Discussion on the Continental engine in the 231

[NotarPilot]

I recently started searching for my first airplane purchase.  After numerous hours of research I decided on the M20J 201.  However, I have seen a couple M20K 231s in my price range that look fairly nice.  From what I've read, the 201 seems to be the best bang for the buck.  I live in the Los Angeles area and my mission profile will likely be short local trips with occasional cross country flights.  I don't see a need for a high altitude airplane for crossing over tall mountains.  But seeing that fuel burn is fairly close between the J and K models I'm wondering is I should consider the K model just to have the capability should I need it in the future.  I realize the overhaul will be more expensive but my greatest concern is reading that a lot of 231s require a top overhaul or some cyclinders to be replaced to make it to TBO.  

 

My question for M20K owners is, how likely are you to need to replace cyclinders to make TBO.  How much better does the M20J fair over the K in this area?  I've read some threads about this but want to really ask the J and K owners what they think about this.  Thanks in advance.

[Lood]

A friend of mine bought a '82 model 231 when it had only 200hrs since brand new. He flew it for 22 years, right up to TBO, without having to touch either the engine or the turbo for all of those 22 years. I think it depends quite a lot on how you handle the engine in general as well as how great your need for speed is.

He never takes more than 35" MP on take off, 30" MP for climb and never cruises at more than 26" MP/ 2400rpm IIRC. This normally returns about 160 - 165kts burning a mere 9.6 gal/hr.

[N9937c]

My 231 is 2045 since reman and has never had a cylinder off. compressions are all better than 70/80 and oil is 1 qt/ 12-15 hrs, Is intercooled and fixed wastegate. 35-36 takeoff, climb 33-2600, cruise 30-2400. A fabulous airplane! I have another engine ready to put on but this one runs too well.

larry

[FAST FLIGHT OPTIONS LLC]

All my compressions are better then 70/80.  Oil burn = 1 qt every 12-15 hrs or so.   39"-40" (takeoff)  30"-31" (climb)  28"-2400 RPM (cruise) 75-100 degrees LoP all day long on stock cylinders up high with 9.5 to 10 gph fuel burn which is 60% - 65% power.  No top work needed since overhaul 850 hours or so ago!

[FAST FLIGHT OPTIONS LLC]

Quote: NotarPilot

...I don't see a need for a high altitude airplane for crossing over tall mountains. 

But a turbo offers you so much more.  I live in Florida where there is hardly a mountain or anything even closely related.  What we do have in Florida, as many others on this board can attest to, is turbulence and traffic down low...both of which I could avoid with my “231”.  My K provides me with the ability to fly above most weather and in an altitude range which is far from congested.  The normally aspirated guys seem to be below me and the heavy metal above me.

 

BEWARE: Once you fly a turbo you become addicted to the performance.

[FAST FLIGHT OPTIONS LLC]

Quote: NotarPilo

...I realize the overhaul will be more expensive but my greatest concern is reading that a lot of 231s require a top overhaul or some cyclinders to be replaced to make it to TBO.  

I would plan for this financially in hopes it’s not needed vice needing it and not having planned for it financially.

 

You know it’s not unheard of for a 201 to be in need of a top overhaul either...just more likely in the 231.

 

Having owned a 201 and now a 231 I can tell you your taking a chance every time you sign on the dotted line.  Risk mitigation is important but there is only so much that a pre-purchase inspection or even an annual will tell you.

 

These are machines and machines break; however, both the Mooney’s I’ve owned have proven to be extremely reliable and maintenance free between annuals.

 

A testament to the 20+ years of MSC maintenance? ...Maybe

 

Luck?... Maybe

 

My flying abilities? Probably not

 

…good luck in your search, TAKE YOUR TIME!

[John Pleisse]

Quote: NotarPilot

My question for M20K owners is, how likely are you to need to replace cyclinders to make TBO.  How much better does the M20J fair over the K in this area?  

 

Many J owners expect cylinders to go to tbo. I do. And even if you opt for a top, Lycoming cylinders will only total 4.

I obviously own a J. If I owned a K, I would pad engine reserve for an 1100 hour top and chalk it up as part of the mission expense. The K is a heck of a capable airplane. If I lived out west, it'd be a must-have.

[NotarPilot]

This is exactly the kind of advice I was looking for.  Nick, I know you have the TSIO-360GB but I'm curious what you other guys are flying.

[jwilkins]

Quote: NotarPilot

  I realize the overhaul will be more expensive but my greatest concern is reading that a lot of 231s require a top overhaul or some cyclinders to be replaced to make it to TBO.  

[jetdriven]

Jim, the biggest scare I had from buying a 231 was the 40K or more overhaul cost vs. ~20K for a Lycoming. Dividing that by the expected 1800 hr TBO vs 2000 hr, that was a little more than twice the engine expense.  Thats assuming nothing goes wrong.  Of course, if you need to fly high, you need the right machine.

[carusoam]

Thoughts on turbo systems...

(1) you get incrementally more performance.

(2) you incrementally pay more for that performance.

(3) they are incrementally more challenging to operate.

(4) if I had the budget, I would own and operate an Acclaim using the tradition of the "fire breathing dragon"

(5) my east-of-the-Mississippi flying style does not lend itself naturally to turbo ops.  I can justify all kinds of stuff aviation, but turbos have alluded me....

Best regards,

-a-

[panther1400]

A guy told me once that if it doesn't have a LB engine that he would deduct 30k? So he recommended staying away from a GB unless it was cheap enough.

[jwilkins]

Quote: jetdriven

Jim, the biggest scare I had from buying a 231 was the 40K or more overhaul cost vs. ~20K for a Lycoming. Dividing that by the expected 1800 hr TBO vs 2000 hr, that was a little more than twice the engine expense.  Thats assuming nothing goes wrong.  Of course, if you need to fly high, you need the right machine.

[KSMooniac]

I agree with everything Jim wrote except item #5... that is an Old Wives Tale that has been de-bunked now with actual measured data.  The turbo is at it's absolute minimum temperature when your wheels touch the runway, and every second after that point it gets warmer, especially when idling for 5 minutes while standing still.

#6 reinforces my desire to add a turbo-normalizer to my J.  I already know I would love to have that extra capability, but I love everything else about my J to the point that I can't fathom selling/trading for a different plane with a turbo.  I live in the plains and have flown to both coasts and into the CO mountains a few times... I could use a turbo on nearly every XC trip and be very, very happy with the incremental boost in performance.

With the market the way it is today (vs. 5 years ago when I was shopping) I very likely would choose a 231 or perhaps a 252 over a J for the type of flying I do.  

Quote: jwilkins

5. The turbo needs to be cooled down before shut down. It really takes some disclipine to idle for a full five minutes (including taxi time) before shut down. I have a sign that sayd 'turbo cool down 5 min' that I can show the line guys so they don't stand there wondering if I forgot how to shut the engine down (Dave Mcgee's suggestion).

6. I REALLY like my 231. I don't expect to every go back to a non-turbo engine. Even with 8K DA I can climb up out of KPRC's airspace instead of out of it laterally. I like being able to climb above a lot of the weather and turbulence that I used to slog through. I enjoy flying the 231 between AZ and  CA on the same routes that ocassionally mde me anxious about weather and turbulence. The 231 is a little faster. Trips that used to take 4 hours ar now 3.5 or 3.6. I like the faster but didn't buy it for that.

Jim

[jwilkins]

Quote I agree with everything Jim wrote except item #5... that is an Old Wives Tale that has been de-bunked now with actual measured data.  The turbo is at it's absolute minimum temperature when your wheels touch the runway, and every second after that point it gets warmer, especially when idling for 5 minutes while standing still.

Jim's comments: I readliy admit that I don't have data and have not put instruments on the turbo. I'm new to turbos so I can't base any of my thoughts on years of actual experience like many long term turbo pilots.

Here's where this cool-down thing came from:

Both a former Mooney Factory pilot and a Mooney pilot / owner with thousands of turbo hours told me that everytime I come down from cruise I MUST allow five full minutes at reduced power for the turbo to cool down before shutting down. The story was that if you don't the oil can overheat and 'coke' in the turbo contributing to early failures. As I said, I have no data and I am a new Turbo pilot, but, knowing that the turbos get so hot in cruise that they actually glow red, and that they do not get that hot at idle, it just seems pudent to go through the cool down procedure. 

If anyone has actual test data from a reliable factory source such as an engine or turbo manufacturer that shows this as an OWT I'd be happy to avoid this cool down time.

Meanwhile, even as the arrogant all-knowing engineer that I am, I'm going to follow the Mooney Test Pilot's advice and go through that 5 minutes cool down.

Logically I don't think I am hurting anything. CHT EGT on all cylinders and TIT  are all low during the 'cool down', oil pressure is OK. The cool down may NOT be necessary but even if there is a remote possibility of avoiding an extra turbo rebuild I'll continue with it. If I'm ever flying your plane you can ask me to shut right down, and, if you are flying mine, I'll ask you to do the unecessary five minute cool down.

I know I'm always absolutely positively right until someone shows me I was wrong. Happens a lot, too.

 

[Shadrach]

Quote: jwilkins

Quote I agree with everything Jim wrote except item #5... that is an Old Wives Tale that has been de-bunked now with actual measured data.  The turbo is at it's absolute minimum temperature when your wheels touch the runway, and every second after that point it gets warmer, especially when idling for 5 minutes while standing still.

Jim's comments: I readliy admit that I don't have data and have not put instruments on the turbo. I'm new to turbos so I can't base any of my thoughts on years of actual experience like many long term turbo pilots.

Here's where this cool-down thing came from:

Both a former Mooney Factory pilot and a Mooney pilot / owner with thousands of turbo hours told me that everytime I come down from cruise I MUST allow five full minutes at reduced power for the turbo to cool down before shutting down. The story was that if you don't the oil can overheat and 'coke' in the turbo contributing to early failures. As I said, I have no data and I am a new Turbo pilot, but, knowing that the turbos get so hot in cruise that they actually glow red, and that they do not get that hot at idle, it just seems pudent to go through the cool down procedure. 

If anyone has actual test data from a reliable factory source such as an engine or turbo manufacturer that shows this as an OWT I'd be happy to avoid this cool down time.

Meanwhile, even as the arrogant all-knowing engineer that I am, I'm going to follow the Mooney Test Pilot's advice and go through that 5 minutes cool down.

Logically I don't think I am hurting anything. CHT EGT on all cylinders and TIT  are all low during the 'cool down', oil pressure is OK. The cool down may NOT be necessary but even if there is a remote possibility of avoiding an extra turbo rebuild I'll continue with it. If I'm ever flying your plane you can ask me to shut right down, and, if you are flying mine, I'll ask you to do the unecessary five minute cool down.

I know I'm always absolutely positively right until someone shows me I was wrong. Happens a lot, too.

 

[jetdriven]

The same group sees no problem running a 440 CHT in a 20C.  Must still be in the green arc.....good to go.  Times change and our interpretation must change along with it.

 

http://www.mooneypilots.com/mapalog/M20C%20Evaluation/M20C_Evaluation_Report.html

[jwilkins]

Quote: jetdriven

The same group sees no problem running a 440 CHT in a 20C.  Must still be in the green arc.....good to go.  Times change and our interpretation must change along with it.

 

http://www.mooneypilots.com/mapalog/M20C%20Evaluation/M20C_Evaluation_Report.html

[KSMooniac]

The Advanced Pilot Seminars course showed the data, and it may be included with my hard copy notes that are at home.  They instrumented a turbo housing and it was glaringly obvious that it got warmer after touchdown due to the reduced airflow.  The cool-down happens during the descent, approach and landing when you are operating at reduced power and have ample airflow.  It makes perfect sense from an engineering standpoint as well.  For the record, it doesn't get hot enough during the idle to do any harm, but it most certainly does no good.

Kromer knows a LOT about Mooneys, but unfortunately he didn't know much about engine management when those articles were published.  (nor did many other folks for that matter)  The development of modern engine monitors and the great work by the folks at GAMI and APS have really enabled the busting of OWTs and increased the level of education of those that seek it out.

[Shadrach]

Quote: jwilkins

 I don't disagree with your comments except "the same group sees no problem" part. This article was 11 years ago. There were many different people at Mooney, with different goals and ideas. I don't think any of us would fly our own planes the way the factory recommended at one time to get maximum performance numbers to make the marketing people happy. 

The whole industry was inflating performance figures during the boom years of GA. Funny how things change. I still try to learn from others, especially if I know them and trust thier opinions. 

I would like to see the source data for the turbo cool down situation.

Jim

 

[jwilkins]

Quote: KSMooniac

The Advanced Pilot Seminars course showed the data, and it may be included with my hard copy notes that are at home.  They instrumented a turbo housing and it was glaringly obvious that it got warmer after touchdown due to the reduced airflow.  The cool-down happens during the descent, approach and landing when you are operating at reduced power and have ample airflow.  It makes perfect sense from an engineering standpoint as well.  For the record, it doesn't get hot enough during the idle to do any harm, but it most certainly does no good.

Kromer knows a LOT about Mooneys, but unfortunately he didn't know much about engine management when those articles were published.  (nor did many other folks for that matter)  The development of modern engine monitors and the great work by the folks at GAMI and APS have really enabled the busting of OWTs and increased the level of education of those that seek it out.

[KSMooniac]

I'll see if I can even find my notes from the course... I moved over the summer and haven't fully (or even barely) unpacked all of my office crap yet!  It may be difficult for me to locate them.  

They did measure the oil at multiple points and the housing IIRC.  I know a lot of their test engines even went so far as to measure CHT at 6 or 8 locations around the circumference of each cylinder to check for uneven cooling due to baffling changes.  (Imagine 48 CHT readings instead of 6!)  They are very, very thorough.  Keep in mind that oil is only cooled by airflow through the oil cooler, and as soon as you stop moving then your oil is not going to cool.  The extended period at lower power before touch down combined with cooling air moving through the oil cooler and over the cylinders is what cools down the engine, turbo, and oil.

[jetdriven]

http://goliath.ecnext.com/coms2/gi_0199-6732264/Top-five-engine-myths-the.html

[jwilkins]

Quote: jetdriven

http://goliath.ecnext.com/coms2/gi_0199-6732264/Top-five-engine-myths-the.html

[John Pleisse]

Quote: jetdriven

http://goliath.ecnext.com/coms2/gi_0199-6732264/Top-five-engine-myths-the.html

 

Mr. Rogers,

Please elaborate on this. The link discusses high rpm engine settings and is referenced in no way to the previous discussions below. Likewise, there is no mention of who wrote it or it's source.

And with the utmost respect considered, TestWest is a great example of someone who puts their "data" where their keyboard is. These threads on engine management seem to all be laced with the catch phrases..... "the data"....."the data suggests"...."supported by data"...."new data indicates/proves"... "I don't have the data right now"...."let me check on the data". Please support your commentary with the........"data".