X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 27 May 2008 18:54:59 -0400 Message-ID: X-Original-Return-Path: Received: from mta10.adelphia.net ([68.168.78.202] verified) by logan.com (CommuniGate Pro SMTP 5.2.3) with ESMTP id 2940442 for lml@lancaironline.net; Tue, 27 May 2008 08:46:10 -0400 Received-SPF: pass receiver=logan.com; client-ip=68.168.78.202; envelope-from=glcasey@adelphia.net Received: from [76.166.22.191] by mta10.adelphia.net (InterMail vM.6.01.05.02 201-2131-123-102-20050715) with ESMTP id <20080527124723.ILDA20419.mta10.adelphia.net@[76.166.22.191]> for ; Tue, 27 May 2008 08:47:23 -0400 Mime-Version: 1.0 (Apple Message framework v753) In-Reply-To: References: Content-Type: multipart/alternative; boundary=Apple-Mail-1--490590504 X-Original-Message-Id: <7F2DCFA7-4412-48C7-82ED-A42D2BFC4AC0@adelphia.net> From: Gary Casey Subject: Re: Electronic ignition spark plugs X-Original-Date: Tue, 27 May 2008 05:45:27 -0700 X-Original-To: "Lancair Mailing List" X-Mailer: Apple Mail (2.753) --Apple-Mail-1--490590504 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=WINDOWS-1252; delsp=yes; format=flowed All this talk about EI spark plugs may be slightly off topic for a =20 Lancair list, but I find it useful, especially since I am about to =20 replace the plugs in my Lycoming (parallel-valve, 10:1 compression. =20 First, I'm confused about the term "automotive plugs" and the idea =20 that they somehow "can't handle the pressure". What pressure are we =20 talking about? Looking at the construction of both automotive and =20 aircraft plugs I see that they are both built essentially the same, =20 with the automotive plugs probably more substantial with most using =20 metal seals while some or most of the aircraft plugs use a =20 composition seal. The only problem there is you might get a trace of =20= leakage, not really a major issue. Whether the plug is designed for =20 a moped or a Ferrari the plugs are essentially identical in =20 construction and quality with the biggest difference being things =20 like heat range and center electrode extension. The key is to use =20 the "right" heat range and I see the plugs that came with my LSE III =20 are very cold, similar to what we used to use in turbocharged race =20 engines. It might be tempting to use a hotter plug to keep the =20 insulator cleaner, but the plug "guru" at Autolite once told me that =20 is playing with fire in an aircraft engine. He said that lead =20 deposits are conductive when hot, just before they burn off. Ground-=20 based lead-burning vehicles work well with hot plugs as the lead is =20 continually burned off. However, aircraft engines can run for a long =20= time cold (on the ground) and then are suddenly run very hot, which =20 can get the lead hot enough to conduct before it can burn off. He =20 had seen cases of total engine failure caused by all the plugs =20 shorting from lead fouling at the same time. Using cold plugs will =20 let the lead build up over time, but won't suffer from the shorting =20 problem Perhaps the difficulties related had something to do with =20 that. By the way, the Denso WEMR27-C plugs supplied with my EI =20 system look about right regarding the heat range after 100 hours, but =20= the electrodes are significantly eroded. As I understood it, the problem with using "aircraft" plugs with =20 automotive coils is coming up with an ignition wire that connects to =20 both. Is there a wire that has an "automotive" connection at the =20 coil end and an "aircraft" connection at the plug end? Apparently =20 one "Lancair group" stopped using "automotive plugs in their EI =20 systems. What "aircraft" plugs do they use now? If that were =20 readily available why not use aircraft plugs? The other discussion centered on fine center wires. As the =20 referenced articles said, the advantages are reduced center electrode =20= erosion (longer life) and reduced voltage requirement. They also =20 imply that there is a slight improvement in "ignitability." Longer =20 life is a no-brainer, but in an aircraft application we probably want =20= to replace the plugs on account of lead buildup anyway, so we won't =20 see longer life. Reduced voltage requirement is a good thing, =20 especially if the rest of the system is on the weak side and is not =20 capable of producing the higher voltages. I don't see that being an =20 issue as long as the plug gaps are reasonable (.035 or less, maybe =20 and they could be set at .025). Ignitability is an issue if you are =20 trying to eliminate misfires under cold, idle or very lean =20 conditions. The ignitability of the mixture in an aircraft engine is =20= never as difficult as in a car engine (we don't have to meet =20 emissions, don't care about an occasionaly miss at idle or when the =20 throttle is closed on short final and we never run really lean. We =20 put in lots of fuel for a cold start). There is another issue that =20 might have a slight effect, and that is that apparently the flame =20 front initiation is a little faster with fine wires - the assumption =20 is that there is less electrode to shroud the flame kernel and =20 therefore the flame builds to a true flame front faster. I would =20 guess that this is probably true, but the effect is ignition timing =20 that is "advanced" slightly on account of that the flame front builds =20= more quickly. Studies I did a long, long time ago showed that simply =20= advancing the ignition time a degree or two did the same thing. So =20 the improvement in BSFC measure by RAM was likely just that effect. Bottom line is the choice between massive wire or fine-wire =20 electrodes in an EI system - which is it to be? Certainly the fine-=20 wire plugs are "better", but are they worth the cost? I'm not sure - =20= the difference is small enough to make it a good question. Sorry about the long opinion. Gary Casey On May 27, 2008, at 3:00 AM, Lancair Mailing List wrote: > > I thought maybe I should add to the anecdotal data base here (even =20 > though I fly a crummy RV8). > > > > I have a parallel valve 360 with 10:1 pistons, forward facing sump/=20 > bendix injection, and 4 pipe exhaust. Like Scott, I run dual Light =20 > Speed Plasma IIIs, and the IK27 spark plugs. I change them once a =20 > year at annual. I also run many of the races, Airventure Cup and =20 > some of the Sport Air Racing League events. These are all low =20 > level, wide open races (for 2 hours in the AirVenture Cup). > > > > I have never seen any damage to any of the plugs, or had any =20 > problem with the LS system. > > > > John Huft > > RV spy > > Race 18, =93Nuisance=94 > > > > > > From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf =20= > Of Sky2high@aol.com > Sent: Sunday, May 25, 2008 10:32 PM > To: lml@lancaironline.net > Subject: [LML] Re: Electronic ignition spark plugs > > > > Randy, > > > > What you said is, of course, contrary to my experience and the =20 > recommendations made by Light Speed Engineering. > > > > Which plugs had "the tips burns down fast or the ceramic crack =20 > under the pressures" and what were the pressures? Were the plugs =20 > ever dropped? > > > > Are you sure the coils shorted internally because the auto plug =20 > gaps were getting larger or were the coils placed in too hot of an =20 > environment? What plugs were used? It is hard to imagine =20 > internal coil arcing in the absence of any plug gap or even the =20 > absence of a plug altogether. > > > > Which actual auto plugs cracked under full power and/or had the =20 > electrodes burned away? What were the other engine conditions? > > > > I have run my 9:1 CR injected 320 at takeoff power (racing is like =20 > that) for hours on end with no difficulty - no difficulty with =20 > either the EI or the Denso IK27's - where the timing and A/F ratios =20= > have been appropriate for the power and the coils are located in an =20= > area behind the engine that usually reaches 70C. > > > > Anyway, you might find it interesting to read: http://=20 > sparkplugs.com/pdfs/iri.pdf even if you only skip to the =20 > conclusions at the end. > > > > You might consider getting rid of your massive electrode plugs =20 > altogether: http://www.ramaircraft.com/Maintenance-Tips/Spark%=20 > 20Plugs-Fine-Wire-vs-Massive.htm as it appears that while the fine =20 > wire plugs cost three times as much, they also last more than 3 =20 > times as long. > > > > You may wish to poke around the web for info on the differences =20 > betwixt Champion and Unison (Autolite) iridium plugs. > > > > BTW, I noticed that you re-gapped your aviation iridium plugs (out =20= > of the box the gaps are too small for EIs, .016-.018.). This is a =20 > very difficult task with Champion plugs (they are happy to re-gap =20 > them for you). > > > > Finally, I didn't even try the LSE recommended W27EBR (27 heat =20 > rating for higher compression engines) since they seemed too =20 > cheap. I did try the W27EMR-C plugs (triple massive electrode), =20 > but didn't like them because I could not control all three gaps =20 > (well, that was one reason). > > > > Scott Krueger AKA Grayhawk > Lancair N92EX IO320 SB 89/96 > Aurora, IL (KARR) > > Pilot not TSO'd, Certificated score only > 70%. > > Not even FAA tested for Repairman Certification. > > > > In a message dated 5/25/2008 7:24:32 A.M. Central Daylight Time, =20 > randystuart@hotmail.com writes: > > In my 360 I use Iridium plugs with my Jeff Rose EI. They work =20 > great. Set to .035. > > I wouldn't use car plugs in an aviation engine. They don't work well. > > I've seen the tips burns down fast or the ceramic crack under the =20 > pressures. > > One multiple failure I've seen is on a friends very low time Legacy =20= > that has had 3 shorted coils on his LSI system. > > This was from the Denso auto plug gaps getting larger from wear =20 > then eventually arcing inside the coil. > > Another failure in a 360 I've seen from auto plugs is the ceramic =20 > cracks under full power and completely burns away the electrodes, =20 > damaging the cylinder. > > Aviation plugs are made for aviation use and can take the abuse. =20 > They last much longer and rarely fail. All the Lancair's in my =20 > group stopped using auto plugs. > > Uppers are Massives with a mag and lowers are Iridium with an EI. > > --Apple-Mail-1--490590504 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=WINDOWS-1252 All this talk about EI spark plugs may be slightly off topic for a = Lancair list, but I find it useful, especially since I am about to = replace the plugs in my Lycoming (parallel-valve, 10:1 compression. = =A0First, I'm confused about the term "automotive plugs" and the idea = that they somehow "can't handle the pressure". =A0What pressure are we = talking about? =A0Looking at the construction of both automotive and = aircraft plugs I see that they are both built essentially the same, with = the automotive plugs probably more substantial with most using metal = seals while some or most of the aircraft plugs use a composition seal. = =A0The only problem there is you might get a trace of leakage, not = really a major issue. =A0Whether the plug is designed for a moped or a = Ferrari the plugs are essentially identical in construction and quality = with the biggest difference being things like heat range and center = electrode extension. =A0The key is to use the "right" heat range and I = see the plugs that came with my LSE III are very cold, similar to what = we used to use in turbocharged race engines. =A0It might be tempting to = use a hotter plug to keep the insulator cleaner, but the plug "guru" at = Autolite once told me that is playing with fire in an aircraft engine. = =A0He said that lead deposits are conductive when hot, just before they = burn off. =A0Ground-based lead-burning vehicles work well with hot plugs = as the lead is continually burned off. =A0However, aircraft engines can = run for a long time cold (on the ground) and then are suddenly run very = hot, which can get the lead hot enough to conduct before it can burn = off. =A0He had seen cases of total engine failure caused by all the = plugs shorting from lead fouling at the same time. =A0Using cold plugs = will let the lead build up over time, but won't suffer from the shorting = problem =A0Perhaps the difficulties related had something to do with = that. =A0By the way, the Denso WEMR27-C plugs supplied with my EI system = look about right regarding the heat range after 100 hours, but the = electrodes are significantly eroded.

As I understood = it, the problem with using "aircraft" plugs with automotive coils is = coming up with an ignition wire that connects to both. =A0Is there a = wire that has an "automotive" connection at the coil end and an = "aircraft" connection at the plug end? =A0Apparently one "Lancair group" = stopped using "automotive plugs in their EI systems. =A0What "aircraft" = plugs do they use now? =A0If that were readily available why not use = aircraft plugs?

The other discussion centered = on fine center wires. =A0As the referenced articles said, the advantages = are reduced center electrode erosion (longer life) and reduced voltage = requirement. =A0They also imply that there is a slight improvement in = "ignitability." =A0Longer life is a no-brainer, but in an aircraft = application we probably want to replace the plugs on account of lead = buildup anyway, so we won't see longer life. =A0Reduced voltage = requirement is a good thing, especially if the rest of the system is on = the weak side and is not capable of producing the higher voltages. =A0I = don't see that being an issue as long as the plug gaps are reasonable = (.035 or less, maybe and they could be set at .025). =A0Ignitability is = an issue if you are trying to eliminate misfires under cold, idle or = very lean conditions. =A0The ignitability of the mixture in an aircraft = engine is never as difficult as in a car engine (we don't have to meet = emissions, don't care about an occasionaly miss at idle or when the = throttle is closed on short final and we never run really lean. =A0We = put in lots of fuel for a cold start). =A0There is another issue that = might have a slight effect, and that is that apparently the flame front = initiation is a little faster with fine wires - the assumption is that = there is less electrode to shroud the flame kernel and therefore the = flame builds to a true flame front faster. =A0I would guess that this is = probably true, but the effect is ignition timing that is "advanced" = slightly on account of that the flame front builds more quickly. = =A0Studies I did a long, long time ago showed that simply advancing the = ignition time a degree or two did the same thing. =A0So the improvement = in BSFC measure by RAM was likely just that = effect.

Bottom line is the choice between = massive wire or fine-wire electrodes in an EI system - which is it to = be? =A0Certainly the fine-wire plugs are "better", but are they worth = the cost? =A0I'm not sure - the difference is small enough to make it a = good question.

Sorry about the long = opinion.
Gary Casey

On May 27, 2008, = at 3:00 AM, Lancair Mailing List wrote:
=A0=A0 = =A0

I thought maybe I should add to the anecdotal = data base here (even though I fly a crummy RV8).

=A0

I have a parallel valve 360 with 10:1 pistons, = forward facing sump/bendix injection, and 4 pipe exhaust. Like Scott, I = run dual Light Speed Plasma IIIs, and the IK27 spark plugs. I change = them once a year at annual. I also run many of the races, Airventure Cup = and some of the Sport Air Racing League events. These are all low level, = wide open races (for 2 hours in the AirVenture = Cup).

=A0

I have never seen any damage to any of the plugs, = or had any problem with the LS system.

=A0

John Huft

RV spy

Race 18, =93Nuisance=94

=A0

=A0

From: Lancair Mailing List [mailto:lml@lancaironline.net] = On Behalf Of Sky2high@aol.com
Sent: = Sunday, May 25, 2008 10:32 PM
To: lml@lancaironline.net
= Subject: [LML] Re: Electronic ignition spark = plugs

=A0

Randy,

=A0

What you said=A0is, of course, contrary to my = experience and the recommendations made by Light Speed = Engineering.

=A0

Which plugs had "the tips burns down fast or the = ceramic crack under the pressures" and what were the pressures?=A0 Were = the plugs ever dropped?

=A0

Are you sure the coils shorted internally because the = auto plug gaps were getting larger or were the coils placed in too hot = of an environment?=A0=A0=A0 What plugs were used?=A0 It is hard to = imagine internal coil arcing in the absence of any plug gap or even the = absence of a plug altogether.

=A0

Which actual auto plugs cracked under full power = and/or had the electrodes burned away?=A0 What were the other engine = conditions?

=A0

I have run my 9:1 CR injected 320 at takeoff power = (racing is like that) for hours on end with no difficulty - no = difficulty with either the EI or the Denso IK27's - where the timing and = A/F ratios have been appropriate for the power=A0and the coils are = located in an area behind the engine=A0that usually reaches = 70C.

=A0

Anyway, you might find it interesting to read:=A0 http://sparkplugs.com/pdfs/iri= .pdf=A0even if you only skip to the conclusions at the = end.

=A0

You might consider getting rid of your massive = electrode plugs altogether: http://www.ramaircraft.com/Maintenance-Tips/Spark%20Plug= s-Fine-Wire-vs-Massive.htm=A0as it appears that while=A0the fine = wire plugs cost three times as much, they also last more than 3 times as = long.

=A0

You may wish to poke around the web for info on the = differences betwixt Champion and Unison (Autolite)=A0iridium = plugs.

=A0

BTW,=A0 I noticed that you re-gapped your aviation = iridium plugs (out of the box the gaps are too small for EIs, = .016-.018.).=A0 This is a very difficult task with Champion plugs (they = are happy to re-gap them for you).

=A0

Finally, I didn't even try the LSE recommended W27EBR = (27 heat rating for higher compression engines) since they seemed too = cheap.=A0 I did try the W27EMR-C plugs (triple massive electrode), but = didn't like them because I could not control all three gaps (well, that = was one reason).

=A0

Scott Krueger AKA Grayhawk
Lancair N92EX IO320 SB = 89/96
Aurora, IL (KARR)

Pilot not TSO'd, Certificated score = only > 70%.=A0

Not even FAA=A0tested for Repairman = Certification.

=A0

In a message dated 5/25/2008 7:24:32 A.M. Central = Daylight Time, randystuart@hotmail.com = writes:

In my 360 I use = Iridium plugs with my Jeff Rose EI.=A0They work great. Set to .035. =

=

I wouldn't use car = plugs in an aviation engine. They don't work well.

=

I've seen the tips = burns down fast or the ceramic crack under the pressures. =

=

One multiple failure = I've seen is on a friends very low time Legacy that has had 3 shorted = coils on his LSI system.

=

This was from the = Denso auto plug gaps getting larger from wear then eventually arcing = inside the coil.

=

Another failure in a = 360 I've seen from auto plugs is the ceramic cracks under full power and = completely burns away the electrodes, damaging the = cylinder.

=

Aviation plugs are = made for aviation use and can take the abuse. They last much longer and = rarely fail. All the Lancair's in my group stopped using auto plugs. =

=

Uppers are Massives = with a mag and lowers are Iridium with an EI.

=


= --Apple-Mail-1--490590504--