Running LOP on IO550N

[Ricky_231]

I recently sold my K and bought an Eagle (poor man's Ovation so I assume I can post here :-)) with the 301HP STC. The engine has just been overhauled and I spent the past 30 hours breaking it in. Now that oil consumption and temps are stable, I figured it was time to start running it LOP and stop burning 17 gph.

I have never run an engine LOP before. I have an EI MVP-50P, so I figured I'd follow the engine manual + STC guidance (50 degrees LOP for best economy) and see what happened. I set the EI on LOP mode and leaned until the last cylinder peaked, then leaned further until 50 LOP. Fuel burn went down to 12 gph (awesome!) but my airspeed also took a big hit (145 KIAS vs 160-165 KIAS I see 50 ROP).

Is that what I was supposed to see? Or did I lean too far? What are folks seeing, and how are you running your engines LOP (MAP/RPM)?

This was at 24" MAP and 2400 RPM @ 3500ft. Should I just go WOT? Or should I go higher (this flight was short so higher didn't make sense)?

LOP rookie questions probably, but I figured if anyone can help me it's this group.

Thanks in advance!

[NickG]

Sent you a PM. Yes, WOT. Assuming you have GAMI’s?

[Ricky_231]

6 minutes ago, NickG said:

Sent you a PM. Yes, WOT. Assuming you have GAMI’s?

unfortunately no GAMIs... feels like that's next on the list.

[Ragsf15e]

2 hours ago, Ricky_231 said:

I recently sold my K and bought an Eagle (poor man's Ovation so I assume I can post here :-)) with the 301HP STC. The engine has just been overhauled and I spent the past 30 hours breaking it in. Now that oil consumption and temps are stable, I figured it was time to start running it LOP and stop burning 17 gph.

I have never run an engine LOP before. I have an EI MVP-50P, so I figured I'd follow the engine manual + STC guidance (50 degrees LOP for best economy) and see what happened. I set the EI on LOP mode and leaned until the last cylinder peaked, then leaned further until 50 LOP. Fuel burn went down to 12 gph (awesome!) but my airspeed also took a big hit (145 KIAS vs 160-165 KIAS I see 50 ROP).

Is that what I was supposed to see? Or did I lean too far? What are folks seeing, and how are you running your engines LOP (MAP/RPM)?

This was at 24" MAP and 2400 RPM @ 3500ft. Should I just go WOT? Or should I go higher (this flight was short so higher didn't make sense)?

LOP rookie questions probably, but I figured if anyone can help me it's this group.

Thanks in advance!

I think you’re going to find most people cruising higher than 3500’ which makes it a little easier/safer to go wot lean of peak because mp (power) will be down some already.  You probably won’t need the full 50lop at higher altitudes (because you’ll already have lower power).  It will also depend on how even your fuel distribution is.  No matter what, you’re just making sure the last cylinder gets to lop and then look at the CHTs.  You can fine tune your mixture to keep a comfortable cht.  At that point, leaner is cooler, richer is warmer/faster.

You mentioned 145KIAS… did you mean KTAS?  Most guys Ive talked to seem to get around 165-170KTAS ON 12.5-13gph up around 9,000’ or so.

[NickG]

13 hours ago, Ragsf15e said:

I think you’re going to find most people cruising higher than 3500’ which makes it a little easier/safer to go wot lean of peak because mp (power) will be down some already.  You probably won’t need the full 50lop at higher altitudes (because you’ll already have lower power).  It will also depend on how even your fuel distribution is.  No matter what, you’re just making sure the last cylinder gets to lop and then look at the CHTs.  You can fine tune your mixture to keep a comfortable cht.  At that point, leaner is cooler, richer is warmer/faster.

You mentioned 145KIAS… did you mean KTAS?  Most guys Ive talked to seem to get around 165-170KTAS ON 12.5-13gph up around 9,000’ or so.

12.4 gph 175 ktas at 9k or so. Will generally get 172 or so 10-16k in the 11-12gph range

[hais]

On 10/17/2024 at 6:37 PM, Ricky_231 said:

set the EI on LOP mode and leaned until the last cylinder peaked, then leaned further until 50 LOP. Fuel burn went down to 12 gph

In case you haven't yet, you might find this useful:

https://youtu.be/X-tKyiUZ3ts?feature=shared

[dkkim73]

This might be referenced in the video, but you probably want to determine your peak spread as well ("GAMI spread"), the fuel flow difference between your first and last injector. You're already aware of using last to peak, but if it's too wide, it may not work as well as you want. 

See the procedure here under Savvy Profile: 

https://www.savvyaviation.com/resources/#resources

I also did the Deacon APS video course, thought it was worth it, though you can find most of the info for free. Including here on MS.

HTH 

David

ETA: with the 550 you ought to be able to get a lot of flexibility once you get it all dialed in...

[Danb]

On 10/17/2024 at 9:37 PM, Ricky_231 said:

I recently sold my K and bought an Eagle (poor man's Ovation so I assume I can post here :-)) with the 301HP STC. The engine has just been overhauled and I spent the past 30 hours breaking it in. Now that oil consumption and temps are stable, I figured it was time to start running it LOP and stop burning 17 gph.

I have never run an engine LOP before. I have an EI MVP-50P, so I figured I'd follow the engine manual + STC guidance (50 degrees LOP for best economy) and see what happened. I set the EI on LOP mode and leaned until the last cylinder peaked, then leaned further until 50 LOP. Fuel burn went down to 12 gph (awesome!) but my airspeed also took a big hit (145 KIAS vs 160-165 KIAS I see 50 ROP).

Is that what I was supposed to see? Or did I lean too far? What are folks seeing, and how are you running your engines LOP (MAP/RPM)?

This was at 24" MAP and 2400 RPM @ 3500ft. Should I just go WOT? Or should I go higher (this flight was short so higher didn't make sense)?

LOP rookie questions probably, but I figured if anyone can help me it's this group.

Thanks in advance!

As far as loss speed i goes I generally fly Lop but my trip this week had 45+ headwinds so i flew Rop at 10,000 feet i had 30/2450 19.8  GPH hottest cylinder 350 true airspeed 202 return trip LOP 9,000 feet 30/2450 14.5 GPH hottest cylinder 315 true airspeed 184.. thats about 5 gallons difference for 18 miles per hour which is a lot. Therefore my engine runs cool at LOP CHTs 295-315 very efficient saving on a 4 hour trip 20 gallons at 7.00 yields a savings of about $140 for two flight nice!! Oh kept TITs around 1580

D

[Bolter]

On 10/17/2024 at 6:37 PM, Ricky_231 said:

I recently sold my K and bought an Eagle (poor man's Ovation so I assume I can post here :-)) with the 301HP STC. The engine has just been overhauled and I spent the past 30 hours breaking it in. Now that oil consumption and temps are stable, I figured it was time to start running it LOP and stop burning 17 gph.

I have never run an engine LOP before. I have an EI MVP-50P, so I figured I'd follow the engine manual + STC guidance (50 degrees LOP for best economy) and see what happened. I set the EI on LOP mode and leaned until the last cylinder peaked, then leaned further until 50 LOP. Fuel burn went down to 12 gph (awesome!) but my airspeed also took a big hit (145 KIAS vs 160-165 KIAS I see 50 ROP).

Is that what I was supposed to see? Or did I lean too far? What are folks seeing, and how are you running your engines LOP (MAP/RPM)?

This was at 24" MAP and 2400 RPM @ 3500ft. Should I just go WOT? Or should I go higher (this flight was short so higher didn't make sense)?

LOP rookie questions probably, but I figured if anyone can help me it's this group.

Thanks in advance!

Usually someone includes a warning that 50ROP is a terrible operating point for the engine, depsite the POH's reference to operating there.  Either be richer, leaner, or well down on power (I think less than 65% is OK).  

For my own practice, at 3500 MSL, I will be a little throttled back, ROP or LOP.  It is rare that I am crusing that low, and it tends to be more fuel burn than I like.  Above 5500 MSL or so, it is WOT, 2500 rpm and LOP at 13 GPH or so to get 62-64% power.  This is 170 KTAS in most cases, but would be a little higher for a non-TKS wing.  

There are several recent threads on OVations/Eagles running LOP, including photos.

[NickG]

17 hours ago, Bolter said:

Usually someone includes a warning that 50ROP is a terrible operating point for the engine, depsite the POH's reference to operating there.  Either be richer, leaner, or well down on power (I think less than 65% is OK).  

For my own practice, at 3500 MSL, I will be a little throttled back, ROP or LOP.  It is rare that I am crusing that low, and it tends to be more fuel burn than I like.  Above 5500 MSL or so, it is WOT, 2500 rpm and LOP at 13 GPH or so to get 62-64% power.  This is 170 KTAS in most cases, but would be a little higher for a non-TKS wing.  

There are several recent threads on OVations/Eagles running LOP, including photos.

Do you have the 310 HP STC? 

[carusoam]

My favorite discussion…. 

Always take the extra time to type a lot of extra details…

just when you think they aren’t important… somebody is going to ask for them anyways…

 

typical flight for my O3 powered O1…

Take off… full rich, or blue/white box if using EGT method at higher altitudes MSL…

 

climb… leaning above 3k’ or so… using the blue box, or white box if you are G1000 equipped.

the boxes keep the EGTs within 2-300°F ROP…

modern Mooney’s with IO550s have calibrated EGT gauges providing real data…

 

Cruise… Above 8k’, the MP is too low to damage the engine…

I typically run about 2°F LOP… ensuring all of the fuel gets converted to noise…

 

Gamis are good…

but, the io550 may already have a Gami spread of about 0.1gph between all of the cylinders…

So… measure your gami spread first…

the curvy intake tubes you paid for actually do something good!

 

If you have the 310hp STC…

climb out at 2700

cruise climb at 2550

cruise at 2550

Some people descend using a lower rpm…

others will adjust the descent rate to maximize ground speed… while being cognizant of the maneuvering speed and bumps…

 

going 50°F LOP has its limitations…

use it when you need to, not because it is a good idea all the time.

getting used to these ideas probably takes a year… getting to know a chart of data, then speeding your way through leaning procedures properly…

 

Start with the blue/white box…

Climbing LOP… nice idea, but too challenging to get right…

with 310hp, your climb rate is 2k+fpm…you won’t be climbing for all that long…

Best regards,

-a-

[NickG]

1 hour ago, carusoam said:

My favorite discussion…. 

Always take the extra time to type a lot of extra details…

just when you think they aren’t important… somebody is going to ask for them anyways…

 

typical flight for my O3 powered O1…

Take off… full rich, or blue/white box if using EGT method at higher altitudes MSL…

 

climb… leaning above 3k’ or so… using the blue box, or white box if you are G1000 equipped.

the boxes keep the EGTs within 2-300°F ROP…

modern Mooney’s with IO550s have calibrated EGT gauges providing real data…

 

Cruise… Above 8k’, the MP is too low to damage the engine…

I typically run about 2°F LOP… ensuring all of the fuel gets converted to noise…

 

Gamis are good…

but, the io550 may already have a Gami spread of about 0.1gph between all of the cylinders…

So… measure your gami spread first…

the curvy intake tubes you paid for actually do something good!

 

If you have the 310hp STC…

climb out at 2700

cruise climb at 2550

cruise at 2550

Some people descend using a lower rpm…

others will adjust the descent rate to maximize ground speed… while being cognizant of the maneuvering speed and bumps…

 

going 50°F LOP has its limitations…

use it when you need to, not because it is a good idea all the time.

getting used to these ideas probably takes a year… getting to know a chart of data, then speeding your way through leaning procedures properly…

 

Start with the blue/white box…

Climbing LOP… nice idea, but too challenging to get right…

with 310hp, your climb rate is 2k+fpm…you won’t be climbing for all that long…

Best regards,

-a-

I use basically the same method on my 94 O with 310HP except I climb WOT, 2700 full rich as I climb lean to keep 1250 on EGT to altitude. My home field is 2550 AGL. John Deakin's articles are gold!

[Bolter]

20 hours ago, NickG said:

Do you have the 310 HP STC? 

Yes.  I should have specified when there are so many variants of the IO 550 depending on model and year.  

[carusoam]

Quick reminder…

IO550s love their cooling fuel at WOT…

what is your max FF?

28, 29, 30gph, or more?

 

PP thoughts only, not a mechanic…

-a-

[NickG]

3 minutes ago, carusoam said:

Quick reminder…

IO550s love their cooling fuel at WOT…

what is your max FF?

28, 29, 30, or more?

 

PP thoughts only, not a mechanic…

-a-

My fuel flow, max power at sea level is 29 GPH

[Jerry Pressley]

mine is 9 gph

[EarthboundMisfit]

If you're new to LOP ops, the APS course is the benchmark for understanding engine management. 

There is an online version ($395, cheapest learning you might ever have!) - https://www.advancedpilot.com/onlinecourse.html - and the classroom course where you can bounce your thoughts off others is worth attending. 

Then you get to apply those principles to your own aircraft.  Should be part of the PPL curriculum!!

[marcusku]

I know this topic has been beaten to death.  In cruise at 2500 rpm, 22", 50 LOP I see a difference of 60-80 degrees.  Is this ok?  At 50 LOP my max egt can be about 1470-1480, is this acceptable.  What EGT is too hot?  I know the blue arc goes to 1450.  Could be in my head but running in this configuration I notice very slight hiccups, is this normal in LOP or should LOP be just like ROP?