1978 M20J turbo normalized - Low(er) oil pressure above 12k

[Fasterthanmycherokee]

Flew from Nashville TN to Burlington VT and back, and noticed when cruised out at above 12k feet, oil pressure fluctuated in the 54-59 range (normal is above 70)per the CGR-30P. Turbo-normalized 20J, I've been playing with ROP settings per the POH, and have only recently started flying higher than 12k since buying o2 tank. Never had this issue previously, wondering if combo of altitude and leaning the engine could have this affect? Doesn't really add up to me. 

[N201MKTurbo]

I’ve never seen this in my plane. 
 

Do you still have the factory oil pressure gauge 

[Fasterthanmycherokee]

Factory oil pressure gauge was removed. I am going up to hangar today to download the last 10 flights from the CGR-30P and see what it looks like. 

[Bartman]

I would also be concerned about CHTs as high as 398 on #3

[N201MKTurbo]

27.5 at 2450 ROP is a lot of power. 
 

That’s the settings I use LOP. 

Your oil temp is kind of high for cruise, I see those oil temps in climb, but in cruise they always come down below 200.

[Shadrach]

In my bird there is a notable difference in oil pressure as the temps cross 200F.  It appears the power is well north of 80% and leaned on the rich side of peak.  CHTs are warmer than I'd like to see, but certainly within reason given that you're running it hard at 12,500 on a hot day.  I'm curious what kind of TAS you're seeing at that altitude.

Edited June 21, 2021 by Shadrach

[N201MKTurbo]

39 minutes ago, Shadrach said:

In my bird there is a notable difference in oil pressure as the temps cross 200F.  It appears the power is wet to north of 80% and leaned on the rich side of peak.  CHTs are warmer than I'd like to see, but certainly within reason given that you're running it hard at 12,500 on a hot day.  I'm curious what kind of TAS you're seeing at that altitude.

On mine I'd see about 170 KTS

[N201MKTurbo]

42 minutes ago, Shadrach said:

In my bird there is a notable difference in oil pressure as the temps cross 200F.  It appears the power is wet to north of 80% and leaned on the rich side of peak.  CHTs are warmer than I'd like to see, but certainly within reason given that you're running it hard at 12,500 on a hot day.  I'm curious what kind of TAS you're seeing at that altitude.

Flight aware was showing ground speeds of about 167 KTS

[N231BN]

Most likely a sender issue, not uncommon.

[Shadrach]

44 minutes ago, N201MKTurbo said:

Flight aware was showing ground speeds of about 167 KTS

I saw that as well. I don’t think it gives much insight though.  My NA F model has logged cruise ground speeds as low as 101KTS and as high as 246KTS.  It can look like a dog or a rocket depending on when you look at FIightAware.

Edited June 19, 2021 by Shadrach

[Shadrach]

45 minutes ago, N201MKTurbo said:

On mine I'd see about 170 KTS

I would have thought faster.  I estimate he's at a DA ~14,000 running well over 80% power.

[wcb]

3 hours ago, Fasterthanmycherokee said:

Flew from Nashville TN to Burlington VT and back, and noticed when cruised out at above 12k feet, oil pressure fluctuated in the 54-59 range (normal is above 70)per the CGR-30P. Turbo-normalized 20J, I've been playing with ROP settings per the POH, and have only recently started flying higher than 12k since buying o2 tank. Never had this issue previously, wondering if combo of altitude and leaning the engine could have this affect? Doesn't really add up to me. 

I would say the issue is you are in FULL Fire Breathing Dragon Mode.  I never flew mine for long periods of time in full fire breathing dragon mode.  Even though it says max continuous is 27.5 inches of MP doesn't mean you have to run it like that.  Your oil pressure is right in line for how you are running the engine in my opinion.  Oil temp 215, #3 Cyl 398 and TIT 1410 all indicate your everything in your engine while "are within spec" but on the higher side of normal would force you oil to be hotter and thinner thus pressure would be on the lower side.   There are better experts than me, but I would run mine at 25 to 26 inches of MP (most of the time lean of peak) and my cyl temps were always under 350 usually like in the 300 - 330 range.  Simply my experience in my old M20F with a RayJay Turbo (I am not sure of your brand of turbo in your J model which of course has the better cowl etc). 

[N201MKTurbo]

1 hour ago, Shadrach said:

I would have thought faster.  I estimate he's at a DA ~14,000 running well over 80% power.

Well, a 201 won’t really do 201 either.

The rule of thumb for turbos is 2 KTS per thousand feet. If a stock 201 does 155 at 6500, add 12 KTS for the extra 6000 and there you are. Go up to 16500 and get another 8 KTS.

BTW, I do understand the effect of wind on ground speed. I just mentioned it because if the winds were light, it looked about right.

Edited June 19, 2021 by N201MKTurbo

[A64Pilot]

4 hours ago, N231BN said:

Most likely a sender issue, not uncommon.

As any sender measures the difference between atmospheric and oil pressure, I’m wondering if maybe the vent on the sender is plugged.

[Fasterthanmycherokee]

Some very good points here, thank you all. I am leaning towards the higher oil temp as leading reason for lower oil pressure. Spoke with previous owner at length today and he concurred. 
 

Going to take her back up this week and test this theory. Would also explain higher oil use on the round trip too. 
 

I'm a relatively new Mooney pilot, right at 100 hours since purchase, so figuring some things out as I go along. 
 

Grateful for the community here. 

[KSMooniac]

You ought to be running her LOP with that TN setup. You'll run much cooler, cleaner, and on less fuel than that power setting.


Sent from my LM-V405 using Tapatalk

[Fasterthanmycherokee]

15 hours ago, KSMooniac said:

You ought to be running her LOP with that TN setup. You'll run much cooler, cleaner, and on less fuel than that power setting.


Sent from my LM-V405 using Tapatalk
 

Why do you recommend that? My POH specifically identifies running ROP. I know there is a lot of debate over the two, but my POH and A/P I/A both recommend ROP. I'm not as concerned with the fuel burn as I am engine health and life, so curious to hear about your take on it. 

[A64Pilot]

Many will argue, but you won’t hurt one if your rich enough. You can hurt one if you don’t understand leaning and don’t lean aggressively enough, not every engine right out of the box will run smoothly LOP.

‘If your after speed, my advice is run it IAW Lycoming’s instructions and leave the LOP stuff for those that don’t mind sacrificing some speed for a pretty big decrease in fuel consumption.

Just from your screen name I’m guessing your primarily after speed, as well as of course your numbers on your engine monitors.

[carusoam]

12 hours ago, Fasterthanmycherokee said:

Why do you recommend that? My POH specifically identifies running ROP. I know there is a lot of debate over the two, but my POH and A/P I/A both recommend ROP. I'm not as concerned with the fuel burn as I am engine health and life, so curious to hear about your take on it. 

What does your POH say about running 27.5” at 12.5k’?

I think you may be making some assumptions that may not hold true… over a wide variety of altitudes…

Including how well engine and oil cooling work with additional altitude…

Turbo Mooneys use a vented oil pressure gauge…. See if yours is vented.  For convenience, there are pics of how an oilP gauge was poorly installed and got its vent hole covered… probably in the Bravo section…

hot oil changes its viscosity and gets very thin with higher temps… much lower pressure results…

See if your oil cooler is working 100%…

See if your oil selection matches what you need… you might want a different oil…

 

Great question….  How else can you avoid a mistake but to ask..?

+1 on flaming dragon mode operations… some people run their Mooneys this way knowing there are additional maintenance costs to fly so fast…

Some people find out later how expensive this can be…

FF number is in the ball park of my Ovation cruising LOP, at 160 KTs…

One thing to seriously verify… the location of the oil T & P sensors… are they in the right location as the original ship’s gauges?

PP thoughts only, not a mechanic…

Best regards,

-a-

[Shadrach]

On 6/20/2021 at 11:21 AM, Fasterthanmycherokee said:

Why do you recommend that? My POH specifically identifies running ROP. I know there is a lot of debate over the two, but my POH and A/P I/A both recommend ROP. I'm not as concerned with the fuel burn as I am engine health and life, so curious to hear about your take on it. 

There are good reasons to run ROP, there are good reasons to run LOP. With a turbo, one is able to operate at high power settings on the lean side of peak EGT and can reap the benefits of high power  while burning less gas, with cooler CHT and Oil temps. 

Does your POH list the power setting that you are using?  The POH for my NA F does not list a setting that the engine can be leaned at 27.5inHg because it's over 75% power.

There really is very little debate over LOP settings being a viable and safe option on the spectrum of available mixture settings.  The science has been well understood for quite sometime.  There are plenty of pilots (of all experience levels) that do not understand combustion much beyond "Suck, Squeeze, Bang, Blow".  Some are not interested nor are they comfortable operating outside of what the POH says.  I think that is a reasonable position.  However, it is a fact that at equal power settings, running ROP leaves some economy and cooler running cylinders on the table.  It is only considered debatable or controversial by folks who don't know what they don't know.

Edited June 22, 2021 by Shadrach

[N201MKTurbo]

On 6/20/2021 at 8:21 AM, Fasterthanmycherokee said:

Why do you recommend that? My POH specifically identifies running ROP. I know there is a lot of debate over the two, but my POH and A/P I/A both recommend ROP. I'm not as concerned with the fuel burn as I am engine health and life, so curious to hear about your take on it. 

First off Mr. Sandman advocated running at full power at peak TIT. That's about as bad as it gets. There are no power settings in the updated POH for the turbo installation. It just says to use the sea level power charts. I don't believe them for a second.

I also wonder why everybody thinks an A&P knows so much about running these engines? They aren't taught much about it in A&P school. There aren't many questions about it in the tests. Pilots on the other hand spend countless hours running these things and watching what happens under different conditions. All A&Ps are taught is how to take them apart and put them back together again.

Edited June 21, 2021 by N201MKTurbo

[A64Pilot]

Who is Mr sandman? Who recommended peak at full power?

Quick question for those that abdicate high power LOP. How lean are you on takeoff?

If your going to run the thing at or above 75% power, turbo or not, your safer if you run it rich, it’s why I hope all of us take off with everything full forward.

I am not against LOP, I can run deep LOP 22 squared and 130 kts on 7 GPH, To go 160 kts down low on my J doubles the fuel consumption and I can assure you reduces its life too, so I don’t, but some choose to. I’m just not in as big a hurry as I used to be, and I haven’t a schedule anymore. 130 kts to me isn’t bad, others couldn’t stand it, but speed is relative. I lived and cruised on a sailboat for three years, 7 kts was fast then.

‘LOP is another tool in the box, but it’s not the best for fangs out, hair on fire speed

[N201MKTurbo]

Mr. Sandman designed and was the STC holder for the M20Turbos turbo normalizer system for the 201. The one we are talking about.

I spoke with him a number of times before he died. He told me that he always runs the engine at peak TIT.

Edited June 21, 2021 by N201MKTurbo

[N201MKTurbo]

In May of 1998, the FAA issued to M-20 Turbos a new STC for an improved turbo normalizing kit for all 200HP Mooneys (IO-360). The developer and owner of M-20 Turbos, Bill Sandman utilized his M20J for the research, development, and certification of this kit. The kit uses a standard Rajay turbocharger located under the engine near the firewall. A fixed cowl flap is installed at the turbo location. This provides airflow through the engine compartment from over the cylinders down past the turbo, exiting at the bottom rear. Unlike the original Rajay turbo kit, M-20 Turbos provides an intercooler and new engine baffling. The baffling enables the engine to operate in the flight levels without overheating. The intercooler allows for efficient engine operation by lowering the compressor discharge temperature. Unlike the Rajay system, M-20 Turbos utilizes a fixed exhaust wastegate. By operating the throttle (not adjusting a vernier control) the pilot controls MP up to 30” Hg. maximum. Close attention must be paid as the engine can be over-boosted at lower altitudes. An intake system overboost valve will limit MP to 32.5” Hg.

M-20 Turbos did extensive flight-testing using computerized monitoring of engine parameters. Under extreme conditions of high altitude and power settings, turbine inlet and compressor discharge temperature, cylinder head, and oil temperature and predetonation conditions were measured to determine critical altitude as 20,000 feet and the service ceiling of 22,000 feet. This testing proved the engine would run cool enough to allow the mixture to be set to only 25°C rich of peak TIT at cruise power settings. The prototype currently has over 1000 hours of flight with no unusual problems.

 

https://www.knr-inc.com/shoptalk-articles/25-shoptalk/90-200005-after-market-turbocharging-considerations

 

[A64Pilot]

15 minutes ago, N201MKTurbo said:

 

M-20 Turbos did extensive flight-testing using computerized monitoring of engine parameters. Under extreme conditions of high altitude and power settings, turbine inlet and compressor discharge temperature, cylinder head, and oil temperature and predetonation conditions were measured to determine critical altitude as 20,000 feet and the service ceiling of 22,000 feet. This testing proved the engine would run cool enough to allow the mixture to be set to only 25°C rich of peak TIT at cruise power settings. 

 

I can buy this statement as being perfectly logical and good, assuming it gives a temp that is within the turbines limits, if not then of course you need to enrichen until below TIT  limits.

Issue is cruise power settings isn’t defined, I’d have to dig, but I believe in many engines Lycoming defines cruise as being at or less than 75% and then throws in a statement that if run at 65% or less, the engine will last longer, but it’s been a long time since I did that reading.

‘So if we are talking about 75% power or less, then I’d say 25c ROP is a acceptable mixture, there are other acceptable mixtures below 75% too of course

‘However as I don’t have any kind of chart for this TN STC, but as it’s a TN setup it’s should still be a 200 HP engine, and if so then 27.5 MP and 2440 RPM is well North of 75%, my SWAG is it’s above 85%, which puts us in the takeoff / climb regime, and when there I think you should operate way rich.

Making that much power continuously you would expect to see high oil temps, and apparently he is, the thinner air at altitude doesn’t help, but that ought to be offset by airspeed, because oil cooler ought to be sized to allow a full power climb on a NA engine, 200 isn’t real high and if you call the oil company and ask they will laugh as 200 isn’t anywhere even close to the oils limit, when you hit 220 on a Lycoming the concern isn’t that your cooking the oil, it’s that your overheating the engine.

I believe he needs to slow down and enjoy life, and if he wants speed, altitude is the way to get it with a blown motor, 75% power at 180 or 200 is I bet faster than WFO at 12,000