Help Please What is IO 360 Wide Open Minimum Fuel Flow

[MikeOH]

One more data point:

IO-360A1A (M20F): 16.2 gph at 2700 rpm, 1350 EGTs, CHTs around 370, DA around 1500 feet at take-off.

I fight high CHTs during the summer months, so I'm interested in knowing the correct fuel flow, as well.  Anecdotally, I've been told mine is low.  Not ready to pull the RSA and send it in for OH just yet, however.

[carusoam]

@aaronk25

There is a request for you, I think... from @Gary V  a couple of posts back from here...

Welcome aboard Gary...

Best regards,

-a-

[Niko182]

pretty good rule of thumb is 0.9 to 1 gallon per 10 HP. that seems to work pretty well at least for the NA variants of engines. 18 to 19 sounds just about right.

[aaronk25]

[mention=8452]aaronk25[/mention]
There is a request for you, I think... from [mention=19193]Gary V[/mention]  a couple of posts back from here...
Welcome aboard Gary...
Best regards,
-a-

Thanks for heads up I’ll call him tomorrow late am.

The fix was at my expense to remove and reinstall snd the overhauler at their expense went though it again and it came back correct.

They said there was nothing wrong and it bench checked within specs, but who knows cause the fuel flow was higher at about 16.8 or so on the roll...... my guess is they messed something up and didn’t fess upto it, but the good thing is it now works correctly.


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[Yetti]

So a couple things here.

EGT are meaningless from engine to engine.    It is installer's choice on how far away to install the thermocouple in the exhaust stream.   The key is to install the same distance on the same engine.

 

Mixture lever and the loose nut behind it (you the pilot) controls fuel rate of flow.    So one check is to make sure the mixture knob/lever can make the full range of travel at the fuel servo.   It is easy and not many turns of the turn buckle to mess this part up.

The guy who did my servo last year wanted the injectors, the divider and the Servo for fuel flow testing.   I think this is the best way to do it.   Aircraft Carburetors of Texas in Justin Texas.   If you don't do it this way you have other variable such as clogged injector that could change the fuel flow.

[M20F]

2 pages of posts (and 6yrs) and nobody has the right answer or a reference to any of the FUD posted. 

[takair]

According to the Lycoming operator manual chart, fuel flow at 200hp is about 15.67 gal/hr.  According to my M20E operators guide, fuel flow at 2500 ft, 2700rpm, 27.5”.....the fuel flow is 15.5.  For some odd reason, they do not seem to specify full fuel flow as a min max....only these performance charts.  So, it would seem that 15.5 to 16 gph would be reasonable based on these two sources.

[jetdriven]

As you climb, manifold pressure decreases, and also fuel flow decreases as well. I think 15.5 gallons an hour at 27.5” manifold pressure is reasonable. But yes usually it’s around 17 something at sea level full throttle and 2700 rpm. Many J models won’t make 2700 static RPM. So the fuel flow increases a little from brake release.  Above 60-80 mph it reaches 2700 RPM and that’s your highest FF. 

[PT20J]

Agree with Byron. My Shadin generally shows about 17.2 gph on takeoff roll at sea level. I extrapolated data from the Lycoming test cell data on my factory rebuilt IO-360-A3B6 and it was about 18. But, that’s with optimized intake and exhaust plumbing. I suspect anything between 17 and 18 gph is good installed on a Mooney.

The fuel servo measures the volume of airflow. What you really want is the mass of airflow because it’s the mass ratio of fuel to air that sets the mixture. But for an incompressible fluid, the mass flow is proportional to the volumetric flow adjusted for air density, so it works out  But, as you climb, the air density decreases which changes the relation between air mass and volume and that’s why you have to lean as you climb.

Skip

 

Edited January 12, 2020 by PT20J

[Guest]

Unfortunately the Bendix/ Precision fuel servo isn’t field adjustable with regard to maximum power fuel flow, nor did they ever publish a metered nozzle fuel pressure to confirm flow rate.

Clarence

[bradp]

I get about 1250 EGT sea level and FF 17.9

[Niko182]

People keep on giving their EGT's but that literally means nothing. How many degrees are you rich of peak on takeoff?

[bradp]

That’s the rub Niko- I don’t run peak at full power sea level so I have no idea.  Something around 300 - 350 ROP I’d guess. 

[carusoam]

53 minutes ago, Niko182 said:

People keep on giving their EGT's but that literally means nothing. How many degrees are you rich of peak on takeoff?

It would mean something...

If all our EGT sensors were precision installed the same way... as in a factory located hole.  Always placed in the same place across all the Mooneys...

This was done in the early 90s for IO550s...

The ship’s EGT sensor is in a standard location at the confluence of three exhaust tubes on one side of the engine...

 

As far as how ROP an IO550 runs during T/O... there is a calibrated EGT sensor mounted on the instrument panel...

If you use the blue box for leaning in the climb... or white box if you have a G1000... Raw EGT numbers have real meaning.   Getting somebody to raise this number outside the recommended range can be an added challenge...

 

If you use the blue box as a reference... you are in the range of 200-300°F ROP...  

These numbers may be a bit fuzzy from old memories, but the Long Body POH covers this detail.

Familiar?

 

Another example of the max and min FF for the 310hp IO550... it is clearly stated in the STC... it is listed in pph. WOT, max rpm...

The oddity, the max FF given in the STC is pretty good for setting power... but doesn’t have the excess for good cylinder cooling... 

Getting somebody to increase the FF outside the documented range may take some negotiation...

PP thoughts only, not a mechanic or CFI...

 

Best regards,

-a-