M 20 K turbo plus and Merlyn

[Arthur]

My previous M20K was  turbo cooled had a 2 bladed prop and it leapt off the ground on take off. I would advance the throttle slowly, feel the turbo kick in and adjust the MP to the proper setting.

I now have an M 20 K with a turbo plus intercooler and a Merlyn Waste gate and a three bladed composite prop. I have not been able to find the groove on this one. The waste gate must be working just at the time I am trying to set the MP and I find myself hunting for the proper position on the throttle. Any suggestions would be appreciated.

[carusoam]

Saturday and crickets...?

Everyone must be out flying... 

Best regards,

-a-

[Rumblestrip]

Can’t speak exactly to this, however, in a turbo race car the wastegate is there to limit overboost. Put it to the floor and you don’t have to worry about boost surge or overboost from whatever amount of boost you’ve decided upon. 

 

My my understanding with wastegate in the Mooney K’s was that you could go full throttle without the worry of managing  the throttle to control manifold pressure. The wastegate would limit you to 36,38,40,41 inches (I don’t know what the correct number is).  

Others with better knowledge can correct me.

[N201MKTurbo]

The Merlyn waste gate should maintain a constant upper deck pressure. This is the pressure ahead of the throttle plate.

If the manifold pressure is unstable, l would remove the waste gate and make sure it is not carbon fouled. You can also blow through the hoses and make sure they are not plugged. You can suck on the ports or use a hand vacuum pump to make sure the plunger moves and the diaphragm isn’t torn.

[Arthur]

I appreciate the answers, but is there anyone out there that flies a Mooney K with both a Merlyn and a turbo plus intercooler? Will the Merlyn prevent an overboost that would be casused by greater MP than called for with the intercooler.

[carusoam]

Arthur... by definition of a pressure controller... your doesn’t seem to be working properly... what would be the point of finding the groove... you paid money to set and forget... ?

See if Jeff Shapiro @Jeff Shapirocan add any light to this discussion...   

also know there are threads regarding cleaning bits and pieces related to the pressure controller...half of it lives in the cruddiest of environments... have you washed anything lately?

Best regards,

-a-

[kortopates]

I appreciate the answers, but is there anyone out there that flies a Mooney K with both a Merlyn and a turbo plus intercooler? Will the Merlyn prevent an overboost that would be casused by greater MP than called for with the intercooler.

No, it's still 100% manual, now with the Merlyn it's an adjustable Wastegate rather than fixed wastegate which significantly raises the critical altitude giving you much better performance at altitude. But automatic it's not. For that you need the -MB or -SB engine with a hydraulic wastgate controller.

 

 

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[carusoam]

Siri made this a political discussion... Watergate in place of Waste gate...

Nixon’s hotel challenge vs. the thing that adjusts turbo pressure... 

oops...

 

So.... the Merlyn is a manual pressure controller... not an automatic pressure controller... where the original, fixed, waste gate... wasn’t adjustable at all....

Now... time to find the procedure for how to set the turbo for the T/O... to allow margin for the bootstrapping to occur..?

NA PP thoughts only, not a turbo pilot...

-a-

[kortopates]

Siri made this a political discussion... Watergate in place of Waste gate...
Nixon’s hotel challenge vs. the thing that adjusts turbo pressure... 
oops...
 
So.... the Merlyn is a manual pressure controller... not an automatic pressure controller... where the original, fixed, waste gate... wasn’t adjustable at all....
Now... time to find the procedure for how to set the turbo for the T/O... to allow margin for the bootstrapping to occur..?
NA PP thoughts only, not a turbo pilot...
-a-

Thanks Anthony, I edited it to correct that.
The throttle is advanced slowly just like it was before the Merlyn, it doesn't change anything there. Still just as easy to overboost.


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[81X]

56 minutes ago, Arthur said:

I appreciate the answers, but is there anyone out there that flies a Mooney K with both a Merlyn and a turbo plus intercooler? Will the Merlyn prevent an overboost that would be casused by greater MP than called for with the intercooler.

I have an 85 K 231 with the Merlyn and Airflow systems intercooler; for this discussion, its the same setup.

No, the Merlyn will not prevent an over boost, it’s not an absolute pressure controller. The pop off valve is the only thing that prevents a severe overboost which opens at about 42”.  The merlyn is basically there to reduce/eliminate bootstrapping/surging and increase the critical altitude of the turbo.  

Small movements of the throttle can go a long way in MP changes and yes, you have to mess with the throttle on the takeoff roll. If not a maximum performance takeoff, usually advance to 32”and then just put in a little more throttle to get to 36 after about 30kt. 

[mooneyspeed]

depends on the throw of your throttle but 2/3 of the way in is a pretty good start.    Put your index finger at that point and slowly increase until your finger tip is touching the stop.  Your turbo should come in about that point.  As you accelerate you will need to fine tune the last portion but that should be a pretty good starting point.

 

Like mentioned above the merlyn will not give you overboost protection.

Edited July 8, 2019 by mooneyspeed

[carusoam]

Now that gets you off the ground in fine fettle...

Next up... operating at altitude... LOP.   There are a couple of threads around here for that... specifically for M20Ks... 

Best regards,

-a-

[Arthur]

Thanks for all your help. I also found an interesting more complex discussion on this site from 2017

[DanM20C]

On 7/7/2019 at 3:47 PM, 81X said:

No, the Merlyn will not prevent an over boost, it’s not an absolute pressure controller.

Just like tailwheel pilots look down on everyone else, we 231 pilots can look down on all the other turbo Mooney pilots.  "A real pilot doesn't need an absolute pressure controller"

I find that throttle/MP response is actually a touch easier with the fixed wastgate.  Merlyn doen't list "easier engine operation" as a benefit in their literature. But most of the listed claims are true, less work for the turbo down low and a 4-5K foot increase in critical alt is worth it.

Cheers,

Dan

[kortopates]

16 minutes ago, DanM20C said:

Just like tailwheel pilots look down on everyone else, we 231 pilots can look down on all the other turbo Mooney pilots.  "A real pilot doesn't need an absolute pressure controller" 

Blasmephy!!! 

You really do need to get a ride in a "real" turbo engine someday just to see what your missing out on. Careful though, it could lead to yet another Mooney upgrade.

[DanM20C]

2 minutes ago, kortopates said:

Blasmephy!!! 

You really do need to get a ride in a "real" turbo engine someday just to see what your missing out on. Careful though, it could lead to yet another Mooney upgrade.

I'm well aware!  It's a way that I cope.  I like flying airplanes.  With the 231 I have to fly the engine.

Cheers,

Dan

[M20F]

10 minutes ago, DanM20C said:

I'm well aware!  It's a way that I cope.  I like flying airplanes.  With the 231 I have to fly the engine.

Cheers,

Dan

Try a Rayjay 

[DanM20C]

33 minutes ago, M20F said:

Try a Rayjay 

Technically the 231 is a Rajay. 

I know what you mean though, manual wastegate.  The aftermarket Rajay is the only Turbo Mooney I haven't flown.  I have always wanted to though.

Cheers,

Dan

[M20F]

1 hour ago, DanM20C said:

Technically the 231 is a Rajay. 

I know what you mean though, manual wastegate.  The aftermarket Rajay is the only Turbo Mooney I haven't flown.  I have always wanted to though.

Cheers,

Dan

Move all 4 levers and still not get what you want.  It is a magical experience at times. 

[81X]

On 7/8/2019 at 5:39 PM, kortopates said:

Blasmephy!!! 

You really do need to get a ride in a "real" turbo engine someday just to see what your missing out on. Careful though, it could lead to yet another Mooney upgrade.

I don’t know, a 50k premium is a lot to pay to shove the throttle all the way in over an inter cooled merlyn’d 231!!!

 

(yes I know there’s more to it but it’s sometimes fun to poke the bear)

[kortopates]

On 7/9/2019 at 6:09 PM, 81X said:

I don’t know, a 50k premium is a lot to pay to shove the throttle all the way in over an inter cooled merlyn’d 231!!!

 

(yes I know there’s more to it but it’s sometimes fun to poke the bear)

ha! ha! But no its not a lot to pay for a real turbo. You probably don't realize, but an intercooled 231 was my first Mooney, shortly after getting it I wished I had kept waiting for a good 252 to show on the market with dual alternator 28V, and all the built-in equip.  I am not surprised about what they are saying over in another thread about 252/Encores selling for more than Bravo's. If I upgrade again, it would be for an Acclaim, but the 252/Encore is at the height of Mooney efficiency for me. The follow on Bravo and Acclaim were all about maintaining the fastest production piston single record.  

Edited July 11, 2019 by kortopates

[81X]

14 hours ago, kortopates said:

ha! ha! But no its not a lot to pay for a real turbo. You probably don't realize, but an intercooled 231 was my first Mooney, shortly after getting it I wished I had kept waiting for a good 252 to show on the market with dual alternator 28V, and all the built-in equip.  I am not surprised about what they are saying over in another thread about 252/Encores selling for more than Bravo's. If I upgrade again, it would be for an Acclaim, but the 252/Encore is at the height of Mooney efficiency for me. The follow on Bravo and Acclaim were all about maintaining the fastest production piston single record.  

I hear ya. If I ever upgraded, the ideal Mooney for me would be a TKS equipped factory Encore- the unicorn of Mooneys.  

My 231 came with mostly top shelf equipment, and now with the GFC500 in it, it’s pretty trick.  Dual alternators would make me much happier Regardless of voltage.