Would you look further?

[carusoam]

%bhp While ROP are a mysterious calculation...  the calculation uses measuring the limited resource in the system... volume of air flow...

a certain amount of fuel is used for cooling and the rest for power delivery... the engine manufacturers determine this calculation using a dynamometer (Dyno) with a highly instrumented engine... essentially measuring the limited resource, Air...

MAPA took these numbers and simplified them for Mooney pilots... they call them key numbers... the simplification uses MP and rpm to define the %bhp.  Be sure this collection of key numbers is an over simplification.  Each Mooney gets a set of key numbers.... to best represent what you are trying to calculate...

%bhp While LOP is less mysterious... all the fuel entering the system is being used to produce power.  Measuring FF accurately is pretty easy... the calculation uses the engine’s compression ratio to personalize it some...

 

JPI has had difficulty using a program to calculate %bhp for all engines ROP and LOP...

Without an airflow meter, %bhp While ROP requires a look-up table...

 

Do some reading from JPI, Find out how accurate the %bhp calcs actually represent your situation...

For NJM... Find out how well calibrated your K-factor really is...

 

For engine instruments this complex... verify first, then build trust... Reagan era philosophy regarding icbms was much easier... the Russians didn’t want to get killed either... your engine monitor has nothing to lose. 

PP thoughts only... not a mechanic.

Best regards,

-a-

[jaylw314]

10 minutes ago, ArtVandelay said:

If they’re assuming ROP, then it’s even worst.  I was using IO360 power schedule, but didn’t know altitude so just pick 5000-6000’ where I had matching FF. Thats why I said to check HP constant, which is used in JPI formula.

Hmm.  The IO-360 cruise power schedule lists 22/2500 as 65% and 10.8 gph (best power)?  The altitude shouldn't matter...

55% is more like 19.5/2500

[ArtVandelay]

5 minutes ago, jaylw314 said:

Hmm.  The IO-360 cruise power schedule lists 22/2500 as 65% and 10.8 gph (best power)?  The altitude shouldn't matter...

55% is more like 19.5/2500

Altitude shouldn’t matter??  This is a NA engine (M20E) I thought, so altitude and OAT matter.

And FF at 55% should be 9.6

[jaylw314]

2 minutes ago, carusoam said:

JPI has had difficulty using a program to calculate %bhp for all engines ROP and LOP...

Without an airflow meter, %bhp While ROP requires a look-up table...

Airflow is theoretically easy to calculate, it's just MP x RPM.  well, multiplied by fudge factors for friction and volumetric efficiency, so maybe not that easy 

Since RPM doesn't vary so much in practice, a lot of people just go by MP + RPM since it's easier to do in your head.

[carusoam]

Jay, the statement ‘Best power’ needs the definition to go with it... 50°F ROP?

The POH table will have that statement at the bottom....

 

Airflow is effected by things like intake design and filter restriction and that bypass door Some Mooneys have...

 

one wants know which variable is the limited one, and measure it... when this can’t be measured easily, we are stuck with a look-up table...

 

now if NJM is climbing full rich.... he starts out about 2-300°F ROP and goes further ROP as he climbs.... cylinders are being cooled at the price of FF being thrown out the exhaust...

Nothing wrong with that... it leaves plenty of space for improvement...

Best regards,

-a-

[jaylw314]

1 minute ago, ArtVandelay said:

Altitude shouldn’t matter??  This is a NA engine (M20E) I thought, so altitude and OAT matter.

Not when you're assuming a specific MP.  It's either set by altitude, throttle, or a combination of both.  You're right, OAT (compared to a standard day) does affect power, too, but only by a few percent unless you fly in Siberia (or Michigan).

[jaylw314]

2 minutes ago, carusoam said:

Jay, the statement ‘Best power’ needs the definition to go with it... 50°F ROP?

The POH table will have that statement at the bottom....

Best regards,

-a-

Actually, mine does not, so I'm assuming that's approximate 125^oF ROP

[ArtVandelay]

8 minutes ago, jaylw314 said:

Not when you're assuming a specific MP.  It's either set by altitude, throttle, or a combination of both.  You're right, OAT (compared to a standard day) does affect power, too, but only by a few percent unless you fly in Siberia (or Michigan).

Ah ok, well then for his first picture, he would almost need to be at sea level to have that high of a manifold pressure:

 

[Oldguy]

10 minutes ago, carusoam said:

ay, the statement ‘Best power’ needs the definition to go with it... 50°F ROP?

The POH table will have that statement at the bottom..

 

6 minutes ago, jaylw314 said:

Actually, mine does not, so I'm assuming that's approximate 125^oF ROP

Looks like your J is a 1986. If your POH is the 9-6-83 version, the Best Power and Economy Power definitions are at the top of the Cruise Power Schedule pages in the Performance section.

Best Power is 100 dF ROP EGT and Economy is defined as 25 dF ROP EGT.

[carusoam]

Best power has to be defined somewhere in the document.  There isn’t a standard that could be used otherwise.

Otherwise everyone would use peak EGT to get the most burnable fuel into the volume of the cylinder, generating the most power...

unfortunately health of the engine doesn’t get taken into account...

1) Avoiding pre-ignition is first...

2) Saving cylinders is second...

3) producing power is third... until running out of runway or trees are getting larger in the windshield... 

 

Fun discussion...

Best regards,

-a-

[Oldguy]

@NJMac, in looking back over your initial pics, I have to ask if there is something out of whack with your EDM 900. I ask because I see you have 116 gals. used in one photo and 496 gals. used in another. Is that a result of not resetting when you fill up or what?

Or do you have the extended, extended range tanks?

[jaylw314]

10 minutes ago, Oldguy said:

 

Looks like your J is a 1986. If your POH is the 9-6-83 version, the Best Power and Economy Power definitions are at the top of the Cruise Power Schedule pages in the Performance section.

Best Power is 100 dF ROP EGT and Economy is defined as 25 dF ROP EGT.

Whoops!  It's right there in bold letters at the top   New glasses are in order!

It actually says 55^oC ROP so that's technically 99^oF ROP

[jaylw314]

11 minutes ago, carusoam said:

Best power has to be defined somewhere in the document.  There isn’t a standard that could be used otherwise.

Otherwise everyone would use peak EGT to get the most burnable fuel into the volume of the cylinder, generating the most power...

IIRC, in our old club Cherokee, it actually defined best power as the mixture that produces the highest airspeed.  That's not a terribly helpful definition  Not all of them had EGT gauges, though

[jaylw314]

22 minutes ago, ArtVandelay said:

Ah ok, well then for his first picture, he would almost need to be at sea level to have that high of a manifold pressure:

 

The cruise power schedule has an entry for 25.8 inHg at 2500 RPM (75% power) at sea level on a standard day, so yeah, pretty close to sea level, which is probably why he was still running full rich.  The IO-360 operator manual might have a graph that shows us the maximum MP at seal level for a given RPM, but I don't have it handy...

[carusoam]

That is why....

Best needs a definition....

Best for the Fbo... who is renting the plane ‘wet’...

Best for the mechanic... selling cylinders...

Best for longevity of the engine... plane owner... Not all owners have the same priority

Best for performance of the plane... pilot who isn’t paying the bills... POH that helps sell planes...

 

The more you know about your plane, the more pleasing it becomes... fewer surprises over time...

Best regards,

-a-

 

[NJMac]

[mention=16476]NJMac[/mention], in looking back over your initial pics, I have to ask if there is something out of whack with your EDM 900. I ask because I see you have 116 gals. used in one photo and 496 gals. used in another. Is that a result of not resetting when you fill up or what?
Or do you have the extended, extended range tanks?

Before I had Willmar reseal my tanks this winter, all last year I didn't tell JPI that I refilled. I'm guessing those high numbers were when I told it I didn't refill when we filled to 1inch under full to keep from leaking.

I can't confirm the JPI is installed or calculating correctly but before this I havnt seen reason to doubt it

Sent from my SM-G930V using Tapatalk

[jaylw314]

7 minutes ago, NJMac said:

Before I had Willmar reseal my tanks this winter, all last year I didn't tell JPI that I refilled. I'm guessing those high numbers were when I told it I didn't refill when we filled to 1inch under full to keep from leaking.

I can't confirm the JPI is installed or calculating correctly but before this I havnt seen reason to doubt it

Sent from my SM-G930V using Tapatalk
 

Have you verified at some point the fuel flow is consistent with what you're putting in?  There are instructions in the user's guide for calibrating the FF K-factor. 

[NJMac]

Have you verified at some point the fuel flow is consistent with what you're putting in?  There are instructions in the user's guide for calibrating the FF K-factor. 

No. I was just happy to have my own plane. Never checked into all the details like this.

Sent from my SM-G930V using Tapatalk

[carusoam]

Something to look forward to....

1) Fuel level gauges are one way to know if you have enough fuel...

2) FF gauges are a way to double check the important FL gauges...

3) Knowing your FL gauges are calibrated to a known, useful fuel, amount is key... 1% accuracy is possible with Cies gauges...

4) Knowing your FF is calibrated to about 1% of accuracy... K-factor needs to be checked...

Verify, then trust...  There is no trusting this device, until the above steps are complete... for each individual plane...

5) this is why some people tanker fuel around...

6) Some people use a science based approach to accurately know what they have, and when they will run out, and the ability to make changes along the way...

7) With MS, and the appropriate hardware... a scientific approach is within the grasp of everyone...

8) Now we have gone from chasing an absolute EGT ghost..l to tracking down some useful details that can be used on every flight!

Nice find everyone...

Best regards,

-a-

[NJMac]

Something to look forward to....

1) Fuel level gauges are one way to know if you have enough fuel...

2) FF gauges are a way to double check the important FL gauges...

3) Knowing your FL gauges are calibrated to a known, useful fuel, amount is key... 1% accuracy is possible with Cies gauges...

4) Knowing your FF is calibrated to about 1% of accuracy... K-factor needs to be checked...

Verify, then trust...  There is no trusting this device, until the above steps are complete... for each individual plane...

5) this is why some people tanker fuel around...

6) Some people use a science based approach to accurately know what they have, and when they will run out, and the ability to make changes along the way...

7) With MS, and the appropriate hardware... a scientific approach is within the grasp of everyone...

8) Now we have gone from chasing an absolute EGT ghost..l to tracking down some useful details that can be used on every flight!

Nice find everyone...

Best regards,

-a-

Shoot. Guess ill have to go flying again soon.

 

Just making sure I understand. You're all saying not to trust the JPI until I verify? Trusting JPI should also not include the egt?

 

Sent from my SM-G930V using Tapatalk

 

 

 

[KLRDMD]

3 hours ago, NJMac said:

LOP? Most of my flights are short hops down low and i shoot for 150 ROP.

Yes, I always cruise LOP. Even short hops but nothing I do is really down low. My airport is at 3,000 MSL with density attitudes often above 5,000 ft., sometimes much higher. That's an advantage of a higher horsepower engine in a relatively slick airframe. You still get reasonable cruise speeds LOP on reasonable fuel flow. Starting at 200 HP versus 285, it is tough to go fast enough at altitude to make many people happy when LOP so they start flying ROP. My personal threshold is 160 KTAS. As long as I can get at least 160 KTAS in cruise, I'll fly LOP and I have been able to do that in my last few airplanes.

[jaylw314]

5 minutes ago, NJMac said:

Shoot. Guess ill have to go flying again soon.

 

Just making sure I understand. You're all saying not to trust the JPI until I verify? Trusting JPI should also not include the egt?

 

Yup   I think @carusoam said it more eloquently, though

[carusoam]

Fly early and often....

Consider getting wing mounted mechanical gauges to measure FL while partially filling the tanks... they take into account the nose high attitude of being on a level ramp...

Check with Cies on how they handle the partial filling... because they can electronically make an adjustment for the attitude and give an electronic reading... I don’t know if they enabled that feature or not...

Unless somebody didn’t follow the installation guidelines... the EGT and CHT sensors don’t usually require calibration... very little calibration is available...  a quick test for calibration... first flight of the day... OAT, CHT, and EGT... should be really close to each other... throw in the oilT as well...

MS had an errant reinstall of a jpi recently... improper wire type was used to extend the thermocouple wires... throws the numbers off somewhat randomly... 

Best regards,

-a-

[Marauder]

No. I was just happy to have my own plane. Never checked into all the details like this.

 

Sent from my SM-G930V using Tapatalk

 

 

I read through most of the posts and I have a few recommendations. Everything you are trying to sort through is dependent on your fuel flow being correct and all of the other factors are applied correctly (FF, degrees ROP, OAT, power settings, etc.). The later model Mooneys have more detail on the power settings and expected fuel flow.

 

In carusoam style:

 

- Calibrate your k factor so that is dead on. If you need a sounding board, let me/us know. I have mine dialed in. The key is to be accurate on how much fuel you add and calibrating using sizable fuel usage. If my FF is off more than 0.1 GPH, I would be surprised.

 

- The % HP value is nice to be able to quickly set power. Mine is off ~4%. I’m just too lazy to update it.

 

- As mentioned earlier, download the Savvy flight profile stuff and fly it. It will check your GAMI spread and also do the inflight mag check. I would use their analysis tool to check the results.

 

- I think Savvy still has a free analysis service. I would get all of the stuff set up correctly above and then fly long enough for them to look over the flight data. If it isn’t free anymore, I highly recommend the $129 service they provide. It has helped me a few times diagnose weird stuff.

 

Here are the POH tables for the F model. It has various altitude and power settings for you to benchmark on.

 

 

 

 

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[ArtVandelay]

5 hours ago, jaylw314 said:

I thought JPI's calculate HP solely by MP/RPM, which only works for ROP?  8.2 gph would be LOP for those settings...

Actually, it’s the opposite:

At the present time HP is only available on single engine 4 and 6 cylinder engines. The EDM800 calculates percent of horsepower in an Over lean condition. Lycoming & Contentinal horse power charts stop at peak EGT on the first cylinder to peak. When you are over lean, every ounce of fuel is burned & used to create horsepower and heat. Cooling is accomplished by excess air in the combustion chamber. JPI has developed an algorithm to calculate horsepower based on fuel consumption and other factors. To obtain HP in this over lean condition you must have an EDM-800 engine analyzer with fuel flow, RPM, MAP, OAT.