X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ch1outboundpool.messaging.microsoft.com ([216.32.181.185] verified) by logan.com (CommuniGate Pro SMTP 6.0.5) with ESMTPS id 6350796 for lml@lancaironline.net; Wed, 26 Jun 2013 22:29:24 -0400 Received-SPF: pass receiver=logan.com; client-ip=216.32.181.185; envelope-from=rpastusek@htii.com Received: from mail105-ch1-R.bigfish.com (10.43.68.236) by CH1EHSOBE009.bigfish.com (10.43.70.59) with Microsoft SMTP Server id 14.1.225.23; Thu, 27 Jun 2013 02:28:48 +0000 Received: from mail105-ch1 (localhost [127.0.0.1]) by mail105-ch1-R.bigfish.com (Postfix) with ESMTP id 10A8E100429 for ; Thu, 27 Jun 2013 02:28:48 +0000 (UTC) X-Forefront-Antispam-Report: CIP:157.56.245.5;KIP:(null);UIP:(null);IPV:NLI;H:CH1PRD0710HT005.namprd07.prod.outlook.com;RD:none;EFVD:NLI X-SpamScore: 7 X-BigFish: PS7(zz98dIc85fha9c8pzz1f42h1ee6h1de0h1fdah1202h1e76h1d1ah1d2ah1fc6hzz1d7338h17326ah18c673h8275bh8275dhz2fh2a8h668h839hd25hf0ah1288h12a5h12bdh137ah1441h1504h1537h153bh15d0h162dh1631h1758h18e1h1946h19b5h19ceh1ad9h1b0ah1bceh1d07h1d0ch1d2eh1d3fh1de9h1dfeh1dffh1e1dh1155h) Received-SPF: pass (mail105-ch1: domain of htii.com designates 157.56.245.5 as permitted sender) client-ip=157.56.245.5; envelope-from=rpastusek@htii.com; helo=CH1PRD0710HT005.namprd07.prod.outlook.com ;.outlook.com ; Received: from mail105-ch1 (localhost.localdomain [127.0.0.1]) by mail105-ch1 (MessageSwitch) id 1372300124642978_22701; Thu, 27 Jun 2013 02:28:44 +0000 (UTC) Received: from CH1EHSMHS003.bigfish.com (snatpool2.int.messaging.microsoft.com [10.43.68.236]) by mail105-ch1.bigfish.com (Postfix) with ESMTP id 911EE3E0045 for ; Thu, 27 Jun 2013 02:28:44 +0000 (UTC) Received: from CH1PRD0710HT005.namprd07.prod.outlook.com (157.56.245.5) by CH1EHSMHS003.bigfish.com (10.43.70.3) with Microsoft SMTP Server (TLS) id 14.1.225.23; Thu, 27 Jun 2013 02:28:44 +0000 Received: from CH1PRD0710MB367.namprd07.prod.outlook.com ([169.254.11.72]) by CH1PRD0710HT005.namprd07.prod.outlook.com ([10.255.152.40]) with mapi id 14.16.0324.000; Thu, 27 Jun 2013 02:28:43 +0000 From: Robert R Pastusek To: Lancair Mailing List Subject: RE: [LML] GAMI test Thread-Topic: [LML] GAMI test Thread-Index: AQHOcnpTquLXCQm9Tk+gETOBqEBPJZlIpW0w Date: Thu, 27 Jun 2013 02:28:42 +0000 Message-ID: <41361035E6613244A377D5AC3BF5EFDD58731C14@CH1PRD0710MB367.namprd07.prod.outlook.com> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [96.241.131.4] Content-Type: multipart/alternative; boundary="_000_41361035E6613244A377D5AC3BF5EFDD58731C14CH1PRD0710MB367_" MIME-Version: 1.0 Return-Path: rpastusek@htii.com X-OriginatorOrg: htii.com --_000_41361035E6613244A377D5AC3BF5EFDD58731C14CH1PRD0710MB367_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable 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 using 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 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's fix, will that investment still be releva= nt? John, I'll take a shot at this and defer to/welcome other comments from the exper= ts. First of all, baffling changes will not significantly affect EGTs...and vic= e versa. EGTs are a closely-related measure of the power being produced by = the cylinder... and a host of other factors related to combustion. CHT's ar= e a measure of how much heat is being transferred to the cylinder...and 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 y= ield high CHTs, the relationship contributes little as compared to other fa= ctors. So with this in mind, consider these points. 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'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 percenta= ge of max rated... With or without this, you need to derive this informatio= n from total fuel flow (LOP only) or a combination of MP and RPM, but it's = important that you know--and operate the engine at lower power settings--if= you want to run LOP. (NOTE: Some experts such as John Deakin "The Pelican"= say that you can run these engines LOP at 100% of rated power AS LONG AS Y= OU CAN KEEP THEM COOL, but then acknowledge that as a practical matter this= can't be done with current production aircraft engines...they produce too = much heat for the available cooling systems at high power settings. 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...on plug= s, valves, etc. So when you run LOP and eliminate this source of cooling, y= ou must offset it by either reducing power (total heat produced) or increas= ing cooling (better baffling). So as you lean the mixture toward max cylind= er EGT, you're reducing the amount of fuel available for cooling and the CH= T's go up. With most Continental engines, this doesn't happen at the same f= uel flow for all cylinders, that is, one cylinder reaches peak EGT at a giv= en fuel flow (around 16-17 GPH if you're running about 65% power) as you le= an, while the other cylinders 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 goin= g down, while the remaining cylinder EGTs (and CHTs) continue to go up. Eve= ntually, all cylinders reach peak EGT and start decreasing. Note the fuel f= low when the last cylinder reaches peak EGT and just starts to decrease. Th= e difference in fuel flow between first and last cylinder EGT to peak is th= e "GAMI lean test." 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 y= ou should test/set up the engine at the normally-expected cruise power sett= ing. Here's the rub: You need to be sure all cylinders are at least 30 degrees b= elow their peak EGT when operating the engine in cruise power, and this is = critically important when LOP. Ideally, all cylinders are all operating at = about the same amount below their individual peak EGTs, but the actual temp= eratures are not significant...it's the peak value and delta below--for eac= h cylinder--that's significant. If the fuel flow is not well balanced among= the cylinders, the first to peak EGT will get so lean by the time that you= get the last to 30 degrees below peak EGT that the first to peak starts mi= s-firing. My cylinders start mis-firing at about 120 degrees LOP as a refer= ence point. Mine are well enough balanced (no GAMIs) that I can operate the= richest cylinder at 60 degrees LOP and the leanest cylinder (first to peak= when leaning) will remain below 100 degrees LOP. That equates to about a 0= .5 GPH fuel flow difference FOR MY ENGINE...but this varies a lot from engi= ne to engine, and with the power/RPM setting. BTW, the TIT's ARE CRITICAL, and you'll want to watch these while you're fi= ddling with the EGTs. Continental says the max TIT is 1750 and the max cont= inuous is 1650. I am more conservative, and have a "yellow warning" set at = 1550 and a "red alarm" set at 1650. As you lean the engine, TIT's will incr= ease with EGTs, and will continue to increase for a short time after the fi= rst 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'll c= ook your cylinders if you operate them anywhere close to that in normal cru= ise flight. I have a "yellow warning" set at 400 and a "red alarm" 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 start= ing to thin/provide fewer molecules to carry away the heat. In any case, wh= en my CHT's get to 420, I increase the fuel flow (low boost if not already = on) , richen the mixture control (climbing ROP anyway) and/or increase airs= peed. As a last resort, I'd pull the power back, but have never had to do t= his...yet. As to CHTs during cruise flight. Get the fuel flow to the cylinders balance= d first...effectively you are making each cylinder produce approximately th= e same amount of power (yields a smoother running engine)--and heat. Rememb= er that this will be optimized only for a small range of power/RPM settings= . Then go to work on balancing the CHTs. This is (at least theoretically) m= uch easier than balancing the fuel flows and EGT peaks because you can do m= any things to change the cooling air flow across the cylinders--and that's = the only variable IF you've balanced the fuel flow/cylinder power output. W= orking CHT's first just won't yield good results...you'll wind up doing it = over and over... Back to precautions you asked about: 1) If you're running LOP, be sure you have the engine producing less t= han 75% of its rated power; below 65% if you're conservative. 2) Be sure that every cylinder is LOP and that the hottest EGT is at l= east 30 degrees below the cylinder's 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's below 420; ideally below 400 (If you do the above th= ings, they will likely be in the 300-340 degree range) As to GAMI's: if you can get the engine to run smoothly, without mis-firing= , with the richest cylinder (last to max EGT as you lean) at least 30 degre= es LOP you probably don't need GAMIs. Older Continentals won't do this; the= newer ones have a Continental version of GAMIs (flow-matched injectors) an= d are better, but not as good/close as the fine-tuned GAMIs. A second measu= re of evaluation is fuel flow. If the fuel flow between the first and last = cylinders to peak is greater than 0.5 GPH, GAMIs will improve this, and lik= ely result in a smoother-running engine. LOTS of stuff here; hope it helps both setup and understanding... Bob --_000_41361035E6613244A377D5AC3BF5EFDD58731C14CH1PRD0710MB367_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

John Barrett wrote:

 

I probably know the answer to my question before I a= sk but I am running my TSIO 550 lean of peak and I want to be sure I am usi= ng 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 r= esulting in, say, a 1 gph difference in FF for  peak EGT among the 6 c= ylinders 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’s fix, will that investment still be relevant?

 

 

John,
I’ll take a shot at this and defer to/welcome other comments from the= experts.

 

First of all, baffling changes will not significantly affect EG= Ts…and vice versa. EGTs are a closely-related measure of the power being produced by the cylinder… and a host of o= ther factors related to combustion. CHT’s are a measure of how much h= eat is being transferred to the cylinder…and how much is being remove= d 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 operated below 75% p= ower. 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’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… With or without this, you need to derive thi= s information from total fuel flow (LOP only) or a combination of MP and RPM, but it’s important that you kn= ow--and operate the engine at lower power settings--if you want to run LOP.= (NOTE: Some experts such as John Deakin “The Pelican” say that you= can run these engines LOP at 100% of rated power AS LONG AS YOU CAN KEEP T= HEM COOL, but then acknowledge that as a practical matter this can’t = be done with current production aircraft engines…they produce too much heat for the available cooling systems at high power sett= ings.

 

When you run rich of peak, some of the fuel is used directly fo= r 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…on plugs, valves, etc. So when you run= LOP and eliminate this source of cooling, you must offset it by either red= ucing power (total heat produced) or increasing cooling (better baffling). So as you lean the mixture toward max cylinder = EGT, you’re reducing the amount of fuel available for cooling and the= CHT’s go up. With most Continental engines, this doesn’t happe= n 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’re running about 65% power) as you lean, while the other cylinders = are still rich of peak EGT. You need to note the fuel flow when the first c= ylinder 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 “GAMI lean test.” Id= eally, 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’s the rub: You need to be sure all 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…= ;it’s the peak value and delta below--for each cylinder--that’s significant. If the fuel flow is not well bala= nced among the cylinders, the first to peak EGT will get so lean by the tim= e that you get the last to 30 degrees below peak EGT that the first to peak= 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…but= this varies a lot from engine to engine, and with the power/RPM setting. 

 

BTW, the TIT’s ARE CRITICAL, and you’ll want to wat= ch these while you’re 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 “yellow warning” set at 1550 and a “red= alarm” set at 1650. As you lean the engine, TIT’s will increas= e 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 convin= ced you’ll cook your cylinders if you operate them anywhere close to that in normal cruise flight. I have a “yello= w warning” set at 400 and a “red alarm” at 420. I only se= e these temps during high power climbs between about 12,000 and 16,000, whe= n 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’s get to 420, I increase the fuel flow (low boost = if not already on) , richen the mixture control (climbing ROP anyway) and/o= r increase airspeed. As a last resort, I’d pull the power back, but have never had to do this…yet.

 

As to CHTs during cruise flight. Get the fuel flow to the cylin= ders balanced first…effectively 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&= #8217;s the only variable IF you’ve balanced the fuel flow/cylinder p= ower output. Working CHT’s first just won’t yield good results…you’ll wind up doing it over and over…= ;

 

Back to precautions you asked about:

1)      If you’re running LOP, be sure you have the engin= e producing less than 75% of its rated power; below 65% if you’re conservative.

2)      Be sure that every cylinder is LOP and that the hottest= EGT is at least 30 degrees below the cylinder’s 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’s below 420; ideally below 400 (If y= ou do the above things, they will likely be in the 300-340 degree range)

 

As to GAMI’s: if you can get the engine 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’t nee= d GAMIs. Older Continentals won’t do this; the newer ones have a Cont= inental 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&= #8230;


Bob

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