Question for turbo pilots about engine ops

[Shadrach]

I am looking for response from anyone flying a turbo or turbo-normalized aircraft. Most of the engines have a max manifold pressure based on continuous ROP max power settings. Have any of you experimented with trying to attain high horsepower numbers on the lean side of peak? I am assuming that running 80-90% HP while LOP may in some cases require MP in excess if not over redline.  I know of more than a few TAT modded Bonanzas that are regularly operated at 85-90% power with excellent CHT numbers, however it does require enough MP to get to 70 to 100LOP.

I would ask that those of you that use the POH recipe please refrain judging those who operate outside those parameters. I'd like to focus on engine ops and theory, so please keep the "you'll shoot your eye out" comments to a minimum unless they're accompanied by data or experience. 

[Parker_Woodruff]

I'm pretty sure that the 87% HP talked about by TN Bonanza pilots is at max rated MP.

I experimented with 85% power climbs LOP, but the atmospheric conditions had to be just right.  In the end, I settled on 100% power ROP climbs and 11.2-11.6 GPH LOP in cruise.

[FoxMike]

This is a difficult question.  The amount of power you get depends on mass flow through the cylinder.  How much mass flow the engine will see is dependent on match of the turbo to the engine.  Their is a lot to getting a good match ( a black science).  Some say the Turbo Alley conversions are capable of this, I do not know.  From more than 40yrs. of operating Turbo Mooneys and a T210 I never found that up in the high teens and above that 90% power was doable nor was it a good idea.  A blower that can produce that much mass flow probably will be a real drag on the system when flying in the low teens and below.  The T210 used appreciably more gas at 4K because the turbo was causing a lot of back pressure when the turbo was running at a slower speed.  The blower became efficient above 10K.  If most of your flying is up high, having a turbo match that optimizes best at high altitude is OK.  I like to fly a variety of altitudes so I prefer a turbo design that is less aggressive.  A good book that gets into designs and matches is "Turbochargers" by Hugh Maclnnes.  One last comment, mass flow is dependent on density altitude, on above standard days a standard cubic of air is a lot bigger than on a below standard day.

[Nemesis]

I think FoxMike is right about one thing in that getting a good match between turbo system and engine is difficult. I have been at GAMI in OK where they make the Tornado Alley Turbo system for the Bo and took the APS class. The guys there are on top of all the data as it relates to piston engine technology. I think I can reasonably say that it is quite likely that they put together the very best turbo system that technology would allow for the Bonanzas.

As for my 231 with it's older and more rudimentary system, my TIT gets to 1600dF at about the 62% mark LOP so - TIT is my limiting factor. I prefer to run at 1550dF TIT or less and I can only do that ROP with higher power settings. I am guessing that my turbocharger itself is somewhat less efficient than others therefore it has to run harder and hotter to give me decent output.

Dave

[Shadrach]

Will it not run at LOP at 1550 at higher MP settings?

[N201MKTurbo]

I have tried it in my turbo normalized 201. The problem I have is hitting the TIT limit. 

 

The system is limited by STC to 30 In MAP. The pop off valve is set to 32 In so that is the most you can get. The other problem is I have no idea how much power the engine is making. Even ROP I beleve the power charts are wrong and when LOP you are just guessing at the power produced. 

At 30 In 2500 RPM and LOP, I can keep enriching the mixture until I hit the TIT limit. 

Exceeding the TIT limit costs 2 AMUs

[Shadrach]

I have tried it in my turbo normalized 201. The problem I have is hitting the TIT limit. 

 

The system is limited by STC to 30 In MAP. The pop off valve is set to 32 In so that is the most you can get. The other problem is I have no idea how much power the engine is making. Even ROP I beleve the power charts are wrong and when LOP you are just guessing at the power produced. 

At 30 In 2500 RPM and LOP, I can keep enriching the mixture until I hit the TIT limit. 

Exceeding the TIT limit costs 2 AMUs

I understand. My question as relates to your set up was what would happen if when you enrichened to say 50 lean of TIT limit and the puses the MP to 32 and leaned again? What is you FF when LOP at TIT redline and 30"? I have to assume that you are rarely if ever making 100% (200hp) power ever with an MP limit of 30". I Don't think its enough to off set the back pressure and heat from the turbo. Even with the WG wide open at SL, I would think that you'd see a HP penalty from the additional plumbing.

Edited September 20, 2015 by Shadrach

[carusoam]

So.....the situation is this: A pilot wants...

1) To fly a TC'd or TN'd airplane LOP at high power output levels.

2) His challenges come in the form of heat generation and dissipation in the turbo, where TIT is roughly measured.

3) The cost of not controlling the TIT adequately is a 2AMU maintenance expense.

Some of the challenges require mechanical enhancements in hardware...

4) Balancing the fuel flow of the fuel injectors is pretty well agreed upon by most Mooney pilots.

5) Balancing the airflow of the intake system is agreed upon by most Mooney pilots with an IO550.

6) Limits of Not balancing the airflow of the intake system is displayed by the TSIO540. A really good engine, but is LOP limited because of the intake hardware.  Bravo owners have had limited success running LOP, but, not at high MP.

Questions to ask...

7) Are your fuel injectors balanced at the high MP cruise setting?  Liquids being non compressible behave predictably at a wide range of operating environments.

8) Is your intake balanced at the high MP cruise setting?  Air being compressible behaves terribly  over a wide range of operating environments.

9) Is your your TIT measuring close to where the turbine wheel really needs it?

 

I think if you had a way of measuring the fuel and air flow into each cylinder and making adjustments for the variations

 

Edited September 20, 2015 by carusoam
Ran out of space...

[carusoam]

Then adding the additional finer details of...

10) proper TC and TN size/design...

11) proper pressure controller design...

12) proper inter cooler design...

13) proper instrument design, placement and display with alarms...

14) proper muffler design or removal...

15) proper O2 design for the pilot...

16) the ability to visually inspect exhaust valves and turbine wheels would help immensely!

17) if the ability to run 50 to 100°F LOP is important or helpful, which engines can do this and at what MP range can they do it at.  The lower MP is more of a challenge than the higher MP to go deep LOP.

This data is not generated by me. It is collected by reading this forum for a few years. I am not a mechanic, nor do I fly a turbo Mooney.

We are in a great position to have so much technical detail become available to us over the last few years.

Best regards,

-a-

Edited September 20, 2015 by carusoam

[carusoam]

 The other problem is I have no idea how much power the engine is making. Even ROP I beleve the power charts are wrong and when LOP you are just guessing at the power produced. 

At 30 In 2500 RPM and LOP, I can keep enriching the mixture until I hit the TIT limit. 

Exceeding the TIT limit costs 2 AMUs

question for 201MK...

Adoes your TN not you to use the LOP HP calculation for your engine?

The simple relationship of FF X engine constant= HP is some idea. Unless you can't use it...

it doesn't work for ROP because it doesn't track excess unburnt fuel leaving the system.

the challenge of rising TIT is also showing where the unburnt fuel is finishing the burn.  High MP is going to lead to high ICP and the ability of burning exhaust gasses going deeper down the exhaust system.  EGTs may continue to rise as the fuel is still burning.  The exhaust gasses will cool as they expand. More back pressure = less or later expansion/cooling.

you guys are having a really interesting conversation...

best regards,

-a-

Edited September 20, 2015 by carusoam

[carusoam]

For the TN version of an NA engine, 100% power is available at 1atm/SL on a standard day?

29.92" and 59°F according to Wiki....

then adjustments are made for intake and exhaust system drags.

It seems that the further you go into developing higher efficient HP, the law of diminishing returns will always be your adversary.

Flying a 310HP TN engine in a Mooney would be awesome!

Ross, are you thinking of adding a TN to your plane?

there isn't anyone better equipped to handle these challenges.  There is an entire system that was offered for sale on MS.  It had been OH'd...

best regards,

-a-

Edited September 20, 2015 by carusoam

[Nemesis]

Will it not run at LOP at 1550 at higher MP settings?

No. Once I get to about 62% and at about 9.5 gph for the low compression engine, the TIT is at 1600dF and any more power (higher MP) produces an even higher TIT. So, it is just a no starter for me. The GAMI injectors seem to be doing their job with less than 0.3 gph spread. I wouldn't mind giving up a small % of power in favor of LOP ops but more than 10% is just too much. That is not what I bought a Mooney for. If I want to fly at less than 62% power I can set the mixture pretty much anywhere if I was trying to get greater range. At higher altitudes, say above FL180, then the CDT also begins to be a problem. I could solve the CDT problem with an intercooler but an intercooler will do nothing for the TIT. Maybe at overhaul time I can exchange the turbo for a different unit. Of course, that also is a risk in case I get one that is even worse.

The system is limited by STC to 30 In MAP. The pop off valve is set to 32 In so that is the most you can get. The other problem is I have no idea how much power the engine is making. Even ROP I beleve the power charts are wrong and when LOP you are just guessing at the power produced.

 Actually N201MKTurbo, provided that all 4 cylinders in your high compression engine are running LOP, the power that your engine is producing is very precisely known !! If all 4 cylinders are running LOP, then multiply your total fuel flow by 14.9 to arrive at your precise horsepower. Divide your horsepower number by the rated horsepower of your engine (200) and you will arrive at your % of horsepower currently in use.  (FF x 14.9) / 200 = %hp  (or) FF x 0.0745 = %hp <--- formula is for 200 hp high compression gasoline engine.

The 14.9 multiplier is for a gasoline high compression engine. For low compression engines such as my TSIO-360LB, the multiplier is 13.7.

Dave

[N201MKTurbo]

At the above power settings, I will hit the TIT limit at about 9.7 GPH. To get the same speed ROP I'll be at 25/25 and 11.5 GPH.

When I used to commute to Tucson, I would fly at 25 in 2300 RPM and 8.2 GPH, doing 145 KTS. Saved enough to buy my lunch.

 

fine then, it hits the limit at 71% power.

 

 

[N201MKTurbo]

This new version does very strange things on my IPAD. 

[Shadrach]

For the TN version of an NA engine, 100% power is available at 1atm/SL on a standard day?

29.92" and 59°F according to Wiki....

then adjustments are made for intake and exhaust system drags.

It seems that the further you go into developing higher efficient HP, the law of diminishing returns will always be your adversary.

Flying a 310HP TN engine in a Mooney would be awesome!

Ross, are you thinking of adding a TN to your plane?

there isn't anyone better equipped to handle these challenges.  There is an entire system that was offered for sale on MS.  It had been OH'd...

best regards,

-a-

I have considered it. I know that Doc Breda has/had an extra Rayjay unit. The thing is I have a 150kt airplane as it stands. The feedback I've gotten in forums and via PM is that could expect up to 175kts at 18,000 ft but that most run folks run them far more conservatively and see 155-160kts at altitude. Roughly half of my flights are into some sort of headwind. When that is the case, I opperate at 3500msl or less if terrain permits (Day VFR only) . Engine is WOTRAO 2500rpm and 35-40LOP. This yields IAS of 140-150kts+ depending on DA.  This keeps me out of the worst winds. Anything under 125kts GS and I am an unhappy traveler. I am not sure I'd want to give up this option for the choice of fighting high winds at alt or babying a turbo down low.

[M20F]

I have considered it. I know that Doc Breda has/had an extra Rayjay unit. The thing is I have a 150kt airplane as it stands. The feedback I've gotten in forums and via PM is that could expect up to 175kts at 18,000 ft but that most run folks run them far more conservatively and see 155-160kts at altitude. Roughly half of my flights are into some sort of headwind. When that is the case, I opperate at 3500msl or less if terrain permits (Day VFR only) . Engine is WOTRAO 2500rpm and 35-40LOP. This yields IAS of 140-150kts+ depending on DA.  This keeps me out of the worst winds. Anything under 125kts GS and I am an unhappy traveler. I am not sure I'd want to give up this option for the choice of fighting high winds at alt or babying a turbo down low.

This is the problem with piston engines going high.  While a jet can make TAS to overcome any headwind a piston is a lot of times going to see negative GS at higher altitudes because the gain in TAS just doesn't offset the wind.  I really only use mine a couple of times a year planned and it is nice when weather pops to where a less then stellar GS is better than landing and waiting.  

[carusoam]

Ross,

how do these logic bites sound...

 

1) There used to be a time that it was challenging to find accurate headwind data before and while flying.

2) we used to climb or descend to see what it was actually like at different altitudes.

3) performance data only came from major publications, because the manufacturer's data couldn't be trusted. The amount and type of data collected came from the week they had access to the machines or parts.

4) with MS, you get actual data how people use these systems with your plane.  Still somewhat limited if they fly differently than you intend to.

5) the RayJay system comes with a pretty strong pedigree.  Many have proven it with Mooney airplanes.

6) if you were not familiar with the Red Box theory, and didn't care to be you could run into expensive issues.

7) if you were not familiar with engine instrumentation or couldn't afford it, you could run into expensive issues.

8) if you maintain TIT and CHTs you will probably follow guidance of 200° ROP shallow 120KIAS climbs.

9) if you buy and install it and later decide the kids need new bicycles and baseball lessons and the additional performance no longer meets expectation. It can all be removed and put back in the box it came in.

10) to cruise at 170kts would probably take buying a different plane.  See Jose' post regarding the TLS for under $100K or a Mooney Missile (extra pair of cylinders vs TN)

11) fuel supply is improving due to horizontal drilling and the competition it provides.

12) there has got to be some extra maintenance for the exhaust system that can be determined by the previous OH history.

13) the cost are easier to spread out over time when you know you are going to keep the plane that long. Compared to my first year where our plan B included selling the plane if it were too expensive to operate and keep.

Continue to do you home work. Expect some increased hourly costs that match the increased speed that you are receiving.  Use caution as to not exceed temperaure limits of cylinders and turbine.

My family tends to travel above 10k' for improved engine out gliding distance.  If I could get another 5" of MP up there, we would all be happier.  There was no TN system for the M20R when I updated my engine...

have I missed anything?

best regards,

-a-

Edited September 21, 2015 by carusoam

[Shadrach]

Didn't miss a thing. The only thing I'd say is I think that a well thought out turbo normalized 200hp Mooney ought to be a 180kt airplane at 18,000 to 20,000, but it appears that none of the available systems are sorted well enough to get there.