pkofman Posted May 25, 2017 Report Share Posted May 25, 2017 (edited) As I'm still learning my bravo please excuse my question. I've flown this plane for a while now and I've read through the forums and the poh. The poh really does not talk much about egt. I fly in cruise at 29 2400 most of the time. At 1600 tit. I keep the Cht below 380. I don't really reference egt. Is that a mistake or should I be cross checking. My settings are pretty conservative in cruise so I should be ok when leaned at 75 to 100 rop. but what do others expect and do for a reasonable egt range at this power setting. Am I ok to use egt only as a reference and backup data for tit. In other words if tit and cht are within the appropriate range should I bother with egt very much Peter Edited May 25, 2017 by pkofman Quote Link to comment Share on other sites More sharing options...
carusoam Posted May 25, 2017 Report Share Posted May 25, 2017 (edited) Because you have a TIT. Want to know something really interesting...? EGTs are lower than the TIT. What makes the TIT higher than the individual EGTs that lead up to the TIT...? There are all kinds of old wive's explanations for this. I have an old NA PP explanation for it... EGTs are an average temp of the flaming exhaust exiting the cylinder and the nothing exiting the closed exhaust valve. TITs are also an average, but include six flaming exhaust peaks in the same time frame. The NA IO550 has the same effect. The ship's EGT gauge is actually a TC that sits in the confluence of three exhaust streams. The three exhaust peaks instead of one shows a higher average temp. Since the TIT is used to safely operate the TC'd engine, that is what these pilots use. The limitations listed in the POH will be printed on the TIT gauge. Typically there is a temperature limitation for the safety of the exhaust turbine. There are three ways to maintain that limit... increasing mixture. ROP, Richer mixture decreases EGT and TIT... if experimenting LOP, leaner than peak mixture decreases EGT and TIT... reducing throttle, decreases EGT and TIT Read up on what other M drivers are using for TIT limits. Too hot leads to earlier and more expensive OH of the TC... How is that for a PP only kind of explanation? PK, what were you flying before the Bravo? Best regards, -a- Edited May 25, 2017 by carusoam Quote Link to comment Share on other sites More sharing options...
jaylw314 Posted May 25, 2017 Report Share Posted May 25, 2017 If you have an engine monitor, I'd suggest monitoring EGT's because they will tell you how each individual cylinder is doing. TIT is only important as an alarm. For example, flying ROP means rich of the FIRST cylinder to peak. peak TIT is kind of the average of all your cylinders, and doesn't tell you if one of your cylinders is taking a beating or how bad it is. I'd suggest flying by EGT's, and only using TIT as a limit. In other words, if you want to fly 75 ROP, set your leanest cylinder to 75 ROP, and then richen more if your TIT is over your comfort threshold (like 1600) Of course, what do I know, I fly a IO-360 Quote Link to comment Share on other sites More sharing options...
pkofman Posted May 25, 2017 Author Report Share Posted May 25, 2017 13 minutes ago, carusoam said: Because you have a TIT. Want to know something really interesting...? EGTs are lower than the TIT. What makes the TIT higher than the individual EGTs that lead up to the TIT...? There are all kinds of old wive's explanations for this. I have an old NA PP explanation for it... EGTs are an average temp of the flaming exhaust exiting the cylinder and the nothing exiting the closed exhaust valve. TITs are also an average, but include six flaming exhaust peaks in the same time frame. The NA IO550 has the same effect. The ship's EGT gauge is actually a TC that sits in the confluence of three exhaust streams. The three exhaust peaks instead of one shows a higher average temp. Since the TIT is used to safely operate the TC'd engine, that is what these pilots use. The limitations listed in the POH will be printed on the TIT gauge. Typically there is a temperature limitation for the safety of the exhaust turbine. There are three ways to maintain that limit... increasing mixture. ROP, Richer mixture decreases EGT and TIT... if experimenting LOP, leaner than peak mixture decreases EGT and TIT... reducing throttle, decreases EGT and TIT Read up on what other M drivers are using for TIT limits. Too hot leads to earlier and more expensive OH of the TC... How is that for a PP only kind of explanation? PK, what were you flying before the Bravo? Best regards, -a- Ive owned all of the following at one point in my career 152 , piper dakota pa 235, mooney m20j m20k ,..... ( big break in flying then back to ) lake 200ep c-182 - and now the bravo. Quote Link to comment Share on other sites More sharing options...
pkofman Posted May 25, 2017 Author Report Share Posted May 25, 2017 18 minutes ago, carusoam said: Because you have a TIT. Want to know something really interesting...? EGTs are lower than the TIT. What makes the TIT higher than the individual EGTs that lead up to the TIT...? There are all kinds of old wive's explanations for this. I have an old NA PP explanation for it... EGTs are an average temp of the flaming exhaust exiting the cylinder and the nothing exiting the closed exhaust valve. TITs are also an average, but include six flaming exhaust peaks in the same time frame. The NA IO550 has the same effect. The ship's EGT gauge is actually a TC that sits in the confluence of three exhaust streams. The three exhaust peaks instead of one shows a higher average temp. Since the TIT is used to safely operate the TC'd engine, that is what these pilots use. The limitations listed in the POH will be printed on the TIT gauge. Typically there is a temperature limitation for the safety of the exhaust turbine. There are three ways to maintain that limit... increasing mixture. ROP, Richer mixture decreases EGT and TIT... if experimenting LOP, leaner than peak mixture decreases EGT and TIT... reducing throttle, decreases EGT and TIT Read up on what other M drivers are using for TIT limits. Too hot leads to earlier and more expensive OH of the TC... How is that for a PP only kind of explanation? PK, what were you flying before the Bravo? Best regards, -a- excellent explanation btw! Ive been flying long enough to know most of it. The mooney poh does not really talk much about egt just tit and most TC drivers will focus on TIT ( thats per my training etc ) I know enough that high cht can kill and engine early not egt. But tit is a the best monitor in a tc engine to monitor. Quote Link to comment Share on other sites More sharing options...
carusoam Posted May 25, 2017 Report Share Posted May 25, 2017 I remember you being around here a while, but the M20M part was not as familiar. As Jay mentioned above... the EGTs are still good for keeping an eye on the individual cylinder operations. Fuel injector clogs, spark plug issues, and magneto challenges will all be noticed the same way as the NA EGT you are familiar with... Good luck with the new bird. Post an avatar picture! Best regards, -a- Quote Link to comment Share on other sites More sharing options...
carusoam Posted May 25, 2017 Report Share Posted May 25, 2017 If you have an early 90s bird, see when the JPI got added... not everybody bought these expensive digital computer things from the factory until after '94 at least... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
pkofman Posted May 25, 2017 Author Report Share Posted May 25, 2017 Just now, carusoam said: I remember you being around here a while, but the M20M part was not as familiar. As Jay mentioned above... the EGTs are still good for keeping an eye on the individual cylinder operations. Fuel injector clogs, spark plug issues, and magneto challenges will all be noticed the same way as the NA EGT you are familiar with... Good luck with the new bird. Post an avatar picture! Best regards, -a- thanks . ill post a pic... 1 Quote Link to comment Share on other sites More sharing options...
jlunseth Posted May 25, 2017 Report Share Posted May 25, 2017 You have gotten pretty good advice, there is not much to add, but here is a little. We treat TIT as an absolute number and EGT's as relative numbers. In other words, it matters whether TIT is 1600 or 1700 - it matters what the absolute number is. It does not matter what the absolute EGT numbers are, it matters what they are relative to peak EGT. TIT has a redline and is there to protect the turbo. The turbo runs at speeds upwards of 100,000 and if it gets too hot, the lower deck blades will stretch. The tolerances inside the housing are already close, so blade stretch leads to the blades contacting the housing, and we don't want that. There are other things that happen also, but that is the main concern at high temps. This ahs to do only indirectly with how far LOP or ROP you are running the engine and at what power setting, indirectly because most likely if you see a redline TIT it is because you are running the engine wrong, but there are other contributors such as a hot day or poor cooling due to altitude. You should go over to the Bravo forum and read some of their engine setting stuff. The Bravo and Acclaim guys tend to run their engines at somewhat higher TITs than I do in my 231. I use 1600 and it works, my turbo is fine after many hours of operation. EGT's are relative. We don't care what the absolute number is, and once you have figured out how to set your engine up for a given phase of flight and desired power output, looking at the EGTs becomes less important. We use EGTs in setting fuel flow an turbo output (MP) because it tells us how far from peak EGT each cylinder is operating. There is always some variance in fuel flows among the cylinders, and it is important, in deciding where to run relative to peak, to use the EGT closest to peak. From the rich side, that is the first cylinder to peak, and leaning over from the rich side to the lean side, that is the last cylinder to peak. If we use these temps, then the other cylinders will all be further from peak and well protected. We normally don't use TIT for this, because TIT doesn't say where each cylinder is, so it is possible to have, say, four cylinders running nicely rich of peak, one more rich, and one running lean and sitting right in the red box. All that side, if you have properly leaned the engine a few times using EGTs, and you know that , say, at 29" and 1600 TIT the leanest cylinder is always at 125 degrees ROP, and you are fine with running that cylinder at 125 ROP, then by all means use TIT and use CHT. I hardly ever look at my EGT's anymore, one of my favorite settings is 11-11.1 gph, 34" MP and TIT at or under 1600. I have run the engine enough at that setting that I know the EGT's will be fine, and I check them only, say, if the fuel flow has been rejiggered at annual or something of that nature. Let me hasten to add, this setting is for my 231, not for your Bravo, ask the Bravo guys what they do. 4 Quote Link to comment Share on other sites More sharing options...
pkofman Posted May 25, 2017 Author Report Share Posted May 25, 2017 3 hours ago, jlunseth said: We treat TIT as an absolute number and EGT's as relative numbers. In other words, it matters whether TIT is 1600 or 1700 - it matters what the absolute number is. It does not matter what the absolute EGT numbers are, it matters what they are relative to peak EGT. Reply: So I suppose that that is why there are no absolute numbers for egt. I think from my NA days that there were absolutes in my 201 for egt non -tc engines. But if i understand this correctly, egt values are all onlyl relative. So If I set tit to lean ( 75 rich of peak ) , note egt differentials , (or to be certain lean to peak egt first cylinder ( not to exceed tit as specified and maintain cht in green) ),then that would give a range of values that could be checked as reference in the future. I have not seen or found any absolute egt numbers in the POH .One thing I'm understanding for sure is that the individual egts should not exceed the tit values. that would be weird if it happened. Thank you Quote Link to comment Share on other sites More sharing options...
Brian Scranton Posted May 25, 2017 Report Share Posted May 25, 2017 I use TIT for leaning purposes first. Then for turbo management second. So...do your BMP, find your peak TIT at your cruise altitude. Then enrich to 100-150 ROP or lean to 25 LOP (if you can). Then, monitor CHTs. If one starts to go above 380, do something (richer for ROP or leaner for LOP). Ok, no you're leaned. Monitor TIT to make sure it doesn't creep up if you are up high-- (above 15,000). Because a nice comfy 1500 at 14,000 can easily become 1700 at 16,000-18,000. Also, some turbos are limited temp wise, so check your POH. Quote Link to comment Share on other sites More sharing options...
Danb Posted May 25, 2017 Report Share Posted May 25, 2017 I'd lean toward flying by your tit, if I read the post correctly you mentioned your primarily following the egt. Heat kills or destroys our Bravos so in important to monitor your cht's as you mentioned along with the tit. There is good info on the Bravo site. DVA has couple great threads. Your 29/2400 at 1600 should give you a nice 17-17.5 gph. Therefore my first concern is the tit keeping the temp at < 1600, then working to keep the cht's below 400. If you keep at or below these your cool engine will go quite awhile. Arguably our exhaust system is a weak link heat kills it, along with the cylinders and our turbos heat eats them up. Hate to jinx myself after 30+ years of flying I've never replaced a jug yet. Keeping a close eye on temps I believe is the primary reason. I never start a cold engine, nor shock cool the engine and monitor the temps as mentioned. The Bravo is an amazing trip machine, keeping it(him or her) happy will reward you with many hours of awesome performance. But they are gas hogs Good luck with your plane. Dan 2 Quote Link to comment Share on other sites More sharing options...
Raptor05121 Posted May 25, 2017 Report Share Posted May 25, 2017 Watch Mike Busch's seminars on the EAA webinar page for CHT, EGT, TIT and leaning tips. Quote Link to comment Share on other sites More sharing options...
carusoam Posted May 25, 2017 Report Share Posted May 25, 2017 (edited) Some funky follow-up... 1) EGTs are relative... but they don't need to be. If they were installed the same way in the same place on the same engine, the absolute values would be absolutely fantastic. 2) The most important value is the peak and how far from peak the mixture has been adjusted. 3) plane and engine builders have simply ignored the opportunity to build the extra precision to put the EGT probe in the exact location in the exhaust tube.... 4) The TIT gauge is precisely located so the absolute numbers are very useable. This way all Bravo flyers can compare these numbers. 5) The ship's EGT gauge in the NA O is very similar. The EGT sensor is precisely located in a boss in the manifold. Unfortunately the analog display makes it challenging to discuss the the actual temps being displayed... it requires more memory than I have available... 6) Leaning technique using this absolute value EGT includes putting the needle in the blue box (range) for climbing. This is the target EGT method oft discussed around here... G1000 users get a white box for their O. @Danb has the advice I needed, but couldn't get when I needed it... it is possible to acquire and operate a great TC'd engine without the high expense of replacing cylinders and turbos. I swapped my first cylinder out within the first 10 hours of ownership of my M20C, during transition training... JL, DVA, and John the lawyer (who has moved on) have done some really interesting writing regarding Turbo ops from different perspectives... Read some more, and write some more... Best regard, -a- Edited May 25, 2017 by carusoam 1 Quote Link to comment Share on other sites More sharing options...
pkofman Posted May 25, 2017 Author Report Share Posted May 25, 2017 I'm sorry but I just have to say this: Perhaps it's not the right place to do this i have belonged to allot of forums on the web for different things over the years. But this forum is outstanding and informative. I ask a basic question and I get respectful deep and thoughtful responses from a community filled with allot of experience and advice. Sometimes forums Do not work out so well. Too me there is never too silly or simple a question and I thank you all for the assistance and advice as I work hard to learn how to operate and stay safe in the machine. Just proves that most pilots and mooney devotees are really committed to understanding and learning. Thanks to all. Pete Bravo TLS. Quote Link to comment Share on other sites More sharing options...
jlunseth Posted May 25, 2017 Report Share Posted May 25, 2017 @pkofman. I am responding to your last post. I see that there have been a few since then. It would indeed be weird if individual EGT's, or even one of them, exceeded TIT. TIT is invariably higher than EGTs. We have had some discussion about why in past threads, its not really important and technical, its really only important to understand that is the way it is. Think of it this way, the engineers who designed the engine found the most important point at which to protect the whole exhaust and turbo, and that was at the inlet side of the turbo. As long as that is within the redline limit, everything else will be fine. So from the standpoint of protecting your engine, the TIT redline, the absolute number, is the important one. CHT's also of course, but they protect the cylinders not the turbo. There is no need or particular usefulness in noting EGT differentials. Now, if you have a 250 degree differential, that might tell you there is a problem that needs looking at. But within normal operation limits don't bother. In installing the probes, the mechanic in most cases must put some probes a different distance from the exhaust port than other probes, and the manifold geometry is not always the same for each cylinder right where the probe is installed. Which means that respective probes won't "see" the same termperature. Which means that differential EGT is a function of probe installation and probe calibration (as in, they are not calibrated to read the same) as much or more than it is actual temp difference. The way to determine if the fuel/air ratio is the same or nearly the same for all cylinders is to run a lean test. APS, and because most of them follow APS, all of the other authorities in the field, want to see a differential of .5 gph. You can find instructions for the lean test on the APS/GAMI website. I don't disagree with the guys who say use TIT when running your Bravo. First, you always use TIT, you use it because you don't want to exceed redline. It is less useful as a way to determine where you are running your engine, in terms of degrees LOP or ROP because of what carusoam touched on, if you don't use EGT's you can have several cylinders running where you want them, and one or two sitting right at peak or in the red box, which you don't want. That isn't to say that if the Bravo POH says lean "x" degrees from peak TIT, that was not good advice at the time. The problem was that engine analyzers were for the most part not present to give us better readings when those things were written. And as I said, if you have an analyzer, and you know where your EGTs are at a given power and fuel flow setting, and its easiest to just set to a TIT because you know that everything else will be good, then by all means use TIT. I might add, I don't have a Bravo and from everything I have read here and elsewhere, the Bravo does not like LOP much and not many Bravo guys fly that way. 1 Quote Link to comment Share on other sites More sharing options...
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