310 HP STC Conversion Performance Data

[Furzol]

Hi All,

I have an Ovation 2GX with the 310 HP STC conversion. Only one new chart in the POH per the STC paperwork.

Anyone know where to find data on Cruise Settings operation.? My POH has data for the 280 HP engine. Perhaps I should just get a 3GX POH. Is there a good source for POHs?

 

I just upgraded to Performance level in ForeFlight and they may have the other data for runway and climb performance.

Thanks as Always!

[kortopates]

The Performance tables are in the TCM IO-500 Installation and Operators Manual OI-16.

Its not free, but perhaps you can find a copy searching on the internet.

Getting a copy of the O3 POH would be a good idea.

Edited October 28, 2021 by kortopates

[ilovecornfields]

[StevenL757]

@Furzol….this   ^ ^ ^ ^

Note the column under each power setting for “2550” in the RPM row.  Use this RPM religiously for climb after takeoff, all through cruise, and during descent.  It was developed and recommended by the STC’s originator, Bob Minnis, during extensive flight testing to be the most optimal power setting for the 310HP upgrade.  More on that if you want…PM me for details.

Steve

[Jeff_S]

The 2550 RPM setting was indeed identified by Bob Minnis during the STC conversion process, but it seems a bit dated with the engine instrumentation you have built into your G1000.  I find 2550 to be a bit loud for a constant cruise, and it will drive your CHTs higher.  I usually dial back to 2450 and WOT at cruise altitudes, and then use the lean finder to get to 25° LOP.  Interestingly, this correlates pretty closely to the numbers in the chart.  My point is that you don't really need to use that chart because you have better instrumentation available to you to manage fuel flow, CHTs and EGTs to stay within acceptable limits.  If you're new to this, I would encourage you to search out articles by John Deakin and Mike Busch on the best ways to operate these IO-550 engines...it's great educational material.  Good luck and fly lots!

[ilovecornfields]

4 hours ago, StevenL757 said:

@Furzol….this   ^ ^ ^ ^

Note the column under each power setting for “2550” in the RPM row.  Use this RPM religiously for climb after takeoff, all through cruise, and during descent.  It was developed and recommended by the STC’s originator, Bob Minnis, during extensive flight testing to be the most optimal power setting for the 310HP upgrade.  More on that if you want…PM me for details.

Steve

I like to fly at 2300 RPM but notice it’s not listed in that chart. I’ve heard from several other sources that 2550 is the most “efficient” configuration as well. Is there any harm in cruising at 2300 RPM if I’m not in a hurry and the CHTs are above 300? 100 LL ain’t cheap, you know. This usually ends up being about “50% power” according to my JPI. 

[Jeff_S]

2 hours ago, ilovecornfields said:

I like to fly at 2300 RPM but notice it’s not listed in that chart. I’ve heard from several other sources that 2550 is the most “efficient” configuration as well. Is there any harm in cruising at 2300 RPM if I’m not in a hurry and the CHTs are above 300? 100 LL ain’t cheap, you know. This usually ends up being about “50% power” according to my JPI. 

There is no harm at all. Mike Busch would tell you to cruise at a low RPM/high MAP setting all day long, just manage your fuel flow correctly to stay out of the range of max cylinder head pressure (e.g. LOP or very ROP).  It's really always just a function of your personal choice between speed and fuel flow, as long as you keep your engine temps in an acceptable range.

[Furzol]

All,

Thank you so much for the information! It has been such a pleasure to join this group since I bought the airplane in July. You are all a wealth of information. I have a few notes and questions below. Please do not feel the need for long responses.

I will get the Performance Tables from the TCM I0-550 Manual along with a 3GX Manual.

I am on board and read all of Mike Busch's books, signed up for his Savvy program, and have uploaded engine data. (engine running well)

Again, brief is fine. I have the normally aspirated IO-550.

1) I've been flying 60-65% LOP in cruise. IF I wanted to fly a bit faster (since I bought a Mooney) I'd like to try 75% cruise ROP some times. You all know the 'Red Fin' chart Busch refers to by Gordon Feingold. It shows approximately 75% 180 degrees ROP to stay our of red zones. Any further suggestions or techniques?

2) Back to 50 LOP Cruise: What do you do with the Throttle and Mixture on descent (forgetting out of yellow or green arc etc.)? I've flown with 2 mechanic and 4 CFI's.  Sharp guys including my mechanic Brian Kendrick and Kevin K. at Mooney Aircraft. Different answers from all of them. Varied from keeping the same EGT in descent (Busch doesn't even look at EGT's), slowly enrichening while pulling back the throttle, to doing nothing and then in the pattern at lower power settings simply enrichening to get back to ROP. As you know if you simply enrichen on the descent your now dealing with crossing back over into ROP ops and temps go up initially.

Suggestions or techniques?

3) Busch's 'Big Pull' for LOP at cruise. He doesn't like Lean Assist as it's based on EGT's and it's too slow and thus too much time is spent with higher combustion chamber pressures. It's all about CHT's and keeping down the ICP's.

You know all of this.

Suggestions or techniques on making that pull over to LOP.

Many thanks for all of your thoughts. I hope to meet everyone at a Mooney Summit or MAPA event some day.

John

 

 

 

[FlyingScot]

Hi All -

A couple of years ago I built an app that I use to calculate the power settings for my 310HP O2 - I posted it here, as both an excel spreadsheet (Best) which I run on my iPhone/iPad Mini, as well as a standalone app (OK, but i don't use that version anymore - less info).

After a lot of reading, I built this performance model from several sources, though, the guts of the parameterization comes from a nice analysis done by Calle Hedberg and John Smith at MGL (https://www.mglavionics.co.za/tools.html).  I have attached the spreadsheet version; as constructed it is specific for the 310 HP NA IO-550. It could be tailored for other engines with the use of appropriate parameters. 

Since %HP can’t be measured directly, all engine monitors use a model of some type to calculate %HP based on sensor data. This model is pretty good, and more sophisticated than most in use. 

In practice, it seems  to produce excellent results, consistent with experience and within a few percent at worst of the published tables where they overlap. It’s much more flexible than interpolating across a table.  It does both LoP and RoP (the interesting case) and plots out a variety of data, including for grins the lean offsets required to keep out of the yellow zone of the redfin for a given set of inputs. 

Excel look like this (fits on the screen nicely):

LOP (click on LOP/ROP to select):

 

ROP Calculation:

 

Thought this might be interesting/useful/relevant, so if it is, it's yours. If you do use it, I would welcome feedback on if it produces results that are consistent with your engine monitors, etc. 

Enjoy! Cheers - Bob

 

Use this version of the Excel Spreadsheet, it has some improvements over 2020 post - EDITED: Here's a cleaned up version - the Halloween Edition of sorts:

IO-550N Performance Calculator - iOS - 2021 Oct 31.xlsx

 

[Furzol]

Thanks Bob! I will take a look. I have the 'N' engine so a bit different per notes above.

John

[carusoam]

Notes…

Bob Minnis is the IO550 Guy, the 310hp guy, a genuine aircraft engine guru…

2550rpm is the most efficient way to operate the TopProp…. But, if you like 2300rpm… you are going to see efficiency gains by going a touch slower, more comfortably… 

And if you want to go for speed…. 2700rpm is good too… flaming dragon mode for NA Mooneys!
 

Go speed and efficiency!

Best regards,

-a-

[carusoam]

On 10/30/2021 at 6:26 PM, Furzol said:

All,

Thank you so much for the information! It has been such a pleasure to join this group since I bought the airplane in July. You are all a wealth of information. I have a few notes and questions below. Please do not feel the need for long responses.

I will get the Performance Tables from the TCM I0-550 Manual along with a 3GX Manual.

I am on board and read all of Mike Busch's books, signed up for his Savvy program, and have uploaded engine data. (engine running well)

Again, brief is fine. I have the normally aspirated IO-550.

1) I've been flying 60-65% LOP in cruise. IF I wanted to fly a bit faster (since I bought a Mooney) I'd like to try 75% cruise ROP some times. You all know the 'Red Fin' chart Busch refers to by Gordon Feingold. It shows approximately 75% 180 degrees ROP to stay our of red zones. Any further suggestions or techniques?

2) Back to 50 LOP Cruise: What do you do with the Throttle and Mixture on descent (forgetting out of yellow or green arc etc.)? I've flown with 2 mechanic and 4 CFI's.  Sharp guys including my mechanic Brian Kendrick and Kevin K. at Mooney Aircraft. Different answers from all of them. Varied from keeping the same EGT in descent (Busch doesn't even look at EGT's), slowly enrichening while pulling back the throttle, to doing nothing and then in the pattern at lower power settings simply enrichening to get back to ROP. As you know if you simply enrichen on the descent your now dealing with crossing back over into ROP ops and temps go up initially.

Suggestions or techniques?

3) Busch's 'Big Pull' for LOP at cruise. He doesn't like Lean Assist as it's based on EGT's and it's too slow and thus too much time is spent with higher combustion chamber pressures. It's all about CHT's and keeping down the ICP's.

You know all of this.

Suggestions or techniques on making that pull over to LOP.

Many thanks for all of your thoughts. I hope to meet everyone at a Mooney Summit or MAPA event some day.

John

 

 

 

John,

 I like your logic up to a point…

The 50°F LOP… is one of those things….

1) If you fly at 10k’…. You are well above the red fin territory in you NA Mooney…

2) Adding LOP to that… is similar to pulling the throttle back…. Why would you want to do that?

3) I tend to use Altitude as a few more minutes of safety drive… in the event of an off airport experience…

4) a few degrees LOP… allows maximum power available, outside the red fin territory, and no other CHT issues…

5) If you are pulling back on the throttle, going that deep LOP, saving the engine…. Or flying around at low altitudes… that may make sense…

6) Having a discussion with Bob Minnis would be great!

7) Often around here… you will see MSers climb at FT, lean using the G1000’s white box, climb to altitude…. Cruise at WOT, leaned to peak so all cylinders are slightly LOP, and do an inflight mag test somewhere in the middle of the flight… with 2700rpm available… 2550 is a great option to have…   (2700 is great for getting off the ground and clearing trees…. And E-descents….)

8) The advantage of all cylinders being Lop… all the lead is being burned, no excess fuel being used for cooling… when it is not required…

9) Going any more LOP at altitude has skipped any extra value that it gets at lower altitudes…

10) The IO550 Mooneys have very nice instrumentation and sensor locations when it comes to reading/using EGT data… there is a very precise Ship’s EGT gauge location… we actually have 7 EGT instruments… not just six…

11) Raw EGT data actually means something when using this gauge… 

12) Of course… somebody goofed up the tag name on the G1000 for Ovations… does yours say TIT on the G1000?

13) Most Ovations don’t have a turbine to measure an inlet temperature….   it’s a relic of the Mooney/Garmin team’s inability to work together all of the time…

14) along with the power chart from the 310hp STC….  Look up the MAPA key numbers method for simple math in your head kind of way of adjusting MP, and RPM to get %power you want…. That’s an easy way compared to memorizing two power charts…

15) Let’s talk max FF… what is your’s set at during T/O at Sea Level?  Many IO550s in the field are set too lean for good CHT control… from Missiles to O3… 25, 27, 28, 29, or 30 gph?

Go IO550!

PP thoughts only, not a mechanic…

Best regards,

-a-

[Jeff_S]

On 10/30/2021 at 6:26 PM, Furzol said:

1) I've been flying 60-65% LOP in cruise. IF I wanted to fly a bit faster (since I bought a Mooney) I'd like to try 75% cruise ROP some times. You all know the 'Red Fin' chart Busch refers to by Gordon Feingold. It shows approximately 75% 180 degrees ROP to stay our of red zones. Any further suggestions or techniques?

I don't have any idea what HP I fly at, nor should you care with the G1000 instrumentation available to you.  Remember that 8500' density altitude is your magic line. If you are above that (and you can determine this easily from the Aux menu on the G1000) you can run whatever power setting you want, as you will not cross into the danger zone. If you want to go fast, burn more fuel. If you want to be efficient, go as LOP as you desire. Now, if you are staying below that line, you do want to manage power to avoid damage. You can pull the throttle and reduce RPM, and you should always lean to save fuel anyway.  But I've developed a few flight profiles that I use depending on my mood, as follows:

• Loafing around, I use 20"/2400 and pull fuel to 10.5 GPH.  Interestingly, this still results in around 150KTAS, which is exactly what my J model used to do. So you can fly the Ovation like a J if you want!
• Low altitude cruise, WOT/2450, then at least 25° LOP, monitor CHT to make sure the highest stays below 350°.
• High altitude cruise, WOT/2450 and slightly LOP, which results in 12.5-13.5 GPH depending on altitude.
• Race mode, WOT/2600 and 26 GPH for cooling (and winning races!)

2) Back to 50 LOP Cruise: What do you do with the Throttle and Mixture on descent (forgetting out of yellow or green arc etc.)? I've flown with 2 mechanic and 4 CFI's.  Sharp guys including my mechanic Brian Kendrick and Kevin K. at Mooney Aircraft. Different answers from all of them. Varied from keeping the same EGT in descent (Busch doesn't even look at EGT's), slowly enrichening while pulling back the throttle, to doing nothing and then in the pattern at lower power settings simply enrichening to get back to ROP. As you know if you simply enrichen on the descent your now dealing with crossing back over into ROP ops and temps go up initially.

Suggestions or techniques?

Those are indeed sharp guys you mention, but I think the differences are solely based on personal preference. On descent, you can slightly enrich (if you were LOP at the top) but have to watch the CHTs. Or you can just leave it alone and enrich once you level off or prepare to land. I usually do the latter.  If I have to make a significant descent on an IFR plan and then still have a ways to go at the new altitude, I'll just enrich to ROP and then go through the lean procedure again to find the new LOP fuel burn.

3) Busch's 'Big Pull' for LOP at cruise. He doesn't like Lean Assist as it's based on EGT's and it's too slow and thus too much time is spent with higher combustion chamber pressures. It's all about CHT's and keeping down the ICP's.

You know all of this.

Suggestions or techniques on making that pull over to LOP.

I know that MB doesn't like to use lean finder, but I think his concern is overblown, especially if you're at significant altitude. As noted above, you may already be at the point where it doesn't matter, or you've pulled power a bit if you're lower. I have never seen my EGTs go up dramatically when using the lean finder on the G1000. They pretty much stay where they were until they start to drop. Of course, I'm leaning throughout the climb, so that would contribute to this effect. So I do lean pretty aggressively to get close to where I know the temps will top out, but then I slow it down a touch to dial in exactly what I want.

Many thanks for all of your thoughts. I hope to meet everyone at a Mooney Summit or MAPA event some day.

John

 

 

 

See my thoughts inside your quote box questions, above.

[skyking1]

Hello can anyone show the ff at takeoff on a screaming Eagle! I used to have it set before overhaul at 29-30 but Mech says 27.2 ! Not enough and runs hot

[StevenL757]

The STC says 27.3 max.  More is ok up to about 31, but I've found the best place on my engine was 29.1.

Edit:  "engine" = IO550N8B, S/N 1010199 (if that matters)

Edited November 17, 2021 by StevenL757

[Furzol]

On 11/1/2021 at 12:05 AM, carusoam said:

John,

 I like your logic up to a point…

The 50°F LOP… is one of those things….

1) If you fly at 10k’…. You are well above the red fin territory in you NA Mooney…

2) Adding LOP to that… is similar to pulling the throttle back…. Why would you want to do that?

3) I tend to use Altitude as a few more minutes of safety drive… in the event of an off airport experience…

4) a few degrees LOP… allows maximum power available, outside the red fin territory, and no other CHT issues…

5) If you are pulling back on the throttle, going that deep LOP, saving the engine…. Or flying around at low altitudes… that may make sense…

6) Having a discussion with Bob Minnis would be great!

7) Often around here… you will see MSers climb at FT, lean using the G1000’s white box, climb to altitude…. Cruise at WOT, leaned to peak so all cylinders are slightly LOP, and do an inflight mag test somewhere in the middle of the flight… with 2700rpm available… 2550 is a great option to have…   (2700 is great for getting off the ground and clearing trees…. And E-descents….)

8) The advantage of all cylinders being Lop… all the lead is being burned, no excess fuel being used for cooling… when it is not required…

9) Going any more LOP at altitude has skipped any extra value that it gets at lower altitudes…

10) The IO550 Mooneys have very nice instrumentation and sensor locations when it comes to reading/using EGT data… there is a very precise Ship’s EGT gauge location… we actually have 7 EGT instruments… not just six…

11) Raw EGT data actually means something when using this gauge… 

12) Of course… somebody goofed up the tag name on the G1000 for Ovations… does yours say TIT on the G1000?

13) Most Ovations don’t have a turbine to measure an inlet temperature….   it’s a relic of the Mooney/Garmin team’s inability to work together all of the time…

14) along with the power chart from the 310hp STC….  Look up the MAPA key numbers method for simple math in your head kind of way of adjusting MP, and RPM to get %power you want…. That’s an easy way compared to memorizing two power charts…

15) Let’s talk max FF… what is your’s set at during T/O at Sea Level?  Many IO550s in the field are set too lean for good CHT control… from Missiles to O3… 25, 27, 28, 29, or 30 gph?

Go IO550!

PP thoughts only, not a mechanic…

Best regards,

-a-

 

On 11/17/2021 at 9:14 AM, StevenL757 said:

The STC says 27.3 max.  More is ok up to about 31, but I've found the best place on my engine was 29.1.

Edit:  "engine" = IO550N8B, S/N 1010199 (if that matters)

I agree with above. Busch uses a quick and easy estimate that is equal to HP. 310 HP equals 31 GPH maximum and he likes it. More fuel, more cooling.

My IO550G also runs well at a bit over 29 GPH on Takeoffnand my mechanic wants it there.

[Furzol]

Anthony,

Thank you so much for the notes. Very helpful. Sorry for the late reply.

See below

 

John,

 I like your logic up to a point…

The 50°F LOP… is one of those things….

1) If you fly at 10k’…. You are well above the red fin territory in you NA Mooney…

Understood.

2) Adding LOP to that… is similar to pulling the throttle back…. Why would you want to do that?

Agreed

3) I tend to use Altitude as a few more minutes of safety drive… in the event of an off airport experience…

So do I.

4) a few degrees LOP… allows maximum power available, outside the red fin territory, and no other CHT issues…

Seems logical. I shouldn't get hung up on 50 LOP when it no longer applies.

5) If you are pulling back on the throttle, going that deep LOP, saving the engine…. Or flying around at low altitudes… that may make sense…
OK
6) Having a discussion with Bob Minnis would be great!

I may track him down but enough experts who know his writings here on-line it seems.

7) Often around here… you will see MSers climb at FT, lean using the G1000’s white box, climb to altitude…. Cruise at WOT, leaned to peak so all cylinders are slightly LOP, and do an inflight mag test somewhere in the middle of the flight… with 2700rpm available… 2550 is a great option to have…   (2700 is great for getting off the ground and clearing trees…. And E-descents….)

That's what I'm doing now though at 2500 RPM

8) The advantage of all cylinders being Lop… all the lead is being burned, no excess fuel being used for cooling… when it is not required…

Yes

9) Going any more LOP at altitude has skipped any extra value that it gets at lower altitudes…

Makes Sense

10) The IO550 Mooneys have very nice instrumentation and sensor locations when it comes to reading/using EGT data… there is a very precise Ship’s EGT gauge location… we actually have 7 EGT instruments… not just six…

Didn't know that.

11) Raw EGT data actually means something when using this gauge… 

I agree more precise. As you know M. Busch could care less about EGT. He doesn't even look at it. Just one opinion but his argument is compelling.

It's all about ICP's (CHT is our only view of that with the current instrumentation)

12) Of course… somebody goofed up the tag name on the G1000 for Ovations… does yours say TIT on the G1000?

I think mine says EGT.

13) Most Ovations don’t have a turbine to measure an inlet temperature….   it’s a relic of the Mooney/Garmin team’s inability to work together all of the time…

Old stuff.

14) along with the power chart from the 310hp STC….  Look up the MAPA key numbers method for simple math in your head kind of way of adjusting MP, and RPM to get %power you want…. That’s an easy way compared to memorizing two power charts…

Great. I'll look that up or call MAPA. I'm all for easy math.

15) Let’s talk max FF… what is your’s set at during T/O at Sea Level?  Many IO550s in the field are set too lean for good CHT control… from Missiles to O3… 25, 27, 28, 29, or 30 gph?

I'm 29.1-29.7 depending on conditions. Runs great.

Go IO550!

PP thoughts only, not a mechanic…

Best regards,

-a-

[Furzol]

On 11/1/2021 at 6:46 AM, Jeff_S said:

See my thoughts inside your quote box questions, above.

Jeff,

Sorry for the late reply. This is great information. Appreciate your thoughtful response.

1) Flight profiles look great and I will keep those notes.

2) I'm sticking with the latter now as well and simply leaving the mixture alone in descent with small reductions on the MP. I will enrichen in the approach environment.

3) I see what your doing during Lean Assist. I think we are both doing it by the book. As you know Busch wonders why we are bothering with EGT. My problem is that he does not give much specific guidance as to what CHT's to look for other than below certain numbers....380 for the Continentals etc.. The process and system are set up to use EGT's. We are not hurting anything as you say and there is no one answer.

Thanks again!

John

[carusoam]

PP thoughts only…

1) The STC for the 310 hp engine gives a range of FF…

2) The documented range in the STC is usable, but simply leaves CHTs higher than some owners would like…

3) The same situation, occurs for the Missile’s 300hp set up, only warmer…

4) Mr. Busch supplies excellent input, one of his team mates is around here often…

5) A couple of challenges arise…

6) It is possible to have too much FF, so there is a limit, even in the experimental world… the air / fuel ratio has a limit…

7) Oddly, somebody documented adjusting the FF to higher levels in a magazine article, using the Screamin’ Eagle…

8) Marketing departments may not like the nmpg numbers achieved during T/O and climb…

9) Owners prefer the better CHT control, when T/O and climb only last a few minutes, at 2kfpm…

10) Acclaim drivers enjoy the same performance all the way to the FLs…

11) The limits of GA Part 91 documentation… covering a complete range of MP, airflow, and fuel flow, over wide range of temps can get really expensive….

12) some times the greats of aviation give awesome presentations at Mooney Summit…

 

The IO550 is an amazing machine… designed and built for a lot more hp than 310…

Some people have put two IO550s on their planes… 
 

Still only PP thoughts…

Best regards,

-a-