation, and are generally a little too advanced for ROP climb.

Both LOP mantras run cleaner, i.e fewer engine deposits and lower fuel burn. The GAMI approach (delayed peak pressure) results in lower cylinder pressures, i.e. less mechanical stress and lower CHT. The more advance method is equally clean and generally results in higher power at upper altitudes, at the expense of higher CHT.

Neither is wrong. I've simply suggested the Surefly's fixed timing capability allows an owner to use the GAMI approach, if desired.

Manifold pressure vs flame speed:

http://www.vansairforce.com/community/showpost.php?p=1344198&postcount=45

Mixture vs flame speed:

http://www.vansairforce.com/community/showpost.php?p=1343913&postcount=43
 
Note the engine control computer in your automobile shifts the advance map in lockstep with fuel mixture; it's invisible to the operator. Unfortunately, none of the currently available ignitions for aircraft have that capability. The advance schedules are biased toward LOP operation, and are generally a little too advanced for ROP climb.

While this may be true of most other aircraft EIs, SDS EIs (CPI, CPI-2, EM-5) have LOP switches (which we pioneered in this market). This allows you to have the best of all worlds- speed/ efficiency, detonation margins and lowest CHTs. Though the feature is not automatic, unlike cars, aircraft engines have no emissions requirements and operate mainly under steady state conditions, so the automatic timing vs. mixture feature maybe wouldn't be worth the extra cost and complexity to implement. I'd suggest that this feature is in the realm of full engine management systems with integrated EFI and EI rather than a hybrid mechanical fuel and independent EI system.
 
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Surefly needs to do like Ross did, add a switch so you can use fixed timing during ROP climb, then flip the switch to take advantage of the Advance feature for cruise. Advance still can?t be optimized for your individual aircraft like the SDS though.
 
...at altitude, the parallel valve engines respond to more and more advance with more and more speed, and no one seems to have found an absolute performance limit (the practical limit is CHT rise). The practical result was a trend toward more advance being incorporated into electronic ignitions...

Let's make sure the readership understands the proper context of "practical limit". I have demonstrated repeatedly that performance drops off very sharply with additional advance beyond optimum. So there very much is a "practical limit", and it is not constrained by CHT. Though CHT will continue to rise with additional advance, the real practical limit is clearly defined by maximum engine efficiency (peak speed). So just to be crystal clear: more advance does not = better performance.

If you are suggesting that the optimum advance value continues to increase with altitude, then the data seems to suggest that. I have not yet explored that regime yet because that's not my typical cruise altitude, but I'll bet Mr. Anders has reams of data near the Flight Levels But point taken: It's impossible to create a canned curve with enough breadth to handle every possible use case. And the larger the canned curve, the higher the probability that someone with an edge case is going to get stung by a dangerous condition.


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...Among consumers, the resulting CHT increases during ROP climb have become synonymous with EI....


Not anymore. Ross changed that a few years ago. And it is EXACTLY because of the advance (or specifically, the ability to manipulate the advance) that allows the SDS user to break free of the canned, arbitrarily derived curve forced on us by other manufacturer's and pull timing way out for those high power, rich mixture conditions. Rather than the straight line characteristic of other canned EI curves, the SDS user is free to alter any point to suit his mission. The SDS user can create a curve that looks like a sine waveform, perfectly flat emulating a magneto, or anything in between. One can even load the Pmag, Surefly, or LSI curve if that makes sense.

So no, one does not have to live with the compromise of high CHT on climb OR good high altitude performance. You can have it all. But you have to go to Ross to buy one.
 
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Dan, you do bring up good points and point towards the gains on a parallel valve engine. Research seems to be lacking in the angle valve department from my research as to optimal timing values. I have sds cpi and believe my total advance with the LOP switch is set around 27-28 degrees. It seemed to be diminishing returns after that. Have you done any testing on the angle valve to determine good baseline settings for those systems capable of utilizing such a curve?
 
Since you have CPI, you can use the LOP functions as a safe "flight test development" switch. Simply start at a known conservative advance setting on the basic curve (switch off), then add +1 degree to the LOP window and activate the switch. It the airplane picks up speed, add another degree, compare... Rinse/repeat until you see the speed peak, then drop off. The advance value that corresponds with peak speed is your "optimized" advance. The cool thing is that if the engine does something you don't like, just turn off the switch to instantly bail out of the test and get back to a known safe condition.

Finding the optimum value for cruise flight should take all of 20 minutes. Will give you something to do on your next long cross country.
 
Let's make sure the readership understands the proper context of "practical limit".

In the context of this thread, it would be 38 BTDC, the Surefly maximum.

But point taken: It's impossible to create a canned curve with enough breadth to handle every possible use case. And the larger the canned curve, the higher the probability that someone with an edge case is going to get stung by a dangerous condition.

Ok, so quit arguing against an absolutely safe alternative, one requiring no deep knowledge or test pilot skills...fixed timing at standard Lycoming values.

But you have to go to Ross to buy one.

A system with dual, in-flight switchable user-configured advance maps? No, you don't have to go to Ross, nor spend anywhere near as much money. However, here we're discussing Surefly.
 
....my total advance with the LOP switch is set around 27-28 degrees. It seemed to be diminishing returns after that.

Your observation matches mine, and Marvin McGraw's; sweet spot about 28 degrees.

The angle valve requires less advance. Given all the 390's going into 14's these days, it is why I object to canned advance maps based on parallel valve observations.

For example, the Surefly max is 38 BTDC at low manifold pressure. I've flown my IO-390 with advance pushed to 35 BTDC at 16,500, and found it wrong as a soup sandwich, slow and hot. 38 would be serious abuse.
 
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Ok, so quit arguing against an absolutely safe alternative, one requiring no deep knowledge or test pilot skills...fixed timing at standard Lycoming values...

I agree that there are some pilots who should not ever be allowed to touch the mixture or propeller controls, but to suggest that tweaking ignition timing in flight requires the skills of a test pilot is quite a stretch. It's certainly not something to be taken lightly and the hardware makes a big difference, but it's not any harder than LOP ops.

I understand the desire to "protect the children" on this forum, but let's try avoid fearmongering.
 
What is obvious from these comments is that the internet experts haven’t bothered to look at the Surefly timing schedule. It is dependent on RPM AND MP. It would take extreme conditions for it to get to 38 BTDC.
We live in a time when your opinion outweighs the facts sad situation. I think it would be a good idea to identify your credentials when making these claims. Anecdotal information is useless.
This is why I no longer frequent this forum, gross misinformation.
The one about fasteners where one guy started claiming the metal being held together is a factor in shear was outstanding, thanks for the guy that was a structural engineer for debunking that.
That people confidently proclaim as truth things they barely understand is why a lot of info here and on many forums is useless.
As someone with over 40 years in aerospace as a airline mechanic, technical writer (translating engineering into English) working closely with engineers and as a freelance consultant and building the X47B prototype many “facts” I see make me cringe.
I really fear for a new to aviation builder that follows some of the “ facts” posted here.
There are some gems though, such as Walt but there are more than a few who should just keep silent, especially the ones who’s replies start with “I don’t know but.,,”
Thanks toVan for designing a idiot proof airplane.
Don’t bother critiquing me with your “expertise” I’m out of here.
 
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What is obvious from these comments is that the internet experts haven?t bothered to look at the Surefly timing schedule. It is dependent on RPM AND MP. It would take extreme conditions for it to get to 38 BTDC.

2700 RPM at any altitude over 9000. Not extreme for a fixed pitch RV.

As someone with over 40 years in aerospace as a airline mechanic, technical writer (translating engineering into English) working closely with engineers and as a freelance consultant and building the X47B prototype many ?facts? I see make me cringe.

Seriously Tom, ranting helps no one. If you have useful information to share, I'm sure your contribution would be appreciated.
 
Sounds like you guys have it all figured out. I look forward to the development of your product and its introduction to the market. I?m sure it will be perfect and there will be no criticism on this forum as a result of all your hard work. I can?t imagine someone undermining your success with strong opinions or speculation. Good luck!
 
To be more precise for a standard Lycoming, it appears to be 36.5 degrees at 2700 rpm

Thanks Gil. Good catch.

However, it will advance up to 38 degrees once your are in the detonation safe zone below 25" manifold pressure.

From post #5. http://www.vansairforce.com/community/showpost.php?p=1349511&postcount=5

Sounds like you guys have it all figured out.

Nope. Set us straight. Is your "high compression IO-360" parallel or angle valve? Fixed pitch or constant speed?
 
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