X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao106.cox.net ([68.230.241.40] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2339774 for flyrotary@lancaironline.net; Wed, 19 Sep 2007 11:00:58 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.40; envelope-from=alventures@cox.net Received: from fed1rmimpo01.cox.net ([70.169.32.71]) by fed1rmmtao106.cox.net (InterMail vM.7.08.02.01 201-2186-121-102-20070209) with ESMTP id <20070919150018.XJLH21920.fed1rmmtao106.cox.net@fed1rmimpo01.cox.net> for ; Wed, 19 Sep 2007 11:00:18 -0400 Received: from BigAl ([72.192.143.193]) by fed1rmimpo01.cox.net with bizsmtp id qF0K1X00Q4AaN600000000; Wed, 19 Sep 2007 11:00:20 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Strange Ignition? Date: Wed, 19 Sep 2007 08:00:39 -0800 Message-ID: <000001c7fad6$39979810$6401a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C7FA93.2B745810" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C7FA93.2B745810 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable =20 Al, I did not catch what your ignition timing you have set when = encountering this. IF you set the ignition timing with little/no advance/retard then = you are around 25 deg BTDC. ED; =20 The static timing is set according to Tracy=92s spec; 35o BTDC with = 2-point trigger aligned. From there it=92s up to the EC2 built-in timing curve. =20 IF you ignition was advancing to the point that the leading plug spark = point was exceeding the optimum for those combustion conditions (rpm, manifold pressure, ignition timing, etc), then the trailing spark which lags = might start to become the optimum spark in relation to the optimum spark = point. If so then I would expect the higher the rpm the more influence the = trailing spark might have. =20 Thank you for that. We had experienced this on the dyno; but my recollection has been backwards. I have been thinking that it indicated = the timing was late. You forced me to go back and check my dyno report; = which says: 2.) Engine ran better on trailing plugs than on the leading plugs. = After much double checking, head scratching, and some further testing we = concluded that the only explanation could be that the timing was actually very = much early. And the only way that could be true was if the timing marks and = the pointer did not relate to the position of the rotors. By viewing the position of the apex seal through the two spark plug = holes, measuring angles, etc. we made a new TDC mark on the pulley, and a new = 20 Degree BTDC mark. Then reset the static timing on the crank angle = sensor, and fired up. Ran well, and disabling leading had a bigger effect than disabling trailing, as one would expect. To verify timing we put a = pressure transducer into the trailing plug hole, ran an oscilloscope trace = triggered by an inductor on the leading plug wire. One step back on the EC2 timing adjustment gave us the trace we wanted. (Fortunately, operators knew = what the right trace looks like based on their prior rotary development = work). The original timing mark was about 15 degrees too early =96 apparently = the result of using a 12A front cover (with pointer) on a 20B; using the = stock 20B pulley. So; now I believe the timing is too early at the higher power. But the question remains =96 why? And is it curious that it seems right at low = power, and too early at high power? In any case, I will retard the spark and = see what that does.=20 2. Unlikely as well, but I assume there is no change the coils (you = have six?) could be sequenced/hooked up improperly. I don't know what the = effect would be if the leading coils were sparking the trailing plugs with the = EC2. I know the timing split between the leading and trailing is much less = than in the automobile ignition timing - but I do not believe it is zero. So = the engine might well run, but might have some unexpected things happening. Worth another check. My understanding from Tracy is that leading and trailing fire at the same time =96 unless it has changed since we talked = about it.=20 =20 3. I have disabled my leading ignition while flying (it helps if you encounter a bad case of SAG) and I notice no difference in power = although the EGT on both will increase about 150F from 1600-1750F. Do you notice = any change in your EGT when you do this? =20 That=92s interesting =96 I would expect that you would/should. Have you = tried disabling the trailing?=20 =20 Al ----- Original Message -----=20 From: Al Gietzen =20 To: Rotary motors in aircraft=20 Sent: Tuesday, September 18, 2007 3:40 PM Subject: [FlyRotary] Re: One for the guys that don't give up =20 The reason Tracy gave for the ECU not working was because of that = set-up, as his Vacuum pick -up is at the Plenum - something to do with fluctuations within the tube, whereby the plenum was static or less successful to = wild fluctuations. George ( down under) =20 I have accumulator and orifice which smooths the MAP nicely. =20 Dave said: Besides a slight difference in the mixture necessary between = the 2 computers, both locations seem to work well. =20 Dave: Mine works well also - except for the anomaly noted. I don=92t = know if you mean that yours specifically doesn=92t exhibit that phenomenon? =20 Al, was 35=B0 BTDC Tracys suggested timing? =20 The 35o BTDC is the static setting specified in Tracy=92s manual; line = up the 2-point trigger wheel with the reluctors at that point. =20 Quite frankly, I haven't tried the coil disable feature at high rpm yet. So, I don't have an answer to your question. Heck, I can't even get my auto-tune to work.=20 =20 Mark; well, whenever you get that far, give it a shot and see what you = get. Good luck with the auto-tune. =20 Does anyone else experience these symptoms? That=92s the question. =20 Thanks, guys, =20 Al =20 =20 =20 =20 =20 OK; Mark; (or anybody). Since we both have 20Bs, and both use the EC2 controller, maybe you have a clue for this one. I=92ve brought this up = here before, but no solution. I have all the latest updates on the EC2, and I have double checked the static timing set at 35o BTDC. From that point on the EC2 is handling = the timing curve with rpm and MAP. At lower power levels, disabling the leading ignition clearly has a = larger effect than disabling the trailing =96 as one would expect. At = somewhere around 18=94 MAP, (don=92t know right now what rpm that is, maybe close = to 4000) the effect is about equal when disabling either set. At higher power levels, there is a larger effect of disabling the trailing than the = leading. That troubles me. I think the leading should always have a greater = effect. It makes me wonder about the timing; or if something else is wrong.=20 I have in the past tried varying the timing 2 or 3 steps while at power, = but couldn=92t discern a change in rpm greater than the normal variation in = the readout. Tracy sent me the XL spreadsheet with the timing curve data, = but I haven=92t yet figured a safe way of checking it with that prop spinning = close by. Does your installation exhibit the same behavior? Is there some = explanation for this? What test should I perform? One thing that occurs to me is that Tracy measures MAP out before the runners. I measure MAP at the manifold, downstream from intake plenum = and three short runners and the 3-barrel TWM throttle body. At WOT my MAP = is not atmospheric pressure =96 it is maybe 2-3=94 HG less. I can=92t = quite see how that is an issue; but maybe someone else with a TWM TB setup with the = MAP port downstream would know. =20 Other than that I=92m very pleased with the new mixture correction table = setup for the 20B. Much less tuning and seamless transistion between tables = and through the stage point. Probably the pulse clamping and injector = isolation diodes are part of that. _____ =20 No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.487 / Virus Database: 269.13.22/1013 - Release Date: = 17/09/2007 1:29 PM ------=_NextPart_000_0001_01C7FA93.2B745810 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

 

Al, I did not catch what = your ignition timing you have set when encountering this.  IF you set = the ignition timing with little/no advance/retard then you are around 25 deg = BTDC.

ED;

 

The static timing is set = according to Tracy’s spec; = 35o BTDC with 2-point trigger aligned.=A0 From there it’s up to the = EC2 built-in timing curve.

 

IF you ignition was = advancing to the point that the leading plug spark point was exceeding the optimum for = those combustion conditions (rpm, manifold = pressure, ignition timing, etc), then the trailing spark which lags might start to become the = optimum spark in relation to the optimum spark point.  If so then I would = expect the higher the rpm the more influence the trailing spark might = have.

 

Thank you for that.=A0 We had = experienced this on the dyno; but my recollection has been backwards. =A0I have been = thinking that it indicated the timing was late. You forced me to go back and = check my dyno report; which says:

2.) Engine = ran better on trailing plugs than on the leading plugs.  After much double = checking, head scratching, and some further testing we concluded that the only explanation could be that the timing was actually very much early.  = And the only way that could be true was if the timing marks and the pointer = did not relate to the position of the rotors.

By viewing = the position of the apex seal through the two spark plug holes, measuring = angles, etc. we made a new TDC mark on the pulley, and a new 20 Degree BTDC = mark.  Then reset the static timing on the crank angle sensor, and fired = up.  Ran well, and disabling leading had a bigger effect than disabling trailing, = as one would expect.  To verify timing we put a pressure transducer into = the trailing plug hole, ran an oscilloscope trace triggered by an inductor = on the leading plug wire. One step back on the EC2 timing adjustment gave us = the trace we wanted. (Fortunately, operators knew what the right trace looks like = based on their prior rotary development work). The original timing mark was = about 15 degrees too early – apparently the result of using a 12A front = cover (with pointer) on a 20B; using the stock 20B pulley.

So; now I = believe the timing is too early at the higher power.=A0 But the question remains = – why? And is it curious that it seems right at low power, and too early at = high power?=A0 In any case, I will retard the spark and see what that = does. 

2.     Unlikely as well, but I assume there is no change the coils (you have six?) could = be sequenced/hooked up improperly.  I don't know what the effect would = be if the leading coils were sparking the trailing plugs with the EC2.  I = know the timing split between the leading and trailing is much less than in = the automobile ignition timing - but I do not believe it is zero.  So = the engine might well run, but might have some unexpected things = happening.

Worth another check.=A0 My = understanding from Tracy is that leading and trailing fire at the = same time – = unless it has changed since we talked about it.

 

3.     I have disabled my leading ignition while flying (it helps if = you encounter a bad case of SAG) and I notice no difference in power although the EGT = on both will increase about 150F from 1600-1750F.  Do you notice any change = in your EGT when you do this?

 

That’s interesting – I = would expect that you would/should.=A0 Have you tried disabling the trailing? =

 

Al

=

----- Original Message = -----

From: Al = Gietzen

Sent: Tuesday, September 18, 2007 3:40 PM

Subject: [FlyRotary] Re: One for the guys that don't give up

 

The reason = Tracy gave for the ECU not working was because of that set-up, as his Vacuum pick = -up is at the Plenum - something to do with fluctuations within the = tube, whereby the plenum was static or less successful to wild = fluctuations.

George ( down = under)

 

I have accumulator and orifice which smooths the MAP = nicely.

 

Dave said:  Besides a slight difference = in the mixture necessary between the 2 computers, both locations seem to work = well.

 

Dave:  Mine works well also - except for the anomaly noted.  I don’t = know if you mean that yours specifically doesn’t exhibit that = phenomenon?

 

Al, was 35=B0 BTDC Tracys suggested timing?

 

The 35o BTDC is the static setting specified in = Tracy’s = manual; line up the 2-point trigger wheel with the reluctors at that = point.

 

Quite frankly, I haven't tried the coil = disable feature at high rpm yet.  So, I don't have an answer to your question.  Heck, I can't even get my auto-tune to = work. 

 

Mark; well, whenever you get that far, give it a shot and see what you get. = Good luck with the auto-tune.

 

  Does anyone else experience these = symptoms?   That’s = the question.

 

Thanks, guys,

 

Al

 

=

 

 

 

 

OK; Mark; (or anybody).  Since we both have 20Bs, and = both use the EC2 controller, maybe you have a clue for this one. I’ve = brought this up here before, but no solution.

I have all the latest updates on the EC2, and I have double checked the = static timing set at 35o BTDC.  From that point on the EC2 is = handling the timing curve with rpm and MAP.

At lower power levels, disabling the leading ignition clearly has a larger = effect than disabling the trailing – as one would expect.  At = somewhere around 18” MAP, (don’t know right now what rpm that is, = maybe close to 4000) the effect is about equal when disabling either set.  At = higher power levels, there is a larger effect of disabling the trailing than = the leading.  That troubles me.  I think the leading should always = have a greater effect.  It makes me wonder about the timing; or if = something else is wrong.

I have in the past tried varying the timing 2 or 3 steps while at power, = but couldn’t discern a change in rpm greater than the normal variation = in the readout.  Tracy sent me the XL spreadsheet with the timing curve data, but = I haven’t yet figured a safe way of checking it with that prop = spinning close by.

Does your installation exhibit the same behavior?  Is there some = explanation for this?  What test should I perform?

One thing that occurs to me is that Tracy measures MAP out before the runners.  I measure MAP at = the manifold, downstream from intake plenum and three short runners and the 3-barrel TWM throttle body.  At WOT my MAP is not atmospheric = pressure – it is maybe 2-3” HG less.  I can’t quite see = how that is an issue; but maybe someone else with a TWM TB setup with the MAP = port downstream would know.

 

Other than that I’m very pleased with the new mixture correction table = setup for the 20B.  Much less tuning and seamless transistion between = tables and through the stage point.  Probably the pulse clamping and injector isolation diodes are part of that.

No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.487 / Virus Database: 269.13.22/1013 - Release Date: = 17/09/2007 1:29 PM

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