231 Climbing Manifold Pressure

[jackn]

13 hours ago, Bob said:

 

jackn- I do not have an automatic wastegate.  It is a ground adjustable, fixed bolt wastegate. 

 

My apologies, I thought you had the Merlyn. Now I’m almost certain you’re dealing with a bootstrapping issue. The LBs had a habit of doing this, that’s why many owners put on the Merlyn. You might try opening the wastegate bolt a bit to see if that helps. 

[N231BN]

When I first got my 231 the FF would be Rock solid when running LOP. After getting the pump overhauled I now have to constantly tweak it or it will shoot up just like yours. My mixture knob slowly turns in due to vibration I'm guessing so after a couple minutes it gets a little more fuel and then it's a chain reaction. More fuel creates more MP which in turn creates more fuel and so on until the engine is running at peak.

[jlunseth]

5 hours ago, jackn said:

My apologies, I thought you had the Merlyn. Now I’m almost certain you’re dealing with a bootstrapping issue. The LBs had a habit of doing this, that’s why many owners put on the Merlyn. You might try opening the wastegate bolt a bit to see if that helps. 

If I understand what Bob has been telling us correctly, his Merlyn was removed in order to troubleshoot this issue.  They wanted to eliminate that as a cause.  So the issue occurred with the Merlyn, and now without the Merlyn.  Assuming the Merlyn was working more or less properly, that would have prevented a bootstrap (that is it main purpose).  Same issue with and without the Merlyn suggests that something else, like fuel flow, is the cause.

[Bob]

2 hours ago, jlunseth said:

If I understand what Bob has been telling us correctly, his Merlyn was removed in order to troubleshoot this issue.  They wanted to eliminate that as a cause.  So the issue occurred with the Merlyn, and now without the Merlyn.  Assuming the Merlyn was working more or less properly, that would have prevented a bootstrap (that is it main purpose).  Same issue with and without the Merlyn suggests that something else, like fuel flow, is the cause.

Yes, I removed the Merlyn to remove one variable to troubleshoot the problem.  When the Merlyn was installed, the problem was amplified.  Happened more often and also the MP & FF climbed much faster. FYI the Merlyn that was installed was new, rather than a worn unit in need of service or maintenance.

[Flying Crab]

After 50 years of flying civilian and military, (ATP Airplane, ATP Helicopter, A/P mechanic, Flight Engineer Turbojet) here’s my two cents worth: If you like to troubleshoot problems and spend more money in the long run, fly LOP in airplanes with engines that were not engineered nor designed to operate in that regime. Engineers and test pilots make good money writing POH’s that are the compromise between power, reliability, and longevity. Reinventing the wheel puts money in the aftermarket gizmo makers. Fun costs money, how much do you want to spend?

[carusoam]

Way to go Crab!

1) Early POHs were written in the marketing department at best...  

2) Engine ops sections were blindly copied from the engine manufacturer... even in the 90s...

3) All of the documents preceded GA pilots ability to monitor their engine sufficiently...

4) Having a decent engine monitor and trained in the knowledge of the red box makes a pretty powerful pilot.

5) How Long does it take to write a POH?  One job for one engineer, it may have lasted a whole year... after that, review and update annually... hard to make good money as an engineer writing manuals...

6) The IO550 at least gets LOPs a fair and full data set...

7) +1 for Continental that wrote that section of the Mooney POH!

8) +1 for Gami who made LOP, a scientific phenomenon, into a simple operation... and providing tools to the Lycoming crowd to allow really good LOP in their engines...

9) Amazing how much technology is available to us through the knowledge of MS.

10) Go MS!

Best regards,

-a-

[Bob]

1 hour ago, Flying Crab said:

Engineers and test pilots make good money writing POH’s that are the compromise between power, reliability, and longevity.  Reinventing the wheel puts money in the aftermarket gizmo makers. 

The engineers and test pilots also have provided power settings for running the TSIO-360 at Peak in the POH.  As we all know running at peak is not good!  In the 231, if the engine is run above 55-60% at peak, according to the recommended POH power settings, the CHT temps will go well above 400.  So I would have to say that the 1980 POH recommends running it in a way that reduces longevity.  Remember the POH also suggest running the engine with a maximum CHT of 450.

The POH was influenced by marketing rather than longevity, in my opinion!  Remember 231MPH is 201Kts, breaking the 200 barrier, under ideal conditions.

If I was attempting to "reinvent the wheel", I would think, I may have done that in the first 7 years of ownership of my "K", rather than just after the engine was rebuilt and for the last 2 years.  FYI Continental is teaching to run LOP thru their webinars and OSH seminars.

[Flying Crab]

Hey guys, not trying to change your religion, just an old geezer sharing thoughts. But my 231 (stock as a rock) seems to run nice when the needles In the gauges are right in the middle of the green arc. No “trouble shooting” required in the 300 hr. I’ve flown it the past two years.