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Van's Offering Electronic Ignition

But - they will only sell you an engine with one pMag. If you want a dual pMag set up (like most people) they will sell you an engine with one pMag and nothing in the other mag slot. You then buy the second pMag from Emag.

I assume there will be a credit for not getting the Slick mag - I drop my order for engine and prop later this week so I'll find out.

Carl
 
But - they will only sell you an engine with one pMag. If you want a dual pMag set up (like most people) they will sell you an engine with one pMag and nothing in the other mag slot. You then buy the second pMag from Emag.

I assume there will be a credit for not getting the Slick mag - I drop my order for engine and prop later this week so I'll find out.

Carl

The reasoning behind one pMag makes sense.

A single pMag will provide 95% of what 2 will provide, why give up redundancy of mag back up? Plus there is no concern over back up electric system to power 2 IE's.

I have one IE and one mag firing top plugs. RPM drop on mag check is same, old mag technology is not all that bad, it works pretty well at least up to 500 hours.
 
The reasoning behind one pMag makes sense.

A single pMag will provide 95% of what 2 will provide, why give up redundancy of mag back up? Plus there is no concern over back up electric system to power 2 IE's.

I have one IE and one mag firing top plugs. RPM drop on mag check is same, old mag technology is not all that bad, it works pretty well at least up to 500 hours.

I do not agree that one mag and one pMag provide any advantage or redundancy over a dual pMag install - and offer that this set up present some disadvantages. Examples:
- With the pMag and mag combination, the mag does little but you are still stuck with overpriced plugs that get fouled.
- The pMag provides it's own power - no backup electrical power required.
- The mag requires more care and feeding than a pMag (personal experience).
- The thumbrule is one pMag and one mag provides 80% of what two pMags provide. I want the other 20%.

For those who fly low and at full power all the time the pMag has less advantage over the mag. I fly high and LOP - where the pMags provide the most value.

Carl
 
One EI of any kind offers improved starting performance, cold or hot, and improved idle. The rest is about spark timing, not how the spark is generated.

As for p-mags, recent data demonstrates what many of us have suspected all along...the advance schedule is wrong as a soup sandwich. Carl's argument about lots of advance to run high and LOP is reasonable, and the p-mag delivers it. However, you must first climb to a suitable altitude, and the advance schedule is not optimal for climb at best power ROP.
 
One EI of any kind offers improved starting performance, cold or hot, and improved idle. The rest is about spark timing, not how the spark is generated.

As for p-mags, recent data demonstrates what many of us have suspected all along...the advance schedule is wrong as a soup sandwich. Carl's argument about lots of advance to run high and LOP is reasonable, and the p-mag delivers it. However, you must first climb to a suitable altitude, and the advance schedule is not optimal for climb at best power ROP.

Dan, can you provide a link and/or data that shows this information? It's a little hard to understand that a mag with fixed timing would somehow be better than EI with MP based variable timing. Thanks.
 
... However, you must first climb to a suitable altitude, and the advance schedule is not optimal for climb at best power ROP.

I'm not sure that is a correct statement.

With my 8.5:1 O-360, which is spec'ed at 25 degrees before TDC, the P-mags do not start advancing until you are going through 4,000 to 6,000' at climb power.

The key to the P-mags is understanding what the proper timing is for your engine and configuring the P-mags to match. Forcing them to the "A Curve" by adding a jumper between pins 2 & 3 is close but it is best to add a negative offset of 1.4 degrees and reduce the maximum advance by the same amount.

If you have an angle valve engine that requires 20 degree timing, then you should enter a negative offset to get it down to 19.6 degrees and reduce the max advance by the same amount.

Once you make a change the P-mags, you do not install the jumper between pins 2 & 3 as that will just force it back to the "A Curve".

These changes can be made with the EICAD program available for free from the Emag website or with our EICommander.
 
Dan, can you provide a link and/or data that shows this information? It's a little hard to understand that a mag with fixed timing would somehow be better than EI with MP based variable timing. Thanks.

It is true.

CAFE FOUNDATION established some years ago with extensive flight testing, EI offers little advantage over magnetos until above about 8500.

Go to cafe.foundation and dig it up, the report is still there somewhere.
 
It is true.

CAFE FOUNDATION established some years ago with extensive flight testing, EI offers little advantage over magnetos until above about 8500.

Go to cafe.foundation and dig it up, the report is still there somewhere.

This report establishes some of the fundamental advantages of EI - namely that the lean mixtures at altitude are hard to light and slow to burn, but we need to remember that the features of variable timing offered in some of the latest ignitions were not explored back then. The ability to retard timing from data plate numbers is a huge benefit from those of us who are concerned about detonation at takeoff power. So yes, when fat and low it does not take much to start the ignition event - but being able to control the slope of that curve is a big deal. Magnetos offer no ability to shift timing, most EI's have a limited ability to alter timing, but a scarce few have the capability to build a complete curve. That's where we in aviation are just beginning to draw back the curtain.
 
Dan, can you provide a link and/or data that shows this information? It's a little hard to understand that a mag with fixed timing would somehow be better than EI with MP based variable timing. Thanks.

http://www.vansairforce.com/community/showthread.php?t=148100

Get an online subscription to Kitplanes. You can read everything in current issues plus all the back issues.

Here on VAF, the quick version:

http://www.vansairforce.com/community/showpost.php?p=1164846&postcount=15

I'm not sure that is a correct statement.

Bill, are you listening to yourself? You and your partner created a device to modify the supplied p-mag advance values.

The result is still not anywhere as good as a dual map system, but that's not your fault.
 
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...

Bill, are you listening to yourself? You and your partner created a device to modify the supplied p-mag advance values.

The result is still not anywhere as good as a dual map system, but that's not your fault.

Dan, I am listening to myself, and I would say the timing of the P-mags is overly conservative, if anything, not overly aggressive.
 
P-Mag Advantage

I can't contribute to the timing discussion but I will say I'm quite happy to be rid of my Bendix magneto. Faced with a choice of overhauling the antiquated Bendix or replacing it with something different, I chose the E-Mag P-Mag. It went in easy, is a piece of cake to time, and works great. Auto plugs and harness is an added advantage. Frankly, I'm surprised any experimental owner is still running a magneto, and I'd be even more surprise that any experimental owner actually paid for a 500 hour IRAN or overhaul on a magneto. The P-Mag is just SO MUCH BETTER.
 
Dan, I am listening to myself, and I would say the timing of the P-mags is overly conservative, if anything, not overly aggressive.

In God we trust. Everybody else has to bring numbers.

With my 8.5:1 O-360, which is spec'ed at 25 degrees before TDC, the P-mags do not start advancing until you are going through 4,000 to 6,000' at climb power.

That's the point Bill.

The published data, from a professional test pilot, says there is no good reason for significant advance while running best power mixture at any reasonable altitude. Yet he measured 36 degrees for the P-mag before 22". Optimum was found to be 28 degrees when less than 23"MP.

It's not anomalous. Here are two examples. On the Sky Dynamics dyno, even a full-boogie motor at 3000+RPM was losing power when advance was pushed past 30 degrees. Best torque was at 25 degrees.

Deg HP-RPM Torque-RPM
20 217-3050 411-2424
25 228-3082 430-2456
30 232-3082 422-2461
33 223-3004 413-2434

I run the 390 at a base timing of 23 degrees. Given best power mixture, there is no detectable speed or power difference at 27 degrees, at any altitude I've checked. All it does is run up CHT.

The above is ROP. LOP is different. One might argue that the P-mag is "conservative" because 36 degrees is less than the 40 degree maximum in Nigel's series, at MP's less than 20". Works for me. Don't think anyone has a complaint with P-mag timing when running high and lean of peak. Trouble is, you gotta get up there in the first place, while we retarded folk have already climbed away into the next county.
 
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You guys are living in the wrong part of the country - out here, we are HIGH and LEAN when we start our take-off roll..... :)
 
You guys are living in the wrong part of the country - out here, we are HIGH and LEAN when we start our take-off roll..... :)

If you're a reader out there on the learning curve, please understand that Paul is kidding.

At higher elevations a pilot may choose to lean before takeoff, in the same manner as the flatland pilot who uses the "target EGT" method of leaning in the climb. The idea is to adjust a mixture that gradually goes rich with increased elevation, returning it to best power or slightly rich of best power. Exact isn't necessary, as the power vs mixture curve is quite flat in this region.

How flat? Paul's home field is at 4400 MSL. As compared to a sea level observation, a Bendix RSA-5 (or Precision EX-5, or Airflow Performance FM150) will enrich enough to reduce EGT by approximately 50F. All a pilot needs to do in order to restore maximum available power for that altitude is lean 50 degrees. If he did nothing and just left the mixture knob in the full rich position, the power loss would be a little more than 1%.

Note that Western pilots lean on the runway and in climb to restore maximum power. Unless in the habit of deliberately reducing power by pulling mixture to the lean side of peak, the situation is exactly the same as detailed in Nigel's work. The optimum timing for rich of peak, best power operation is less than 30 degrees BTDC, for all altitudes tested.

If anything, the P-mag's advance schedule is even more wrong for a mountain pilot than it is for a flatlander. At least the flatlanders get to climb a little before the advance starts rising.
 
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Another thing guys tend to forget is with old Lycoming technology engine, fuel, in addition to creating power, is also a median for cylinder head cooling.

Get the internal temperatures too hot for too long, the exhaust valves will fail.

That and very poor inlet airflow distribution convinces me to be cautious about this stuff. This engine is not a modern auto engine designed to do what some are trying here.
 
Come on guys & girls ,it's about time aviation moved into this century, in 1995 I would not trust electronic ignition, but today ,no reason not to use it along with NORMAL spark plugs !
 
Come on guys & girls ,it's about time aviation moved into this century, in 1995 I would not trust electronic ignition, but today ,no reason not to use it along with NORMAL spark plugs !

Perhaps it's time to follow the discussion a bit more closely, which is not about mags vs EI, or inductive vs CDI, or self-powering vs external power.

This is about selecting optimal advance values for the two very different mixture regimes, economy lean of peak and best power rich of peak. The available data says the P-mag's advance map is reasonable for LOP operation, but very poor for ROP operation. The result in the field has been hot cylinder heads in climb, or step climbing, or low rate, high speed climbs, or reworked fuel controls to pour on excess fuel.

Moving forward in technology would be an ignition which provides for two individual maps, one for each operating regime. Even with the addition of an EI Commander, P-mag users can't do it...which is not to say it can't be done. We're talking about a toggle switch and a software change, with maybe a chip swap or two in the bargain. Dual map ignition controllers are available to the car guys for peanuts. The two I'm flying cost me $140 each on sale. It's not cold fusion.

BTW, moving into this century would require an engine management system linking ignition advance to mixture state at the chip level, and varying it automatically...very limited advance while ROP, and much more advance with LOP mixture and low MP. Ross at SDS has already stated his intent to start system development now, in anticipation of widely available no-lead avgas, which will allow reliable exhaust sensor operation...you know, like cars.
 
As far as ignitions go, we're already offering fully optimized timing, albeit manually controlled at the moment. We typically program WOT ROP timing at around 24-25 degrees on 100LL and about 22 on 91 mogas. We may advance about 4 more degrees at MAPs down around 20 inches and a couple degrees around 25 inches. In any case, the CPI is user programmable in logical 1 degree increments for both rpm and MAP should you want to change the curves to suit different compression ratios, fuels or special flight conditions.

With the LOP switch, you can add whatever you want to the basic, automatic mapping. Users are typically adding about 4 to 7 degrees more timing with the LOP switch. One Lancair user adds 10 degrees (base rpm timing 24 degrees) as he flies high and LOP almost all the time.
 
http://www.vansairforce.com/community/showthread.php?t=148100

Get an online subscription to Kitplanes. You can read everything in current issues plus all the back issues.

Here on VAF, the quick version:

http://www.vansairforce.com/community/showpost.php?p=1164846&postcount=15



Bill, are you listening to yourself? You and your partner created a device to modify the supplied p-mag advance values.

The result is still not anywhere as good as a dual map system, but that's not your fault.

It appears to me that the baseline advance is a bit high. My very simple understanding of the Pmag believes that can be easily fixed using either programming an offset or by "fooling" the system by physically retarding the Pmag by a couple of degrees from TDC prior to setup.

The slope of the advance curve seems a little steep and starts a little early. That would be a bit harder for the user to correct.

I've asked the Emag folks to respond to my concerns brought to light by you and Nigel.
 
With the LOP switch, you can add whatever you want to the basic, automatic mapping. Users are typically adding about 4 to 7 degrees more timing with the LOP switch. One Lancair user adds 10 degrees (base rpm timing 24 degrees) as he flies high and LOP almost all the time.

Ross, confirm my understanding please.

In the context of separate, switch controlled ROP and LOP advance values, the CPI is an offset system, i.e. the LOP switch adds an offset to the base map, that offset being a single value?

Simple example; assume a base map with no advance, just a fixed 25 degrees BTDC for all RPM and MP conditions. The LOP switch allows adding one value to all points on the base map, i.e. if the owner selected 5 degrees, flipping the switch would result in 30 BTDC at all RPM and MP points?

If so, then it is not possible to create two independent maps, one with limited or no advance (flat across all conditions), the other with advance ramping up significantly with reduced MP (a steep slope)?
 
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Ross, confirm my understanding please.

In the context of separate, switch controlled ROP and LOP advance values, the CPI is an offset system, i.e. the LOP switch adds an offset to the base map, that offset being a single value?

Simple example; assume a base map with no advance, just a fixed 25 degrees BTDC for all RPM and MP conditions. The LOP switch allows adding one value to all points on the base map, i.e. if the owner selected 5 degrees, flipping the switch would result in 30 BTDC at all RPM and MP points?

If so, then it is not possible to create two independent maps, one with limited or no advance (flat across all conditions), the other with advance ramping up significantly with reduced MP (a steep slope)?

Default timing is generally set for ROP operation with the LOP switch off.

Your example is correct.

It's not possible or probably necessary to have two independent timing maps for a Lycoming unless you're running 2 different fuel octanes and want to increase detonation margins.

Normal map is programmable to let you have total timing wherever you want to make best power ROP. If we go LOP, and flame speed drops by 30%, when we throw the LOP switch, we initiate ignition say 5 degrees sooner to make up for the slower flame speed and still get peak cylinder pressure (PCP) at the optimal point for extracting best power and energy from the fuel.

The standard map if done correctly, has already optimized for rpm and MAP variables so LOP slower burn speed is the only significant one left to compensate for.

Most flight and dyno data show Lycomings are relatively insensitive to timing regarding power at WOT, ROP. 22 to 27 degrees.
 
Nigel's engine is an IO-360 parallel valve with 10:1 compression pistons and was used for all of his testing.

How much of an impact would this have on his results over a standard 8.5:1 compression engine?
 
Ross, confirm my understanding please....

I know this is directed at Ross, but let me help out as a user of this system until he weighs in...

Yes, the LOP feature of CPI throws a set value (4 degrees, in my case) on top of whatever point in the curve you happen to be at. So no matter where you are from idle to WOT, if you flip the LOP switch you get 4 more degrees of advance.

While this is not a "dual map" scenario you envision, we need to keep in context the laws of diminishing returns for "absolute" optimization. Keep in mind that even the tightly controlled, squeaky clean world of automobile emission compliance a WOT acceleration run is "open loop" and very rich, to the point of intentionally dumping raw fuel into the exhaust just to keep the cats alive. Even in cars, there is a optimized "normal" condition, and a "close enough" outlier condition. It's hard to expect even tighter optimization in airplanes.

I think that for most people, LOP ops is most often a very specific flight condition, not used for general utility. And while I have not done specific testing of optimized LOP ops at anything other than my normal cruise altitude of 8500, I do often go LOP during cruise formation work, LOP climbs as a means of CHT temp control, and low power, low altitude cruising around stuff. In short, I am LOP anytime I am not asking for big power from the engine, and I'd bet that the added 4 degrees I find optimal at 8500 cruise LOP is going to be pretty dang close at my other LOP conditions too. Yes, I know I need to prove it.

So while a dual map (LOP/ROP) would be "neat", I'm questioning how much practical utility one would derive beyond what is available today. And considering just how radically the ignition advance curve ramps up with the distance from peak, can you really have just one map for LOP? It's a slippery slope.
 
So while a dual map (LOP/ROP) would be "neat", I'm questioning how much practical utility one would derive beyond what is available today. And considering just how radically the ignition advance curve ramps up with the distance from peak, can you really have just one map for LOP? It's a slippery slope.

Aaahhh - and that's where we get into good oxygen sensors and precision injectors with flow monitoring, and a 3D surface for the mapping rather than a simple 2D curve. How far down the rabbit hole shall we chase?
 
How far down the rabbit hole shall we chase?

Not very far. The big takeaway from Nigel's article seems to be that the potential gains from timing tweaks are pretty small and as you state, things get a little messy when throwing mixture into the mix

I retarded the timing on my Pmags across the board by moving the flywheel off of TDC by a few degrees during set up to fix a recurrent kickback issue on start up. Didn't realize it til later, but that change also signiicantly lowered my in-flight CHTs while not having any noticeable negative effect on speed. I'm calling it good.

Erich
 
It's not possible or probably necessary to have two independent timing maps for a Lycoming unless you're running 2 different fuel octanes and want to increase detonation margins.

Certainly possible. I'm flying a system with two independent maps right now, switchable in flight.

Certainly not necessary. After all, we've been flying fixed timing for a long, long time with satisfactory results. Variable timing is about optimizing.

Different octanes wouldn't require independent maps. An offset would work fine.

Most flight and dyno data show Lycomings are relatively insensitive to timing regarding power at WOT, ROP. 22 to 27 degrees.

Exactly, which is why a P-mag ramping to 38 is fine for LOP, but a poor choice for ROP. All it does it increase CHT.
 
I retarded the timing on my Pmags across the board. ...Didn't realize it til later, but that change also significantly lowered my in-flight CHTs while not having any noticeable negative effect on speed.

See what I mean?
 
Been reading this thread, and can add another data point. IO-540-D4B5. I have an SDS ignition running the top plugs and a mag timed to 25* running the bottom plugs. Most of my flying is local, ~3000' ASL, 23 squared (55%), LOP at 9.5 - 10.0 gph. The SDS is set at 28* for those numbers, and my advance switch adds 4*.

Today I flew these numbers, and every 5 minutes for 3 cycles I threw the advance switch. Analyzed the resulting data and the only discernable change is adding 4 more degrees advance would lower my EGTs across the board by ~20*. CHT did not change. Could not identify any trends in airspeed - 3000' here is flying the valleys and keeping a constant elevation means airspeed fluctuates quite a bit as you move through rising and falling air currents.
 
Not very far. The big takeaway from Nigel's article seems to be that the potential gains from timing tweaks are pretty small and as you state, things get a little messy when throwing mixture into the mix...

Well let's not let the pendulum swing too far with overgeneralizations...

The benefit for playing with advance is far from linear, but it is certainly there. High and lean, the performance benefit is significant. At least I think a change from 198 to 201 knots at the same FF is significant. And as stated, the ability to build in detonation margin when down low and fat with a retarded timing set is also significant.

The big takeaway is what Dan and I and others have been stating for a long time now:

Variable timing is no good by itself; you need the RIGHT timing for the condition. There are no "one size fits all" solutions.
 
You guys are funny!

When I was a kid my dad you to laugh at me because I knew that one car was 1/10th of a second quicker to 60 than another. Therefor, he should buy the faster car.

He knew he wasn't racing his car to church on Sunday so that extra speed wouldn't do him a lot of good.

The same thing goes for electronic ignitions.

Yes, the can be tuned better and ideally would be tuned to each individual engine.

However, the P-mags in standard form are working and working well for 99% of the people who install them. Assuming they are installed and timed correctly.

Yes, there are better timing maps and some of the other ignitions out there can be tuned in increments of X RPM's. However, how many people understand the finer points of ignition timing and can time their engines to maximize performance. Not to mention the risk tolerance involved in doing so. Not only do you risk damaging a very expensive engine but possibly risk your life.

The P-mags in standard form are a plug-and-play installation, for the most part.

Once installed you can fly high, low, LOP, ROP, or whatever you want and they will not damage your engine.

The best part is that once installed, timed, and configured properly, they are a never worry about device that keeps your engine humming along happily.

While we are a group of "experimenters", not everyone wants to experiment with their engine but they do want better performance. The P-mags provide that and they provide the backup power redundancy most pilots look for in their system.

The advantages of electronic ignition, coupled with an internal generator, and easy installation are the selling point of the P-mag ignitions.

If the timing curves where so dangerously aggressive, as mentioned in this thread, then there would be melted engines all over the world and that is just not the case. Could the timing curve be better? Yes it could, but it is still a LOT better than a fixed time magneto.
 
Oh Bill... :). What was that peak CHT you saw again?

Another shot of coolaid for me please.
 
We have dual P-Mags on our 7.

We rock up, pull it out, it starts 3rd blade cold or hot. Uses $8 NGK plugs and flies really well.

Because we can now analyse the far end of the fart, doesn't make the fart any better or worse :D:D

Why haul a dumb mag and big spark plugs around when you can just enjoy simple, great engineering ?

Bill - the EI Commander went on the 8 to a new owner, he says it it is great !
 
But - they will only sell you an engine with one pMag. If you want a dual pMag set up (like most people) they will sell you an engine with one pMag and nothing in the other mag slot. You then buy the second pMag from Emag.

I assume there will be a credit for not getting the Slick mag - I drop my order for engine and prop later this week so I'll find out.

Carl

Can you provide a link to where it says only one Pmag. When I read the announcement (cannot find it now), it was a $1,000 upgrade. Delete the price of two Slick Mags and add in two Pmags and $1,000 sounds about right.
 
Oh Bill... :). What was that peak CHT you saw again?

Another shot of coolaid for me please.

Over 500 Scott, but that was with an early version of the P-mag hardware and software and lead us to the development of the EICommander. The issue was a lost timing mark, not a bad timing map. Since then, Emag has updated both the hardware and software. Also, my airplane is not a good example for this group because of the Sam James cowl. I just don't believe they cool as well as a standard Van's cowl. It has take me some time to get everything sorted out, much of which had nothing to do with the P-mag and their timing map.

Since Version 40 came out a few years back, the P-mags have been rock solid.

Granted, having the ability to monitor and tune them is a bonus!
 
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We have dual P-Mags on our 7.

...

Bill - the EI Commander went on the 8 to a new owner, he says it it is great !
I'm with you Mike, I wouldn't fly behind a traditional mag.

Let the new owner know that they can contact me, if they have any questions.
 
However, how many people understand the finer points of ignition timing and can time their engines to maximize performance.

I'm sure most assumed the best choice was pre-installed.

Using a set of P-mags and your EI Commander, Nigel demonstrated that the factory settings are too advanced for ROP, all the way up to 16,000 feet.

Facts are facts. You've seen the data. Do you find fault with it?

BTW, this is not a hardware or brand condemnation. It's just a poor choice of factory installed timing values. Any ignition, magneto or EI, would offer the same result given the same timing values. The values can be changed with keystrokes, or as in Nigel's example, with an EI Commander. So it really does come down to acceptance or dispute of the data.
 
Can you provide a link to where it says only one Pmag. When I read the announcement (cannot find it now), it was a $1,000 upgrade. Delete the price of two Slick Mags and add in two Pmags and $1,000 sounds about right.

Not specifically documented. You have to call Van's. The extra $1000 gets you one pMag and one slick mag. Don't yet know how much extra one pMag and no slick mag will be. There is no option to get two pMags from Van's.

Carl
 
Not specifically documented. You have to call Van's. The extra $1000 gets you one pMag and one slick mag. Don't yet know how much extra one pMag and no slick mag will be. There is no option to get two pMags from Van's.

Carl

Why are they charging you an extra $1000 for the P-mag?

Are the price of a P-mag and one Slick close to the same cost? Shouldn't it just be an even trade?
 
I'm sure most assumed the best choice was pre-installed.

Using a set of P-mags and your EI Commander, Nigel demonstrated that the factory settings are too advanced for ROP, all the way up to 16,000 feet.

Facts are facts. You've seen the data. Do you find fault with it?

....
I would ask, is the test that Nigel performed is unique to his engine with the higher compression pistons? How about his induction, exhaust, propeller, and fuel delivery?

Will someone with a completely different setup experience the same thing?

Nigel mentioned that his tests were to see the impact timing changes have on performance and not as a definitive test of the P-mag's timing curve.

Someone with a fixed pitched prop might experience different timing variations because their MAP / RPM numbers will be different, meaning the P-mag may select a different timing for each combination.
 
I would ask, is the test that Nigel performed is unique to his engine with the higher compression pistons? How about his induction, exhaust, propeller, and fuel delivery?

Ok, so you're suggesting the existing data might be anomalous, but apparently have no alternate to present.

The good news is that you happen to have an available airframe, engine, and prop which are totally different from Nigel's, equipped with P-mags and an EI Commander, which you know how to use.

There is data available. Here's what Michael Robinson found...with an entirely different airframe and engine, stock compression, and different RPM:

http://www.vansairforce.com/community/showpost.php?p=1054086&postcount=44

Short version:

100% power (0 MSL) 31.1"/2700 no power difference from 20 to 28 degrees
Cruise at best power (8,500 MSL) 23"/2300 best timing 27~28
Cruise at Peak EGT (8,500 MSL) 23"/2300 best timing 30
Cruise at 50 LOP (8,500 MSL) 23"/2300 best timing 33

Parallels Nigel's observations very well, i.e. advancing past 30 or so is entirely non-productive when ROP, in particular at high power settings. All you get is less HP and higher CHT...yet the stock P-mag advance was delivering 35 degrees at 23"

My own observations (which I'll be expanding in due course) are that when running ROP, my 8.9 angle valve motor may prefer even less advance. At 8500 and 65%, there is no detectable speed difference between 23 and 27 degrees, just a CHT increase, and that increase matches Nigel's observation of 2.5F per degree of advance.

Recall that many certified angle valve motors have a choice of 20 or 25 degrees, and Lycoming backed timing down to 20 for a lot of them, including the 390. Maybe it's because they have a dyno, eh?
 
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You guys are funny!

...If the timing curves where so dangerously aggressive, as mentioned in this thread, then there would be melted engines all over the world and that is just not the case...

I would caution the use of hyperbole in the context of a technical discussion. One purpose of "...operating an Experimental airplane..." is education, and I have learned an awful lot about ignition timing in the last couple of years. So has Dan, Nigel, and others. I think we're all trying to present this information so that others can benefit from all the avgas and brain cells we have expended in the collection of this data. I dont think anyone has suggested that the Pmag product has "dangerously agressive" curve in this thread, but it is certainly agressive. And while there are not "melted" engines all over the world, there are scores of threads concerning elevated CHT's among the RV fleet. And while many of them are primarily cooling related, the sub optimal timing curve is certainly a contributor.

As Dan points out, you are in a perfect position to gather and present data - I'd encourage you to do so. Pmag and some of the other ignitions certainly broke new ground, but its time to get on board with developing a new understanding of ignition timing so we can take the next step. Ross' SDS products are the cutting edge today WRT tunability, but I know he'll add new features as soon as they become apparent. In other words, we've come a long way, but there is still plenty of work left to do.
 
Thread Drift !!!

I have 2 P mags on a 150HP 0320 and as expected no problems. I purchased 2 EPI ignitions from Ross for a 8.5:1 0360 but stayed with AFP injection BECAUSE I didn't want to deal with the variety of sensors associated with direct electronic fuel injection ON MY CURRENT PROJECT.

Since then, I read reference to 100LL affects on O2 sensors. At this point I feel justified for not experiencing the cutting edge of performance. So, I hope this stimulates useful dialog... Let the flames begin !
 
Let the flames begin !

Let's not.

Again, this is not a hardware or vendor condemnation, nor a debate about EI vs magneto, and it surely has nothing to do with fuel delivery. The issue is timing. Any ignition (CDI, EI inductive, or magneto) would net approximately the same result if timed the same for a given operating condition.

The P-mag has been very popular, and I'm sure that's why Vans chose it for the option list. Its advance schedule can be corrected, at least in part, with an EI Commander, as demonstrated by a professional test pilot. Although there is always some percentage of an audience who prefers their belief system over fact, the only real debate left is how much the values might shift with engine configuration change. In the RV world, it mostly means parallel valve vs angle valve.

I wouldn't bet on big differences, as all the av engines are pretty similar in the combustion chamber. Returning to Bill's doubts, here's another example, a turbo Continental on a famous dyno, at 30.4" and 2400. BSFC is 0.565, so it's ROP and pretty close to best power mixture.

Ignition timing is about lighting the mix BTDC so peak pressure arrives at the point of best mechanical advantage, generally accepted as 12 to 15 crankshaft degrees ATDC. This dyno is instrumented to measure that point of peak pressure (theta PP, yellow, upper right) and the actual spark point in degrees BTDC (green, upper left). Here we see spark between 20.1 and 21.7 BTDC resulting in thetaPP between 9.8 and 17.1, the average being 13.6, right where it belongs. More advance would be counter-productive.

 
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Let's not.

Again, this is not a hardware or vendor condemnation, nor a debate about EI vs magneto, and it surely has nothing to do with fuel delivery. The issue is timing. Any ignition (CDI, EI inductive, or magneto) would net approximately the same result if timed the same for a given operating condition.

Actually, it wasn't even that. It was a simple question or observation about Van's offering EI. It then morphed into this discussion, which has been great. Perhaps a change to the Post title might help protect the discussion for future reference.

I know a lot about engines, but each time I think I know a lot about something, this group of folks here makes me feel like I know very little about anything. Great discussion.
 
Not specifically documented. You have to call Van's. The extra $1000 gets you one pMag and one slick mag. Don't yet know how much extra one pMag and no slick mag will be. There is no option to get two pMags from Van's.

Carl

To save others time here is Copy / Paste of relevant communication with Van's who contacted Lycoming.

..."customers selecting the E-Mag option, this would include replacing the Plain Magneto (on right of the accessory housing) with the E-Mag System. This would include a fully installed & tested unit at the Lycoming factory with all the required spark plugs, adapters and harnesses of the E-Mag EIS." ...

..."Therefore, each cylinder will have one aviation spark plug (for impulse magneto) and one automotive spark plugs (for E-Mag) installed." ...

I did this because I am leaning toward purchasing a New Lycoming engine from Van's for my RV-8 under construction. Have not seen a better value than a new Lycoming from Van's. May be able to pickup at Lycoming factory if I have not built on the airpark lot that I want to buy.
 
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