Turbo Charger Cool Down

[Marcopolo]

GSXR,

 

  Ok, then I miss-understood, but are there any specifics around how the extended idling "hurts" the turbo?  I'm not asking you to teach the course, and I do plan on attending one soon, but for all of the claims and counter-claims that get referenced here on MS from these courses I still have trouble grasping some things.  Now that thought alone should drive me to attend sooner rather than later, I know.  

  Now, I am really not trying to start an argument with you, trust me, I have much respect for just about everyone on here, but If you say to listen to APS or GAMI over Hartzell or Mike Bush isn't that based on your opinion of who and how the data is presented?  again, its a questions not meant to offend(I'll buy the beer). I just think that we all have information to offer and my "thoughts" are stated as such so people can counter with theirs and so its not taken as gospel.

 

Regards,

Ron

[jackn]

fwiw, I'm an engineer, or was until I retired. 

[donkaye]

1 hour ago, Marcopolo said:

GSXR,

 

  Ok, then I miss-understood, but are there any specifics around how the extended idling "hurts" the turbo?  I'm not asking you to teach the course, and I do plan on attending one soon, but for all of the claims and counter-claims that get referenced here on MS from these courses I still have trouble grasping some things.  Now that thought alone should drive me to attend sooner rather than later, I know.  

  Now, I am really not trying to start an argument with you, trust me, I have much respect for just about everyone on here, but If you say to listen to APS or GAMI over Hartzell or Mike Bush isn't that based on your opinion of who and how the data is presented?  again, its a questions not meant to offend(I'll buy the beer). I just think that we all have information to offer and my "thoughts" are stated as such so people can counter with theirs and so its not taken as gospel.

 

Regards,

Ron

This whole discussion is meaningless (in my opinion).  My plane has over 3700 hours on it and I'm past the halfway point on the second engine.  I did the 5 minute cool down on the first engine before I took the APS course, and no cool down after.  Both engines needed the turbo and waste gate overhauled half way through TBO.  No other turbocharger problems.  Figure an overhaul once per engine TBO for a couple of thousand dollars.  End of story.

[carqwik]

Can anyone supply APS turbo bearing temperature data?  Uh...all I hear is crickets...  So let's look at Cummins data:

Seems to me this contradicts whatever APS says...  A turbocharger works the same way whether it's in an airplane, boat, or automobile.  But since there's no watercooling available in a turbo Mooney, looks like the data strongly suggests there is value to a cool down period at idle.

[ArtVandelay]

The problem with the cummings data is that they may have been redlining the engine starting at time 0, if you take 3 minutes taxiing you end up at the same spot 

[DonMuncy]

1 hour ago, carqwik said:

Can anyone supply APS turbo bearing temperature data?  Uh...all I hear is crickets...  So let's look at Cummins data:

Seems to me this contradicts whatever APS says...  A turbocharger works the same way whether it's in an airplane, boat, or automobile.  But since there's no watercooling available in a turbo Mooney, looks like the data strongly suggests there is value to a cool down period at idle.

Sure, this is likely true. So if you get on the ground at full throttle, you ought to let it cool down. What they are missing is that we start retarding the throttle during or at the start of descent, and by the time we touch down, it has already cooled as far as it is going to, and taxiing around with decreased air flow actually heats it back up. At least this is what APS actual data shows.

[Guest]

All this trouble with turbos makes me glad I have an IO720, Piper was right after all.

Clarence

[ArtVandelay]

9 minutes ago, M20Doc said:

All this trouble with turbos makes me glad I have an IO720, Piper was right after all.

Clarence

Does no one use superchargers?

[jlunseth]

1 hour ago, teejayevans said:

Does no one use superchargers?

Well, first of all let's get the semantics straight.  "Supercharger" once was the generic term for boosting, and the "TS" in "TSIO" stands for turbosupercharger, which is a boost device driven by a turbine in the exhaust stream.  Nowadays the term "supercharger" is generally understood as being a mechanically driven boost device, i.e. driven by belt, chain or gears from the engine.  And the short answer is that the supercharger is better suited to acceleration than cruise.  The turbo charger has turbo lag, so there will be an amount of time before the engine spins up and generates exhaust to drive the turbine.  We don't care about lag in aircraft, and the turbo is more efficient at cruise than the supercharger.  It requires less shaft horsepower to drive the turbo.  Therefore, it is the right solution for aircraft.

Edited December 17, 2016 by jlunseth

[PMcClure]

I always thought he merlins in the p51 were supercharged with mechanical boost? 

[PMcClure]

I always thought he merlins in the p51 were supercharged with mechanical boost? 

[gsxrpilot]

6 hours ago, Marcopolo said:

GSXR,

 

  Ok, then I miss-understood, but are there any specifics around how the extended idling "hurts" the turbo?  I'm not asking you to teach the course, and I do plan on attending one soon, but for all of the claims and counter-claims that get referenced here on MS from these courses I still have trouble grasping some things.  Now that thought alone should drive me to attend sooner rather than later, I know.  

  Now, I am really not trying to start an argument with you, trust me, I have much respect for just about everyone on here, but If you say to listen to APS or GAMI over Hartzell or Mike Bush isn't that based on your opinion of who and how the data is presented?  again, its a questions not meant to offend(I'll buy the beer). I just think that we all have information to offer and my "thoughts" are stated as such so people can counter with theirs and so its not taken as gospel.

 

Regards,

Ron

Ron, 

Likewise sorry if I'm coming across rude or too strong. I don't mean to offend either.  You'll really like the APS course. I only wish I'd taken it sooner. And I'll likely go back and audit the course a second time. There is so much information, and mountains of data, so that a weekend is hardly enough time to absorb it all. We do have a very thick binder of material that we take away from the course and much of the data is there. I wouldn't want to even try to teach the course anywhere, much less here on this forum. But even if I tried, the books are at home and I'm in Buenos Aries on my way to Antarctica for Christmas.

In the APS course, the instructors directly address the claims of Hartzell and Mike Bush. They mention that Mike Bush has attended their course three times and they are all good friends and respect each other. But Mike doesn't have any data to go on except for maintenance records of planes his company work on and his own experience with his personal twin cessna.  APS on the other hand has built the measuring equipment. They will show it to you. You will spend time in their test cell watching the equipment work. APS doesn't ask anyone to believe them because they know better. They show exactly how they measure, how they test, and what experiments they run. Then they give you all the data so you can see for yourself. It's really an amazing experience.

To finally respond to carqwick (apple keeps wanting to spell check this to carsick). There is APS data on this. Everyone on this board who has spent the money to take their course agrees with this and was convinced by it. The math checks out. But you'll likely have to take the course to get the data for yourself.

Cheers,

Paul 

[carusoam]

After all this discussion...

Do we agree

1) the problem is oil degrading in the turbo?

2) oil degrades with a combination of time and temperature?

3) temperature (heat energy) is supplied by the Ship's collected EGT( three into one), TIT (six into one), Turbine blades are next hottest, turbo body is then a bit cooler, oil channels with flowing oil are the coolest part....

4) the oil temp entering the turbo's oil channels is the engine oilT.

5) the oil temp leaving the turbo is unknown without instrumentation.

6) The average time for the oil to leave the turbo oil channels is dependent on engine rpm and oilP.  Oil viscosity will also effect this number...

7) the hot side of the turbo's body is glowing red.  This indicates 500+°F.  The inside surface of the turbo will be pretty close to the TIT.

8) oils typically break down when left over 375°F (inexact fuzzy memory) for a period of time.

9) Descending from the flight levels at reduced MP with good air flow is great for cooling.

10) taxiing around is done without a lot of cooling, but it is also done without a lot of heating as well.

11) if the cooling isn't done by the descent, it would have to come from somewhere else...?

12) unfortunately, cooling of this important chunk of metal, oil channels, and bearings is unique to each machine. Even if they are using the exact same oil.  The collective experience is spectacular.  But, the need for the cooling off after landing is both machine and operation dependent.  Flying a group of paratroopers to 12,500', flying a mooney, and stop and go traffic in a turbo diesel are going to be different enough to make the comparison un-usable without the actual data.

13) an oilT thermocouple at the exit of the turbo charger, close to the bearings would tell a lot about what is going on. Measure the oil's temp as it leaves the hottest part of the oil flow's channel.

14) APS is great about doing research.  they don't usually publish it for free distribution.  Much of their published work is done on two Continental engines.  It would be important to know how closely a pair of turbo-normalizers mounted on a TNIO550 (in a lab) represents all the turbocharged Moonies in the fleet when using their data....

15) similarly, oil degrades in the channels of the exhaust valve guides in O360s.  The best way to avoid this problem is to have actual data. CHT on all four cylinders is enough to maintain control over this situation.  Not having any CHT data to review is a problem waiting to befall the lower budgeted pilot.

16) once oil begins to degrade, it is a self catalyzing challenge.  The flow channels start to constrict as carbon begins to deposit itself and block more flow...increasing the residence time, and reducing the streamlined flow, in the hot channel...

17) burnt oil is bad, hot turbos can cook oil, get the turbo cooled during descent (according to APS)...cooling in the descent is better than cooling on the ground.

18) engine oil is used to cool exhaust valves and turbo bearings.  If the oil flow stops while these devices are still hot the oil will degrade...

19) In aviation, we have used calculations to define things we can't often easily measure.  FF, FL, time, gallons, and distance to the airport...  over the years we have added much better instrumentation to avoid less accurate calculations...

20) I would bet...  a well placed (as Defined by APS) thermocouple couple would tell a lot about the effectiveness of our cooling procedure in our machines.

21) by measuring the oil pressure drop from the entrance to the exit of the turbocharger, the pilot could determine the oil flow through there as well...  This is a bit over the top, but somebody mentioned their engineering degree.  Go ChEs!

This is all off the top of my head, after reading the thread once through.  Let me know if I missed something.  I'll be back much later...

Best regards,

-a-

[ArtVandelay]

I thought all Mooney turbos are normalized, so they will be bypassed at lower altitudes (via waste gate) and when taxiing except at high elevations?

[Guest]

8 hours ago, teejayevans said:

Does no one use superchargers?

Yes there are still Lycoming IGSO-480 and IGSO-540 engines in service.

Clarence

[Tony Armour]

3 hours ago, teejayevans said:

I thought all Mooney turbos are normalized, so they will be bypassed at lower altitudes (via waste gate) and when taxiing except at high elevations?

No, Bravos and pretty sure the 231 line are not normalized. I would say the wastegate is not bypassing (other than to limit high boost) at lower altitudes. In taxi there is not enough airflow to spin the turbo to make boost.

The correct answer to cool down is 2.5 minutes, split the difference of all opinions LOL

Everyone gets to vote with their wallet......if it even matters 

[carusoam]

Nice picture of a modern supercharger, Clarence! Looks like a carburetor feeds fuel mixed with air into the SC at the back of the engine. A WnB challenge when mounting the engine further forward to make things fit....

The big difference between the SC and the TC is the gear box driving the SC.  (Seen in Clarence's picture where the alternator and starter motor are mounted)

The big difference between turbo charged and turbo normalized engine is the CR (compression ratio) of the pistons.

there is an optimized power efficiency with the TC'd power plant.

there is an optimized safety level with the TN'd power plant in the event the TN system goes off line due to a plumbing leak or Turbine failure.

Interestingly, the Continental TNIO550 does not share the exact CR as the IO550.

their version of TN'd is using sea level MP up into the flight levels.  Where their TC'd engines use 40" or so...

Losing MP due to a plumbing leak or failed turbocharger will cause the engine to quit because the compression cycle doesn't have the compression needed to support fuel ignition.  A decrease in altitude to a level in which the compression is enough to support ignition may be below a safe flying altitude when in the mountains.

A TN'd engine will have a higher altitude to relight the engine over the TC'd engine...

It would be important to know what altitude is needed to support relighting the engine in the event of a turbo system failure.

This is also another plus for Factory built airplanes over the home built variety.  So many variables in just the plumbing to get right.  Selecting the wrong hose clamp or installing one incorrectly can leave a pilot gliding to lower altitudes....

Best regards,

-a-

[jlunseth]

52 minutes ago, Tony Armour said:

No, Bravos and pretty sure the 231 line are not normalized. I would say the wastegate is not bypassing (other than to limit high boost) at lower altitudes. In taxi there is not enough airflow to spin the turbo to make boost.

The correct answer to cool down is 2.5 minutes, split the difference of all opinions LOL

Everyone gets to vote with their wallet......if it even matters 

Tony is right on the Bravo and the K's.  Takeoff MP with the nonintercooled 231 engine is 40", way above ambient.  The aircraft are fully turbo'd, not TN.  They also have a lower compression ratio than an NA.  The purpose is to avoid detonation, but it is the case that to a certain extent the fully turbo'd engine needs more MP.   At sea level and std. temp., an NA would takoff at 29.92.  I would use 36".  

On supercharger aircraft engines again, its not that an SC  can't be used, because it certainly can, but it is generally used where power and acceleration are desired over fuel efficiency, as in the P51.  The reason is the method of control.  A conventional supercharger is always wasting some work.  It is regulated either by a throttle on the intake side, which means that the SC is doing extra work to draw against a restriction, or by an air (not exhaust) wastegate, which means that the supercharger is doing the work of compressing air that is then wasted.  In cars, SC's are great for getting a dragster off the line, but often a turbo then takes over.  There is some interesting work on a more elegant control solution, see hansen-engine.com.  

On the operation at idle or taxi, in my 231 cyl.2 and sometimes 1 often don't even register a CHT on my JPI until i do a run up because the CHT is below the monitors displayed scale.  I think it wants at least 200 or maybe 220.  They are the last in line in a nontuned induction system and don't get much fuel until boost is added, then they are happy.

[KSMooniac]

I thought all Mooney turbos are normalized, so they will be bypassed at lower altitudes (via waste gate) and when taxiing except at high elevations?

The only Mooney turbo systems like you describe were the aftermarket Rajay systems with the manual wastegate control, which is like a second throttle.

All of the Mooney factory systems are turbo-charged (not normalized) with lower compression pistons. Those are the K, M, and TN models. The Acclaim (TN) is NOT turbo-normalized...Mooney made a bad choice IMO calling it that when in reality it uses lower compression pistons and thus lower efficiency and just limits the horsepower to 280. They should have just purchased a fully optimized firewall-forward package from the folks in Ada, OK and gotten a better solution than the continental version.



Sent from my VS985 4G using Tapatalk

[bradp]

Would seem relatively simple to measure oil at inflow and outflow. If the oil flow is known, and the temp difference is known, then the thermodynamics can be calculated or at least inferred from the whole of the turbo (bearing, shaft, body, gas).


Sent from my iPhone using Tapatalk

[ArtVandelay]

So NA 4 cylinder Lycoming makes 200 HP,

the TCM 6 cylinder with turbo, not normalize, full turbo makes only 210?

 I know it makes HP  at higher altitudes, but I would have expected more.

[carusoam]

TJ,

Check the size of the pistons... The TSIO360 uses six cylinders to have the same volume/displacement as the four cylinder IO360...

When it comes to nominal HP, it is often a theoretical value that can be influenced by several things like some laws...

When it comes to real HP, the TC and TN do a nice job of providing full HP up to their critical altitude. A nice way to improve cruise performance where air resistance is decreased by air density.

With automotive comparisons, smaller engines with boosted MP make similar output to larger displacement NA engines. This gives a power to weight advantage that isn't often used in aviation. The automotive comparison immediately falls into a dead zone... TC'd engines in cars run at RPMs that would require a gear box that isn't practically useable in aviation... too much weight for the needed strength.

An example of using an improved HP:wt in the Mooney world... you can go from a 280hp M20R to a 310hp M20R.  The improved HP to weight ratio gives better T/O and Climb performance.

In some cases an extra pair of cylinders on an NA engine gives the power to weight advantage some pilots are looking for.  Ask Clarence.  He has found two extra pairs of cylinders in his NA Comanche to be his liking...

The downside will be quickly pointed out by José, who will tell you that the more parts you have the higher the likelihood of a problem will be.

Sticking an exhaust valve in a four cylinder engine is terrible while climbing out on three cylinders.  Climbing out with five out of six will be only slightly better...

Fun Stuff they didn't teach us about in our PP lessons...

Best regards,

-a-

 

 

[N201MKTurbo]

36 minutes ago, bradp said:

Would seem relatively simple to measure oil at inflow and outflow. If the oil flow is known, and the temp difference is known, then the thermodynamics can be calculated or at least inferred from the whole of the turbo (bearing, shaft, body, gas).


Sent from my iPhone using Tapatalk

Not quite as simple as it sounds. You could measure the temperature and flow of the oil going into the turbo, but what comes out is a mixture of oil, inlet air and exhaust gas in unknown proportions. The turbos in the 231 and RaJay conversions use a scavenge pump. This is a positive displacement pump that pumps approximately twice the volume of oil going into the turbo. The rest is made up of inlet air and exhaust gas which is pulled past the seals and just vacuum cavitation. The oil leaving the turbo looks a bit foamy. The volume of inlet air and exhaust gas is small, but it is there.

I was just looking around the web and found timers for race cars hooked to an electric oil pump that pumps oil through the turbo for 5 min after engine shutdown. Their problem was drag racers doing a run and immediately shutting down the engine. Going from 150% power to 0% instantly is hard on the turbo. That is not what we do...

[Guest]

2 hours ago, KSMooniac said:

 

The only Mooney turbo systems like you describe were the aftermarket Rajay systems with the manual wastegate control, which is like a second throttle.

All of the Mooney factory systems are turbo-charged (not normalized) with lower compression pistons. Those are the K, M, and TN models. The Acclaim (TN) is NOT turbo-normalized...Mooney made a bad choice IMO calling it that when in reality it uses lower compression pistons and thus lower efficiency and just limits the horsepower to 280. They should have just purchased a fully optimized firewall-forward package from the folks in Ada, OK and gotten a better solution than the continental version.



Sent from my VS985 4G using Tapatalk
 

 

I'm not sure I would rush to install a TATI system.  The ones installed on Cirrus airframes sure have their share of issues.

Clarence

[jlunseth]

3 hours ago, teejayevans said:

So NA 4 cylinder Lycoming makes 200 HP,

the TCM 6 cylinder with turbo, not normalize, full turbo makes only 210?

 I know it makes HP  at higher altitudes, but I would have expected more.

The TCM 6 that makes 210 was installed when Mooney was still thinking about efficiency.  You don't really need more though, the K's are not underpowered.