Ray Jay Turbo Question

[M20F]

Since I picked up my M20F have been running through various tests to get a more factual basis for fuel burn, speeds, etc.  This weekend on a trip went up to FL190 which was a density altitude of @21,500ft.  I leveled out of the climb with about 25in/2600rpm with turbo fully in (normally I climb 26/26) so got full performance up in the climb and about 500FPM at 120mph.

When I leveled out I dialed the manifold on the turbo back to 23 and then spun the rpm back to 23 (I normally cruise 23/23 or 24/24 or 23/24 still figuring out what works best in terms of speed/fuel/noise) and as soon as the rpm came back the manifold dropped like a rock (down to 18-19 inches).  Pushed the rpm's back up and the manifold came back.  I finally settled in at 23in/2400rpm and got around 150kts true which is what I see essentially from 15,000 up depending on temp/pressure.  Soon as I tried to lean it though same issue the manifold would drop to 18-19 inches.  Other issue is at what should be about 67% power I was burning about 16-17 gallons an hour which even with no leaning seems awfully high.

I have flown at 17,500 (probably around 19,500 density) and haven't had this issue so sort of puzzled.  At 17,500 at 23/23 see about 150kts with about 9.5-10.0 gallons per hour burned. 

Overall real happy and have sort of settled in at 12,000 feet / 140kts TAS as where I like to be burning about 9-10 gph (lean till rough and then push it back in some), where the winds make sense 15-17000ft works well at about 150kts (19 gph in the climb at 26/26).  Would though like to understand what the deal was this weekend as while I wouldn't plan generally for Class A being able to squeak up another 4-5000ft at times can get you over stuff so would like the option.

[jetdriven]

Sounds like reverse boostrapping, IE the lower RPM (less exhaust volume) decreased turbine speed to the point it could not maintain set MP.  Sounds like going leaner decreases the exhaust volume in the same manner.   I'm no turbo man but in a M20J 2500, even 26 or 2700 is a perfectly acceptable cruise RPM at high altitude.  Figure out if you are at peak or LOP because on an IO-360 lycoming "lean to rough" mught be as much as 100 LOP, or right to peak.  That fuel flow seems awful high.  GAMI test will let you know how balanced your injectors are.  Ross will be on here shortly. 

[Ron McBride]

Is your Turbo working correctly? I do not have a turbo, but with my stock 69F I can get 140K TAS at 12,000 ft.

I would think that you would get better speeds out of the turbo than this. Hopefully Ken Reed can comment on this. He had a turbo F.

Ron

[testwest]

You might have experienced a compressor stall. This can happen if the mass flow through the turbine is insufficient to maintain the demanded pressure ratio across the compressor. Attached is a JPI data dump from a compressor stall in a TN IO-540-S1A5. Other than two extra cylinders, it is basically the same engine as yours (e.g. angle valve Lycoming, TN, ~50hp/cylinder).

If the rest of the turbo system is operating normally, you may just have a not-so-great match of the turbo map with those conditions. A little more RPM will be OK, but if it is really cold and you see a slow down while adding a lot more RPM, you are starting to see some transonic losses at the prop tips. Doesn't hurt anything, but is annoying.

Also, that fuel flow seems awfully high. Again, looking at the attached picture, at the right side I got the engine settled at 26"/2300 RPM after recovering from the stall (by adding back the RPM, just like you did). The fuel burn is about 16 gph from the graph, ROP, 26"/2300 and ~70%ish power on this engine....but it is a 290 hp six-cylinder.

[M20F]

Quote: N9154V

Is your Turbo working correctly? I do not have a turbo, but with my stock 69F I can get 140K TAS at 12,000 ft.

I would think that you would get better speeds out of the turbo than this. Hopefully Ken Reed can comment on this. He had a turbo F.

Ron

[aschardt]

You've got something not working right if you're only seeing 140kts at 12,000 with the turbo normalizer.  I'll typically see 160-165kts running 26.5/25 and 13-14 gal fuel flow at 12-14k altitudes.     I'll admit I've never pulled the power back while running the turbo, not really sure why you would.  The goal is to go high / go fast.  Floor it and watch the temps! 

[testwest]

Hi M20f (RL name is?)

For the next major holiday in which you expect to receive gifts, ask for a JPI 830 engine monitor. Add on fuel flow and compressor discharge temeprature (and IAT if you have an intercooler). Then, learn what the supplied information means. Your engine and wallet will thank you.

[jetdriven]

I think if it compressor stalls thats basically reverse flow and the MP should decrease extremely rapidly.  If it is just an exhaust volume A/R deal it would fall off gradually.  I second Norman's opinion, I am a little leery running a M20J without a multi-point EGT and CHT with FF. A Turbonormalized IO-360 Lycoming is pushing the limits even further.  More ways to ruin a set of 2,000$ each cylinders. 

[aschardt]

I'll throw a vote for the need for a JPI when running the turbo normalizer.  For someone who was new to turbo's I was very uneducated on how much heat can build up and how fast.  There is a delicate balance between power, fuel flows, and temps given that you have a manual wastegate.   A good engine monitor is neccessary to stay out of trouble here.  Best $2k you'll spend. 

[aschardt]

I'll throw a vote for the need for a JPI when running the turbo normalizer.  For someone who was new to turbo's I was very uneducated on how much heat can build up and how fast.  There is a delicate balance between power, fuel flows, and temps given that you have a manual wastegate.   A good engine monitor is neccessary to stay out of trouble here.  Best $2k you'll spend. 

[testwest]

A stalled centrifugal flow compressor can still provide a "slight" boost above ambient MP, the flow is still in the normal direction, it's just...crappy, for lack of a better word.

A sudden drop of MP to above ambient pressure, happening rght after some reduction in exhaust flow or increase in demanded MP, is likely a compressor stall. If undoing what you just did makes the MP come back, that's it.

A sudden drop of MP to ambient pressure, however, is a serious emergency. That is likely a broken exhaust pipe, and an engine fire may quickly ensue. Throttle idle and look for a place to land. Shutdown the engine, fuel pump and close the fuel valve if there are any other bad indications. From turbo altltudes above most places in the US you have lots of landing options. Use a) your glider rating and your recent practice in a simulated forced landing scenario to assure a survivable outcome.

If you are c) none of the above, there are some more things on your gift list!!!

[M20F]

Quote: aschardt

You've got something not working right if you're only seeing 140kts at 12,000 with the turbo normalizer.  I'll typically see 160-165kts running 26.5/25 and 13-14 gal fuel flow at 12-14k altitudes.     I'll admit I've never pulled the power back while running the turbo, not really sure why you would.  The goal is to go high / go fast.  Floor it and watch the temps! 

[jetdriven]

26.5" / 2500 RPM is more like 85% power while ROP and unless he has an intercooler, the charge temps lower it further maybe to 75% power.  If LOP then certainly the engine is not putting out more than 75% power; and Lycoming authorizes peak at 75% and below.  I think his 13-14 GPH FF he is running quite ROP.    LOP is cooler. As long as your injectors are balanced and you monitor every CHT.  Thats the important thing. A JPI will serve you well.

Quote: M20F

I am running 23/23 which is about 64% power you are running 26.5/25 which is almost 90% power, I would be interested in seeing specific conditions (density altitude, CAS, etc.) that are getting you 160-165kts at.

 

[testwest]

Hi Mike

Sorry, I did not know you had the C320 (Cessna Skyknight, right?) time.    Was it your own airplane, or flown for an operator?

I try to make my posts helpful for the recipient as well as maybe giving some info to third parties who are here to visit and learn, did not mean to "give you a lesson", as it were.

Having said that, depending on the C320 model, the engines were either Continental TSIO-470x or TSIO-520x. Both were low-compression engines with certificated cooling margins under boost. Your F, unless it has an intercooler, is a bit of a different animal. Even though the TN boost may not be nearly the amount of boost as a turbocharged low compression engine, the intake charge can get pretty hot. Notice again on the graph I posted the CDT of almost 175 degF.

So in your case, with no intercooler, you could be feeding 150 degF+ air to an 8.7:1 engine, versus the 7:1 or 7.5:1 of the Skyknight. I'll gently suggest, one more time, as owner-operator who is on the hook to pay the maintenance bills, to consider the engine analyzer as a top priority. I have personally saved significant maintenance money on at least 10 events with various airplanes with analyzers, and had my butt saved twice. 

Hope this helps!

[KSMooniac]

I'll add to the chorus that you should really add an engine monitor as your top priority, and the sooner the better.  Certainly before LR tanks.  You should also get the formal education about running an airplane engine from here:  www.advancedpilot.com  Those two purchases are the best bang-for-the-buck and most important you'll likely make as an aircraft owner.  I'll never own a plane without an engine monitor, especially a turbo!  If you can't buy an EDM-930 now, then consider getting a -700 as it will more than do the job, and I expect the probes can be re-used if/when you want to move up to a -930 in the future.  (Installing/routing the probe wires is the hardest or most tedious part of the installation.)

I would expect a TN-F should be able to do better than 170 KTAS at 17k on 10 GPH while LOP, with very good CHTs. 

[testwest]

Here is a nifty owner web site for a Turbo F, the referenced page has a large chart of performance data:

http://www.cnrepperson.com/flying/9791m/9791m-enginePerformance.htm

At FL200, DA218, 25 squared, they get 121 KIAS, 171 KTAS. No mention of fuel flow, though.

KSMooniac, +1.

We are getting ready to upgrade our J to an EDM-930 from a -700, and Scott is right on that as well, all the probes can get re-used. It is a nice upgrade path.

[FoxMike]

M20F,

Years ago I owned an M20E  to which I added a Ray Jay system.  My recollection of its performance was not far off the numbers you stated.  I added lots of "speed mods" and the performance and engine cooling got better.  I then got into the mode of redesigning the intake system and relocating the oil cooler.  At the time the FSDO in my area would approve "one time" STCs (a little less work and testing required).  The time and expense of all this was outrageous but it really improved the performance of the E model.  I found that in spite of all the airframe and engine work the high compression IO 360 engine did not flow enough exhaust to keep the turbo turning at optimium RPM above 20K.  I thought that the engine turbo/match was pretty good at lower altitudes and particularily down low when the headwinds were blowing hard.  The T210  and TLS that I have owned, both did better above 20K but the turbos produced a lot of exhaust back pressure and poor engine efficiency (at lower altitudes).  Its all a matter of compromise.  If your F model does not have the 201 mods you might look at investing in some, it does help (both climb and cruise).

Walt

[M20F]

Quote: testwest

I try to make my posts helpful for the recipient as well as maybe giving some info to third parties who are here to visit and learn, did not mean to "give you a lesson", as it were.