Auto plugs versus aircraft plugs

[Jekyll]

I ordered an engine from Mattituck with E-MAG and P-MAG but must still inform them as to my choice of auto plugs or aircraft. I have a bit of time to decide. I'm looking for some insight to help with the decision. Mattituck's default position was the use aircraft plugs but my POC didn't really have any justification for the position.

I posted this on another thread (What engine to buy) but the replies were a bit off the target of my question, so I'll start a dedicated thread here. Vern, thanks for your relevant input on the other thread.

GMCPilot George mentioned "documentation" that indicates auto plugs achieve less performance. Could you direct me to that information?

Any justified recommendations on the way to go? I read the thread on NKG plugs but that really didn't help other than highlight that replacement auto plugs are MUCH less costly.

Auto plug longevity, plug adapter reliability, electrical interference or anything else to consider? I know a lot of folks are using auto plugs and if I recall, Lycoming is now making a cylinder for use with auto plugs. I'm using ECI Titan jugs.

Jekyll
7A
installing systems

 

[RV7Guy]

Auto plugs

I have the same system and use the auto plugs. In nearly 50 hours I have had no problems. The plugs have been out twice and look great. I see no real reason to spend more on aviation plugs when the auto plugs work fine.

 

[RV7Guy]

Another point

Forgot to mention I have the ECI IO 360.

 

[gmcjetpilot]

I like the aviation plug just because

I posted this on another thread (What engine to buy) but the replies were a bit off the target of my question, so I'll start a dedicated thread here. Vern, thanks for your relevant input on the other thread.

GMCPilot George mentioned "documentation" that indicates auto plugs achieve less performance. Could you direct me to that information?

Any justified recommendations on the way to go? I read the thread on NKG plugs but that really didn't help other than highlight that replacement auto plugs are MUCH less costly.

Auto plug longevity, plug adapter reliability, electrical interference or anything else to consider? I know a lot of folks are using auto plugs and if I recall, Lycoming is now making a cylinder for use with auto plugs. I'm using ECI Titan jugs. Jekyll 7A installing systems

That is me! "Documentation" I got you're documentation right here.

Jeky, I don't recall any documentation, may be it was documented post's I was referring to; I never saw any actual test reports I recall at this time. But let me give you some anecdotal evidence. I don't recall any reports however the cafe foundation did test the Jeff Rose's ignition.

Did you check Matronics? Post from auto plug users who had minor and some more serious problems with auto plugs. A quick check of archives, yes there has been debate and some reported issues with auto plugs going back many years. One was kind of scary and caused partial power loss. To be fair and balance, many post claim auto plugs are great with no issues!

I personally talked to Jeff Rose the original designer of the Electroair in 2004-2005. He told me he recommended aviation plugs, the REM37BY in particular. He promoted auto plugs at first but changed to recommending aircraft plugs. Jeff also stated to me aviation plugs gave better performance, which I think he did evaluate (document). Look at an autolite or NGK. They have one single electrode over the top of the tip. That blocks some of the spark. An aviation plug his massive dual side electrodes. Which one do you think is better spark maker without any documentation? You get what you pay for?

I read one post where a guy with an Electroair went from Aviation plug to Autolite 386 and than back to aviation. He noted slight power loss with the Autolite, noting major but he could tell. His plan was to go back to aviation plugs for good. This post also mentioned a friend flying a O360 powered RV cracked two Autolite 386's in flight, causing some excitement.

This is what the electroair site now says:

"What spark plugs do you recommend? Do you recommend automotive spark plugs?
You may use either the aircraft or automotive spark plugs. There are several hundred airplanes running the EIS with automotive plugs. Additionally, you must verify that the heat range of an automotive plug is correct for your engine or you risk causing severe damage. We prefer, however, the aircraft plugs as they have been designed to work with aircraft engines and do not require any modifications for installation."

Hold an aviation plug in one hand and look at the massive metal case and massive dual electrodes. Now look at an auto plug. There is a big difference in mass. I think the aviation plug has much more potential to draw heat out of the core, electrode and cone. Heat is key to prevention pre-ignition which can lead to detonation. I can't claim an auto plug is not as good "thermally" but it seems like the aviation plug has more margin to absorb heat and transfer it to the cylinder. Also the aviation plug is more rugged and durable.

I recall one auto plug user having a miss fire at high power (temps) but it would go away when the power was reduced. It was determined the plug was getting too hot. I think lead fouling with auto plugs is from the wrong heat range, but think they may be more susceptible than aviation plugs.

Main advantage of auto plug is suppose to be cost. For me there is no questions about the aviation plug so I am going with the REM37BY. Also you don't have to buy adapters and they are more rugged.

An auto plug is $2.75 a pop and aviation plugs $19.50 a pop. That is $134 more. However aviation plugs last a long long time. Some pilots replace auto plugs every 100 hour or so. I have no idea why or if that is needed. An aviation plug I know can go quite a long time. I have no exact number for aviation plugs in hours either. The massive electrode and tip can wear down to 50% and be still be good to go. Some might say, hey there is exotic auto plugs. There are exotic auto plugs, but they cost $20 a pop or more.

Aviation plugs do have to be cleaned. Cleaning them is easy but requires a few tools: gap tool, vibrator and hand held bead blast. You can get those tools cheap enough. I use a friendly FBO's bomb test to do the visual spark under pressure test. The auto plugs are cheap so you just toss them, so that is easier. However you could clean auto plugs for more use. How long would they last? With the smaller electrode and tip I think much less.


Spark plug costs are peanuts in the big scheme of things (gas, oil, hanger, insurance). The cost difference is not that great, when you add the cost of the adapters and replacing auto plugs more often.

Sorry no Black & White one is better. I personally trust the aviation plug. Do what makes you happy. My advice is if you are a cheap son of biscuit than buy the auto plugs to save that nickle. If you want a guarantee will work no monkey motion with adapters get Aviation plugs. You know what is going to happen with an aviation plug. I don't screw with the basics if I can avoid it. There are may be a hand full post with odd or negative things regarding automotive plugs and that is enough for me. I just don't think a $2.75 auto plug has the same quality as an aviation plug. I could be way off, but that is my story and I'm sticking to it.


Good luck George

 

[Highflight]

Spark plug costs are peanuts in the big scheme of things (gas, oil, hanger, insurance). The cost difference is not that great, when you add the cost of the adapters and replacing auto plugs more often.

Sorry no Black & White one is better. I personally trust the aviation plug. I just don't think a $2.75 auto plug has the same quality as an aviation plug. I could be way off, but that is my story and I'm sticking to it.

Good luck George

Jekyll, George's answer can be easily condensed to the above.

Looking at it from the other direction, I challenge anyone to "document" that auto plugs are better for aircraft use. Common sense dictates that a plug designed for aircraft use must withstand running at high power settings for most of the engines life. Probably one reason for them having dual electrodes and more massive cases.

But the best point to make is that aviation plugs, even at their higher cost, have an inconsequential impact on the cost of maintenance. If you feel the need to replace them every 100 hours, you'll pay about $70 more than if you replaced auto plugs (assuming you can count on getting 100 hours from auto plugs).
In that time, you will have spent about $2700 in fuel, $3000 in hangar fees, $1800 in insurance. One hamburger flight will cost you $100 or more.

If you have other reasons to use auto plugs, great, but saving so little money on something as critical as a part that's required to work well to keep your engine running doesn't make a lot of sense.
I've already saved enough money in the two group buys we just had here to pay for aviation plugs for several years. A couple more of those kind of deals and I might even think about a CS prop.... nah.

 

[jclark]

From the guy George referenced ...

That is me! "Documentation" I got you're documentation right here.

<<<SNIP>>>

I personally talked to Jeff Rose the original designer of the Electroair in 2004-2005. He told me he recommended aviation plugs, the REM37BY in particular. He promoted auto plugs at first but changed to recommending aircraft plugs. Jeff also stated to me aviation plugs gave better performance, which I think he did evaluate (document). Look at an autolite or NGK. They have one single electrode over the top of the tip. That blocks some of the spark. An aviation plug his massive dual side electrodes. Which one do you think is better spark maker without any documentation? You get what you pay for?

I read one post where a guy with an Electroair went from Aviation plug to Autolite 386 and than back to aviation. He noted slight power loss with the Autolite, noting major but he could tell. His plan was to go back to aviation plugs for good. This post also mentioned a friend flying a O360 powered RV cracked two Autolite 386's in flight, causing some excitement.

This is what the electroair site now says:

"What spark plugs do you recommend? Do you recommend automotive spark plugs?
You may use either the aircraft or automotive spark plugs. There are several hundred airplanes running the EIS with automotive plugs. Additionally, you must verify that the heat range of an automotive plug is correct for your engine or you risk causing severe damage. We prefer, however, the aircraft plugs as they have been designed to work with aircraft engines and do not require any modifications for installation."

<<<SNIP>>>

Good luck George

And that person was me!!

I also had a long talk with Jeff (who told me he did auto plugs long time ago ...maybe even before they we so cool ). He changed his mind after a discussion with either an engime manufacturer or a plug manufacturer told him there would be a performance difference. Hed went a did some checking and confirmed same.

I also did a change *from* aviation (REM37BY) *to* auto (Autolite 386) and then *back to* aviation plugs. Using my calibrated "seat of the pants" measurements, I could tell a slight performance difference. My friend happily uses NGK (??) Platinums.

I was ALSO the person that wrote about a friend who had an interesting experience using Autolite 386's (they cracked). This caused a bit of misfiring. He was using them on the single Jeff Rose EI and had REM37BY's on the mag side of an O-360.

Now I don't know why they cracked. Maybe they had been dropped without his knowledge. Maybe they couldn't take the heat. Again, I don't know. I had some "spare" 386's so I gave them to him so he could make it back home. I think his plan was to switch over to all REM37BY's when he got home.

So obviously, your mileage may vary. Your costs will for sure with the aviations costing 10x per plug. But what price for peace of mind???

James

 

[Kahuna]

For what its worth,
I ran auto plugs for 600 hours on an o-360 before replacing them on an LSE system.
I have no idea on the performance difference. I never got past 200 on a set of aviation plugs.

Never had a failure. Ran dual LSE's for the last 800 hours I flew the plane and never has a plug fail, foul, or otherwise give me any trouble.

Just another data point.
Best

 

[Jekyll]

Thanks guys. These replies were definately the type of input I was looking for. My gut said aircraft plugs were tailor made for the environment and application so they are spotted 1 touchdown at the start of the game. That being said, they were not necessarily designed for EI so the issue can get a bit muddled. The real issue is: do auto plugs EQUAL aircraft plugs in performance, safety and reliability? If they do, then and only then, does the price delta enter the equation.

Thanks
Jekyll

 

[RV6_flyer]

How long do aviation plugs last?

I ran my first set of Alburn plugs for 900 hours. Dual Mags O-320.
They could have went longer but I was flying to Alaska and did not want any problems out in the middle of no-where. Only needed to clean plugs about every 200 hours. I now have 939 hours on the 2nd set of plugs and they are Champion. Total time is 1,839 hours. It looks like they will go 500 hours or more.

I have two P-Mags on order. I am going to use Auto Plugs. I know of one person that has had problems with an IO-360 that had auto plugs. They had a Jeff Rose ignition and were getting detonation. Jeff told him to go back to Aviation plugs. His engine was timed at 25 degrees BTDC but the Lycomng spec was 20. I think he was causing his own problem.

Everyone that I know that is flying auto plugs are having no problems. Most of them just throw them away and put new ones in when the inspect the plugs not becasue there is something wrong with them but becasue they are cheap.

Auto plugs are available in differt electrode configurations so the dual electrodes on the aviation plug does not necessarly make it better. The aicraft plugs are next to impossible to open up the gap to get a larger gap that will work with electronic ignition but not work with mags.

I agree with someone that wants to see the documentation on any peformance differences.

Gary
DAR

 

[gmcjetpilot]

Calm down everyone, no one is going to get hurt

I ran my first set of Alburn plugs for 900 hours. Dual Mags O-320.
They could have went longer but I was flying to Alaska and did not want any problems out in the middle of no-where. Only needed to clean plugs about every 200 hours. I now have 939 hours on the 2nd set of plugs and they are Champion. Total time is 1,839 hours. It looks like they will go 500 hours or more. Gary DAR

Thanks for the back -up, I was thinking aviation plugs in the 900-2000 hour range. In the planes I have owned, I never replaced the plugs before selling the plane and they where going to TBO.

Kahuna has an preference for auto plugs, cool, but his service life hours are way off. However to be fair the auto plugs I hear go about 600 hours, may be more. (Kajuna, no one said auto plugs = bad, just my preference, plane plugs are for planes, car plugs for cars. However the LS is awesome system BTW )


As far as cost 19.50/2.75= 7 to 1. Assume conservatively aviation plugs are good for twice to life the cost ratio is 3.5 to 1 or better. I think some one said 10x.

-It is a moot point if you have regular mags or Lasar, you have to go w/ aviation plugs
-It is a moot point if you have Light speed, you have to use auto plugs.
-Only Electroair and P/E-mag offer the aviation/auto plug option

To test performance difference would be easy, one plane and two sets of harnesses and plug's with P/E-mags or Electroair.

I have no stock in aviation spark plug companies, so get what you all want. It ain't no big deal. I tend to think that aviation plugs should give better get up and go, which is Jeff Rose's opinion. I do think they should be more durable and less prone "issues". Although the auto plug "issues" are few and far between for the number in service, but just a few occurrence turned me off. Also I don't like the plug hole adapter, no big deal, just a preference.

George

 

[osxuser]

Why does everyone use the Champion BY's? It would seem kind of pointless since they are slightly more expensive than the REM38B's usually, and don't really add any benefits in the O-360 series.

 

[dan]

Why does everyone use the Champion BY's? It would seem kind of pointless since they are slightly more expensive than the REM38B's usually, and don't really add any benefits in the O-360 series.

They're easier to gap, imho.

Supposedly they're less prone to fouling as well. I don't have much to compare it to since I've always run UREM37BY's on my bottom plugs. But I have never, not ever, seen any lead. I have never, not ever, cleaned my spark plugs.

 

[osxuser]

If you have never seen lead, then it won't make any difference anyway. Since you run a lot of LOP ops, you burn off the lead very easily anyway. The whole point of the BY plug with O-235 engine (Cessna 152) was that the electrode was sticking farther into the combustion chamber, therefore it gets hotter and the lead burns off it. If you were going to foul plugs, the bases would still fill up with lead.

So basically there is no benefit in the terms of the initial design of the plug. But if you find them easier to gap, I guess there is no reason why they wouldn't work fine. I think there might be some concern for people running high compression pistons about the BY's getting a bit to close to the piston at TDC...

And back on topic, one more for Avaition plugs over Autos. Who wants to go to pep boys to buy spark plugs for there airplane? I have enough trouble finding decent ones for my Saturn...

 

[gmcjetpilot]

Love this forum

Dan and Osxusesr:

Good post and would add that The REM37BY is made so the insulator core nose and electrode assembly projects further out, reduces fouling problems, which are caused by low power operation with leaded fuels. I am sure that the 38B will work fine. I did own a O230L2C engine known for lead fowling so some engines are more prone, but your basic O(I)320, O(I)360's are not as prone.

I also agree that if you operate your engine LOP or even ROP (properly) you will not have lead fouling issues. Lean the heck out of it on the ground and lean it in flight as much as you can, as allowed by acceptable (approved) practice.

George

 

[dan]

Where are you buying your plugs? I see them as the same price:

http://www.skygeek.com/autavsparplu1.html

 

[Bryan Wood]

Today I installed four new Autolite aviation plugs in the bottom, and 4 new NGK auto plugs in the top, used with the lightspeed. My airplane has 253 hours now, so while the aviation plugs didn't need replacing I did it anyway to have spares for my growing list of items to carry on board. The old ones were cleaned, gapped, and added to the tool box. As for the auto plugs, I change them every other oil change. It might seem crazy, but the plane just runs so much stronger with new plugs. It idles different, sounds different, and generally runs smoother with new plugs on top. The ones that I took out looked almost new with no visable wear on the electrodes and nice color also. So, can anybody explain why the plane seems so much smoother when the auto plugs are changed? This isn't just my imagination either because my wife has commented on how smooth the engine is without being aware that the plugs have just been changed out, twice!

Blue Skies,

 

[osxuser]

They do look about the same price from Spruce and others... at the shop I work at we charge a bit more for um, I guess because we don't use as many so we stock them for longer... or something. Who knows really?

 

[gmcjetpilot]

Mass hysteria

It might seem crazy, but the plane just runs so much stronger with new plugs. It idles different, sounds different, and generally runs smoother with new plugs on top. The ones that I took out looked almost new with no visable wear on the electrodes and nice color also. So, can anybody explain why the plane seems so much smoother when the auto plugs are changed? This isn't just my imagination either because my wife has commented on how smooth the engine is without being aware that the plugs have just been changed out, twice! Blue Skies,

Mass hysteria?
Auto roughness? (always runs rough over water and mountains)

You know if you told your wife its better to keep using the old plugs because they have proved to be reliable and statistically are safer and better than new "Unknown" plugs, she might think different? I am making all this up, but may be it is in your head.

Does it run like crap on the old plugs? That is not a real good advertisement for automotive plugs? I am just pulling your leg, but subjective stuff is hard to measure. If is smoother than darn it, it is!

How about a study, have some one change your plugs or NOT? See if you can tell. Do it three times to see if you can guess if the plugs are new.

George

 

[Bryan Wood]

George,

That would be an interesting test wouldn't it? It's certainly one that I wouldn't bet any significant amount of money on being able to "Really" tell the difference. But in the mean time , that's my story and I'm stickin' to it.

Best,

 

[dserratt]

I have to charm in on this one

Aviation plugs have to be avle to deliver dependible spark from a low power mag at altitude where it can sometimes be esier for the spark to jume to another distributer electrode then to the one it's suposed to so aviation plugs have more shielding then auto plugs to help eliminate this. also any EI that can revert back to mag in case of power loss needs aviation plugs.
that being said the advantage to auto plugs aside from price is plug gap as EI can provide a much higher energy spark if you gap for it since your ignition system only produces as much voltage as is required to arc the plug gap if that is 1000 volts then thats what you get.
Automotive or should I say marine plugs have multiple grounds 2 or 4 around the electrode but since current takes the path of least resistance it will jump to the easiest ground I think this would only help in a fouled situation.
EI has another benifit it produces consistant performanse throughout it's life unlike mags with wearing and burning points.
And another a very high energy very acuratly timed spark which is much more suitable for ignition in a piston engine.
I would like to find out what the RPM drop is when doing a mag check with two EI systems, I would guess almost none which means a truley reduntant ignition system as mags require both to run properly and because of there reliability isues.
dont mean to ruffle any feathers

 

[frankh]

I have 4 hours on auto plugs

And theryre GREEEAT...

And the Emagair recommended plugs cost $1:39 each!

As to higher pressures...With 8.5:1 CR, cylinder pressures cannot be higher than that of the average car engine. Think about it ...Lycs Have trash can sized cylinders....They make a lot of torque (380ft lbs roughly) but that is spread over a large cylinder.

The larger gap of auto plugs has got to be an advantage if anything.

In my old Subaru engine I used the 3 prong racing plugs. These would be an option if you can get them in the right heat range for those that don't like the top cover electrode. Not that the engine will care one bit.

Atoplugs for me...Lets see if I change my mind after a few hundred hours.

Frank

 

[dserratt]

I think you missed my point

HEI systems are not prone to the problems that low energy mags are hence the expensive plugs and wires
As for performance I agree a larger gap is an advantage if you have HEI system
If aviation plugs had any performance advantages at all they would have been adapted by every racing organation on earth.
Also I would trust an alternator and battery over two sets of points as I always carried a spare set for my car and motorcycle at all times and they were alyays considered to me the weakest dependibility link with possibility the master link for my chain comming in second. My tool box always had a point file and feeler gauge. Now i don't even think about my ignition failing come to think about it i don't think about my systems after they are installed.
after all the talk about HEI saving fuel, smother running, better starts, and more power we still have people comming back to the reliability thing and mags being proven well so are generators and carbs and lets not forget good old vacum tube radios and mono planes will never out do biplanes
Electronic ignition is not the future its now.
Again don't mean to ruffel any feathers

 

[frankh]

and if you have a Pmag

You don't even have to worry about your electrical system dying either as it is self powered just (almost ish) like a mag

Frank
7.5 hours of engine Break-in thrash!

 

[gmcjetpilot]

Well one correction

HEI systems are not prone to the problems that low energy mags are hence the expensive plugs and wires
As for performance I agree a larger gap is an advantage if you have HEI system
If aviation plugs had any performance advantages at all they would have been adapted by every racing organization on earth.
Also I would trust an alternator and battery over two sets of points as I always carried a spare set for my car and motorcycle at all times and they were alyays considered to me the weakest dependability link with possibility the master link for my chain comming in second. My tool box always had a point file and feeler gauge. Now i don't even think about my ignition failing come to think about it i don't think about my systems after they are installed.
after all the talk about HEI saving fuel, smother running, better starts, and more power we still have people comming back to the reliability thing and mags being proven well so are generators and carbs and lets not forget good old vacum tube radios and mono planes will never out do biplanes
Electronic ignition is not the future its now.
Again don't mean to ruffel any feathers

I think you are mixing the advantages of Electronic Ignition and Mags with a discussion of Auto plugs verses Aircraft plugs. The type of iginiton you use does relate to the plug used but in my opinion for a different reason than what you state.

You have to look at plugs alone first.

People who have switched between the auto and av plugs with EI have felt, perceived greater power. You can say that is not true, but this is what some people have experienced. Also Jeff Rose whos opinion I value preferred the Av plug for this reason.

Now I have no dog in the fight and don't care, so I will play my own devils advocate.

The reason for the greater power in my opinon may be from the design of the plug, MASSIVE side electrodes and extended reach like on a REM37BY.

Most of the auto plugs have one "HOOK" over the top of the center electrode. This shields and blocks the spark from the combustion chamber. This makes sense. HOWEVER you can buy expensive "Racing" side multi-electrode automotive plugs, so this may be moot. However some of the racing automotive plugs cost more than aircraft plugs.

Your argument that the world would rush to use Av plugs if they where better is not fair. First they would NOT FIT. Av plugs are larger. Also it is not a who is better. Part of the reason for massive Av plugs is we know that a cracked or overheated plug can cause pre-ignition. Is a Av plug better at preventing pre-ignition and heat build up? Who knows, however Av plugs are made for one purpose, aircraft and do look stronger. They don't have porcelain to exposed to crack. Automotive plugs are adapted to work in aircraft engines. That does not make them bad, but each has its strength. Both can make sparks. If you think about it, spark plugs are dirt simple in theory. None of this is earth shaking one is better, just different.



Now I will argue FOR automotive plugs with EI. The big reason is the plug wires or harness is easier to make and has high voltage advantages. Let me explain.

The big reason, as I was told by Klaus at LS, for going with the auto plug is it is easier to hook up with EI with automotive wires. With an auto plug you have a snap on connection and a boot. It is right there. There is a fairly tight snap fit with pressure between the wire contact and the plug contact. The down side of the Av plug is you have the spring contact at the bottom of the plug barrel. There is not a lot of pressure and there can be corrosion, moisture and low contact pressure. A good Aviation harness should be sealed and and corrosion free, but because electronic ignitions make so much more spark energy, you get some weird things going on, oxidization and arcing, as I am told. You can get an Av plug to work with EI, but it is more cumbersome according to Klaus. Bottom line according to Klaus and I value his opinion, the Av plug was not set up to take high voltage. I believe that.

So in my mind, the main advantage to use auto plugs is the wire harness connection. Cost is not a factor and performance is a wash. If someone come up with some good wire harnesses for electronic ignition to Av Plugs, I would still prefer Av plugs. However considering the possible issue with high voltage and the spring contact, I am revising my opinion. The favor has tipped towards auto plug for ease of harness connection for high voltage. I know the silicon boot works on my car for years so it should be fine in the plane.

 

[dserratt]

The other reason for AV plugs

AV plugs and wires are designed to reliably deliver a low energy spark at high altitude where the spark may find it easier to arc somewhare else, for instance if there is a loose connection where the plug and whire meet the spark may find it easier to jump to another electrode in the distributer cap and fire another plug.
for this purpose everything is designed to have good connections. but I would have to see proof that AV plugs with EI have anymore power then auto plugs because to take advantage of the increased potential of EI you need a much larger plug gap then .018 since the voltage used in an ignition system is only what is needed to jump the gap. I don't know if it is possible to gap AV plugs to .035 - .045 or more.

Also the ability to install AV plugs for racing applications is only a matter of designing the head to accept them since most race heads are aftermarket anyway.

I agree that AV plugs may last longer then auto plugs but i haven't seen any data about how long they last using EI since most of the auto plugs suffer from the ground and electrode eroding away over time due to higher energy, however they still last for a very long time without any service like a 100,000 miles.

Now back to EI many of the EI systems have even eliminated the distributer or mag in this case, the cap and rotor and the rotating shaft associated with them. NO MOVING PARTS TO WEAR OUT, no service interval for the electronics or coils just plugs and wires
and again i would like to point out that EI is truely redundant since the engine will run great with just one system where as with mags the engine will run with one but really needs two to run normal.

I keep reading that mags are proven but proven for what, yes they run without any outside power source but thats because when they were devoloped over a century ago there was no outside energy source and even after generators came into being they to were unreliable and so was battery technology and mechanical regulators. today with self contained lightwaight alternators and new battery technology charging systems are IMHO more reliable then mags, how often do pilots send there alternators out to get rebuilt just because there is 500 hours on them.
Aircraft engins have two mags because one mag would be so incredibly unreliable and the engine would run so poorly. to be truley redundant an engine really needs 3 mags since the engine does not run acceptbly with the lose of one.
I hope this dosn't heat thing up to much

 

[N941WR]

Great topic, now for a twist.

Here is a twist to this issue.

My O-290-D2 is a 7.5 to 1 compression engine and in my -9 it will have duel Pmags.

Because of the lower compression I suspect I will have more of an issue with lead fowling as I did in my A-65 powered T-Craft.

All other auto/aviation plug issues aside, to help alleviate lead fowling in this engine, should I run auto or aviation plugs?

 

[N395V]

Has anyone run automotive plugs at high altitude (18K and greater) with or without problems?

 

[dan]

Has anyone run automotive plugs at high altitude (18K and greater) with or without problems?

FWIW, I've run mine above FL200. NGK BR8ES (#5422) fired by a Lightspeed Plasma II. No problems.

 

[Steve Brown]

My auto plugs easily go 100 hours

.......
But the best point to make is that aviation plugs, even at their higher cost, have an inconsequential impact on the cost of maintenance. If you feel the need to replace them every 100 hours, you'll pay about $70 more than if you replaced auto plugs (assuming you can count on getting 100 hours from auto plugs).........

I've replaced my auto plugs at about 100hrs & 200hrs. In both cases the plugs could have been cleaned and used again as they showed virtually no wear. Actually, they didn't really even need to be cleaned. I replaced them because they're so cheap.

Remember the "tune-up" for cars that involved (among other things) replacing or cleaning/re-gaping plugs? With modern electronic ignition that chore is at 50,000-100,000 mile intervals.

Aviation plugs were conceived and designed with mags in mind, not electronic ignition. I think they are not very relevant anymore.

The other side of your argument is that if auto plugs are rugged enough for the application, why spend more?

 

[osxuser]

Setup a RV-6 recently with Autolite 386's in the bottom, no perceivable problems. $2 a plug. The main problem I've got is finding leads for the EI to the aviation type plugs.

 

[BillSchlatterer]

Non-Fouler Plug Adapters ????

The adapters that the auto plugs screw into look to be exactly (other than the threads) what we used to buy at autoparts stores years ago as "non-foulers" back when engines actually burned oil. They worked OK as I remember it and would think they may provide some protection from oil fouling in this application.

Never seen anyone comment on how this effects ignition and fouling but it has to have some impact?

Bill S
7a finishing

 

[N941WR]

How about running unleaded fuel. No lead=No lead fouling.
I know, I know, that's not what this thread is about.

Seth,

That post was made 10 1/2 months before my first flight and I had no experience with this engine and 100LL. Now after 165 hours on my O-290, lead fouling is not an issue at all. This is probably due to my duel electronic ignition (P-mag’s) burning off the lead.

As for running auto fuel, I had thought I would do that as I can run regular unleaded (87 octane), if I can find ethanol free stuff, in this 80 octane engine. However, with regular unleaded going for $4.08 a gallon and 100LL available for $4.80 it really isn't worth the hassle of dealing with gas cans or other fueling methods at this time.

Regarding the reliability of auto plugs... When you can replace all eight plugs for less than the price of one aviation plug, I just replace them rather than clean and re-install them. For me, this is every 100 hours and when I pull them out, they look clean and the gap hasn't changed. If these plugs were in a car, I would have no issue just putting them back in and running them for another 100 hours.

 

[Andy_RR]

Iridium tipped plugs?

Has anyone used iridium tipped plugs in a Lycoming? These are the plugs that are specified in automotive applications where plug life is 60000 miles.

Most of the problem with conventional automotive spark plugs is that the edges wear off the electrodes causing the spark to be more random and diffuse. The tiny iridium tips are supposed to be the solution to this, although the expense of the material is also a consideration!