IO 360 M1B FF at T/O full power

[Airhead]

Now this is getting interesting. I personally have learned a lot during this investigation into my (possible) problem, both from data contained herein (albeit with a little drift as normal), and from further reading.

I think so far I have some very useful data from this post, as well as good points concerning comparision of data taken at different atmospheric conditions. Therefore, a range in flows should be expected, even with identical engine/prop/FI setups. However, I still think we are seeing that the M1B/Hartzell CS/PA FI gives a range of FF somewhat on the low side of the overall responses (but please keep the data coming in, particularly for this specific setup) and that my FF is not abnormally low. That is half of the answer I was trying to get by making this post, the other half being is this FF (15-16 gph at full power T/O) )so low as to be detrimental to engine life or performance? That is obviously only answerable by each individual owner , but I don't believe the complete answer lies in the Lycoming manual.

One test I have not yet performed that has been mentioned here and in most writings about this subject (and specifically mentioned in my discussions with Precision Airmotive as the definitive test as to whether my FI is delivering low flow during full power) is leaning from full rich to peak EGT at full power setting. I should see about at least 100 to 200 degree increase (hopefully at least 150, and no, I will not try this during T/O ). Will report back on this.

Response to Davd Brown's comments;
Well taken concerning engine thrust movement possibly affecting cable/arm movement. Was going to check this possibility.

My probes are all at 2 inches from head, and the spread I refer to is min and max between the 4 cylinders, ie, that (as I understand it) would indicate I am getting fairly even fuel distribution to the cylinders, and the reason I think credit is due PA is because the spider & injector nozzles are supplied as part of their system. The EGT at full power T/O is 1320-1330 (hotest cyl) at about 500 ft. (my airport is at EL. 40) At altitude (have not yet performed low level leaning tests as mentioned above) I see 1430 peak at 60 to 75 % power setting.

My K value has been adjusted only in small increments, and I did see a small drop in indicated FF as would be expected. I have kept a full accounting of my fuel burned and added since initial fill up at hour 1. I only made small incremental K adjusments (3 so far) at the point when the Dynon EMS (running total) fuel consumption exceeded my actual (carefully measured) consumption by a total of 2-3 gal (initially about 10 to 12 hours hobbs). However, I will continue to track this.

I went back and looked at my downloaded data (using Savvy Analysis) and noticed that although my airport is near sea level, since Florida temps are typically so far above normal, I have not yet flown at a DA of less than 500 and most flights started at 1000-2000' DA.

[BillL]

Bob,

Also consider the fuel density varies in batch and temperature. I just looked at density and with temp it is .16%/DegC. This may affect variance and may explain why the factory setting would be richer than "best power" as listed on charts. Another reason for higher than dyno stabilized FF would be that the engine is not fully up to temp on TO and will pump more air (and thus fuel) than a thermally stabilized engine.

None of this gives a definitive number for fuel flow, but may help (at least me) understand why real TO it is set different than the "best performance" nominal published for the engine.

Regarding your fuel flow decrease, you didn't happen to go through the fuel flow path and snug up the fittings after the first flights did you? Just wondering if the FF drop is real.

Good thread, this information will be helpful when I fly as your configuration is like mine.

[RV7A Flyer]

Originally Posted by RV10inOz

What do you think all the variances are about?
The simple way to tell is going through 500' AMSL you should get 1250-1300dF EGT or there about on each cylinder. But with the following stipulations. WOT/2700/Full rich, sea level & ISA day, static mag timing at 25dBTDC, 8.5:1 CR engine, all plugs in good order, no induction leaks, even half reasonable F/A ratio's (i.e.less than perfect GAMI spread).

I presume you meant 5000', not 500'?

(EDITED: correction...I think you meant 500' AGL, not MSL, in which case your statement makes more sense...but my situation is unchanged, as below...essentially no change in measured values in the 1st 500' of takeoff...I'm there before turning crosswind )

I don't know about WOT/2700 at 5000' because I never do that. But looking at my data, at 1000', WOT/2700/full rich (I've never seen an ISA day , so we'll have to fudge that), 25 BTDC, 8.5:1, plugs just cleaned and gapped at annual, no leaks, GAMI spreads 0.1 or thereabouts, I get EGTs of (hey, guess what?) 1250-1280 (but I thought exact values of EGTs didn't matter because placement could affect the reading????). I also have CHTs < 400 (or just a tad above 400 on hot summer days, easily fixed by lowering the nose). Most recent flight had 15.5 gph.

So I've got values that seem to match the other 5 with the same engine/prop combo, are in line with whatever info we can glean from Lycoming, meet your EGT criteria, keep the cylinders reasonably cool and below 400...what's wrong here? What would upping the FF rate at full rich do "better"?

And...this is how the thing came from the factory, so is Lycoming all wet on how to set up their engines?

And...what would I do about it, anyway? I'm not going to tear apart my FI servo, I get good (28 psi engine-driven pump only, > 30 psi w/ boost pump) fuel pressure, mixture control is on the mechanical stop on the servo...what else would I do? Change the injectors to ones with bigger ports? I'm serious...I don't know what I'd change if what I have is wrong.

Two other things (sorry for the lengthy post with multiple questions)...I see "FF should be HP/10". Hmmmm...sounds like a "magic number" to me (and everyone admits it's just a rule of thumb). HP is an artificial number, not tied to any fundamental constants. 10 is, as always, a nice, round number, easy to remember, but again, arbitrary. So I'm not accepting that HP/10 is anything other than what a lot of people like.

And...help me out here...why do you say "normal full rich of around 0.57 - 0.58"? That may be correct, but why? Is it to avoid the "red cube" or red square or whatever people are calling it?

This would all be moot if Lycoming would just publish what the FF value should be...

[RV7A Flyer]

Originally Posted by RV10inOz

The chart you are referring to where it states BEST POWER is nowhere near the fuel flow at takeoff full rich. Best power is around 75dF ROP, always!.

I don't understand this statement. The chart has a curve for "Best Power" at 2700 RPM. Where that line intersects 180 HP, the value of "Fuel Consumption Pounds/Hour" is approximately 87 (app 14.5 gph). If best power is 75 deg F ROP, and this chart shows you what the fuel flow for best power is, then that fuel flow is 75 deg F ROP, right?

So > 14.5 gph is *even richer* than 75 deg F ROP. There are only so many variables to play with in these charts...HP? 180, check. RPM? 2700, check. Best Power curve is being used? Check.

That's it...then you read off 87 PPH on the ordinate. Thus, 87 PPH *is* 75 ROP if what you're saying is correct.

> 87 PPH is richer still. How rich is required is the question, and why.

[RV10inOz]

Originally Posted by Airhead

Now this is getting interesting. I personally have learned a lot during this investigation into my (possible) problem, both from data contained herein (albeit with a little drift as normal), and from further reading.

I think so far I have some very useful data from this post, as well as good points concerning comparision of data taken at different atmospheric conditions. Therefore, a range in flows should be expected, even with identical engine/prop/FI setups. However, I still think we are seeing that the M1B/Hartzell CS/PA FI gives a range of FF somewhat on the low side of the overall responses (but please keep the data coming in, particularly for this specific setup) and that my FF is not abnormally low. That is half of the answer I was trying to get by making this post, the other half being is this FF (15-16 gph at full power T/O) )so low as to be detrimental to engine life or performance? That is obviously only answerable by each individual owner , but I don't believe the complete answer lies in the Lycoming manual.

One test I have not yet performed that has been mentioned here and in most writings about this subject (and specifically mentioned in my discussions with Precision Airmotive as the definitive test as to whether my FI is delivering low flow during full power) is leaning from full rich to peak EGT at full power setting. I should see about at least 100 to 200 degree increase (hopefully at least 150, and no, I will not try this during T/O ). Will report back on this.

Response to Davd Brown's comments;
Well taken concerning engine thrust movement possibly affecting cable/arm movement. Was going to check this possibility.

My probes are all at 2 inches from head, and the spread I refer to is min and max between the 4 cylinders, ie, that (as I understand it) would indicate I am getting fairly even fuel distribution to the cylinders, and the reason I think credit is due PA is because the spider & injector nozzles are supplied as part of their system. The EGT at full power T/O is 1320-1330 (hotest cyl) at about 500 ft. (my airport is at EL. 40) At altitude (have not yet performed low level leaning tests as mentioned above) I see 1430 peak at 60 to 75 % power setting.

My K value has been adjusted only in small increments, and I did see a small drop in indicated FF as would be expected. I have kept a full accounting of my fuel burned and added since initial fill up at hour 1. I only made small incremental K adjusments (3 so far) at the point when the Dynon EMS (running total) fuel consumption exceeded my actual (carefully measured) consumption by a total of 2-3 gal (initially about 10 to 12 hours hobbs). However, I will continue to track this.

I went back and looked at my downloaded data (using Savvy Analysis) and noticed that although my airport is near sea level, since Florida temps are typically so far above normal, I have not yet flown at a DA of less than 500 and most flights started at 1000-2000' DA.

Bob, now you are in the learning and discovery process.

By your get data alone the values seem a little higher than I expected, perhaps your FCU is on the edge of acceptable. Perhaps your mag timing is slightly retarded.

[RV10inOz]

Gotta run to the airport....back soon for RV7flyer

[Lars]

Originally Posted by RV7A Flyer

(My comment about answers to other questions was about responses for engine/prop/FI systems *other* than what the OP had, which is what he asked...he doesn't have a 540, he doesn't have a Superior, he doesn't have ECI, he doesn't have an Airflow Perf FI, he doesn't have an -A1A or whatever...he has a Lycoming IO-360-M1B with a Hartzell BA prop and PA FI. Which is exactly what I have, so I gave him the manual page number applicable, and my data).

Acknowledged in my case- But there are more similarities than differences.

The most significant difference in my engine compared to the Lycoming IO-360 M1B is the vertical draft sump. The M1B should actually make a little more power (and thus flow a little more fuel at WOT) than mine, due to the intake air not being preheated by the hot oil in the sump. Like the Lycoming, mine has parallel valve cylinders with 8.5:1 pistons and Precision Airmotive injection. Like the OP observed for the first 20 hours, I've always gotten close to 18 gph, full rich, on takeoff.

I don't remember the calibration factor I'm using for my Red Cube, but my fuel totalizer (Grand Rapids EIS, for what it's worth) but since I initially calibrated it the thing reads about .8 gallons high (indicating I've burned more than I actually have) in 100 gallons consumed, according to my records.

My home field is at 100 feet MSL. We've actually had some standard days around here lately (California drought, yay, but it makes for great flying weather).

I have done a WOT throttle full rich to peak EGT test, at various altitudes. Typical EGT rise is around 190? F.

Oh yeah, Hartzell blended airfoil prop.

Per post #15, it seems that the real issue here is that something changed.

Precision Airmotive's documentation on the Silverhawk injection system has something that might be of interest. Have a look at section 10.0:
http://www.precisionairmotive.com/Pu...s/25-020_a.pdf

Superior's operator's manual for my engine lists a maximum fuel flow at full rich of 108 pph, for what it's worth.

[RV10inOz]

I meant 500 AMSL (Five hundred) not 5000.

Is your 1000' quoted AMSL not AGL?

I don't know about WOT/2700 at 5000' because I never do that. But looking at my data, at 1000', WOT/2700/full rich (I've never seen an ISA day , so we'll have to fudge that), 25 BTDC, 8.5:1, plugs just cleaned and gapped at annual, no leaks, GAMI spreads 0.1 or thereabouts, I get EGTs of (hey, guess what?) 1250-1280 (but I thought exact values of EGTs didn't matter because placement could affect the reading????). I also have CHTs < 400 (or just a tad above 400 on hot summer days, easily fixed by lowering the nose). Most recent flight had 15.5 gph.

Unless we know the density height, but lets assume it was 2000' but with EGT values in the range of normal, barring advanced timing, then doing a reverse engineered guess like I did on Bob Redmans that would give an equivalent of about 16.6GPH.

What can we deduce from this, perhaps you have the fuel flow but due to boost pump being on it under reads? Maybe the K factor is not right? Maybe the density height is higher? Maybe your timing is not accurately 25DBTDC and this offsets the lower FF.

This is a very difficult thing in internet posts, one of the reasons we do a 2.5 day course on engine management and EMS diagnosis. And even then there could be a lot more.

If you have some data files, and if they are from a system like the Dynon which captures everything I am happy to take a look.

As for the rule of thumb, it is exactly that and applies to NA engines at typical standard CR's. It is really about 2-3% less than that HP/10 but it is near enough. It all relates back to the required BSFC for detonation margin and that does vary from engine to engine.

Ohhh and an ISA day.....I have seen a couple but you do have to be lucky!

[RV7A Flyer]

David,

Just to follow up and answer your questions...my home field elevation is 1000' MSL, so those were the numbers I was quoting (but there's virtually no change at 2000' MSL or 1000' AGL). Red cube is located after the fuel injection servo, before the spider, and has been calibrated (filling up, even 3/4 tanks because I don't run them dry, the actual vs. computed values are within .1 gallon). I don't see how having the boost pump on would change the value (the fuel flow transducer has no way of knowing whether there is a boost pump or 3 or if any or all are on or off), so that doesn't seem likely.

I just did the mag timing check at annual...dead on at 25 BTDC, just like it was a year ago.

So back to my questions...essentially, this engine is set up the way it came from the factory and was run on the test stand. Is Lycoming wrong in the way they set up their engines?

Are you saying that it should be 18 gph (i.e., 3.3 gph higher than best power at rated power per the chart, or 22% higher) to avoid the "red box"? If so, I can understand that...

Assuming all that, how do you increase FF if, as I've said, the system is already "at the stops"? (N.B., I have no intention of doing this, short of an unbelievably compelling reason to do so, and with the concurrence of the manufacturer...especially given that it looks like 100% of the responders here with identical engine/prop combos are seeing essentially the same FF).

I'm genuinely trying to learn here, but I'm also hesitant to change a system which is as the factory set it up and which has performed flawlessly to date...

[RV7A Flyer]

BTW, David...thanks for the PM...reply sent! Appreciate the offer to help...