X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 19 Nov 2010 16:53:13 -0500 Message-ID: X-Original-Return-Path: Received: from imr-mb02.mx.aol.com ([64.12.207.163] verified) by logan.com (CommuniGate Pro SMTP 5.3.10) with ESMTP id 4584967 for lml@lancaironline.net; Fri, 19 Nov 2010 08:56:05 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.207.163; envelope-from=Sky2high@aol.com Received: from imo-da03.mx.aol.com (imo-da03.mx.aol.com [205.188.169.201]) by imr-mb02.mx.aol.com (8.14.1/8.14.1) with ESMTP id oAJDt65S005577 for ; Fri, 19 Nov 2010 08:55:06 -0500 Received: from Sky2high@aol.com by imo-da03.mx.aol.com (mail_out_v42.9.) id q.c77.6e8b0434 (55834) for ; Fri, 19 Nov 2010 08:55:01 -0500 (EST) Received: from magic-m25.mail.aol.com (magic-m25.mail.aol.com [172.20.22.198]) by cia-md06.mx.aol.com (v129.7) with ESMTP id MAILCIAMD062-da1a4ce681b4313; Fri, 19 Nov 2010 08:55:00 -0500 From: Sky2high@aol.com X-Original-Message-ID: <3b2b7.35f20bec.3a17dbb4@aol.com> X-Original-Date: Fri, 19 Nov 2010 08:55:00 EST Subject: Re: [LML] Re: Electronic Ignition X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_3b2b7.35f20bec.3a17dbb4_boundary" X-Mailer: AOL 9.5 sub 5400 X-AOL-IP: 24.15.17.119 X-Spam-Flag:NO X-AOL-SENDER: Sky2high@aol.com --part1_3b2b7.35f20bec.3a17dbb4_boundary Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en Doug, =20 Your worries are over. At takeoff power with my 9:1 CR I see about 22=20 DBTDC at a MAP of 29.9" and 2740 RPM. My home airport is at 700 MSL. Cr= uise=20 (180 KIAS) at about 5000 MSL, MAP about 26", RPM 2500 and 10.3 gph I see= =20 24-25 DBTDC (still not running LOP as the power is too high). Higher up= and=20 at pretty low power, ROP/LOP with a KTAS of 187 to 195 I see timing=20 reaching 29-30 DBTDC. LOP down to 5.5 gph (I only lose about 6-8 Knots ru= nning=20 LOP, but save about 2 gph to extend my range). =20 =20 While LSE doesn't publish timing data, one can determine that from the =20 optional display and various flight regimes. Even P-Mag displays its mode= l =20 mapping on its web site and has announced that a display is (or will be)= =20 available. Only LASAR's peculiar system keeps its maps as a trade secret= . I=20 have no idea about the existing FADEC systems. =20 The only problem with GAMI's opinion is that they tout a competing =20 vaporware system. I respect the engine knowledge that they have and comm= unicate=20 and I utilize the engine management procedures they propound. I hope the= ir=20 no-lead fuel formulation becomes the standard of the future. =20 =20 I have drunk from the EI Koolaid pitcher with the smiley face and =20 demonstrated to myself its value, even after struggling with LASAR. =20 =20 Another difference I have with GAMI relates to the method one might utiliz= e=20 to reach A/F ratio happiness betwixt cylinders. A first approach for a= NA=20 injected engine might be to balance the air reaching last century=20 injectors to equalize the atomization first. Before dickering with nozzl= e size, =20 one can use a plenum, along with shrouded injectors, to even out the air= =20 supply. If one flies fast enough and uses ram air induction that can rais= e =20 the MAP 1.5 or more inches above ambient, it is even more argument to use= the=20 same shrouded injectors that turbo charged engines use to make sure the=20 deck pressure supplying air to the injectors is a match to the MAP. I us= e ram=20 air to supply the plenum and am insured of equally distributed atomizatio= n=20 air at or above MAP. If that doesn't work with a GAMI lean test, one=20 should consider further tuning the nozzle sizes. =20 Let's go fly, =20 Scott =20 =20 In a message dated 11/19/2010 7:03:21 A.M. Central Standard Time, =20 douglasbrunner@earthlink.net writes: Scott, You said: Remember that magneto systems don't measure any factor yet the engine=20 manufacturer has no problem with LOP or ROP operations with some restrict= ions=20 (see below). Indeed, there are no timing adjustments for CR while EIs=20 provide fjor such. As I have said, EIs don't provide much timing change= from=20 the base timing (dependent on CR) for power settings over 75% as inferred= by=20 a combination of RPM and MAP - a typical way of expressing power. At low= er=20 power settings there is a benefit of advancing the spark to get more work= =20 done by the combustion event occurring in the cylinder. At low power=20 settings it is hard to get bad events to occur, including damaging peak= cylinder=20 pressures. Finally, please stop using ROP settings where the EGT is -50F from peak= as=20 that is outside the good operating range of my engine (that's info from= =20 both Lyc and GAMI, worst peak pressures) - Of course, if you are running= a=20 Continental engine, well, uh, you have to find your own info. Scott Krueger Scott, As a graduate of the AP Seminars, I have drunk the GAMI Koolaid. What=20 they said about Electronic Ignition makes sense to me - the advance curve= s are=20 proprietary and do not take into account the effect of mixture on timing. Several quick comments: * Does your abbreviation "CR" mean compression ratio? My engine has= =20 a 10:1 compression and the timing has been retarded to account for this.= =20 * "please stop using ROP settings where the EGT is -50F from peak"= I=20 do not use this setting although I think it is acceptable to use this=20 power setting at low enough power settings - <70%. If I am at a low powe= r =20 setting I am typically LOP. * You say: "EIs don't provide much timing change from the base=20 timing (dependent on CR) for power settings over 75%" What is the timin= g=20 change that EI uses? Do you have data on this that you can share? I think we would all like an electronic ignition system that provides a= =20 hot consistent spark, easy starting and does not have the maintenance and= =20 arcing problems of magnetos. We would also like one that kept the effect= ive=20 timing at 16 deg ATDC. The problem with current electronic ignition syst= ems=20 is that since they don't take mixture into account, they can't maintain= =20 the same effective timing with different mixtures. I would actually like to be able to advance my spark during certain fligh= t=20 regimes (LOP at less than 70% power) in which I am fairly certain nothing= =20 bad will happen and advanced timing will give better power/economy. It= is=20 the rest of the flight regime (like takeoff at 2700 RPM, 30" MAP and 10:1= =20 compression) that I am worried about -----Original Message-----=20 From: Sky2high@aol.com=20 Sent: Nov 18, 2010 7:52 PM =20 To: lml@lancaironline.net=20 Subject: [LML] Re: Electronic Ignition =20 Doug, =20 You said: =3D=3D=3DMy point was that electronic ignition systems measure only 2 of= the 3=20 factors that influence timing. Mixture can have a significant effect on= =20 when Peak Intracylinder Pressure (=3D effective timing) occurs. Hence th= e =20 effective timing at a best power mixture (50 to 100 deg ROP) would be =20 significantly advanced compared to the effective timing at best economy = mixture=20 (approx 50 LOP). This is not accounted for by electronic ignition system= s and=20 could lead to excessive spark advance. =3D=3D=3D =20 Remember that magneto systems don't measure any factor yet the engine =20 manufacturer has no problem with LOP or ROP operations with some restrict= ions=20 (see below). Indeed, there are no timing adjustments for CR while EIs=20 provide fjor such. As I have said, EIs don't provide much timing change= from=20 the base timing (dependent on CR) for power settings over 75% as inferred= by=20 a combination of RPM and MAP - a typical way of expressing power. At low= er=20 power settings there is a benefit of advancing the spark to get more work= =20 done by the combustion event occurring in the cylinder. At low power=20 settings it is hard to get bad events to occur, including damaging peak= cylinder=20 pressures. =20 Finally, please stop using ROP settings where the EGT is -50F from peak= as=20 that is outside the good operating range of my engine (that's info from= =20 both Lyc and GAMI, worst peak pressures) - Of course, if you are running= a=20 Continental engine, well, uh, you have to find your own info. =20 Scott Krueger =20 PS If you are talking about supercharged/turbocharged engines always =20 running at high power then the benefits of EIs are simply a better, more= =20 reliable spark without worrying about esoteric things such as that the ma= gneto is=20 properly pressurized so no sparking occurs in the mag. =20 =20 In a message dated 11/16/2010 6:11:46 P.M. Central Standard Time, =20 douglasbrunner@earthlink.net writes: =20 Scott,=20 I will concede your point about the hotter, longer and more consistent = =20 spark, although in most flight regimes (no extreme of F/A mixture) it =20 probably doesn=E2=80=99t make much difference.=20 With respect to your comment:=20 =E2=80=9Cyour argument of moving timing by messing with the mixture is,= uh, not=20 good operational practice=E2=80=9D=20 I think you misunderstood my point. I certainly do not advocate =E2=80= =9Cmessing=20 with the mixture=E2=80=9D =E2=80=93 especially at power levels above 70%.= =20 My point was that electronic ignition systems measure only 2 of the 3=20 factors that influence timing. Mixture can have a significant effect on= when =20 Peak Intracylinder Pressure (=3D effective timing) occurs. Hence the =20 effective timing at a best power mixture (50 to 100 deg ROP) would be =20 significantly advanced compared to the effective timing at best economy = mixture (approx=20 50 LOP). This is not accounted for by electronic ignition systems and=20 could lead to excessive spark advance.=20 D. Brunner=20 =20 =20 From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of = =20 Sky2high@aol.com Sent: Tuesday, November 16, 2010 9:25 AM To: lml@lancaironline.net Subject: [LML] Re: Electronic Ignition =20 Doug, =20 =20 I have a problem with your argument. It seems to be upside down. In=20 reference I refer you to my 11/2/2010 email entitled "NA Injected Engine= =20 Performance LOP". In any event, for any given proper fuel/air ratio (mix= ture),=20 there is a narrow timing range that produces efficient cylinder pressures= =20 at the correct crank angle range. The Lycoming engine manual (for my 320= )=20 displays the acceptable range for the EGT for best power as 100F to 180F= =20 ROP, and best economy as 0F to 80F LOP. Running 50F ROP is very bad for= =20 cylinder pressures as stated by GAMI - thus your argument of moving timin= g by=20 messing with the mixture is, uh, not good operational practice. =20 =20 Secondly, you imply that the only function of an electronic ignition is= to=20 advance the timing. Au contraire mon ami! An electronic ignition =20 provides for a hotter, longer, more consistent spark over a greater plug= gap that=20 better insures the reliable and timely ignition of the combustible mixtur= e=20 even though the F/A may be at some extreme. This results in greater=20 efficiency/HP depending on the way one looks at it. See the pamphlet on= the=20 benefits of the LASAR electronic ignition that shows speed increases for= the=20 same fuel burn or reduced fuel burn at the same speed of a magneto driven= =20 engine. =20 =20 The fixed timing of a magneto (i.e. 25 DBTDC) is a compromise. Generall= y=20 speaking, EIs advance the base spark timing minimally until the power, as= =20 measured by RPM and MAP, is reduced below 75%. Bad events, such as=20 pre-ignition, detonation and incorrectly timed cyl pressure, are less lik= ely in=20 this regime (that is why the GAMI lean test is done at less than 75% powe= r). =20 Furthermore, EGTs (representing F/A ratios) are still maintained in the= =20 engine manufacturer's recommended ranges and the timing is a better match= =20 for the combustion event pressures. =20 =20 Note that during my best power cruises at middle altitudes (2500 RPM, MAP= =20 > 22", EGT > 120F ROP), the EI timing is about 25 DBTDC plus or minus a= =20 degree.=20 =20 =20 Yes, more HP. Better speed for the same fuel burn holding other =20 conditions equal. =20 Yes, in all the modes you mentioned. =20 =20 I haven't reached TBO yet, I go too fast to accumulate that much time. =20 =20 Scott Krueger =20 IO 320 Dual Lightspeed Plasma III EI =20 =20 =20 In a message dated 11/15/2010 8:21:27 P.M. Central Standard Time, =20 douglasbrunner@earthlink.net writes: =20 At the risk of starting a =E2=80=9Ctheological=E2=80=9D controversy, I wo= uld like to=20 raise some reservations about electronic ignition systems (other than =20 reliability and loss of electrical power)=20 Peak intracylinder pressure (the point in the combustion cycle at which= =20 pressure in the cylinder is highest =3D effective timing) is related to 3= =20 things; spark timing, rpm and MIXTURE. =20 Why mixture? Because air and fuel mixtures burn at different rates=20 depending on how rich or lean they are. So at a given RPM, MAP and spark= advance=20 you can vary your effective timing by changing the mixture. =20 =C2=B7 Want to advance your timing? Change your mixture to a 50= deg=20 ROP mixture =E2=80=93 which is the fastest burning.=20 =C2=B7 Want to retard your timing? Make your mixture richer or= leaner=20 from 50 deg ROP.=20 And since optimal power is achieved at an effective timing of 16 deg ATDC= ,=20 advancing the spark timing may or MAY NOT increase horsepower depending= =20 on the mixture. But advancing the timing will likely increase the magnit= ude=20 of peak intracylinder pressure leading to higher intracylinder pressures,= =20 higher cylinder head temperatures and greater stress =3D shorter enging= life.=20 For those of you who are using electronic ignition (I am not):=20 =C2=B7 Are you sure you are getting more horsepower? How do you= =20 know?=20 =C2=B7 If you are getting more horsepower, are you getting it du= ring=20 all modes of engine operation? Rich of peak, lean of peak, high MAP, low= =20 MAP, etc=20 =C2=B7 What is happening to your TBO?=20 D. Brunner=20 =20 The biggest advantage of any of the electronic systems (in my opinon) is= =20 that they provide a spark advance that is a function of at least manifold= =20 pressure, giving an advantage any time the manifold pressure is much lowe= r=20 than maybe 25 inches. But there is very little combustion taking place= in=20 the exhaust system regardless. The reason the exhaust temperature rises= is=20 that more of the combustion occurs after TDC and that means less of the= =20 energy is being converted to work. The down side of advancing the spark= is=20 that since more combustion occurs at the highest cylinder pressure, more= heat=20 is transferred to the cylinder head and piston. =20 -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.htm= l --part1_3b2b7.35f20bec.3a17dbb4_boundary Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en <= FONT id=3Drole_document color=3D#000000 size=3D2 face=3DArial>
Doug,
 
Your worries are over.  At takeoff power with my 9:1 CR I see=20 about 22 DBTDC at a MAP of 29.9" and 2740 RPM.  My home airport= is at=20 700 MSL.  Cruise (180 KIAS) at about 5000 MSL, MAP about 26", RP= M 2500=20 and 10.3 gph I see 24-25 DBTDC (still not running LOP as the power is= too=20 high).  Higher up and at pretty low power, ROP/LOP with a KTAS of 187= to=20 195 I see timing reaching 29-30 DBTDC. LOP down to 5.5 gph (I only lose=20 about 6-8 Knots running LOP, but save about 2 gph to extend my=20 range). 
 
While LSE doesn't publish timing data, one can determine that from th= e=20 optional display and various flight regimes.  Even P-Mag displays its= model=20 mapping on its web site and has announced that a display is (or will= be)=20 available.  Only LASAR's peculiar system keeps its maps as a trade=20 secret.  I have no idea about the existing FADEC systems.
 
The only problem with GAMI's opinion is that they tout a competi= ng=20 vaporware system.  I respect the engine knowledge that they= have=20 and communicate and I utilize the engine management procedures they= =20 propound.  I hope their no-lead fuel formulation becomes the sta= ndard=20 of the future. 
 
I have drunk from the EI Koolaid pitcher with the smiley face&nb= sp;and=20 demonstrated to myself its value, even after struggling with LASAR. =
 
Another difference I have with GAMI relates to the method one might= utilize=20 to reach A/F ratio happiness betwixt cylinders.  A first approach for= a NA=20 injected engine might be to balance the air reaching last century injector= s to=20 equalize the atomization first.  Before dickering with nozzle si= ze,=20 one can use a plenum, along with shrouded injectors, to even out the air= =20 supply.  If one flies fast enough and uses ram air induction that can= raise=20 the MAP 1.5 or more inches above ambient, it is even more argument to= use=20 the same shrouded injectors that turbo charged engines use to make sure th= e deck=20 pressure supplying air to the injectors is a match to the MAP.  I use= ram=20 air to supply the plenum and am insured of equally distributed atomization= air=20 at or above MAP.  If that doesn't work with a GAMI lean test, one sho= uld=20 consider further tuning the nozzle sizes.
 
Let's go fly,
 
Scott
In a message dated 11/19/2010 7:03:21 A.M. Central Standard Time,=20 douglasbrunner@earthlink.net writes:
Scott,

You said:
 
Remember that magnet= o systems=20 don't measure any factor yet the engine manufacturer has no problem with= LOP=20 or ROP operations with some restrictions (see below).  Indeed, ther= e are=20 no timing adjustments for CR while EIs provide fjor such.  As I hav= e=20 said, EIs don't provide much timing change from the base timing (depende= nt on=20 CR) for power settings over 75% as inferred by a combination of RPM and= MAP -=20 a typical way of expressing power.  At lower power settings there= is a=20 benefit of advancing the spark to get more work done by the combustion= event=20 occurring in the cylinder.  At low power settings it is hard to get= bad=20 events to occur, including damaging peak cylinder pressures. 
Finally, please stop using ROP=20 settings where the EGT is -50F from peak as that is outside the good ope= rating=20 range of my engine (that's info from both Lyc and GAMI, worst peak press= ures)=20 - Of course, if you are running a Continental engine, well, uh, you have= to=20 find your own info.
 =
Scott=20 Krueger
 

Scott,

As a graduate of the AP=20 Seminars, I have drunk the GAMI Koolaid.  What they said about Elec= tronic=20 Ignition makes sense to me - the advance curves are proprietary and do= not=20 take into account the effect of mixture on timing.

Several quick= =20 comments:

  • Does your abbreviation "CR" mean compression ratio?  My engin= e has=20 a 10:1 compression and the timing has been retarded to account for thi= s.=20
  • "please stop using ROP settings where the EGT is -50F from peak"&n= bsp; I=20 do not use this setting although I think it is acceptable to use this= power=20 setting at low enough power settings - <70%.  If I am at a low= power=20 setting I am typically LOP.
  • You say: "EI= s don't=20 provide much timing change from the base timing (dependent on CR) for= power=20 settings over 75%"   What is the timing change that= EI=20 uses?  Do you have data on this that you can share?

= I think=20 we would all like an electronic ignition system that provides a hot cons= istent=20 spark, easy starting and does not have the maintenance and arcing proble= ms of=20 magnetos.  We would also like one that kept the effective timing at= 16=20 deg ATDC.  The problem with current electronic ignition systems is= that=20 since they don't take mixture into account, they can't maintain the same= =20 effective timing with different mixtures.

I would actually like= to be=20 able to advance my spark during certain flight regimes (LOP at less than= 70%=20 power) in which I am fairly certain nothing bad will happen and advanced= =20 timing will give better power/economy.  It is the rest of the fligh= t=20 regime (like takeoff at 2700 RPM, 30" MAP and 10:1 compression) that I= am=20 worried about


-----Original=20 Message-----
From: Sky2high@aol.com
Sent: Nov 18, 2010 7:52 PM= =20
To: lml@lancaironline.net
Subject: [LML] Re: Electronic Igniti= on=20

Doug,
 
You said:
=3D=3D=3DMy=20 point was that electronic ignition systems measure only 2 of the 3 fac= tors=20 that influence timing.  Mixture can have a significant effect on= when=20 Peak Intracylinder Pressure (=3D effective timing) occurs.  Hence= the=20 effective timing at a best power mixture (50 to 100 deg ROP) would be= =20 significantly advanced compared to the effective timing at best econom= y=20 mixture (approx 50 LOP).  This is not accounted for by electronic= =20 ignition systems and could lead to excessive spark=20 advance.
=3D=3D=3D
 
Remember that magneto systems don't measure any factor yet the en= gine=20 manufacturer has no problem with LOP or ROP operations with some= =20 restrictions (see below).  Indeed, there are no timing adjus= tments=20 for CR while EIs provide fjor such.  As I have said, EIs don't pr= ovide=20 much timing change from the base timing (dependent on CR) for pow= er=20 settings over 75% as inferred by a combination of RPM and MAP - a typi= cal=20 way of expressing power.  At lower power settings there is a bene= fit of=20 advancing the spark to get more work done by the combustion event occu= rring=20 in the cylinder.  At low power settings it is hard to get bad eve= nts to=20 occur, including damaging peak cylinder pressures.
 
Finally, please stop using ROP settings where the EGT is -50= F from=20 peak as that is outside the good operating range of my engine (that's= info=20 from both Lyc and GAMI, worst peak pressures) - Of course, if you are= =20 running a Continental engine, well, uh, you have to find your own=20 info.
 
Scott Krueger
 
PS If you are talking about supercharged/turbocharged engines alw= ays=20 running at high power then the benefits of EIs are simply a better, mo= re=20 reliable spark without worrying about esoteric things such as tha= t the=20 magneto is properly pressurized so no sparking occurs in the mag. = ;=20
 
 
In a message dated 11/16/2010 6:11:46 P.M. Central Standard Time,= =20 douglasbrunner@earthlink.net writes:

Scott,

 

I=20 will concede your point about the hotter, longer and more consistent= =20 spark, although in most flight regimes (no extreme of F/A mixture)= it=20 probably doesn=E2=80=99t make much difference.

 

With=20 respect to your comment:

 

=E2=80=9Cyour=20 argument of moving timing by messing with the mixture is, uh, not go= od=20 operational practice=E2=80=9D

 

I=20 think you misunderstood my point.  I certainly do not advocate= =20 =E2=80=9Cmessing with the mixture=E2=80=9D =E2=80=93 especially at= power levels above 70%. =20

 

My=20 point was that electronic ignition systems measure only 2 of the 3= factors=20 that influence timing.  Mixture can have a significant effect= on when=20 Peak Intracylinder Pressure (=3D effective timing) occurs.  Hen= ce the=20 effective timing at a best power mixture (50 to 100 deg ROP) would= be=20 significantly advanced compared to the effective timing at best econ= omy=20 mixture (approx 50 LOP).  This is not accounted for by electron= ic=20 ignition systems and could lead to excessive spark=20 advance.

 

D.=20 Brunner

 

 

From: Lancair=20 Mailing List [mailto:lml@lancaironline.net] On Behalf Of=20 Sky2high@aol.com
Sent: Tuesday, November 16, 2010 9:25= =20 AM
To: lml@lancaironline.net
Subject: [LML] Re:= =20 Electronic Ignition

 

Doug,

 

I=20 have a problem with your argument.  It seems to be upside down.=  =20 In reference I refer you to my 11/2/2010 email entitled "NA Injected= =20 Engine Performance LOP".  In any event, for any given=20 proper fuel/air ratio (mixture), there is a narrow timing= range=20 that produces efficient cylinder pressures at the correct crank= angle=20 range.  The Lycoming engine manual (for my 320) displays the=20 acceptable range for the EGT for best power as 100F to= 180F=20 ROP, and best economy as 0F to 80F LOP.  Running 50F ROP is ver= y bad=20 for cylinder pressures as stated by GAMI - thus your argument of mov= ing=20 timing by messing with the mixture is, uh, not good operational=20 practice.

 

Secondly,=20 you imply that the only function of an electronic ignition is to adv= ance=20 the timing.  Au contraire mon ami!  An electronic ignition= =20 provides for a hotter, longer, more consistent spark over a greater= plug=20 gap that better insures the reliable and timely ignition= of the=20 combustible mixture even though the F/A may be at some extreme. = ; This=20 results in greater efficiency/HP depending on the way one looks at= =20 it.  See the pamphlet on the benefits of the LASAR electronic= =20 ignition that shows speed increases for the same fuel burn or reduce= d fuel=20 burn at the same speed of a magneto driven=20 engine.

 

The=20 fixed timing of a magneto (i.e. 25 DBTDC) is a compromise. = ;=20 Generally speaking, EIs advance the base spark timing mini= mally=20 until the power, as measured by RPM and MAP, is reduced be= low=20 75%.  Bad events, such as pre-ignition, detonation and incorrec= tly=20 timed cyl pressure, are less likely in this regime (that is why the= GAMI=20 lean test is done at less than 75% power).  Furthermore, EGTs= =20 (representing F/A ratios) are still maintained in the engine=20 manufacturer's recommended ranges and the timing is a better ma= tch=20 for the combustion event pressures.

 

Note=20 that during my best power cruises at middle altitudes (2500 RPM= , MAP=20 > 22", EGT > 120F ROP), the EI timing is about 25 DBTDC= plus or=20 minus a degree. 

 

Yes,=20 more HP.  Better speed for the same fuel burn holding other=20 conditions equal.

Yes,=20 in all the modes you mentioned.

 

I=20 haven't reached TBO yet, I go too fast to accumulate that much=20 time.

 

Scott=20 Krueger

IO=20 320 Dual Lightspeed Plasma III EI

 

In=20 a message dated 11/15/2010 8:21:27 P.M. Central Standard Time,=20 douglasbrunner@earthlink.net writes:

At=20 the risk of starting a =E2=80=9Ctheological=E2=80=9D controversy,= I would like to raise=20 some reservations about electronic ignition systems (other than=20 reliability and loss of electrical power)

 =

Peak=20 intracylinder pressure (the point in the combustion cycle at which= =20 pressure in the cylinder is highest =3D effective timing) is relat= ed to 3=20 things; spark timing, rpm and MIXTURE. =20

 =

Why=20 mixture? Because air and fuel mixtures burn at different rates dep= ending=20 on how rich or lean they are.  So at a given RPM, MAP and spa= rk=20 advance you can vary your effective timing by changing the=20 mixture. 

 =

=C2=B7        =20  =

And=20 since optimal power is achieved at an effective timing of 16 deg= ATDC,=20 advancing the spark timing may or MAY NOT increase= =20 horsepower depending on the mixture.  But advancing the timin= g will=20 likely increase the magnitude of peak intracylinder pressure leadi= ng to=20 higher intracylinder pressures, higher cylinder head temperatures= and=20 greater stress =3D shorter enging life.

 =

For=20 those of you who are using electronic ignition (I am=20 not):

=C2=B7        =20  =

D.=20 Brunner

 

The=20 biggest advantage of any of the electronic systems (in my opinon)= is=20 that they provide a spark advance that is a function of at least= =20 manifold pressure, giving an advantage any time the manifold press= ure is=20 much lower than maybe 25 inches.  But there is very little=20 combustion taking place in the exhaust system regardless.  Th= e=20 reason the exhaust temperature rises is that more of the combustio= n=20 occurs after TDC and that means less of the energy is being conver= ted to=20 work.  The down side of advancing the spark is that since mor= e=20 combustion occurs at the highest cylinder pressure, more heat is= =20 transferred to the cylinder head and piston. =20

&= nbsp;

<= /DIV>

--

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