EGT on initial Climb Out

[Guest]

4 hours ago, Shadrach said:

I respectfully dissagree. Back when John Deakin (of APS) was still writing a column for avweb we exchanged a few emails regarding why 1150-1250 is ideal. I also put a lot of stock in what APS recommends  (I've not taken the course, but have conversed with their instructors and I think they've been a very positive force in the GA community). The bottom line is that the engine should be a MINIMUM of 200ROP, preferably 250.  Everyone parrots the "EGT raw numbers don't mean anything" line. You're right, they don't. But they do mean something relative to peak.  1350 + 250 is 1600. Will your Bonanza peak at 1600 under full power? My gues is you're running closer to 150ROP on take off. If you think that's good, then by all means.

Setting with CHT Is fine if you understand what's going on. The problem is when some newb reads what you've written and thinks as long as they keep CHTs under 400 they're being kind to their engine.  An engine setting that yields a 385 CHT on day when the OAT is 15df is not being kind to an engine. The same setting on a standard day would would be well over 400. Sure the engine will tolerate it for the most part, but given the past QC issues with Continental cylinders, it's likey prudent to be as kind to the cylinders as possible.

1350 is perfectly healthy for a low C/R turbo that peaks ~1700, not so good for an NA engine running 8.7 or 8.5 to 1.

I read a lot of complaints about high CHTs in the summer.  Folks will ask for advice after they've finished chasing every baffle seal leak they can find. Then we find out their EGT on the hot cylinder is 1430 in the climb...then I suggest that it might be a fuel issue which then cues the chorus of "raw EGT numbers don't matter."

My bird runs very cool in climb; all full power EGTS are 1200 or less. The baffle seals are in good shape and reasonably well installed. I think the latter helps a bit, but the former is the key reason it runs so cool.

Ross,

How are you able to keep EGT values so low? Bendix fuel injection is not adjustable like TCM, at lest in the field.

Clarence

[M20S Driver]

1 hour ago, Cruiser said:

Interesting, I cannot maintain full power T/O and keep the CHT in check. My #5 cylinder will slowly climb unless I pull the RPM back to 2500. 

What is your fuel flow at full power?  I climb at 125-135 kts and had no issues.

Your fuel set up needs to  be on the high side of the limit on the high pressure side and low side of the limit on the low pressure (idle?) side. This will give max fuel flow at max power since you will open the mixture setting to compensate for the low pressure side of the fuel pump setting.  

I am not a mechanic but I read the blogs on Mooneyspace.  

[Cruiser]

Take off fuel flow is 27.8 to 28.2 

I may have it increased to 29.0 next time it is in the shop

[jclemens]

14 hours ago, Shadrach said:

I respectfully dissagree. Back when John Deakin (of APS) was still writing a column for avweb we exchanged a few emails regarding why 1150-1250 is ideal. I also put a lot of stock in what APS recommends  (I've not taken the course, but have conversed with their instructors and I think they've been a very positive force in the GA community). The bottom line is that the engine should be a MINIMUM of 200ROP, preferably 250.  Everyone parrots the "EGT raw numbers don't mean anything" line. You're right, they don't. But they do mean something relative to peak.  1350 + 250 is 1600. Will your Bonanza peak at 1600 under full power? My gues is you're running closer to 150ROP on take off. If you think that's good, then by all means.

Setting with CHT Is fine if you understand what's going on. The problem is when some newb reads what you've written and thinks as long as they keep CHTs under 400 they're being kind to their engine.  An engine setting that yields a 385 CHT on day when the OAT is 15df is not being kind to an engine. The same setting on a standard day would would be well over 400. Sure the engine will tolerate it for the most part, but given the past QC issues with Continental cylinders, it's likey prudent to be as kind to the cylinders as possible.

1350 is perfectly healthy for a low C/R turbo that peaks ~1700, not so good for an NA engine running 8.7 or 8.5 to 1.

I read a lot of complaints about high CHTs in the summer.  Folks will ask for advice after they've finished chasing every baffle seal leak they can find. Then we find out their EGT on the hot cylinder is 1430 in the climb...then I suggest that it might be a fuel issue which then cues the chorus of "raw EGT numbers don't matter."

My bird runs very cool in climb; all full power EGTS are 1200 or less. The baffle seals are in good shape and reasonably well installed. I think the latter helps a bit, but the former is the key reason it runs so cool.

1150-1250 might be ideal in your situation.  The APS people have dispelled a lot of old wives tales in the way we run our engines.  You should take their online course, I have, it's very informative.  Yes, my 285 HP 6 cylinder will peak above 1600 at full power.  My target EGT is 1350.  As compelling as the APS is, I don't run LOP, it makes the plane go slower.  You have guessed poorly, with the fuel flow I have at full power you need to lean if you actually need all 285 HP, it is almost 300 degrees ROP.  I am not advocating setting the mixture with the CHT gauge.  I am sick of hearing about the perceived quality control problem with Continental cylinders.  Having actually operated an engine shop for the last 20 years or so I have seen my share of QC issues.  TCM had a problem 10 years ago that people the internet experts won't let go.  Both ECI and Superior have had issues in the past the resulted in FAA action in the form of an AD.  Lycoming cylinders on brand new factory IO-360's are having guide problems of their own right now.  In my TSIO-360 turbo mooney, I target 1450 on climb and at altitude will run at 1550 or higher on the TIT.  You are correct in pointing at the top end fuel flow if CHT's are high, also that raw EGT numbers do not matter.  I could make your EGT gauge read higher without changing anything about the way it runs by moving the probe.  Since you have no way of increasing the top end fuel flow on your particular engine, it would still run just fine with the new raw EGT number.  If you have a TCM engine you could increase your top end fuel flow because you think the new EGT is too high, which would result in an overly rich condition at full power and a decreased power output.

[jetdriven]

The Continental cylinders have sloppy valve and guide machining which almost always results in "valve slide" and burning right around 800 hours. Beechtalk members have confirmed this with a large sample size of factory engines, digital megapixel bored cope evidence, and yes, collaboration and crowd-sourcing data. Msny people send their factory engines to Powermasters to get the sloppy valve guides and seats re-machined, even before installing the engine. Then they will usually make TBO.  You may not believe this any more than you don't believe that Lycoming lifters and cams self-destruct every few hundred hours, but the evidence is there for both. 

[wishboneash]

In my J, EGT is abotut 1250 at sea level, WOT, 2700 rpm, 19gph FF. 

[co2bruce]

Wow, here's something to chew on

 

 

http://www.avweb.com/news/pelican/182176-1.html

 

[jclemens]

13 hours ago, jetdriven said:

The Continental cylinders have sloppy valve and guide machining which almost always results in "valve slide" and burning right around 800 hours. Beechtalk members have confirmed this with a large sample size of factory engines, digital megapixel bored cope evidence, and yes, collaboration and crowd-sourcing data. Msny people send their factory engines to Powermasters to get the sloppy valve guides and seats re-machined, even before installing the engine. Then they will usually make TBO.  You may not believe this any more than you don't believe that Lycoming lifters and cams self-destruct every few hundred hours, but the evidence is there for both. 

I am not disputing that there is a large sample size of factory cylinder which exhibiting the same failure mode after a similar time in service.  I have been using borescopes to look at valves before Beechtalk or Mooneyspace existed.  I have seen these failures.  I have also seen my fair share of cam failures, in both brands.  We just reassembled a TSIO-550 that had a cam follower fail.  It was an 800 hour factory engine.  All the cylinders were fine however.  The oil pump was also rejected.  This particular engine exhibited no signs of anything wrong at all.  It was torn down due to a prop strike.  I have also watched hundreds of engines run to TBO and beyond without a single issue in a training environment.  I am not defending the QC (or lack of) of any manufacturer.  I wonder what the average age, in years, of the sample size was?  

[Shadrach]

11 hours ago, co2bruce said:

Wow, here's something to chew on

http://www.avweb.com/news/pelican/182176-1.html

Thanks Bruce! In the article Mr. Deakin makes the following statement of heresy:

"In general, and speaking very roughly, if you see EGTs anywhere over about 1,300°F (lower will not hurt a thing and is probably “better”) during a sea-level takeoff, or CHTs above about 360°F right after takeoff, YOUR FUEL FLOW IS TOO LOW. Having a good understanding of the proper relationship between the EGTs and the fuel flow at very rich mixture settings will always give you a good cross-check on whether or not you are getting adequate fuel flow -- even if your fuel flow needle breaks off and falls to the bottom of the instrument!

If your fuel flow is too low on takeoff, don't let your mechanic talk you out of setting it up a bit, and if necessary, find a mechanic who will do it. VERY few mechanics understand the importance of this. Far too many mechanics consider the fuel flow redline a maximum, and they consider a little bit less as "good," or "better for the engine," thinking they are being "conservative." After all, we all like to stay a little bit (or a lot) away from all sorts of redlines, right? That fuel flow redline is a MINIMUM, not a maximum. Treat it as such."

 

 

[Shadrach]

On May 16, 2016 at 9:15 PM, M20Doc said:

Ross,

How are you able to keep EGT values so low? Bendix fuel injection is not adjustable like TCM, at lest in the field.

Clarence

I know, I have all of the Precision Airmotive pub docs and have studied them pretty thoroughly.  Once in climb I just shoot to keep it under 1300. It's likely probe placement as much as anything.  Depending on OAT, my EGTs very (the colder the higher).  I'll get exact numbers next time I take off. Maybe I'm off a bit. I know my numbers are typically well under 1300. I misspoke when I said  under 1200 and will edit accordingly.

[Shadrach]

13 hours ago, wishboneash said:

In my J, EGT is abotut 1250 at sea level, WOT, 2700 rpm, 19gph FF. 

That's about dead solid perfect for that engine!

[Shadrach]

On May 16, 2016 at 8:16 PM, Browncbr1 said:

I think the TO egt values mike Busch talked about were at sea level.  In any case, my cht never goes over 360 on hottest #3 on hot days with 25 degree timing.  FF at about 17-16.5... but as an added measure to be good to my engine, I back off on MAP and rpm just after take off.  I know it's certified to run harder, but I don't. 

16.5-17 seems low at anything close to sea level.

[Shadrach]

On May 15, 2016 at 7:40 PM, M20S Driver said:

"And does WOTFR 2700 yield cool CHTs?"---  YES.  

I upgraded to 310 HP last year. I used to struggle to keep it below 380 deg f during full power T.O.s  in the summer but now it is a non-issue.  

My EGT during my sea level WOTFR take off today was very near top of the blue line and around 1440 Deg F (Moony EGT not JPI).  Fuel flow was at 27.9 GPH.

It make sense that it's running cooler now. Reduced RPM at WOT typically increases internal cylinder pressure. Ignition occurs at the same point, roughly the same volume of fuel and air enters the cylinder and the flame front travels at the same speed. The variable is piston speed; before your redline upgrade the piston was traveling at slower speed meaning the pressure spike was closer to TDC. That equals more pressure and more heat for every power stroke.

[wishboneash]

9 minutes ago, Shadrach said:

That's about dead solid perfect for that engine!

Now if only I could get the 165kt TAS one reads about! The engine is doing its job, but the airframe is probably dirty :-)

[Browncbr1]

8 hours ago, Shadrach said:

16.5-17 seems low at anything close to sea level.

I'm glad you have questioned my data because it led me to take another look, as I haven't taken a hard look since resetting the timing on my engine from 20 to 25 degrees.  It seems that the higher EGT values I mentioned earlier can be explained by the 20 degree timing that the engine was running at the time.   EGT values have dropped quite a bit since going to 25 degree timing .. 

I just looked at data from my last flight and it shows 17.1, peaking at 17.3gph..  my hottest EGT was 1283.    The below data was take off from 1000ft field with 79 F OAT  WOT Full rich.

I also just remembered that I have yet to dial in my K factor.. dang it!  Anyway, it seems, with respect to EGT values people have thrown around, it appears to be in line with 25 degree timing.

 

Edited May 17, 2016 by Browncbr1

[jclemens]

https://www.savvyanalysis.com/flight/1160789/51d617d3-d606-49a5-8d99-cb6c90d770f2

[co2bruce]

That's a tight group. Is your cylinder #1 a front? Our #6 reads like that, it's up front without the alternator in front of it so it gets the full blast.

[jclemens]

Thank you, a lot of time (money) was spent making everything run so evenly.  No, Cylinder #1 is the right rear.  The factory CHT probe resides in the location of the other 5 JPI probes on the #1 cylinder.  It has a piggy back style probe underneath the factory one.  It's not accurate.  I have removed the factory probe and made test flights with all 6 identical JPI probes and the #1 cylinder is the same as the rest.  I contemplated leaving it that way, but the inoperative factory CHT annoyed me.  The factory gauge is not accurate either.  The inaccurate reading on the JPI annoys me too, but, too a lesser degree.