M20M LOP Discussion

[DVA]

2 minutes ago, donkaye said:

There's always my landing video in case you don't have it, but then again you're probably being too modest. ;-)

Oh... I have your video! (I’ll do the ad - kids, get it here.) Your site has a wealth of great Mooney info - I’ve been all over it. I am mustering up the energy to do my own site on Owner Maintenance as that’s a passion of mine as you might be able to tell. 

Back to landings - my radio call on final usually goes like this: “Watch out below! You have a green Mooney on final and if I get too close to you, don’t worry, I’ll just bounce out of the way!” (You should have heard what I called out BEFORE I watched your video :-)

[Rick Junkin]

Greetings all, and thanks for the wealth of knowledge you share.

 

Which Tempest fine wire plug are you using? URHB36S and URHB32S are called out on the applicability chart, and I'm ready to order a set.

 

Best regards,

Rick

[Danb]

I'm changing from fine wire champions to tempest 32s, I called an engineer at Tempest to see his recommendation and said the32s unless I am having trouble with getting oil on the plug or have a need for a hotter plug? Now I'm clueless regarding mechanical stuff, reason I called, I ordered the Tempest today, I explained I have the older champs with only 450 hours on them, he explained the cirrus SB to remove the champs and further explained the design flaws in the champs after thought I felt keeping the older champs was to risky and bit the bullet 

[Tony Armour]

28 minutes ago, Danb said:

I'm changing from fine wire champions to tempest 32s, I called an engineer at Tempest to see his recommendation and said the32s unless I am having trouble with getting oil on the plug or have a need for a hotter plug? Now I'm clueless regarding mechanical stuff, reason I called, I ordered the Tempest today, I explained I have the older champs with only 450 hours on them, he explained the cirrus SB to remove the champs and further explained the design flaws in the champs after thought I felt keeping the older champs was to risky and bit the bullet 

http://servicecenters.cirrusdesign.com/techpubs/pdf/SB/SR2XBulletins/SB2X-74-01/SB2X-74-01.pdf

service bulletin 

i have always ran massive s's with great service but needed replacements this year so my IA (and friend) put fine wires in, used that he had, free. Not sure of the manufacture though. Might have come out of a Cirrus LOL

[DVA]

1 hour ago, Junkman said:

Which Tempest fine wire plug are you using? URHB36S and URHB32S are called out on the applicability chart, and I'm ready to order a set.

H Rick,

For the report and results I wrote about here, I used the colder 32S plugs. Generally, the higher the power output of the engine, the more you want to use a colder plug as the internal combustion temperatures will be naturally higher. The TIO-540 in the M20M falls in that category of high performance.

[Tony Armour]

I agree, the colder plug for sure unless there are oil issues. In racing (with tons of nitrous) we called spark plugs = fuses. Of course it didn't always work out 

[Danb]

Tony the service bulletin TAT SB11-05.9-23-2011 dated.. I was referring to  from Cirrus to remove all fine wire plugs, the Tempest man explained it was the Champs with the poor design that had the cracked insulators and associated piston damage. 

[Rick Junkin]

17 hours ago, Danb said:

I'm changing from fine wire champions to tempest 32s, I called an engineer at Tempest to see his recommendation and said the32s unless I am having trouble with getting oil on the plug or have a need for a hotter plug? Now I'm clueless regarding mechanical stuff, reason I called, I ordered the Tempest today, I explained I have the older champs with only 450 hours on them, he explained the cirrus SB to remove the champs and further explained the design flaws in the champs after thought I felt keeping the older champs was to risky and bit the bullet 

 

17 hours ago, DVA said:

H Rick,

For the report and results I wrote about here, I used the colder 32S plugs. Generally, the higher the power output of the engine, the more you want to use a colder plug as the internal combustion temperatures will be naturally higher. The TIO-540 in the M20M falls in that category of high performance.

 

17 hours ago, Tony Armour said:

I agree, the colder plug for sure unless there are oil issues. In racing (with tons of nitrous) we called spark plugs = fuses. Of course it didn't always work out 

 

Thanks Gents, I appreciate the immediate help!

Cheers,

Rick

[LANCECASPER]

On 11/10/2016 at 8:27 PM, Danb said:

I'm changing from fine wire champions to tempest 32s, I called an engineer at Tempest to see his recommendation and said the32s unless I am having trouble with getting oil on the plug or have a need for a hotter plug? Now I'm clueless regarding mechanical stuff, reason I called, I ordered the Tempest today, I explained I have the older champs with only 450 hours on them, he explained the cirrus SB to remove the champs and further explained the design flaws in the champs after thought I felt keeping the older champs was to risky and bit the bullet 

I just finished up an annual on my TLS and put in the Tempest URHB32S and it's unbelievable the difference. It feels like a turbine now compared to what it felt like before.

[Danb]

Lance I pulled my fine wire Champs and replaced with the tempest just for the issues with the older champs had, I didn't expect any differences, but the plane starts a little better I was fooling around with LOP, I have a little mechanical brain, with the old champs it was rough, with the tempest was smooth, it looks like I may be able to do it. I was running 28/2400 at 14 gph for the first time it was smooth. Now I'll pick daves brain to gain further knowledge.

[DVA]

7 minutes ago, Danb said:

Lance I pulled my fine wire Champs and replaced with the tempest just for the issues with the older champs had, I didn't expect any differences, but the plane starts a little better I was fooling around with LOP, I have a little mechanical brain, with the old champs it was rough, with the tempest was smooth, it looks like I may be able to do it. I was running 28/2400 at 14 gph for the first time it was smooth. Now I'll pick daves brain to gain further knowledge.

When I run LOP (which is about 70% of the time) I normally run about 5-10dF LOP as that gives me a great balance of economy vs speed vs cool CHT’s. But to show that this Bravo could be tuned to run smoothly at significantly greater LOP, heres a flight yesterday at about -55dF LOP.

[donkaye]

20 minutes ago, DVA said:

When I run LOP (which is about 70% of the time) I normally run about 5-10dF LOP as that gives me a great balance of economy vs speed vs cool CHT’s. But to show that this Bravo could be tuned to run smoothly at significantly greater LOP, heres a flight yesterday at about -55dF LOP.

Dave,  Would you explain the °F bar above 410° and the TIT bar approaching 1750°?  Thanks.

[Marauder]

10 minutes ago, donkaye said:

Dave,  Would you explain the °F bar above 410° and the TIT bar approaching 1750°?  Thanks.

The scale on the left is a user settable min/max for the cylinder head temps. Looks like he has it set for 225 and 410 degrees. The TIT temp is showing 1646 degrees. What is considered acceptable?

[DVA]

10 minutes ago, donkaye said:

Dave,  Would you explain the °F bar above 410° and the TIT bar approaching 1750°?  Thanks.

Don, please excuse me if I did not understand your questions, but this may help others who have this display.

In the picture below, disregard the area in RED during LOP tuning, Its the label for CHT when the display is in normal mode and JPI should actually hide it in this mode to avoid confusion.

When tuning for LOP on the JPI 830, the bars fall from the top down to show dF from peak, as the magenta arrow shows. The delta of the peak of each EGT for each of the six cylinders is the row of cyan negative numbers (-57) and just below them is the actual CHT for that particular cylinder. The TiT on this run is 1646dF, the max is set for 1750 on the bar line. 

Did I answer your question or did I totally misunderstand?

[donkaye]

24 minutes ago, DVA said:

Don, please excuse me if I did not understand your questions, but this may help others who have this display.

In the picture below, disregard the area in RED during LOP tuning, Its the label for CHT when the display is in normal mode and JPI should actually hide it in this mode to avoid confusion.

When tuning for LOP on the JPI 830, the bars fall from the top down to show dF from peak, as the magenta arrow shows. The delta of the peak of each EGT for each of the six cylinders is the row of cyan negative numbers (-57) and just below them is the actual CHT for that particular cylinder. The TiT on this run is 1646dF, the max is set for 1750 on the bar line. 

Did I answer your question or did I totally misunderstand?

Dave, you understood the questions.  I didn't understand why the CHT bar in Red box was indicating over 400, and in fact don't understand its purpose ROP when the CHTs are indicated for each cylinder.  I like to keep my TIT between 1575 and 1625.

[DVA]

47 minutes ago, Marauder said:

The scale on the left is a user settable min/max for the cylinder head temps. Looks like he has it set for 225 and 410 degrees. The TIT temp is showing 1646 degrees. What is considered acceptable?

Correct. I have my high CHT alarm set for 410. The max TiT is 1750df for the Bravo (below FL220). Some people are afraid of TiT temps for some reason, it comes from not understanding why TiT is important. Run all day long at 1650dF+ is you want to, it won’t hurt a thing. High TiT can cause blade stretch first which is a true problem, well before the heat begins to affect the metal, bearings or other parts negatively and these issues come well past 1750dF. Borg-Warner has some very good technical papers on turbo design and limitations.

[donkaye]

1 hour ago, DVA said:

Correct. I have my high CHT alarm set for 410. The max TiT is 1750df for the Bravo (below FL220). Some people are afraid of TiT temps for some reason, it comes from not understanding why TiT is important. Run all day long at 1650dF+ is you want to, it won’t hurt a thing. High TiT can cause blade stretch first which is a true problem, well before the heat begins to affect the metal, bearings or other parts negatively and these issues come well past 1750dF. Borg-Warner has some very good technical papers on turbo design and limitations.

From my experience the high temperatures have caused problems with the waste gate and on each of my engines, even though run at the lower TITs, I have had to replace it at mid time.

[aaronk25]

I wouldn't have any issues operating at max continuous TIT. There designed for it and it should save 3 or so gallons of fuel per hour so that $12 bucks a hour or $24,000 over the life cycle of a tbo, assuming 2000 hours. Even at 1/2 that $12,000 a wastegate doesn't cost that much, plus the lower chts most likely mean the cylinders will make tbo.


Sent from my iPhone using Tapatalk

[carqwik]

What is "blade stretch?"

[DVA]

11 minutes ago, carqwik said:

What is "blade stretch?"

There are extremely tight tolerances between the turbine and the housing - the pic below is the cold side used for reference only. On the hot side, as the blades heat up to a red hot glow, the metal on the turbine wheel (especially at the tips) stretches a bit due to the combination of heat and high tensile loads from centrifugal force. If the blade tips “stretch” to far they will come in contact with the housing - high heat will exacerbate this. Some of the newer high performance turbos made are designed to operate at TiTs past 2000dF. The alloys used in the turbos we find on airplanes are normally factory rated to 1850dF or a touch higher, then derated for a margin of safety by the engine and airframe manufacturers.

[DVA]

1 hour ago, donkaye said:

From my experience the high temperatures have caused problems with the waste gate and on each of my engines, even though run at the lower TITs, I have hade to replace it at mid time.

I would initially argue against the temperature as a source of the waste-gate issues. What exactly was failing?

[donkaye]

1 hour ago, aaronk25 said:

I wouldn't have any issues operating at max continuous TIT. There designed for it and it should save 3 or so gallons of fuel per hour so that $12 bucks a hour or $24,000 over the life cycle of a tbo, assuming 2000 hours. Even at 1/2 that $12,000 a wastegate doesn't cost that much, plus the lower chts most likely mean the cylinders will make tbo.


Sent from my iPhone using Tapatalk

Certainly each to this own, but one other very important consideration was the very poorly designed exhaust system plumbing that will quickly eat up any projected savings in fuel costs.  Each repair I've had cost nearly $3,000.  Bottom line, no matter what anyone on this list says and for whatever seemingly logical reason, after 3,700 of Bravo ownership and maintenance expenses, from experience I'm not going to run my engine anywhere near the maximum operating limits.  Do so at you own peril.  I hope you all have a very big reserve for your engine when doing so.

[donkaye]

On 12/25/2016 at 10:33 AM, DVA said:

I would initially argue against the temperature as a source of the waste-gate issues. What exactly was failing?

The spring (?) freezes up and the wastegate won't function.  This has happened on both engines just after mid time.

[aaronk25]

If I knew for sure that with the right hardware, plugs, fresh mags, gamis that I could run LOP in a bravo I'd buy one. Range and/or useful load is a big part of my mission consideration and it seems that the non stop flights MN to FL are dependent on LOP ops. Has every one else that has done their due diligence for this engine to run good LOp? I've read some have had difficulty but what about those who updated and replaced wear parts?


Sent from my iPhone using Tapatalk

[donkaye]

1 hour ago, aaronk25 said:

If I knew for sure that with the right hardware, plugs, fresh mags, gamis that I could run LOP in a bravo I'd buy one. Range and/or useful load is a big part of my mission consideration and it seems that the non stop flights MN to FL are dependent on LOP ops. Has every one else that has done their due diligence for this engine to run good LOp? I've read some have had difficulty but what about those who updated and replaced wear parts?


Sent from my iPhone using Tapatalk

DVA, Dave did the best writeup I have seen on LOP ops with the Bravo Engine.  I have a student who runs his LOP.  There is enough roughness that I wouldn't do it.  I have mine set up to be able to run LOP with a GAMI Lean differential of .5, but I just like the smoothness of ROP so I just bite the bullet and run 17.5-18 gal/hr at 75% power.  At the moment I think the worst thing about the Bravo engine is what I consider the underdesigned exhaust system.  The risers between cylinders 1 and 3 have broken on each of my 2 engines and I've had problems with risers on the other side breaking, too.  The walls are just too thin.

Regarding long nonstop trips, I have gone nonstop San Jose to Colorado Springs many years ago with regular tanks. No more.   I like to stop every 2½ to 3 hours.  Makes for a much more enjoyable day.  However, remember totally topped off, standard tanks hold 100 gallons even though not the STC version.  The older Bravo POHs are mum on that fact.  I don't count on that fuel when I truly top off.  It's backup to the planned reserve.