X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 27 Jun 2013 12:56:30 -0400 Message-ID: X-Original-Return-Path: Received: from omr-d09.mx.aol.com ([205.188.108.133] verified) by logan.com (CommuniGate Pro SMTP 6.0.5) with ESMTPS id 6351412 for lml@lancaironline.net; Thu, 27 Jun 2013 10:18:05 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.108.133; envelope-from=vtailjeff@aol.com Received: from mtaomg-ma04.r1000.mx.aol.com (mtaomg-ma04.r1000.mx.aol.com [172.29.41.11]) by omr-d09.mx.aol.com (Outbound Mail Relay) with ESMTP id BB3B0700806B4 for ; Thu, 27 Jun 2013 10:17:19 -0400 (EDT) Received: from core-mna003c.r1000.mail.aol.com (core-mna003.r1000.mail.aol.com [172.29.106.9]) by mtaomg-ma04.r1000.mx.aol.com (OMAG/Core Interface) with ESMTP id 855D8E000088 for ; Thu, 27 Jun 2013 10:17:19 -0400 (EDT) References: X-Original-To: lml@lancaironline.net Subject: Re: [LML] Re: GAMI test In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: vtailjeff@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8D041582AE44572_A48_995AC_webmail-d142.sysops.aol.com" X-Mailer: AOL Webmail 37834-STANDARD Received: from 12.110.229.82 by webmail-d142.sysops.aol.com (149.174.18.32) with HTTP (WebMailUI); Thu, 27 Jun 2013 10:17:19 -0400 X-Original-Message-Id: <8D041582A3B438B-A48-29107@webmail-d142.sysops.aol.com> X-Originating-IP: [12.110.229.82] X-Original-Date: Thu, 27 Jun 2013 10:17:19 -0400 (EDT) x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:480296608:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d290b51cc496f5e67 This is a multi-part message in MIME format. ----------MB_8D041582AE44572_A48_995AC_webmail-d142.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" To all the folks that read these posts, operate LOP or ROP and wonder -- "h= ow do I do that?'-- my simple recommendation is "TAKE THE CLASS!" Your engi= nes are too expensive and the downside in a single engine aircraft is too s= evere to leave it to folklore and chance. The GAMI course is available onli= ne and in person. You will learn more about your engines in three days than= from a lifetime of posts. Jeff -----Original Message----- From: John Barrett <2thman1@gmail.com> To: lml Sent: Thu, Jun 27, 2013 7:07 am Subject: [LML] Re: GAMI test Bob and others who kindly added to my knowledge base, thanks. The answer d= iffered from what I expected and in a good way. I know this subject has be= en discussed in some depth in the past and now that I need the information = I'm grateful you are willing to rehash it for me. Best, John Barrett Sent from my iPad On Jun 26, 2013, at 7:28 PM, Robert R Pastusek wrote: John Barrett wrote: =20 I probably know the answer to my question before I ask but I am running my = TSIO 550 lean of peak and I want to be sure I am using adequate precautions= and am doing the best for the engine. =20 To that end, if my engine baffling is not as good as it could be and I inte= nd to continue to improve it, will a GAMI test now resulting in, say, a 1 g= ph difference in FF for peak EGT among the 6 cylinders be useful for me to= send to Tornado Alley for GAMIjectors? In other words, if I improve my ba= ffling after I get George Braly=E2=80=99s fix, will that investment still b= e relevant? =20 =20 John, I=E2=80=99ll take a shot at this and defer to/welcome other comments from t= he experts. =20 First of all, baffling changes will not significantly affect EGTs=E2=80=A6a= nd vice versa. EGTs are a closely-related measure of the power being produc= ed by the cylinder=E2=80=A6 and a host of other factors related to combusti= on. CHT=E2=80=99s are a measure of how much heat is being transferred to th= e cylinder=E2=80=A6and how much is being removed by cooling air. Again, lot= s of other factors affect cylinder temperatures, and while logic would tell= you that high EGTs will yield high CHTs, the relationship contributes litt= le as compared to other factors. So with this in mind, consider these point= s. =20 To run a TSIO 550 lean of peak, it must be operated below 75% power. My per= sonal rule is to run it at or below 65% of rated power. Engine component he= at, and particularly cylinder heat is the limiting factor, and the TSIO-550= can produce almost 100% of rated power up into the teens if you leave the = controls full forward. You=E2=80=99ll find power setting info in the engine= manual, and if you have a modern engine monitoring system you can probably= program this into the monitor to give a direct readout of horsepower or a = percentage of max rated=E2=80=A6 With or without this, you need to derive t= his information from total fuel flow (LOP only) or a combination of MP and = RPM, but it=E2=80=99s important that you know--and operate the engine at lo= wer power settings--if you want to run LOP. (NOTE: Some experts such as Joh= nDeakin =E2=80=9CThe Pelican=E2=80=9D say that you can run these engines LO= P at 100% of rated power AS LONG AS YOU CAN KEEP THEM COOL, but then acknow= ledge that as a practical matter this can=E2=80=99t be done with current pr= oduction aircraft engines=E2=80=A6they produce too much heat for the availa= ble cooling systems at high power settings. =20 When you run rich of peak, some of the fuel is used directly for cooling an= d passes through the engine without burning. As a matter of course, it cool= s by evaporation, and leaves nasty lead and other deposits behind=E2=80=A6o= n plugs, valves, etc. So when you run LOP and eliminate this source of cool= ing, you must offset it by either reducing power (total heat produced) or i= ncreasing cooling (better baffling). So as you lean the mixture toward max = cylinder EGT, you=E2=80=99re reducing the amount of fuel available for cool= ing and the CHT=E2=80=99s go up. With most Continental engines, this doesn= =E2=80=99t happen at the same fuel flow for all cylinders, that is, one cyl= inder reaches peak EGT at a given fuel flow (around 16-17 GPH if you=E2=80= =99re running about 65% power) as you lean, while the other cylinders are s= till rich of peak EGT. You need to note the fuel flow when the first cylind= er reaches peak EGT. As you continue to lean, the EGT (and CHT to a lesser = extent) of the first to peak starts going down, while the remaining cylinde= r EGTs (and CHTs) continue to go up. Eventually, all cylinders reach peak E= GT and start decreasing. Note the fuel flow when the last cylinder reaches = peak EGT and just starts to decrease. The difference in fuel flow between f= irst and last cylinder EGT to peak is the =E2=80=9CGAMI lean test.=E2=80=9D= Ideally, the fuel flow between first and last should be less than 1 GPH; u= se of GAMIs can tune this to less than half a gallon per hour, BUT NOTE THA= T THIS IS OPTIMIZED FOR ONLY ONE POWER/RPM setting, so you should test/set = up the engine at the normally-expected cruise power setting. =20 Here=E2=80=99s the rub: You need to be sure all cylinders are at least 30 d= egrees below their peak EGT when operating the engine in cruise power, and = this is critically important when LOP. Ideally, all cylinders are all opera= ting at about the same amount below their individual peak EGTs, but the act= ual temperatures are not significant=E2=80=A6it=E2=80=99s the peak value an= d delta below--for each cylinder--that=E2=80=99s significant. If the fuel f= low is not well balanced among the cylinders, the first to peak EGT will ge= t so lean by the time that you get the last to 30 degrees below peak EGT th= at the first to peak startsmis-firing. My cylinders start mis-firing at abo= ut 120 degrees LOP as a reference point. Mine are well enough balanced (no = GAMIs) that I can operate the richest cylinder at 60 degrees LOP and the le= anest cylinder (first to peak when leaning) will remain below 100 degrees L= OP. That equates to about a 0.5 GPH fuel flow difference FOR MY ENGINE=E2= =80=A6but this varies a lot from engine to engine, and with the power/RPM s= etting.=20 =20 BTW, the TIT=E2=80=99s ARE CRITICAL, and you=E2=80=99ll want to watch these= while you=E2=80=99re fiddling with the EGTs. Continental says the max TIT = is 1750 and the max continuous is 1650. I am more conservative, and have a = =E2=80=9Cyellow warning=E2=80=9D set at 1550 and a =E2=80=9Cred alarm=E2=80= =9D set at 1650. As you lean the engine, TIT=E2=80=99s will increase with E= GTs, and will continue to increase for a short time after the first EGT pea= ks are reached, and then start decreasing. I normally see about 1500 on my = TITs in cruise flight; I lean the mixture more if they go above 1550 in cru= ise flight. =20 Continental says the max CHT is 460 degrees. I am pretty convinced you=E2= =80=99ll cook your cylinders if you operate them anywhere close to that in = normal cruise flight. I have a =E2=80=9Cyellow warning=E2=80=9D set at 400 = and a =E2=80=9Cred alarm=E2=80=9D at 420. I only see these temps during hig= h power climbs between about 12,000 and 16,000, when the engine is still pr= oducing lots of power but the air is starting to thin/provide fewer molecul= es to carry away the heat. In any case, when my CHT=E2=80=99s get to 420, I= increase the fuel flow (low boost if not already on) , richen the mixture = control (climbing ROP anyway) and/or increase airspeed. As a last resort, I= =E2=80=99d pull the power back, but have never had to do this=E2=80=A6yet. =20 As to CHTs during cruise flight. Get the fuel flow to the cylinders balance= d first=E2=80=A6effectively you are making each cylinder produce approximat= ely the same amount of power (yields a smoother running engine)--and heat. = Remember that this will be optimized only for a small range of power/RPM se= ttings. Then go to work on balancing the CHTs. This is (at least theoretica= lly) much easier than balancing the fuel flows and EGT peaks because you ca= n do many things to change the cooling air flow across the cylinders--and t= hat=E2=80=99s the only variable IF you=E2=80=99ve balanced the fuel flow/cy= linder power output. Working CHT=E2=80=99s first just won=E2=80=99t yield g= ood results=E2=80=A6you=E2=80=99ll wind up doing it over and over=E2=80=A6 =20 Back to precautions you asked about: 1) If you=E2=80=99re running LOP, be sure you have the engine producing= less than 75% of its rated power; below 65% if you=E2=80=99re conservative= . 2) Be sure that every cylinder is LOP and that the hottest EGT is at le= ast 30 degrees below the cylinder=E2=80=99s max EGT (without consideration = of the actual value, nor the values of any other cylinder) 3) Keep the TITs below 1650 degrees; ideally below 1550. 4) Keep the CHT=E2=80=99s below 420; ideally below 400 (If you do the a= bove things, they will likely be in the 300-340 degree range) =20 As to GAMI=E2=80=99s: if you can get the engine to run smoothly, withoutmis= -firing, with the richest cylinder (last to max EGT as you lean) at least 3= 0 degrees LOP you probably don=E2=80=99t need GAMIs. Older Continentals won= =E2=80=99t do this; the newer ones have a Continental version of GAMIs (flo= w-matched injectors) and are better, but not as good/close as the fine-tune= d GAMIs. A second measure of evaluation is fuel flow. If the fuel flow betw= een the first and last cylinders to peak is greater than 0.5 GPH, GAMIs wil= l improve this, and likely result in a smoother-running engine. =20 LOTS of stuff here; hope it helps both setup and understanding=E2=80=A6 Bob ----------MB_8D041582AE44572_A48_995AC_webmail-d142.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="utf-8"
To all the folks that read these posts, operate LOP or ROP a= nd wonder -- "how do I do that?'-- my simple recommendation is "TAKE THE CL= ASS!" Your engines are too expensive and the downside in a single engine ai= rcraft is too severe to leave it to folklore and chance. The GAMI course is= available online and in person. You will learn more about your engines in = three days than from a lifetime of posts.
 
Jeff
-----Original Message-----
From: John Barrett <2thman1@gmail.com>
To: lml <lml@lancaironline.net>
Sent: Thu, Jun 27, 2013 7:07 am
Subject: [LML] Re: GAMI test

Bob and others who kindly added to my knowledge base, thanks.  Th= e answer differed from what I expected and in a good way.  I know this= subject has been discussed in some depth in the past and now that I need t= he information I'm grateful you are willing to rehash it for me.

Best,
John Barrett

Sent from my iPad


On Jun 26, 2013, at 7:28 PM, Robert R Pastusek <rpastusek@htii.com> wrote:

John Barrett wrote:
 
I probably know the answer to my question before I= ask but I am running my TSIO 550 lean of peak and I want to be sure I am u= sing adequate precautions and am doing the best for the engine.
 
To that end, if my engine baffling is not as good = as it could be and I intend to continue to improve it, will a GAMI test now= resulting in, say, a 1 gph difference in FF for  peak EGT among the 6= cylinders be useful for me to send to Tornado Alley for GAMIjectors?  In other words, if I improve my baffling afte= r I get George Braly=E2=80=99s fix, will that investment still be relevant?=
 
 
John,
I=E2=80=99ll take a shot at this and defer to/welcome other comments from t= he experts.
 
First of all, baffling changes will not signi= ficantly affect EGTs=E2=80=A6and vice versa. EGTs are a closely-related measure of the power being produced by the cylinder=E2=80=A6 and a host of= other factors related to combustion. CHT=E2=80=99s are a measure of how mu= ch heat is being transferred to the cylinder=E2=80=A6and how much is being = removed by cooling air. Again, lots of other factors affect cylinder temperatures, and while logic would tell you that high EGTs will = yield high CHTs, the relationship contributes little as compared to other f= actors. So with this in mind, consider these points.
 
To run a TSIO 550 lean of peak, it must be op= erated below 75% power. My personal rule is to run it at or below 65% of rated power. Engine component heat, and particularly cylinder heat = is the limiting factor, and the TSIO-550 can produce almost 100% of rated p= ower up into the teens if you leave the controls full forward. You=E2=80=99= ll find power setting info in the engine manual, and if you have a modern engine monitoring system you can probably= program this into the monitor to give a direct readout of horsepower or a = percentage of max rated=E2=80=A6 With or without this, you need to derive t= his information from total fuel flow (LOP only) or a combination of MP and RPM, but it=E2=80=99s important that you = know--and operate the engine at lower power settings--if you want to run LO= P. (NOTE: Some experts such as John Deakin =E2=80=9CThe Pelican=E2=80=9D say that= you can run these engines LOP at 100% of rated power AS LONG AS YOU CAN KE= EP THEM COOL, but then acknowledge that as a practical matter this can=E2= =80=99t be done with current production aircraft engines=E2=80=A6they produce too much heat for the available cooling systems at high power sett= ings.
 
When you run rich of peak, some of the fuel i= s used directly for cooling and passes through the engine without burning. As a matter of course, it cools by evaporation, and leaves nasty = lead and other deposits behind=E2=80=A6on plugs, valves, etc. So when you r= un LOP and eliminate this source of cooling, you must offset it by either r= educing power (total heat produced) or increasing cooling (better baffling). So as you lean the mixture toward max cylinder = EGT, you=E2=80=99re reducing the amount of fuel available for cooling and t= he CHT=E2=80=99s go up. With most Continental engines, this doesn=E2=80=99t= happen at the same fuel flow for all cylinders, that is, one cylinder reaches peak EGT at a given fuel flow (around 16-17 GPH if yo= u=E2=80=99re running about 65% power) as you lean, while the other cylinder= s are still rich of peak EGT. You need to note the fuel flow when the first= cylinder reaches peak EGT. As you continue to lean, the EGT (and CHT to a lesser extent) of the first to peak starts = going down, while the remaining cylinder EGTs (and CHTs) continue to go up.= Eventually, all cylinders reach peak EGT and start decreasing. Note the fu= el flow when the last cylinder reaches peak EGT and just starts to decrease. The difference in fuel flow between = first and last cylinder EGT to peak is the =E2=80=9CGAMI lean test.=E2=80= =9D Ideally, the fuel flow between first and last should be less than 1 GPH= ; use of GAMIs can tune this to less than half a gallon per hour, BUT NOTE THAT THIS IS OPTIMIZED FOR ONLY ONE POWER/RPM setting, = so you should test/set up the engine at the normally-expected cruise power = setting.
 
Here=E2=80=99s the rub: You need to be sure a= ll cylinders are at least 30 degrees below their peak EGT when operating the engine in cruise power, and this is critically important when LOP. Ide= ally, all cylinders are all operating at about the same amount below their = individual peak EGTs, but the actual temperatures are not significant=E2=80= =A6it=E2=80=99s the peak value and delta below--for each cylinder--that=E2=80=99s significant. If the fuel flow is not well ba= lanced among the cylinders, the first to peak EGT will get so lean by the t= ime that you get the last to 30 degrees below peak EGT that the first to pe= ak starts mis-firing. My cylinders start mis-firing at about 120 degrees LOP as a reference point. M= ine are well enough balanced (no GAMIs) that I can operate the richest cyli= nder at 60 degrees LOP and the leanest cylinder (first to peak when leaning) will remain below 100 degrees LOP. T= hat equates to about a 0.5 GPH fuel flow difference FOR MY ENGINE=E2=80=A6b= ut this varies a lot from engine to engine, and with the power/RPM setting.=  
 
BTW, the TIT=E2=80=99s ARE CRITICAL, and you= =E2=80=99ll want to watch these while you=E2=80=99re fiddling with the EGTs= . Continental says the max TIT is 1750 and the max continuous is 1650. I am more conserv= ative, and have a =E2=80=9Cyellow warning=E2=80=9D set at 1550 and a =E2=80= =9Cred alarm=E2=80=9D set at 1650. As you lean the engine, TIT=E2=80=99s wi= ll increase with EGTs, and will continue to increase for a short time after the first EGT peaks are reached, and then start decreasing. I normally see= about 1500 on my TITs in cruise flight; I lean the mixture more if they go= above 1550 in cruise flight.
 
Continental says the max CHT is 460 degrees. = I am pretty convinced you=E2=80=99ll cook your cylinders if you operate them anywhere close to that in normal cruise flight. I have a =E2=80=9Cyel= low warning=E2=80=9D set at 400 and a =E2=80=9Cred alarm=E2=80=9D at 420. I= only see these temps during high power climbs between about 12,000 and 16,= 000, when the engine is still producing lots of power but the air is starting to thin/provide fewer molecules to carry away the heat. In any= case, when my CHT=E2=80=99s get to 420, I increase the fuel flow (low boos= t if not already on) , richen the mixture control (climbing ROP anyway) and= /or increase airspeed. As a last resort, I=E2=80=99d pull the power back, but have never had to do this=E2=80=A6yet= .
 
As to CHTs during cruise flight. Get the fuel= flow to the cylinders balanced first=E2=80=A6effectively you are making each cylinder produce approximately the same amount of power (yields a smo= other running engine)--and heat. Remember that this will be optimized only = for a small range of power/RPM settings. Then go to work on balancing the C= HTs. This is (at least theoretically) much easier than balancing the fuel flows and EGT peaks because you can do= many things to change the cooling air flow across the cylinders--and that= =E2=80=99s the only variable IF you=E2=80=99ve balanced the fuel flow/cylin= der power output. Working CHT=E2=80=99s first just won=E2=80=99t yield good results=E2=80=A6you=E2=80=99ll wind up doing it over and over= =E2=80=A6
 
Back to precautions you asked about:
1)      If you=E2=80=99re running LOP, be sure you have t= he engine producing less than 75% of its rated power; below 65% if you=E2=80=99re conservative.
2)      Be sure that every cylinder is LOP and that the h= ottest EGT is at least 30 degrees below the cylinder=E2=80=99s max EGT (without consideration of the actual value, nor the values of any = other cylinder)
3)      Keep the TITs below 1650 degrees; ideally below 1= 550.
4)      Keep the CHT=E2=80=99s below 420; ideally below 4= 00 (If you do the above things, they will likely be in the 300-340 degree range)
 
As to GAMI=E2=80=99s: if you can get the engi= ne to run smoothly, without mis-firing, with the richest cylinder (last t= o max EGT as you lean) at least 30 degrees LOP you probably don=E2=80=99t n= eed GAMIs. Older Continentals won=E2=80=99t do this; the newer ones have a = Continental version of GAMIs (flow-matched injectors) and are better, but not as good/close as the fine-tuned GAMIs. A second me= asure of evaluation is fuel flow. If the fuel flow between the first and la= st cylinders to peak is greater than 0.5 GPH, GAMIs will improve this, and = likely result in a smoother-running engine.
 
LOTS of stuff here; hope it helps both setup = and understanding=E2=80=A6

Bob
 ----------MB_8D041582AE44572_A48_995AC_webmail-d142.sysops.aol.com--