M20K - Leaning and Engine Temp Practices

[SkyBound]

As I continue to get more familiar with my 1979 M20K with a TSIO-360LB-1 with TurboPlus Intercooler, Merlyn Automatic Wastegate and GAMIjectors I was wondering what practices other members use for leaning.  What temperature ranges do you try to keep your engines in (EGT, CHT, TIT) and what fuel flow do you typically aim for during climb, cruise and descent? 

 

I had fuel schedule adjusted on the engine and feel that it may be running too lean as I need to keep cowl flaps in trail in cruise when running full rich in order to keep CHT for the #1 cylinder below 380 in cruise at any altitude above 8,000 feet or so.  Contrary, I am finding that the #6 cylinder is typically the coolest, running at just below 300 CHT in cruise. My fuel flow is around 13.8 - 14.1 gph at 28" and 2500 RPM for cruise.  Do others see the same spread?

 

Any K tricks that you'd like to share to get the best temps, speed, and economy?

 

Thanks everyone in advance for sharing your wisdom and advice.

 

--Alex

[FAST FLIGHT OPTIONS LLC]

I fly my 231 @ 65% power 28"/2450RPM LoP and my fuel flow is 9.5 GPH mostly. Might want to try LoP for better economy

[rainman]

You may find these articles useful regarding engine management of a turbocharged engine when cruising LOP. As you have GAMIs this may be of help.

http://www.avweb.com/news/pelican/182544-1.html

When cruising LOP at 8000, 28MAP, 2500RPM, 9.5 GPH, my CHTs are generally 340-360 except #6 which is about 320., TIT 1560.

I'm still learning how to use my new JPI 830 and Jlunseth on this site had very good practical advise. I'll watch this thread for more input as I am still trying to refine my engine management.

Ray

[jackn]

Alex,

Sounds good to me. my engine is similar to yours. At 28/2500 I'll burn 13.9 gph RoP when cold outside. When warm, I'll trail cowl flaps or more fuel or both. I prefer 360 CHTs. #6 is coolest, I believe because it's the front cyl and may be caused by slight baffling differences. 9.5 gph sounds right for LoP, but that's only 62% pwr on your engine, 13.7 x 9.5= 130hp. At that setting RoP I burn about 12 gph. Still, that saves 2.5 gph and cooler CHTs. I don't like to spike my TiT  over 1600 and won't cruise with a TiT over low 1500s. As far as climb is concerend, my 220 hp likes 25 gph.

Jack

[FBCK]

Skybound, I have the same setup as your, the Turbo plus and the Mrylyn waste gate.  On mine I have to watch cylinder 2 which is infront of the oil cooler so the airflow might not be as good an there mayve adition heat there as well as a result.  On take off I run 36 inches and 21 gallons per hour, any less and the TIT and cht get hot, I dont push the mixuture all the way in, its perhaps out .5 inches.

 

I used to do the 28 inches and 13.5 gph but the end was way to hot and required constant monitoring. There was a disussion on the site with Parker Woodruff and others and they outline how they fly there planes so I tried that, oit was like night and day.  In cruise I now go lean, 31-32 inches with a fuel burn of 10.8-11.2 gph. Cylinder 2 is 360, 1 is 320 and its difficult to keep the others over 300, TIT is 1550-1575. Agian a little diference in the fuel burn seem to make a big differnce in the temps, if I see the temps start to climb I just lean a little more.  I also fine the fuel flow is constantly drifting up and down .3 gph and need adjusting, again a little diffence seems to make the temps drift up and down as well.

 

I would seach for that discusion but cant figure out how too.

[SkyBound]

Thank you all who have posted.  The comments are very helpful.

 

What TAS cruise speeds do you get with the settings you are suggesting running LOP?  I would be curious to hear how your planes perform compared to mine in a variety of altitude ranges say below 10K, low teens, mid to high teens, and flight levels if you go up that high.

 

Could you please also comment if you are trailing cowl flaps in cruise or if you are able to keep them closed to keep your CHTs under control?

 

Thanks again.

[skeptic]

I recently discussed this with a 231 owner.  His airplane has GAMI's, intercooler, Merlyn, and LB engine.

 

He said that in the mid teens he gets about 165 KTAS at 9.7 gph LOP.  This is with CHT's all in the mid 300's or lower, and TIT well within limits.  At lower altitudes he said speed was slightly less, around 160 KTAS if LOP.

[FBCK]

That would be concisitent to what I get, 160 down low, say 7500ft and at 15000 with 32 inches, 11gph its around 170kts, sorry could give you more but I never pay attention to it, usually only fly those alttude as well.

[FAST FLIGHT OPTIONS LLC]

Same speeds for me for the most part

[SkyBound]

I have continued experimenting running LOP and would like to get some more advice from the 231 pilots. 

• What procedure/steps do you use to go LOP? 
• What FF do you target and what %HP, RPM, MP do you use at various altitudes and what corresponding TAS do you observe?
• What are your EGT, CHT, and TIT preferred temperature ranges for LOP operations?  Do you trail cowl flaps or are you able to keep them closed to keep those temps?
• How do handle descents and temporary level offs on descent?
• Are there times when you won't use LOP? i.e. short hops, flying a lower altitudes, etc.?

Thanks!

 

--Alex

[aaronk25]

Question for you turbo guys. Will this small bore turbo run 30" and 2100rpm like mike busch's 310t ???

[Parker_Woodruff]

Question for you turbo guys. Will this small bore turbo run 30" and 2100rpm like mike busch's 310t ???

 

I couldn't get smooth LOP operations below about 2450 RPM with my TSIO-360-MB/SB.

 

Two totally different engines.  The TSIO-360 does well between 2500 and 2600 RPM.

[Parker_Woodruff]

I have continued experimenting running LOP and would like to get some more advice from the 231 pilots. 

• What procedure/steps do you use to go LOP? 
• What FF do you target and what %HP, RPM, MP do you use at various altitudes and what corresponding TAS do you observe?
• What are your EGT, CHT, and TIT preferred temperature ranges for LOP operations?  Do you trail cowl flaps or are you able to keep them closed to keep those temps?
• How do handle descents and temporary level offs on descent?
• Are there times when you won't use LOP? i.e. short hops, flying a lower altitudes, etc.?

Thanks!

 

--Alex

 

What procedures / steps for LOP?

Figure out a power setting that is LOP and then just pull the mixture straight back to that fuel flow.  Some power settings that worked for my 220 hp TSIO-360-MB/SB:

• 29" / 2550 RPM, 11.2 GPH
  • 10,000 ft: 168-170 KTAS
  • 15,000 ft: 179-180 KTAS
  • 16,000 ft: 180-183 KTAS
  • 17,000 ft: 184-185 KTAS
• 30" / 2550 RPM, 11.5 GPH
  • 17,000 ft: 188-190 KTAS
• 31" / 2550 RPM, 11.8 GPH
  • FL190: 190-192 KTAS
  • FL210: 191-195 KTAS

 TIT is generally 1550-1570 up in the mid-high teens to lower Flight Levels.  Fuel flow to maintain all CHTs below 380dF.  Cowl flaps on the infinitely adjustable 252 would be just barely open. (first notch in cruise).

 

I always fly LOP, except for in the climb.

[SkyBound]

Parker,

 

Thank you for taking the time to share the information.  Your 252 is about 10 kts. faster than my 231.  Very impressive!

 

I look forward to hearing from others.

 

--Alex

[SkyBound]

Special thanks to all who posted responses to my questions.  I lost my LOP virginity on a trip earlier this week.  I was able to do 165 kts TAS at 17,000 burning 9.5 GPH using 28.5" and 2500 RPM.  Like everyone has said the CHTs were in the mid 300s and TIT stable at 1550.  ROP at the same altitude with 28.5" and 2500 RPM yielded only 7 kts more (172 TAS) burning 14.8 GPH and having to trail cowl flaps to keep temperatures below 380.

 

My JPI was showing 75% power for both ROP and LOP with the above settings, but that is not correct, right?  When running LOP the equation 13.7 X GPH = HP applies.  Thus for my 210 HP engine as jackn pointed out I was only doing 62% power LOP.  Could one take this equation as a general philosophy for LOP flight and then say that for my engine I could try various power setting combinations as long as I stay at or below 11.5 GPH which would be equivalent to 75% while keeping CHTs below 380 and TIT below 1600?

 

Parker - I notice that you mentioned that your engine runs rough below 2450 RPM, is that why you stay with 2550 RPM - 100 RPM above that setting?  Does that additional 50 RPM above 2500 make a big difference?

 

Do others with my LB engines like mine cruise faster than 2500 RPM?

 

Thanks for the additional comments and advice.

 

--Alex

 

PS: For those 231 and other Turbo Mooney drivers going to Oshkosh would anyone like to get together in the North 40?  Post here and may be we'll have a chance to get together next week.

[jlunseth]

Well, I don't think it works in a 231 to make a power setting and then pull straight back to LOP because the waste gate controller is not automatic, that is, if you set it for 29" it does not know to maintain 29". So when you get to the LOP side the MP starts to fall off and it does so fairly dramatically. My experience is that you have to pull the mixture to the LOP side then put MP back in, which of course increases, fuel flow so you have to pull fuel out again. It is a matter of getting the two happy with each other over on the LOP side.

[Parker_Woodruff]

Hey Alex - Nice performance while LOP.

At 9.5 GPH, you don't have to be very far LOP to be doing it safely.

2550 was just what I found to be the sweet spot for my engine at higher power LOP settings. 2500 was fine for lower power LOP settings.

Wish I could meet you and others at OSH this year.

[SkyBound]

Parker - thanks for your note.  I was able to get my fuel flow up to about 10.7-11.0 GPH on the way to OSH yesterday, but don't seem to be able to keep CHTs and TIT at bay and run smoothly to get a little more power above that.  I was hoping to get to 11.5 GPH, but 11.0 GPH is close enough.  The airplane was doing 165 kts TAS at 14,000 ft. I am excited to know that the airplane can be happy performing that way.  Very impressive how much faster your airplane was.  

 

I hope that you can return to Oshkosh soon!

[1doorman]

Well, I don't think it works in a 231 to make a power setting and then pull straight back to LOP because the waste gate controller is not automatic, that is, if you set it for 29" it does not know to maintain 29". So when you get to the LOP side the MP starts to fall off and it does so fairly dramatically. My experience is that you have to pull the mixture to the LOP side then put MP back in, which of course increases, fuel flow so you have to pull fuel out again. It is a matter of getting the two happy with each other over on the LOP side.

I'm going to embarrass myself on my first post to is blog. I just popped my LOP cherry in my 1981 M 20K. JLunseth comment addresses something I noticed on my virgin voyage. As I did the mixture pull I noticed a substantial MP drop., in the range of 5"'s. I did it several times. And wondered, crap what did I do wrong. Ignorance in my own plane. I've had 231 VF for over 5 years, flown it about 350 hrs and seem to remember someone telling me it has an auto waste gate! From jLunseth's note, I must NOT have that auto waste gate. I did play the teeter-tawter with adding a little power, then leaning little, the adding a little power etc. Being hypersensitive to what I was hoping to accomplish, I began to feel rough operations. I swear I was so focused on vibration I felt the shock waves of an ant farting 10,500 below me. A stressful flight for several reasons, but this wavering of the MP was of great concern. All ended well, absolutely no problems with anything other than what my imagination conjured up. All that being said, how can I confirm that's do not have an auto waste gate? If I do have an auto W G, why would I have these drops with the big mixture pull?

It's humbling to come to a new sight (for me) and in 10 minutes of reading, realize I don't know crap about a plane I love. Does this mean I don't know much about my wife, either?

[FAST FLIGHT OPTIONS LLC]

When you take off.... if you firewall your throttle (at sea level or close to it ) to get to 40" you have an automatic waste gate. I'm going to go out on a limb and say you have one because if you didn't you would probably have overboosted and blown up your engine by now by not knowing

[chrisk]

I'm going to embarrass myself on my first post to is blog. I just popped my LOP cherry in my 1981 M 20K. JLunseth comment addresses something I noticed on my virgin voyage. As I did the mixture pull I noticed a substantial MP drop., in the range of 5"'s. I did it several times. And wondered, crap what did I do wrong. Ignorance in my own plane. I've had 231 VF for over 5 years, flown it about 350 hrs and seem to remember someone telling me it has an auto waste gate! From jLunseth's note, I must NOT have that auto waste gate. I did play the teeter-tawter with adding a little power, then leaning little, the adding a little power etc. Being hypersensitive to what I was hoping to accomplish, I began to feel rough operations. I swear I was so focused on vibration I felt the shock waves of an ant farting 10,500 below me. A stressful flight for several reasons, but this wavering of the MP was of great concern. All ended well, absolutely no problems with anything other than what my imagination conjured up. All that being said, how can I confirm that's do not have an auto waste gate? If I do have an auto W G, why would I have these drops with the big mixture pull?

It's humbling to come to a new sight (for me) and in 10 minutes of reading, realize I don't know crap about a plane I love. Does this mean I don't know much about my wife, either?

 

Here is a good article on turbos.  http://www.avweb.com/news/maint/182847-1.html

 

As to your plane:  There is a 99% chance it either has a fixed waste gate, or a Merlyn automatic waste gate.  http://www.merlynproducts.com/blackmagic.html  If you have the Merlyn, it should be in the log book and you should also have an STC.  You can also see it when you open the turbo inspection port.  --But if you don't know what you are looking for.....

 

I  don't believe the Merlyin is an absolute pressure controller, so you still have to be careful about over boosting your engine.  It is however better than a fixed waste gate.

 

 

As to your experience of loosing MP when you went LOP.  I had a similar experience and I have the Merlyn auto waste gate.   I don't recall the degree of MP loss, but there was some.

[1doorman]

I limit TO power to 37", due to the Air Flow intercooler.  With all reading I've done lately, it sure seems the vast majority of those with intercooler seem to have an auto waste gate, as well.  Thanks for the note about a waste gate not being a absolute pressure controller.  I'm finding that LOP operations get very sensitive.  So a slow hand is helpful when running there.  I keep my logs in the hangar.  I must remember to read back over history.  Seems the more I know the more confused I get!  But I'm comfortable with the LOP ops now.  I have a printed chart for percentages of power with a notation of where the re box is, with each power setting.   I'm careful to run under 65% and stay out of the red box.  If I need more speed, I increase power, check my red box numbers and have faith in all the test data.  

[SkyBound]

1doorman - would you mind sharing a copy of the power chart that you use?  Also any speeds (IAS/TAS), fuel flows, etc. that you can share at various altitudes would be helpful to those of us learning about our 231s and LOP ops if you can share those as well.

 

Thanks in advance.

[dham1956]

With the inter cooler, merlyn wastegate, gami injectors and jpi engine monitor all I do is pull the mixture back to 11.5gph starting at 33mp and full rich. It's called the big pull. When you get to 11.5 you are at 75% power and LOP. Should run cool. If not pull the mixture back a tad more which increases the air vs fuel ratio and slows the combustion event.

[jwilkins]

I All that being said, how can I confirm that's do not have an auto waste gate?

 

1. Ask your mechanic if you have AWG and intercooler installed. If you do, the manufacturers will probably give you the pilot operating guides free. Intercooler manuals typically show lower MP settings than non-IC engines. I got the AWG on line and the IC guys emailed me their pilot guide which was not in the 15 pounds of paperwork that came with the plane

2. Check your log books. The information should be in your log books with the STC and a copy of the 337 forms.

3. Send to the FAA for the ownership and 337 history. It's pretty inexpensive and very interesting.

 

Jim

 

My Merlin is the typical not fully automatic wastegate. It's better than the fixed WG but not as good as the 252 fully automatic 'set and forget'