LOP Turbo Operation

[Emmet]

Hi,

I installed my gamis this week and even after reading tons of posts I still have some questions. Engine is a TSIO360-GB with Merlyn.

I started at 65% (approx. 28", 2400rpm), 1st cylinder was 60°lop, last about 15°lop, power went down to about 56%, fuel flow 8-8.5 gph.

How can I increase the power back to 65%? Simply advancing the MP? Will it still be lop then?

Is 15° lop enough for a turbocharged engine?

How do you guys manage higher power settings? Setting power to 75% -> BMP -> leaning from lean side?

Which power settings do you use?

 

Thanks for your comments !

Emmet    

[jetdriven]

I am not a turbo operator. I do have 500 in  Twin cessna and Piper chieftain,  but it was all ROP.

 You can set 65% MP and RPM, then go LOP, then add 2".  FF will tell you your true % of power when LOP.  You could also do it in the other order, IE, set 2" above your desired 65 or 75% power MP and RPM, then do a BMP to the lean side, then richen to your desired % power FF.  In any case do not exceed recommended max TIT.   I believe it is 13.9*GPH=HP on yours, but verify.

[Parker_Woodruff]

I have the TSIO-360-MB/SB engine (210 HP converted to 220hp)

 

I know for a fact what settings will leave me LOP. So I configure the MP, RPM, and then set fuel flow. I typically use 32-34", 2550 RPM, and then lean to more or less 12.0-12.3 GPH. 

 

That works out to something like 75% of 220hp available to me.

[Emmet]

How did you figure those numbers out?

Using the EDM LOP mode didn't sound wise to me at75% ..

[danb35]

...which is related to something I've wondered about.  Many of the TN Cirrus or A36 guys climb at 85-90% LOP.  How do you determine peak at those settings (so you can know you're far enough LOP)?  I wouldn't think peak EGT or TIT would be a constant for the engine--IOW, I'd expect peak at 85% to be different from peak at 55%.  And, of course, the red box is pretty big at 90% power.  So how would you do that?  Obviously, once you've done that a couple of times, you can lean to a fuel flow (which is what I do now), but slowly leaning through peak at high power seems like a bad idea.

Don't fly a turbo now, but still hoping...

[aviatoreb]

Quote: danb35

...which is related to something I've wondered about.  Many of the TN Cirrus or A36 guys climb at 85-90% LOP.  How do you determine peak at those settings (so you can know you're far enough LOP)?  I wouldn't think peak EGT or TIT would be a constant for the engine--IOW, I'd expect peak at 85% to be different from peak at 55%.  And, of course, the red box is pretty big at 90% power.  So how would you do that?  Obviously, once you've done that a couple of times, you can lean to a fuel flow (which is what I do now), but slowly leaning through peak at high power seems like a bad idea.

Don't fly a turbo now, but still hoping...

[donshapansky]

I had trouble running LOP with high TIT's over 1700F while pulling through peak EGT's and then a rough running engine. Remember the first step is to do the spreadsheet and determine if all cylinders peak within .5 gph. Once you have the spread within spec then and only then will you get all cylinders to run minimum of -50F LOP. After I found a leakdown problem and rebuilt the cylinders, had the spread within .5 gph I could finally run smoothly LOP with max TIT's of 1580F at 70% power, I was able to easily increase 3 " MAP to gain back the power. My leanest cylinder is 85 - 90 LOP and richest -48 LOP. The last change I made was Tempest Plugs and that removed all of the roughness to where there is no sensation of marginal cylinder firing, which points to how critical plug voltages are to smooth LOP operations. You can operate at higher than 70% power on turbo engines if you can keep the TIT's down, because the CHT's will certainly permit high power settings like they do with TN550's. The low compression Lycomings will not run LOP at power settings of 65% and higher due to 1700+ TIT's 

[ChrisH]

I have a 231 and fly at 75% LP. Couple of things I've found:

1. Lean fast, the TIT gauge seems to respond the quickest and best, I use that to get quickly in about the right area (it'll raise and fall smoothly, then fine tune with the fuel flow (like Parker, I've used the EDM often to get to a set of MP/RPM/FF settings that have a known LOP). 

2. RPM seems to help, I stay at 2650. It seems to help keep everything cool better than low RPM for the same fuel flow. (Makes sense right, more air, turbo works less hard, and ANR takes care of the noise).

3. Be a bit careful with the Fuel flow method, I have 3 FF gauges running off 2 different sensors. They all give slightly different readings (off by ~0.5gph) 

4. Altitude becomes a problem, because TIT is usually the limiting factor. I can only run LOP up to ~FL 190, after that the turbo has to work too hard to keep the MP at 33" or so. 

Chris. N1163D. 

[jetdriven]

Quote: aviatoreb

I have always wondered that too - how they can confidently find ENOUGH far LOP at such a high power setting since I wouldn't think you would want to creep through the red box to use your EDM to find peak and lean from there at such a high setting.  One thing is that it seems as if there is fundamentally a difference between a turbo normalized engine and a ground boosted turbo engine like we find in most Mooneys.  They seem to get very low TiT readings LOP.  I have not had success running LOP beyond 70-72% since my limiting factor becomes how hot I am willing to run my TiT even though the engine is still running smoothly and balanced. TiT readline is 1650 and I am very uncomfortable running it hotter than 1600.  Generally for this reason I LOP up to about 65% where I can keep TiT down to 1550-1580 depending on the day and altitude.  I know some others with the rocket TSIO520NB have had different specific results but in any case being TiT limited is not uncommon I understand with the TSIO engines generally, as opposed to the TN engines you cited.

[aviatoreb]

Quote: jetdriven

I have always wondered that too - how they can confidently find ENOUGH far LOP at such a high power setting since I wouldn't think you would want to creep through the red box to use your EDM to find peak and lean from there at such a high setting.  One thing is that it seems as if there is fundamentally a difference between a turbo normalized engine and a ground boosted turbo engine like we find in most Mooneys.  They seem to get very low TiT readings LOP.  I have not had success running LOP beyond 70-72% since my limiting factor becomes how hot I am willing to run my TiT even though the engine is still running smoothly and balanced. TiT readline is 1650 and I am very uncomfortable running it hotter than 1600.  Generally for this reason I LOP up to about 65% where I can keep TiT down to 1550-1580 depending on the day and altitude.  I know some others with the rocket TSIO520NB have had different specific results but in any case being TiT limited is not uncommon I understand with the TSIO engines generally, as opposed to the TN engines you cited.

[FBCK]

There was a piece I read just last week, but I can't remember where, Bonaza forum or one of the pelican briefs from John Deakin and he said that high rpms and lop don't mix well because of the strock of the piston.  Comes to think of it it was one of the online seminars, sorry I can't find the link.

[ChrisH]

Pelican's perch (Deakin) has a whole series on turbos. Here's a link with some discussion of RPM.

http://www.avweb.com/news/pelican/182104-1.html

The series runs from #31-#36 (here's an index of some of his publications)

http://www.avweb.com/news/pelican/182146-1.html

Good reading. 

 

Chris.

[FBCK]

Bingo, found it it was an EEA seminair:

http://www.eaavideo.org/video.aspx?v=1678859198001

John goes though the combustion event and talks about RPM LOP of peak, I usually run my 231 at 2500-2600 in cruise, which is higher that John Deakin runs his.

[bd32322]

Moderators: can we pin this to the top of the forum listing?

The posts here have great links for LOP operations !!

Thanks

[Cruiser]

I can't get the video to run.

[bd32322]

I can't get the video to run.

Worked for me on my PC and ipad too