LOP - Evaluation Please

[kris_adams]

Hi Everyone,

I guess with gas at $6+ a lot more of us are seriously looking at LOP operations.  I hope the chart I'm attaching is readable.  These values were recorded on a flight today.  6500'/2300RPM/23"MP/OAT=15c/.

http://mooneyspace.com/images/userGalleries/8848/207472db3048721f501ad93966a365d1.png

(this is the link. I can't get it to show up automatically.  it is in my gallery).

For those that may not remember, I had my engine majored last year (w/GAMI).  I have about 100 hours on it.  Today was the first time that I attempted the GAMI lean test and it appears that all of my cylinders peaked at 9.5g/hr.  It was surprising to me what the difference in EGT was at peak though:

#1 peak at 1432 and 9.5g/hr

#2 peak at 1380 and 9.5 g/hr (this looks odd)

#3 peak at 1427 and 9.5g/hr

#4 peak at 1425 and 9.5g/hr

I have a lot more questions, but I'm hoping to start with a review of the chart I created as well as the peak EGT listed above.  Thanks in advance for all your help!

Kris

[kris_adams]

User error

[M016576]

Quote: Kris_Adams

Hi Everyone,

I guess with gas at $6+ a lot more of us are seriously looking at LOP operations.  I hope the chart I'm attaching is readable.  These values were recorded on a flight today.  6500'/2300RPM/23"MP/OAT=15c/. (link to this is file is in the next post.  still figuring this out). 

http://mooneyspace.com/images/userGalleries/8848/207472db3048721f501ad93966a365d1.png (this is the link. I can't get it to show up automatically.  it is in my gallery).

For those that may not remember, I had my engine majored last year (w/GAMI).  I have about 100 hours on it.  Today was the first time that I attempted the GAMI lean test and it appears that all of my cylinders peaked at 9.5g/hr.  It was surprising to me what the difference in EGT was at peak though:

#1 peak at 1432 and 9.5g/hr

#2 peak at 1380 and 9.5 g/hr (this looks odd)

#3 peak at 1427 and 9.5g/hr

#4 peak at 1425 and 9.5g/hr

I have a lot more questions, but I'm hoping to start with a review of the chart I created as well as the peak EGT listed above.  Thanks in advance for all your help!

Kris

[Cruiser]

Chart looks normal. LOP should be no problem. Give it a try.

[testwest]

Hi Kris

That GAMI spread is really nice. Don't forget the engine is far more efficient if it is unthrottled, e.g. wide open throttle or WOT as it is abbreviated. I see you are running 23" and 2300 RPM. Remember any advice to run "square" or "undersquare" you may have received in your training for the complex airplane endorsement to your license (or any subsequent "advice") is absolute balderdash.

Try your run at 6500' WOT and do another GAMI lean test, and share the results if you are so inclined. 23 square at 6500' is 62% power at "best economy" for the IO-360-A3B6D as installed in the M20J (from Benchmark) so ~58-59% or so LOP depending on your fuel flow, at WOT/2300 you are at 68% BE and maybe 63% ish LOP.

Also, if you ever have the slightest indication of any spark plug issues, such as a poor runup, see the posts here regarding Tempest spark plugs.

By the way, thanks for posting the data. Flight test types just eat that stuff up!

[kris_adams]

Thanks everyone.

@Norman: What RPM?  Full throttle and prop?  I have some more data for 2500 RPM and 23".  I'm still working on putting it together.  Here are both charts.  I finally figured out how to post inside the thread.  I don't think this site likes my Mac.

Kris

[testwest]

Hi Kris

If you want, just repeat the same test except at wide open throttle (and 2300 RPM)...you should get about 25" of MP under those conditons. If you have ram air, you can open it up and gain back (some) manifold pressure.

Of course, for a trip your choice of power settings for most efficient operation is completely dependent upon winds, so you may be at 2700 RPM WOT at 11,500 (~65%) for increasing tailwinds at altitude, or 2200' WOT at 5500' for the same power if the winds are worse (i.e. they increase by altitude faster than the TAS you can get at WOT).

Thanks for your post, and interest. It is really neat that folks here are interested in facts and data (instead of dogma) regarding their engine operations.

[testwest]

Also I see on the chart that you just posted the GAMI spread is more like .6 gph. So, when you are optimizing your injectors with GAMI, be sure to check WOT/65% power and use those data as the reference.

By the way, are you using EZtrends to post your data, or importing to Excel or Numbers? I am a Mac guy too.

[kris_adams]

Thanks Norman.  I posted both of the charts in my previous post above.  Interestingly, I'm not sure I can get 25" MP at 6500'.  ('79 M20J w/RAM open).  I'll try this again at WOT and see what I get.  Now that I've done it once, it's pretty easy to make these charts.

I did the GAMI test at 23/2300.  I guess I need to do it at a higher power setting.  I'm using Excel for Mac 2011.  My real issue was figuring out how to post using Safari on MooneySpace.  I downloaded Chrome and the pic's uploaded no problem.

[testwest]

Yeah, no joy with Safari either. I wound up using Firefox for Mac.