Mooney M20 E best cruise EGT / CHT practice

[Pilot boy]

I recently purchased a 64 M20E.  I'm at about 20 hrs in it now but had something come up in recent cruise at around 6500 feet.  Basically I closed the cowl flaps for cruise but leaned the mixture fairly far out (I didn't use the JPI 700 I have installed for this I just leaned it out a good bit.).  I'm still learning the JPI procedures for ROP and LOP by reading the engine manual.  The JPI (not Lycoming) manual seems to indicate that 1350 to 1550 EGT is okay in cruise.  What I noticed on my xcountry was that with cowl flaps open (below 150 mph I think is the restriction on when you can open/close them) the EGTs stayed fairly low.  Like 1250 to 1350.  When I closed cow flaps I noticed the EGT went up to about 1480.  I was concerned so I enriched the mixture to keep it down below 1400.  CHTs were all still in the green, I think around 400 area.  I have read posts on here that says EGT doesn't matter for operations, etc.  

My questions are :

1.  Is there a good EGT you should shoot for in cruise?  Or what is the max you don't want to see it go above?

2.  What CHT should you use in cruise?  What's the max allowable?

3.  I've been trying to time build so I'm trying to save fuel by pulling the manifold pressure (throttle) back to about 19 or 21 inches but I'm not sure if this makes any difference for fuel consumption or if the mixture leaning is probably way more important?

4.  What's max drop to avoid shock cooling in descent?  And what procedure do you use?

5.  Do you always close cowl flaps in cruise if below the speed limitation?  Even in summer heat?  

Prop usually have around 2400 rpm.  I'm going to lean for rich of peak though I know lean of peak is better for fuel savings...but I want to baby the engine.  The 64 E has an rpm restriction from about 2100 to 2350 or something like that marked on the tach.  The prior owner told me he always did 2500 RPM max in the pattern and possibly on climbs but I've been using 2600 RPM or even 2700 Tom (full in) on climbs and touch and gos.  Any insight from E or F owners on the RPM restrictions especially valuable.

I fly in the Midwest so OAT at surface is 90F plus, we takeoff at about 1000 ft msl (3000 ft da).  

The E has been a blast to fly so far.  I love 1500+ from climbs.  (100 to 120 mph for cooling) and the speed over the old rental 172s is great.

-Ben

 

 

 

 

 

 

 

 

 

[takair]

30 minutes ago, Pilot boy said:

1.  Is there a good EGT you should shoot for in cruise?  Or what is the max you don't want to see it go above?

2.  What CHT should you use in cruise?  What's the max allowable?

3.  I've been trying to time build so I'm trying to save fuel by pulling the manifold pressure (throttle) back to about 19 or 21 inches but I'm not sure if this makes any difference for fuel consumption or if the mixture leaning is probably way more important?

4.  What's max drop to avoid shock cooling in descent?  And what procedure do you use?

5.  Do you always close cowl flaps in cruise if below the speed limitation?  Even in summer heat?  

 

1.  It will vary with altitude and power.  Best use peak referenced EGT.

2.  For an E, best kept below 380, even better below 350.

3.  It should make a big difference, but so does leaning.  Unlimited threads on LOP ops if your aircraft is set up for it.

4. don’t make huge power changes.  I usually target 5” MAP reduction for 500fpm descent.  You might also pitch over toward redline if in smooth air.

5.  I almost never open cowl flaps accept in climb.  Based on your info and questions I suspect your dog house needs work.  The 64E model was somewhat unique and had the least evolved dog house.  They are usually beat up and cracked.  I am continually replacing cracked parts and they make a huge difference in temperatures.  I would start there, otherwise your operating technique is masking an issue.  
 

For my aircraft, 100ROP, 2500 RPM and WOT clearly gives best power cruise with no real temperature concerns.  Below 65% you can run 25ROP with good temps too.  These were the old school book recommendations.  It may run smooth 25 LOP with better efficiency, but I prefer the speed of ROP.

[Matt Ward]

I fly a 66 M20E.  I target low 8's GPH in cruise.  At that, I'm a bit LOP with EGTs in the high 1400s and CHTs in the low to mid 300s.  Here is a flight from Yellowstone back to Denver from this weekend if you want to look at what that profile is.

https://apps.savvyaviation.com/flights/4237292/e57581b5-3aeb-447b-b23c-bac7dff9926d

I close my cowl flaps at cruise and don't reopen until landing, assuming there isn't a CHT issue I'm trying to cool down.  If there is, I apply a mix of descent, cowl open, mixture richen.

I run WOT and full RPM until established in cruise (assuming no noise abatement issues I'm trying to avoid).  In cruise, I target about 65% BHP which is about 8.3 GPH, WOT, and 2500 RPM.

Like a lot of other Mooney drivers, I subscribe to the "touch and little as I can" school of thought.

On climb, I do lean to a target EGT of about 1250.  I takeoff in the mid 14s and end up climbing in the 13s or maybe high 12s.

I'm based at 5600 ft and typically cruise 10.5 to 12.5, YMMV.

Enjoy your E!

 

[gsxrpilot]

1 hour ago, Pilot boy said:

1.  Is there a good EGT you should shoot for in cruise?  Or what is the max you don't want to see it go above?

-- The numbers don't matter. What does matter is how many degrees you are before or after they peaked. Go out figure out the numbers for your engine. Go up to around 8000 ft so you're at low enough power you can't hurt anything. Then as you slowly lean the mixture, watch the EGT numbers rise. As you keep leaning the mixture, you'll eventually see the numbers start to come back down. Note the highest EGT number for each cylinder. That is your Peak EGT for that cylinder. Also note which cylinder was the first to peak and start back down and the last cylinder to peak and to start back down. Once you know those numbers, you can now know at any given time, how many degrees before peak (ROP) or how many degrees after peak (LOP) you are. We measure the ROP based on the first cylinder to peak and LOP based on the last cylinder to peak.

2.  What CHT should you use in cruise?  What's the max allowable?

-- Ideally you can keep everything at 380 or below.

3.  I've been trying to time build so I'm trying to save fuel by pulling the manifold pressure (throttle) back to about 19 or 21 inches but I'm not sure if this makes any difference for fuel consumption or if the mixture leaning is probably way more important?

-- Both have an effect, do you have a GPH gauge?

4.  What's max drop to avoid shock cooling in descent?  And what procedure do you use?

-- This is a myth that has been fully debunked. Shock cooling is not a thing.

5.  Do you always close cowl flaps in cruise if below the speed limitation?  Even in summer heat?  

-- Cowl flaps as required. If the CHT's are a little high, open the cowl flaps.

 

[corn_flake]

 

1.  Is there a good EGT you should shoot for in cruise?  Or what is the max you don't want to see it go above?

Variation on how the EGT prob is mount on each engine will result in different EGT number.  The important thing is relative temperature from the peak unique to your installation.  25 LOP or 50 ROP....

2.  What CHT should you use in cruise?  What's the max allowable?

Lycoming allows for 500 degree as the Max.  But, most pilot won't go past 420 even in a climb.  During cruise, it's best to keep below 400. 

3.  I've been trying to time build so I'm trying to save fuel by pulling the manifold pressure (throttle) back to about 19 or 21 inches but I'm not sure if this makes any difference for fuel consumption or if the mixture leaning is probably way more important?

Reduce MP would reduce fuel consumption.  But, a fuel flow gauge would be helpful to determine much fuel you are burning. 

4.  What's max drop to avoid shock cooling in descent?  And what procedure do you use?

I learned from MS, shock cooling has not been proven.  

5.  Do you always close cowl flaps in cruise if below the speed limitation?  Even in summer heat?  

Open cowl if the engine is running hot, even in cruise.  

[carusoam]

Shock cooling/heating doesn’t exist in Mooney aviation...

Or we would need to avoid flying under various weather conditions that don’t get mentioned while discussing the topic...

Nothing more shock cooling than a rain storm...

 

Keep in mind raw EGT Numbers aren’t very helpful... they are highly dependent on mm(s) down the exhaust pipe... 

Where they are really helpful... when they are located in a tightly controlled way... The IO550 has an engineered EGT position for the ships gauge...

So... we use a relative term when discussing leaning... °F LOP, ROP,   Or right at peak....

If you fly a TC’d bird... the TIT is an EGT mounted exactly in one place in the turbo... 

So... the raw numbers can be meaningful... just most often they depend on the environment to make them not so useful....

 

keep reading there is a lot to know...

PP thoughts only, not a CFI...

 

Best regards,

-a-

[Pilot boy]

2 hours ago, corn_flake said:

 

1.  Is there a good EGT you should shoot for in cruise?  Or what is the max you don't want to see it go above?

Variation on how the EGT prob is mount on each engine will result in different EGT number.  The important thing is relative temperature from the peak unique to your installation.  25 LOP or 50 ROP....

2.  What CHT should you use in cruise?  What's the max allowable?

Lycoming allows for 500 degree as the Max.  But, most pilot won't go past 420 even in a climb.  During cruise, it's best to keep below 400. 

3.  I've been trying to time build so I'm trying to save fuel by pulling the manifold pressure (throttle) back to about 19 or 21 inches but I'm not sure if this makes any difference for fuel consumption or if the mixture leaning is probably way more important?

Reduce MP would reduce fuel consumption.  But, a fuel flow gauge would be helpful to determine much fuel you are burning. 

4.  What's max drop to avoid shock cooling in descent?  And what procedure do you use?

I learned from MS, shock cooling has not been proven.  

5.  Do you always close cowl flaps in cruise if below the speed limitation?  Even in summer heat?  

Open cowl if the engine is running hot, even in cruise.  

I do have a fuel flow meter on the JPI 700.  Any suggestions on mixture and prop combinations that work well to start testing?

[Pilot boy]

3 hours ago, gsxrpilot said:

 

I do have GPH gauge.  I will have to start experimenting.

[Yooper Rocketman]

Great advice @takair @Matt Ward @gsxrpilot @corn_flake and @carusoam !!!  Very timely for me.  I just finished the Annual Inspection on Steve's 1964 "E" (my best friend/hangar partner/building buddy on my Lancair).  Flew it yesterday for the first time it's seen the air in over two years.  "My" last E time was maybe 10 years ago?  I have a ton of F time (1400 hours) but that was back in 1996 to 2001, before my 18 year stint with my Rocket.  To say it's an adjustment from the Rocket and my prop-jet would be an understatement.  Sure nice to see some advice on power settings.  I'm dealing with a high #4 cylinder temp, started some corrections this afternoon, and will probably start a thread on it soon.

Tom

 

[carusoam]

Adjusting things...

1) Go to savvy to become familiar with the Gami spread test... determine your Gami spread....

2) Gami spreads closer to 0 are best... 0.5 and above may want some work...  (Could be a FI cleaning)

3) EGTs are the source of heat.... if they are all similar, with a narrow small Gami spread... the CHTs are getting evenly heated...

4) Cylinder Cooling Is the other half of the CHT equation.... Good airflow is required... to get good airflow... Good baffling is required for even CHTs...

5) Knowing the status of all the TCs on the engine helps... see what they are reading while the engine is cool... they should be easy to have in the same range of temperature... within a couple of degrees...

6) Knowing the fifth CHT sensor... the ships gauge... where it is, what type it is... Will help...

7) SparkPlug Mounted TCs can add an extra 50°F to the reading... piggy back TCs mounted near the CHT well read 25°F higher than down inside the well...
 

8) light test.... in a dark hangar... looking for holes and cracks in the baffling...there isn’t much resistance to keep air flowing the righ direction.... it likes to escape through holes, cracks and missing seals around things like the starter and alternator...

9) if the starter and alternator have the old felt seals... Guy Ginby has some new silicone ones that can make a nice update...

10) Some EGT issues might come from leaky intake seals... pretty easy to test and update...
 

11) Summary...  Good EGTs, are the result of good airflow, and fuel flow to the engine...  Good CHTs are the result of good airflow around the engine...

When you get to altitude... say hi for us....  

PP thoughts only, not a mechanic...

Best regards,

-a-

[Hank]

I'll echo the above. 25°Lean of last cylinder to peak or 50° Rich of first cylinder to peak. Use that fancy engine monitor, it's more than eye candy! ROP will give more speed than LOP because it burns more fuel.

Many people like to keep CHT at or below 380, but will permit 400-ish in the climb (not counting one cylinder with factory and engine monitor connections).

Descents are simple--push the yoke for 500 fpm, spin trim wheel for hands off flight. Check your speed every now and again, make sure it stays below redline. My C stabilizes very well at 165 mph (yellow starts at 175), I almost never reduce throttle until I'm slowing for pattern entry (allow 2-3 nm for that, the brakes on these planes are really weak  ). 

My cowl flaps are fixed, so I can't address that much. But there are some threads around here discussing how far the flap should be open with the knob firmly in the Closed position. Seems it's an inch or so. There's a picture of mine complete with a tape measure in at least one of those threads.

[Pilot boy]

23 hours ago, takair said:

1.  It will vary with altitude and power.  Best use peak referenced EGT.

2.  For an E, best kept below 380, even better below 350.

3.  It should make a big difference, but so does leaning.  Unlimited threads on LOP ops if your aircraft is set up for it.

4. don’t make huge power changes.  I usually target 5” MAP reduction for 500fpm descent.  You might also pitch over toward redline if in smooth air.

5.  I almost never open cowl flaps accept in climb.  Based on your info and questions I suspect your dog house needs work.  The 64E model was somewhat unique and had the least evolved dog house.  They are usually beat up and cracked.  I am continually replacing cracked parts and they make a huge difference in temperatures.  I would start there, otherwise your operating technique is masking an issue.  
 

For my aircraft, 100ROP, 2500 RPM and WOT clearly gives best power cruise with no real temperature concerns.  Below 65% you can run 25ROP with good temps too.  These were the old school book recommendations.  It may run smooth 25 LOP with better efficiency, but I prefer the speed of ROP.

I have an updated cowling on this E.  I believe the lower half is a different design than stock...I can't recall the name of the mod...might be from LASAR? 

[Ross Taylor]

I also have an E...a 1966.   I don't touch the throttle from takeoff until I'm ready to head back down...I'm WOT all the way.  If I'm trying to be efficient, I'll reduce RPMs and, of course, I lean aggressively.  I recommend these videos for you:

 

 

[carusoam]

Savvy is an excellent resource!

We have a Savvy MSer...

Often MSers use Savvy to upload monitor data graphs to be seen by other MSers...

Best regards,

-a-

[Yourpilotincommand]

In my E model I typically cruise 2500rpm@23”mp. I lean to -20 LOP or more based on my EDM730. I typically burn 9gph. I am an avid Mike Busch fan and recommend listening to all his webinars on YouTube. I my tach may be off calibration a little so my numbers may not be exactly right and hope to get that corrected soon. You listen to Mike Busch.. and you will have alll of your answers I swear! Btw, my CHTs during cruise are in the low 300s. Lower the better for cylinder longevity. EGTs you cannot depend on a target EGT, it is subject to many variables. You just use that to determine where you wanna be wrt peak EGT. Cheers!

[Yourpilotincommand]

21 hours ago, carusoam said:

Savvy is an excellent resource!

We have a Savvy MSer...

Often MSers use Savvy to upload monitor data graphs to be seen by other MSers...

Best regards,

-a-

I TOTALLY agree with you carosam!!!

[Yourpilotincommand]

21 hours ago, Ross Taylor said:

I also have an E...a 1966.   I don't touch the throttle from takeoff until I'm ready to head back down...I'm WOT all the way.  If I'm trying to be efficient, I'll reduce RPMs and, of course, I lean aggressively.  I recommend these videos for you:

 

 

Amen Ross. Ive listened to those more that once and will again!  The best resource ever. I also have a 66 E model!

[Pilot boy]

33 minutes ago, Yourpilotincommand said:

In my E model I typically cruise 2500rpm@23”mp. I lean to -20 LOP or more based on my EDM730. I typically burn 9gph. I am an avid Mike Busch fan and recommend listening to all his webinars on YouTube. I my tach may be off calibration a little so my numbers may not be exactly right and hope to get that corrected soon. You listen to Mike Busch.. and you will have alll of your answers I swear! Btw, my CHTs during cruise are in the low 300s. Lower the better for cylinder longevity. EGTs you cannot depend on a target EGT, it is subject to many variables. You just use that to determine where you wanna be wrt peak EGT. Cheers!

How do you like the EDM 730?  I have the 700 but JPI is offering me to swap out for $1300 for the 730 if I trade the 700 on.  The digital display sure seems more appealing and probably easier to use.  The 700 is like an 80s computer.

[carusoam]

The newer more complex JPIs double the data flow rate from 2sec per data set down to 1sec per data set...

This is helpful while doing diagnostics during the run-up...

If you can get MP, RPM, and FF, with location and altitude all saved in its memory... that would be good too...

Best regards,

-a-

[ArtVandelay]

The newer more complex JPIs double the data flow rate from 2sec per data set down to 1sec per data set...
This is helpful while doing diagnostics during the run-up...
If you can get MP, RPM, and FF, with location and altitude all saved in its memory... that would be good too...
Best regards,
-a-

The 1 sec sampling will quickly overwrite entries in the log, in like 12 hours. Also it screws up the gps speed (becomes negative) with my level of firmware.

[gsxrpilot]

11 hours ago, carusoam said:

The newer more complex JPIs double the data flow rate from 2sec per data set down to 1sec per data set...

This is helpful while doing diagnostics during the run-up...

If you can get MP, RPM, and FF, with location and altitude all saved in its memory... that would be good too...

Best regards,

-a-

I've got my JPI EDM 900 set at a 2 sec sample rate. It seems to be good enough resolution for @kortopates and the Savvy team to monitor and evaluate my engine performance. If I'm troubleshooting an issue, I'll slow down my actions. Such as take a few seconds longer on the mag check. I'd be happy for 1 sec resolution, but it seems to bring some other issues with it at the moment.

[skydvrboy]

I may be way off base here, but I'm going to try to answer the questions you aren't asking, but seem to be implying.  Below is a good starting point for flying your E using the KISS method.

Normal Operation
Takeoff and climb = Wide open throttle, max RPM, Full Rich.  Note EGT on takeoff and lean to keep that EGT* as you climb.

Cruise = Reduce RPM to 2500, close cowl flaps, trim for level flight, and lean until last cylinder is 25 LOP**.

Descent = Push nose over for 500 fpm and trim to keep 500 fpm***.

Landing = Reduce throttle to slow to gear speed and land****.

* Better if you can note sea level takeoff EGT and lean to that.
** Assumes you are about 7000 MSL or higher
*** Assumes smooth air, otherwise reduce throttle to stay out of yellow arc and comfortable.
**** Set prop and mix if you are used to doing that before landing.

Time Building
Cruise = Reduce throttle to 20", prop to 2400, lean until rough, enrich just until smooth.  Alternatively, throttle to 22", prop to 2000, lean as before (my prop didn't seem to govern well at that low RPM, YMMV).  At these power settings you can't hurt the engine no matter how you lean.  Enjoy your 5-6 GPH! :-)

[kortopates]

53 minutes ago, gsxrpilot said:

I've got my JPI EDM 900 set at a 2 sec sample rate. It seems to be good enough resolution for @kortopates and the Savvy team to monitor and evaluate my engine performance. If I'm troubleshooting an issue, I'll slow down my actions. Such as take a few seconds longer on the mag check. I'd be happy for 1 sec resolution, but it seems to bring some other issues with it at the moment.

Yes, at Savvy we request the data sampling rate set to 1-2 sec to provide sufficient data resolution for diagnosing issues. The coarser the data the harder it becomes to tell if for example changes in MAP may be leading changes in FF or vice versa. All the EDM's leave the factory with a default of 6 sec which is so coarse its easy to miss short events entirely. Many others the OEM uses a 1 sec rate including the Garmin (e.g. G1000) EIS systems. I also prefer the 1 sec rate for its finer resolution. It can be  a trade off with memory storage but shouldn't be a concern with the modern EDM 9XX  systems. For example, JPI claims more than 300 hrs at the 6 sec rate, dividing that by 6 (for a 1 sec rate) gives 50 hrs. It will vary a bit based on how many parameters your monitor logs. That right at the average annual hours per year for the average GA pilot and still plenty for me to make my longer 2-3 week flying safari's. Plus we really want you to upload your flights as frequently as possible so that the Savvy algorithms can alert you, for example if your data shows signs or a burnt/burning valve.

10 hours ago, ArtVandelay said:

The 1 sec sampling will quickly overwrite entries in the log, in like 12 hours. Also it screws up the gps speed (becomes negative) with my level of firmware.

   You gotta stop flying with such strong headwinds! What unit only gives you 12 hrs at 1 sec? That sounds awfully short. Is it one you have to send it back in, to get that firmware fixed? 

[Yourpilotincommand]

On 8/15/2020 at 3:39 PM, Pilot boy said:

How do you like the EDM 730?  I have the 700 but JPI is offering me to swap out for $1300 for the 730 if I trade the 700 on.  The digital display sure seems more appealing and probably easier to use.  The 700 is like an 80s computer.

I friggin love it. The 730 is plug n play to your cabling. So much better than the 700. You will know exactly which button to push.  I could barely use the 700. The 730 is so easy to use. It was worth the $1300. I can now download and analyze my data,.

I did the upgrade program. It was a few weeks before I got my rebate. I had to call JPI and Aircraft spruce back n forth.. a little hassle, but be diligent.

[Josue]

On 8/13/2020 at 1:51 PM, Pilot boy said:

I recently purchased a 64 M20E.  I'm at about 20 hrs in it now but had something come up in recent cruise at around 6500 feet.  Basically I closed the cowl flaps for cruise but leaned the mixture fairly far out (I didn't use the JPI 700 I have installed for this I just leaned it out a good bit.).  I'm still learning the JPI procedures for ROP and LOP by reading the engine manual.  The JPI (not Lycoming) manual seems to indicate that 1350 to 1550 EGT is okay in cruise.  What I noticed on my xcountry was that with cowl flaps open (below 150 mph I think is the restriction on when you can open/close them) the EGTs stayed fairly low.  Like 1250 to 1350.  When I closed cow flaps I noticed the EGT went up to about 1480.  I was concerned so I enriched the mixture to keep it down below 1400.  CHTs were all still in the green, I think around 400 area.  I have read posts on here that says EGT doesn't matter for operations, etc.  

My questions are :

1.  Is there a good EGT you should shoot for in cruise?  Or what is the max you don't want to see it go above?

2.  What CHT should you use in cruise?  What's the max allowable?

3.  I've been trying to time build so I'm trying to save fuel by pulling the manifold pressure (throttle) back to about 19 or 21 inches but I'm not sure if this makes any difference for fuel consumption or if the mixture leaning is probably way more important?

4.  What's max drop to avoid shock cooling in descent?  And what procedure do you use?

5.  Do you always close cowl flaps in cruise if below the speed limitation?  Even in summer heat?  

Prop usually have around 2400 rpm.  I'm going to lean for rich of peak though I know lean of peak is better for fuel savings...but I want to baby the engine.  The 64 E has an rpm restriction from about 2100 to 2350 or something like that marked on the tach.  The prior owner told me he always did 2500 RPM max in the pattern and possibly on climbs but I've been using 2600 RPM or even 2700 Tom (full in) on climbs and touch and gos.  Any insight from E or F owners on the RPM restrictions especially valuable.

I fly in the Midwest so OAT at surface is 90F plus, we takeoff at about 1000 ft msl (3000 ft da).  

The E has been a blast to fly so far.  I love 1500+ from climbs.  (100 to 120 mph for cooling) and the speed over the old rental 172s is great.

-Ben

 

 

 

 

 

 

 

 

 

 

 

 

I suggest that you look for your airplane engine user manual. It contains text and graphs showing the max CHT to not damage your engine. Very informative reading. if i recall 400F is just about the max  CHT for the io-360 A1 series( my engine). I hope this is of help to you.