Definitive guide for managing turbo M20K with automatic wastegate?

[oisiaa]

Can anyone point me toward a resource on how to properly manage a TSIO-360 with an automatic wastegate? I'm specifically looking for how to lean the engine in all phases of flight.

I don't currently own an aircraft, just trying to build some engine management knowledge before I commit to buying.

My assumption is that if you are doing a full power climb, the automatic wastegate will maintain manifold pressure (40"?) up to the critical altitude. During the climb, I'd guess you run full rich to deal with the high manifold pressure. In cruise, manifold pressure could still be higher than sea level (right?) so can you lean?

Thanks for any / all advice. 

[Crawfish]

I’m not sure you realize you’re about to start a war in the comments. 
 

While this is not for the M20K specifically I think it’s better to understand why you’re doing things and this will definitely help you in that regard. 

turbocharged engines really make leaning simple. (I believe the MB is limited to 36” MP) 

 

[Pinecone]

https://www.advancedpilot.com/#:~:text="The APS classes are state,economical and just plain easier."

APS Seminar.  The ultimate learning on leaning any engine.

I climb with everything full forward.  Level off, accelerate, then pull back the power to the desired manifold pressure, then set RPM, then do a BMP (Big Mixture Pull) to 10.1 GPH (63% power), trim the manifold pressure and done.

[oisiaa]

Thanks for the quick replies. I'm an Air Force trained pilot so I've spent 99.5% of my time behind a turbine (and will continue to do so with a turbocharger......) so I have very limited knowledge and experience with managing a piston engine. 

[Fly Boomer]

1 hour ago, oisiaa said:

During the climb, I'd guess you run full rich to deal with the high manifold pressure

Not sure what you mean by "deal with the high manifold pressure", but the reason to run full rich is to manage temperatures.  Heat is the thing that can keep you away from getting full power out of your engine.  Failing to control temperatures by any means at your disposal will, at best, require one or more top overhauls before TBO.

Also, be aware that @Pinecone with an Encore conversion is probably flying behind a TSIO-360-SB.  When you mention a manifold pressure of 40 inches, it suggests that you are looking at a 231 which probably has either a TSIO-360-GB or TSIO-360-LB, and those engines need to be managed slightly differently.  There are quite a few 231 people around here that can provide more details.

[Johnny_SA]

1 hour ago, Fly Boomer said:

Also, be aware that @Pinecone with an Encore conversion is probably flying behind a TSIO-360-SB.  When you mention a manifold pressure of 40 inches, it suggests that you are looking at a 231 which probably has either a TSIO-360-GB or TSIO-360-LB, and those engines need to be managed slightly differently.  There are quite a few 231 people around here that can provide more details.

Yip, the 231 automatic waste gate (merlin in my case) is not so automatic.

Take-off - you have to manually stop it with the throttle to not exceed 40 inches and to prevent over boast. So not full forward.

Once you high enough hight, then 33 inches, 2600rpm,  full rich,  cowl flaps open for the climb.  You have to adjust the MP as you climb, little movements, I find tighning the throttle friction nut and pushing/puling against it help.

 

 

Edited October 15, 2023 by Johnny_SA

[oisiaa]

Yes, I'm looking at a 231 with a Merlin wastegate. Are there any STC systems that allow for wide open throttle all the way to cruise? Maybe I should look at something other than a 231 with a Merlin?

I'm currently flying a King Air 200 (for work) so I'm used to not setting the power levers all the way to the stops for takeoff and then constantly bumping power in the climb, but was hoping for something with a bit less management.

I really appreciate the help here as a new member of the forum. 

Edited October 15, 2023 by oisiaa

[Aerodon]

Yes, Mooney 252.

[Danb]

Or Bravo or Acclaim 

[natdm]

There’s a ton of knowledge on this forum about the 231. I have one and while a 252 is better, a 231 with intercooler and wastegate is supposed to come close, except controlling the throttle. 
 

IMO there’s a lot more that the 252 seemed to improve on other than the turbo that makes it worth it. But I love my 231 and am not sure how much more I’d spend to get to a 252. 

[hubcap]

2 hours ago, oisiaa said:

Yes, I'm looking at a 231 with a Merlin wastegate. Are there any STC systems that allow for wide open throttle all the way to cruise? Maybe I should look at something other than a 231 with a Merlin?

I'm currently flying a King Air 200 (for work) so I'm used to not setting the power levers all the way to the stops for takeoff and then constantly bumping power in the climb, but was hoping for something with a bit less management.

I really appreciate the help here as a new member of the forum. 

 Negative. You cannot wide open throttle a 231 all the way to cruise. With cowl flaps open and full rich, gradually apply throttle on takeoff until the turbo kicks in and then set to 36”. After getting above 1000’ AGL pull back to 33” and 2600 RPM until you level off. You will need to occasionally increase the MP in the climb. After leveling off you can set your cruise MP and lean as you see fit. I run lean of peak 100% of the time in cruise. You will need to occasionally reduce MP during your descent.
 

The amount of management required is not significant, even when operating in a busy IMC environment.

[231LV]

As a 20 plus year 231 owner/operator, I can say everything previous posters have said is correct. A 252 lets you set it and forget it as they say but the 231 requires a bit of "finesse" on the throttle. The Merlyn is a great wastegate but it will allow you to easily over boost the engine if you are too aggressive on the throttle. I like to use a whip analogy to describe the way a Merlyn works. Think of the difference in distance traveled between the handle(throttle) of the whip and the tip(engine boost). That is how the Merlyn reacts to throttle input. Hence, I added a vernier throttle which makes fine tuning the engine much, much easier. An intercooled turbocharged engine requires different MP settings...so you will not be able to get 40 inches without risking a head separation. Most 231 drivers will admit(under duress) a 252 is a better engine/airframe combo but you pay for that and the 231 gets you pretty close to the 252 on a significantly reduced budget.

[PeteMc]

7 hours ago, Pinecone said:

I climb with everything full forward. 

With the Encore you can take off from basically sea level with everything full in?  Not something you can do with the 231 even with the Merlyn.

 

[PeteMc]

1 hour ago, 231LV said:

so you will not be able to get 40 inches without risking a head separation.

From various mechanics, various Mooney groups and attending multiple PPPs, I've never heard anyone say you can't use 40" on takeoff or in climb in a 231 (vs 252).  I've been doing it for decades and have never had a head separation. 

Do you have a few sources or is it an old wives tale you're hanging on to??? 

 

Edited October 15, 2023 by PeteMc

[Fly Boomer]

7 minutes ago, PeteMc said:

With the Encore you can take off from basically sea level with everything full in?  Not something you can do with the 231 even with the Merlyn.

 

You can treat the 252 the same.  All in all the way up.

[PeteMc]

7 hours ago, oisiaa said:

Can anyone point me toward a resource on how to properly manage a TSIO-360 with an automatic wastegate?

If you only have the Merlyn Wastegate and not the intercooler, then you just lean per the manual and temps for ROP.  If you're going to go LOP, then it's mostly with temps and a feel for the engine.  As temps vary during the year I'll have various luck with my engine for LOP if I want to keep any power.  No issues if I'm just cruising.  

I'll agree with most of the comments that you need to be light handed with the throttle, but MUCH less than if you had the Fixed Wastegate (that was a pain).  But after a few flights you'll know how much to crank (or push) the throttle to get enough power to spin up the turbo without overboosting.  Then it's just a quick glace over to bring your power up to 39/40".  A little more attentions obviously needs to go into the power on a shorter field to make sur ethe power is good when you release the brakes. 

In the climb, pending how high you're going, you will need to watch the MP and add a little every so often.  Even more so in the descent!  As you come down the pressure will build faster than a normally aspirated engine.  So you need to keep an eye on it if you were up in the high teens or even FLs and you come all the way down.  The speed increasing will be a good clue. 

Big advantage of the Merlyn is you still have some throttle left and additional power as you keep climbing above 15K.  That's where with the Fixed Wastegate (pending air temps) the engine would start to preform like a normally aspirated engine. 

 

 

Edited October 15, 2023 by PeteMc

[kortopates]

From various mechanics, various Mooney groups and attending multiple PPPs, I've never heard anyone say you can't use 40" on takeoff or in climb in a 231 (vs 252).  I've been doing it for decades and have never had a head separation. 
Do you have a few sources or is it an old wives tale you're hanging on to??? 
 

I think you just misunderstood his statement since he was referring to an intercooled 231 - which reduces your redline MAP from 40” to 38” or a little less (when based on degrees of cooling) depending on which intercooler vendor or product. Using 40” on and intercooled 231 would be over boosting the engine since the cooled air is much denser. The documentation is in the STC. But i assume you’re aware and just missed the intercooled part.

To the OP, there is no such thing as an “automatic” waste gate on the 231. It’s either “fixed” (bolt) or “manual” with the Merlyn pneumatic waste gate.

Only hydraulically controlled waste gates are “automatic” using an additional turbo controller, which are used in the 252 and Encore. The latter two are identical except that the Encore has been boosted up an additional 10 HP and allow an additional 230 lbs to be added to the maximum gross takeoff weight. They are among the most efficient and most sought after Mooney’s.
A 252 can be converted to an Encore but not a 231.

The 231 was introduced as the poor man’s turbo since it was much cheaper than a full turbo with wastegate and controller (they used a bolt for a waste gate). Most 231’s though have STC’s to add the manual pneumatic waste gate and an intercooler which very significantly improves their high altitude performance. But they are by no means as easy to operate as the full turbo 252/encores with automatic waste gates. All 252/Encores also came standard with 28V electrical systems, speed brakes, standby vacuum, built in oxygen and most with dual alternators.

[T. Peterson]

2 hours ago, PeteMc said:

From various mechanics, various Mooney groups and attending multiple PPPs, I've never heard anyone say you can't use 40" on takeoff or in climb in a 231 (vs 252).  I've been doing it for decades and have never had a head separation. 

Do you have a few sources or is it an old wives tale you're hanging on to??? 

 

I am wondering the same thing. From whence cometh the 33 MP in climb? If all my temps are good I climb at least 36 and sometimes 38. I have the Merlyn, but no intercooler. I hope I am not being a Dumkopf!! (Yes, I do realize I just left myself wide open!!)

I have seen nothing in my manuals limiting climb MP to 33.

[T. Peterson]

3 minutes ago, kortopates said:

I think you just misunderstood his statement since he was referring to an intercooled 231 - which reduces your redline MAP from 40” to 38” or a little less (when based on degrees of cooling) depending on which intercooler vendor or product. Using 40” on and intercooled 231 would be over boosting the engine since the cooled air is much denser. The documentation is in the STC. But i assume you’re aware and just missed the intercooled part.

To the OP, there is no such thing as an “automatic” waste gate on the 231. It’s either “fixed” (bolt) or “manual” with the Merlyn pneumatic waste gate.

Only hydraulically controlled waste gates are “automatic” using an additional turbo controller, which are used in the 252 and Encore. The latter two are identical except that the Encore has been boosted up an additional 10 HP and allow an additional 230 lbs to added to the maximum gross takeoff weight. They are among the most efficient and most sought after Mooney’s.
A 252 can be converted to an Encore but not a 231.

The 231 was introduced as the poor man’s turbo since it was much cheaper than a full turbo with wastegate and controller (they used a bolt for a waste gate). Most 231’s though have STC’s to add the manual pneumatic waste gate and an intercooler which very significantly improves their high altitude performance. But they are by no means as easy to operate as the full turbo 252/encores with automatic waste gates. All 252/Encores also came standard with 28V electrical systems, speed brakes, standby vacuum, built in oxygen and most with dual alternators.

Well said! My question is answered as I don’t have the intercooler. Thank you!

[kortopates]

Well said! My question is answered as I don’t have the intercooler. Thank you!

Thanks.
You’re actually better off climbing at full redline as long as your fuel flow is set up correctly - many are too lean. Doing so, and climbing at Vy + 10-20 kts will keep the engine cooler than pulling back a couple inches. Just note the TIT at redline versus 38”. The TIT at 38” will be higher because FF isn’t linear at the upper range.


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[T. Peterson]

36 minutes ago, kortopates said:

Thanks.
You’re actually better off climbing at full redline as long as your fuel flow is set up correctly - many are too lean. Doing so, and climbing at Vy + 10-20 kts will keep the engine cooler than pulling back a couple inches. Just note the TIT at redline versus 38”. The TIT at 38” will be higher because FF isn’t linear at the upper range.


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Just to make sure that I understand. By redline, you mean 40”. As long as tit/head temps are well within limits I may climb at 40”? Also, climbing at 115 kts +or- a couple will enhance both cooling and performance. 
I generally climb at 115 to 120, and 35-36”. My next flight I will cautiously try 40” and carefully monitor all other parameters including oil temperature. So far my climb rate has been about 500fpm. Hopefully the new technique will bolster that a bit. Thank you!

[PeteMc]

1 hour ago, kortopates said:

he was referring to an intercooled 231

I did totally miss that.  Thanks for the catch!

 

[Jetpilot86]

I quit looking at 231's because I did not wish to deal with, excuse me, learn the nuances of managing the 231's turbo setup.  I'm an airline pilot, and prefer as much "set and forget" as my wallet allows for.

More than likely, I've gone from the frying pan to the fire, as I skipped the 252's and went straight for a TLS-Bravo, which has it's own set of quirks to deal with.

I hope to be back on here in a month or so vacuuming up all the Bravo tips I can find....

 

Good Luck!

[kortopates]

Just to make sure that I understand. By redline, you mean 40”. As long as tit/head temps are well within limits I may climb at 40”? Also, climbing at 115 kts +or- a couple will enhance both cooling and performance. 
I generally climb at 115 to 120, and 35-36”. My next flight I will cautiously try 40” and carefully monitor all other parameters including oil temperature. So far my climb rate has been about 500fpm. Hopefully the new technique will bolster that a bit. Thank you!

Yes, but TIT needs to be below 1400f full rich (preferably lower) else the max FF isn’t high enough.


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[oisiaa]

Fascinating information here. While I was hoping for a "full forward on everything" airplane, I still think a 231 is my best bet from a cost/performance standpoint. I'm no stranger to complex aircraft so I think I'll be able to manage. I'm honestly the type of person who likes managing systems so I'll probably be happy as long as I learn how to not damage anything.