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Will a Gallon make a Big Difference?


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22 hours ago, Missile=Awesome said:

Thanks for input. My A&P agrees with you. Not sure I agree with your way high fuel flow assessment. We are 26-26.5gph from 870’-1000’. I am cruise climbing at 150-160 knots (about 500fpm) and still cracking 400 cylinder temps. That is unacceptable and doesn’t reflect a high full power fuel flow. Other Missile drivers are saying 27.5 minimum and 28 better...I am just seeking information. We have gami’s...original is analog of course and is in line with edm830. Injectors pulled and cleaned 50 hours ago. Have not noticed pre lean fuel flow at 2700rpm before leaning. Egt’s were 15lop with 12.2gph

Yeah, as we texted Scott, it sounds like you need to increase the full power takeoff fuel flow just a bit. The cooling effect of the fuel will help. You'll also be able to climb faster (120-130 knots) and thus get to altitude faster so you'll burn similar fuel, if not less during the climb, and then get better "mileage" at your cruise settings. anywhere from 11-18 GPH depending on LOP or ROP speed 170-190 TAS.

-Seth

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Expect that the IO720 probably gets set up for 40gph for the SL TO run...

Twin engine performance... without the off center thrust issues of a pair of engines... :)

But... 1gph probably doesn’t make a big enough difference here... Closer to 2gph for that....

 

So...

When tuning up the FF for the IO550... be sure to collect the before and after data... JPI, and CloudAhoy if able...

  • Raw EGTs will be meaningful 
  • CHTs will be interesting
  • FF of course
  • T/O distance,  in the event power isn’t being delivered properly...  it will be measurable...

PP thoughts only, not a mechanic...

Best regards,

-a-

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46 minutes ago, Missile=Awesome said:

Savage...Clarence won’t let that stand.  Like dueling banjos...here we go... :)

Can a moth NOT fly into a flame?

I feel no pain.  Piper never made a Cherokee 400 that I’m aware of.  My Comanche 400 on the other hand loves 100LL and uses 9%(36gph) at take off power for average EGT of 1250.  
 

Clarence

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On 8/19/2020 at 9:23 AM, Seth said:

There are two screws that adjust the fuel flow on the IO550 set up in the Missile. One adjusts the top end full power flow and one adjusts the idle flow. They are supposed to be independent of each other but they do affect each other. There is a balance - if you get the full power setting screw set properly, it can effect the idle flow which will cause flooding and your engine will burble and then quit on you. Happens after landing or during low idle. So you to make sure the engine is flowing enough fuel at takeoff (min 27.5 - I like closer to 28 or 28.5 and does not sputter and flood/shut off at idle).

Ding! Ding! Ding! 

I need to start by saying I have a very different engine, the TCM TSIO360LB, but the same fuel flow issue as far as getting mechanics to set the flow correctly. My max fuel flow for takeoff is supposed to be 22.5-24. If you fly out west, particularly, and do a high hot takeoff followed by a long climb to altitude you need every ounce of that 24 GPH and more would be nice. Every time I get the plane back from annual the max flow is more like 21.5, ok for a lot of operations but not in the heat of the summer.  I am quite sure the mechanic gets fixated on the idle setting, sets the max flow first, and then adjusts the idle screw which winds up bringing the max flow down a gallon.

One, somewhat counterintuitive thing to try is to max the throttle in the climb. You would think that adding power would add heat, but that is not how it works in my engine. I don’t pretend to know how this would work in a Missile, but in the 231 equipped with an aftermarket intercooler, the SID-97 setting is supposed to be done at around 37.4 MP, but the general teaching is to use 36” for full power. You can’t develop full max fuel flow at 36” if the shop, as they should, used 37.4 when it set the flow. The fix is to crank the MP up, and the fuel flow will go up with it.  I don’t know if that helps with the Missile, but it is what I have found with my engine.

I can adjust for overrich mixture on short final or during taxi by leaning out, and that is exactly what I do to get rid of the burble. What I can’t do, is override the mechanic’s max fuel flow setting if it is too low. Grrrr.  Every. Single. Annual.

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Ding! Ding! Ding! 
I need to start by saying I have a very different engine, the TCM TSIO360LB, but the same fuel flow issue as far as getting mechanics to set the flow correctly. My max fuel flow for takeoff is supposed to be 22.5-24. If you fly out west, particularly, and do a high hot takeoff followed by a long climb to altitude you need every ounce of that 24 GPH and more would be nice. Every time I get the plane back from annual the max flow is more like 21.5, ok for a lot of operations but not in the heat of the summer.  I am quite sure the mechanic gets fixated on the idle setting, sets the max flow first, and then adjusts the idle screw which winds up bringing the max flow down a gallon.
One, somewhat counterintuitive thing to try is to max the throttle in the climb. You would think that adding power would add heat, but that is not how it works in my engine. I don’t pretend to know how this would work in a Missile, but in the 231 equipped with an aftermarket intercooler, the SID-97 setting is supposed to be done at around 37.4 MP, but the general teaching is to use 36” for full power. You can’t develop full max fuel flow at 36” if the shop, as they should, used 37.4 when it set the flow. The fix is to crank the MP up, and the fuel flow will go up with it.  I don’t know if that helps with the Missile, but it is what I have found with my engine.
I can adjust for overrich mixture on short final or during taxi by leaning out, and that is exactly what I do to get rid of the burble. What I can’t do, is override the mechanic’s max fuel flow setting if it is too low. Grrrr.  Every. Single. Annual.
The next time you are near SE North Dakota drop into K74, I would be happy to adjust your FF in accordance with the STC.
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Be careful what you wish for. KFAR is in my logbook quite a bit so far this year.

I am convinced it is the idle screw. The mechanic sets the high fuel flow per the STC and then tweaks the idle screw, so I wind up with a max fuel flow that is about 2 GPH low at full power.

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When I discussed fuel flow at take off power (MP and Prop full forward) being a gallon low he said “Won’t make much difference”.  My response was “I am having to cruise climb at 150knots indicated and I STILL have cylinders over 400” so let’s raise fuel flow a gallon and let me SEE the difference...My plane NOW as configured will NOT allow leaning on ground at idle...It will kill the engine.  I am full rich and taxing at 2GPH...  This is going to change.  Looking forward to seeing 27.5GPH on totalizer when I am going down runway on takeoff...

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My Missile @SL I do lean at idle for smoother running. Takeoff is full rich. Flying again later today and will report current flow full power takeoff full rich. Do you know if you have the altitude compensating fuel pump? I do have it. I have read a few Bonanza articles to remove it and put on the standard pump.

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27 minutes ago, N56394 said:

My Missile @SL I do lean at idle for smoother running. Takeoff is full rich. Flying again later today and will report current flow full power takeoff full rich. Do you know if you have the altitude compensating fuel pump? I do have it. I have read a few Bonanza articles to remove it and put on the standard pump.

Yes, please give elevation of airport and your fuel flow at full power on take off.  I am NOT a lean to EGT guy.  I don’t mess with mixture as I climb.  I get up there at max MP and mixture and I reduce RPM and run LOP in cruise.  Not sure if I have the altitude compensating fuel pump on my Missile.

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30 minutes ago, N56394 said:

My Missile @SL I do lean at idle for smoother running. Takeoff is full rich. Flying again later today and will report current flow full power takeoff full rich. Do you know if you have the altitude compensating fuel pump? I do have it. I have read a few Bonanza articles to remove it and put on the standard pump.

EVERY OTHER Missile owner I have talked with is flowing 27.5 to 28 at take off power with elevations <2,000’.  My sampling is SMALL (three other owners), but the total Missile fleet is also small.  (We are #42 out of? I believe <60 total conversions)

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9 minutes ago, Missile=Awesome said:

EVERY OTHER Missile owner I have talked with is flowing 27.5 to 28 at take off power with elevations <2,000’.  My sampling is SMALL (three other owners), but the total Missile fleet is also small.  (We are #42 out of? I believe <60 total conversions)

Talk to guys that have A36's with the io550 conversion and ovations and eagles with the 310hp conversion. The engines are nearly identicle, and setup fuel wise is going to be the same.

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Yes, please give elevation of airport and your fuel flow at full power on take off.  I am NOT a lean to EGT guy.  I don’t mess with mixture as I climb.  I get up there at max MP and mixture and I reduce RPM and run LOP in cruise.  Not sure if I have the altitude compensating fuel pump on my Missile.
Does your FF decrease as you climb or stay the same? If you have a standard pump and don't lean it you will be very rich in the climb at higher altitudes.
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2 minutes ago, N231BN said:
23 minutes ago, Missile=Awesome said:
Yes, please give elevation of airport and your fuel flow at full power on take off.  I am NOT a lean to EGT guy.  I don’t mess with mixture as I climb.  I get up there at max MP and mixture and I reduce RPM and run LOP in cruise.  Not sure if I have the altitude compensating fuel pump on my Missile.

Does your FF decrease as you climb or stay the same? If you have a standard pump and don't lean it you will be very rich in the climb at higher altitudes.

Our fuel flow decreases with climb.  We must have the altitude compensating fuel pump.  I would WELCOME having more fuel flow in the climb and having option to lean manually.

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A 310 HP Continental requires 27-28.5 GPH at sea level at 59dF. This will give a full power EGT of 1250 dF. Any more flow, will cause the engine to lose power and leave a trail of black smoke like an old 707. More fuel doesn't "cool" the engine, it just makes it less efficient, and that means less heat. 

The book settings are low on virtually all Continentals. And most people are adjusting using the fuel flow gauge, which is incorrect. Calibrated pressure gauges are the only way to do this correctly. I find that the very top end of the specs are where the engine will be happier.

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A 310 HP Continental requires 27-28.5 GPH at sea level at 59dF. This will give a full power EGT of 1250 dF. Any more flow, will cause the engine to lose power and leave a trail of black smoke like an old 707. More fuel doesn't "cool" the engine, it just makes it less efficient, and that means less heat. 
The book settings are low on virtually all Continentals. And most people are adjusting using the fuel flow gauge, which is incorrect. Calibrated pressure gauges are the only way to do this correctly. I find that the very top end of the specs are where the engine will be happier.
I generally agree but there is a problem with only using pressure gauges. Continental specifies 25.6 gph max for the IO-550-A which corresponds to 17.2 psid. If you want to turn the FF up to 27-28.5 your only reference will be the FF gauge. The actual metered fuel pressure is pointless if you aren't getting enough FF.
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4 minutes ago, N231BN said:
41 minutes ago, philiplane said:
A 310 HP Continental requires 27-28.5 GPH at sea level at 59dF. This will give a full power EGT of 1250 dF. Any more flow, will cause the engine to lose power and leave a trail of black smoke like an old 707. More fuel doesn't "cool" the engine, it just makes it less efficient, and that means less heat. 
The book settings are low on virtually all Continentals. And most people are adjusting using the fuel flow gauge, which is incorrect. Calibrated pressure gauges are the only way to do this correctly. I find that the very top end of the specs are where the engine will be happier.

I generally agree but there is a problem with only using pressure gauges. Continental specifies 25.6 gph max for the IO-550-A which corresponds to 17.2 psid. If you want to turn the FF up to 27-28.5 your only reference will be the FF gauge. The actual metered fuel pressure is pointless if you aren't getting enough FF.

Agreed, @Philiplane is right on with an expected EGTs and that TCM's spec being low on all Continentals. The worst part of Continentals spec to the unknowing or inexperienced is that TCM gives a range of two number, but the reality is that the high number really should be considered  as the absolute minimum and most folks in the industry recognize we really need more like 0.5 to 1.0 GPH ABOVE TCM's high number to get adequate FF.

But I'll disagree on using the gauges, as long as the plane has calibrated FF, its going to a lot easier setting up the metered FF using the FF indicator - which is entirely approved by TCM's superceded SID and the current M-0 Chapt 6 instructions.  I 'll also add the that most shops I see don't have adequate instrumentation to set up the metered fuel pressure on gauges for Turbo's anyway. NA's aren't a problem but Turbo's require a 1% differential pressure meter to get the difference between metered fuel pressure and UDP, but few mechanics have the expensive differential meter and many use two separate gauges for the turbo metered fuel pressure measurement. But when bouncing around they become really hard to get an accurate difference. And I should probably add  TCM specifies a very expensive box for the preferred method of doing doing fuel setup that very few shops can afford that makes the differential pressure gauge for Turbo's a bargain!

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20 hours ago, philiplane said:

A 310 HP Continental requires 27-28.5 GPH at sea level at 59dF. This will give a full power EGT of 1250 dF. Any more flow, will cause the engine to lose power and leave a trail of black smoke like an old 707. More fuel doesn't "cool" the engine, it just makes it less efficient, and that means less heat. 

The book settings are low on virtually all Continentals. And most people are adjusting using the fuel flow gauge, which is incorrect. Calibrated pressure gauges are the only way to do this correctly. I find that the very top end of the specs are where the engine will be happier.

So this has been frustrating (trying to fix high temps in climb and NOT be “exceeding recommended fuel flow”/losing efficiency in our engine), but I “believe” (based on a LOT of information) that we are not “too high on fuel flow now” with our Missile.  We are seeing EGT’s up at 1400-1450 in climb (With 1500 in cruise up high)...some of this, of course, could be probe placement or k factor setting in our Shadin totalizer.  The Missile has NO cowl flaps and is pretty tightly cowled.  Regardless of Continental “specs” for max fuel flow for IO-550A it would appear that in the Missile conversion the flows for 310 Eagle appear more “on target” to give cylinder temps/Efficiency/EGT that is closer to 1250.  I look forward to having full power adjustment to 27.5 (Max per my A&P that he can apply for our engine) and doing a climb with fuel flow % power in our EDM830 vs. separate Shadin configuration we have now.  Shadin and JPI say our K factor should be 29.2.  Ours is currently set for 28.6.  I am going to plug in 29.2 on EDM830 AFTER the engine fuel flow is adjusted and I complete a couple of climbs to NOTE changes.  Anybody know what did in those two k factors theoretically means?

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34 minutes ago, N231BN said:

That is the number of pulses per gallon from the sender. It is just a starting point, every installation is different and should be calibrated by recording actual fuel burn.

Sigh.  Not trying to be a “nit”, but come on.  The k factor was set with the Shadin that has been in the plane for years...PRIOR to our getting the plane.  I am not going to “assume”, but I would do just that regarding the previous owner.  I would think they moved “beyond” a starting point...and so THAT is why the difference from that starting point of 29.2 to our current setting of 28.6 is being given the “benefit of the doubt” that IS the correct fuel flow for engine vs. the starting point.  So again, my question “is 29.2 a HIGHER or LOWER indicated fuel flow compared to 28.6?

We JUST had tank resealed and I am trying to get a better understanding of on board fuel with crossover into AUX tanks (gauge reading/accuracy etc.) that was NOT possible with unknown of seeping fuel/quantity in vs. indicated vs. evaporated in seepage...

I can research k factor on my own, but thought someone might know...

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