LOP GUY POURS ON THE COAL SURPRIED BY RESULT

[MyNameIsNobody]

-a- Never thought I was LOP at that fuel flow.  Just didn't think to re-set at 5500.  12GPH would NOT be the fuel flow I would use in my IO-360.  This review was for little vintage 4-bangers not for the IO-550 drivers.  I evaded a thunderstorm and some serious winds and rain with my temporary High Fuel Flow/power exercise.  As I stated, No regrets.  Found a new tool I will definitely be using to confirm what are theoretical safe power fuel flows and power settings for specific altitudes.  A LOP guy never hung out in the box, but he is going to break out of the theoretical absolute of lower speed in his bird.  Especially when Up High...

[jaylw314]

If you run ROP, the POH lists MP/RPM settings of 27.0/2400 as a cruise setting for 75% (10.3 gph at 25 ROP). That seems a little cray-cray in the long run, but operating under square will apparently not cause your engine to immediately blow up.

For the MP/RPM settings, I keep it simpler and just add the second digits, e.g. 7 + 4 = 11 in the above example.  If I'm operating below 20 inHg or 2000 RPM, I'm not making enough power to worry anyway, so the first digit is not that important.  If they add up to 10 or less, that's in my comfort zone while ROP.

[MyNameIsNobody]

1 hour ago, jaylw314 said:

If you run ROP, the POH lists MP/RPM settings of 27.0/2400 as a cruise setting for 75% (10.3 gph at 25 ROP). That seems a little cray-cray in the long run, but operating under square will apparently not cause your engine to immediately blow up.

For the MP/RPM settings, I keep it simpler and just add the second digits, e.g. 7 + 4 = 11 in the above example.  If I'm operating below 20 inHg or 2000 RPM, I'm not making enough power to worry anyway, so the first digit is not that important.  If they add up to 10 or less, that's in my comfort zone while ROP.

Ya, not flying 25-50ROP.  The AP I found gives easy data that I can experiment with keeping power at 65%.  I can match these and see how my plane performs.  I have "revisited" my G3 operating procedures for lean-find as my "stupidity" on NOT re-leaning with altitude changes is pretty epic....Oh well, learn something every day, right?

 

[carusoam]

Sorry Scott, I was trying to be part of the community discussion.

I was relating the IO550 to IO360 data because they are incredibly similar in this respect.  The data I gave is actual, collected this week.

So many pages had gone by I had forgotten the beginning...

Best regards,

-a-

 

[jetdriven]

17 hours ago, MyNameIsNobody said:

Ya, not flying 25-50ROP.  The AP I found gives easy data that I can experiment with keeping power at 65%.  I can match these and see how my plane performs.  I have "revisited" my G3 operating procedures for lean-find as my "stupidity" on NOT re-leaning with altitude changes is pretty epic....Oh well, learn something every day, right?

 

There is been some discussion on BT  about the EI percent of horsepower algorithm that they use. APS has written to them and offer them some tips about it. Basically the percentage of horsepower number you're looking at is not very accurate ROP and is not accurate at all LOP.   

[Bob_Belville]

45 minutes ago, jetdriven said:

There is been some discussion on BT  about the EI percent of horsepower algorithm that they use. APS has written to them and offer them some tips about it. Basically the percentage of horsepower number you're looking at is not very accurate ROP and is not accurate at all LOP.   

The % power displayed on the JPI EDM 930 on my IO360 seems to be pretty accurate LOP. Coming home from Summit Yesterday at 7000' (BARO was fairly high at ~30,45) I tweaked the FF between 8.2 and 8.8 to see how much the TAS was affected going 50 LOP and noted that the JPI displayed power from about 62% to about 65%.

[MyNameIsNobody]

1 hour ago, jetdriven said:

There is been some discussion on BT  about the EI percent of horsepower algorithm that they use. APS has written to them and offer them some tips about it. Basically the percentage of horsepower number you're looking at is not very accurate ROP and is not accurate at all LOP.   

Interesting.  That is unfortunate.  I will do some comparisons with my plane at 100 ROP and see how close they are to the AP/theoretical listings.  They worked out close to Hank's "47" formula, which is a good "basic rule" to keep power below 70 down low where "red box" and pressure issues are more pronounced.  The re-leaning/lean find at different altitudes was a duh/aha moment for me.  Cylinder temps have always been happy where I have resided for power, but tool is only as good as the input provided for sure.

[MyNameIsNobody]

20 hours ago, carusoam said:

Sorry Scott, I was trying to be part of the community discussion.

I was relating the IO550 to IO360 data because they are incredibly similar in this respect.  The data I gave is actual, collected this week.

So many pages had gone by I had forgotten the beginning...

Best regards,

-a-

 

I am sorry for snippy reply.-a-.  I re-read what you wrote and it is a good spot-on comparison.

[Shadrach]

On 9/29/2017 at 7:36 PM, Ned Gravel said:

Scott:

Isn't the red box from 50 LOP to 50 ROP at or below 7500' when you are pulling more than 70% power?

 

Good God no. 50 LOP at 7500 is leaving a lot of speed on the table. Peak to 15 LOP is a good setting at 7500. 

I run 50LOP down low (under 3000) Or more if CHTs dictate.

[Hank]

13 hours ago, MyNameIsNobody said:

Interesting.  That is unfortunate.  I will do some comparisons with my plane at 100 ROP and see how close they are to the AP/theoretical listings.  They worked out close to Hank's "47" formula, which is a good "basic rule" to keep power below 70 down low where "red box" and pressure issues are more pronounced.  The re-leaning/lean find at different altitudes was a duh/aha moment for me.  Cylinder temps have always been happy where I have resided for power, but tool is only as good as the input provided for sure.

Wish I could take credit for that, but:

• It's from MAPA's Fly By the Numbers presentation at PPP
• It's accurate for my C; your injected engine has a different Key Number that I don't know  (48? 50?)

Fly safe!