Fuel Flow on Take Off

[Alan Maurer]

Hello Everyone,

Flying Ovation so 280 HP available at sea level. With full throttle for take off,  the fuel flow is just over 22. gallons per hour. Mike Busch said , in his book, that the fuel flow should be more like 28 gallons per hour. Our mechanic at my airport says the lower full power flow is correct. Engine is IO550G-7.   What is the correct answer?

Thanks

Alan.  N913ND (2008 Ovation  using G1000 data.)

 

 

[Guest]

A few documents for you from Mooney and Continental.  However many people will raise the maximum power fuel flow higher than book for lower EGTs.

https://www.mooney.com/wp-content/uploads/2020/12/SIM20-107.pdf

Clarence

[Harry Wightman]

I'm feeding my 280hp Ovation 26 Gph on takeoff to good effect on takeoff. It does require leaning on climb though.

[Alan Maurer]

Thank you and special thanks to Harry in Adelaide. I'm heading back to Australia in a few months....not that far! Agree that 26 sounds better than 22 gal/hr. 

My cylinder head on #5 is just over 400 F on take off....too hot!

[Alan Maurer]

Thanks to our friends in Canada also.

[Will.iam]

While my TSIO-360 is 70 hp less my CHT was a struggle to keep below 400 in the summer last year even though my ff was 22gph and in accept range abit in the lower portion. At annual i requested my fuel flow to be set at max allowable 24.7gph. Now i can easily keep my cylinders below 380 on climbout and this past winter with cooler temps i could climb out with my cowl flaps closed and keep my CHT’s below 380!  I’m a firm believer that after checking that your baffling is correct if you still struggle with high CHT’s it’s an inadequate fuel flow problem.  

[GeeBee]

11 hours ago, Alan Maurer said:

Hello Everyone,

Flying Ovation so 280 HP available at sea level. With full throttle for take off,  the fuel flow is just over 22. gallons per hour. Mike Busch said , in his book, that the fuel flow should be more like 28 gallons per hour. Our mechanic at my airport says the lower full power flow is correct. Engine is IO550G-7.   What is the correct answer?

Thanks

Alan.  N913ND (2008 Ovation  using G1000 data.)

 

 

I have the same airplane as you and I was at 24.1 gph. I recently cranked it up to 24.7 gph. It is pretty hard to get up to 28 and still keep the idle where it where the book says it needs to be. That all said, with those kind of T/O CHTs, I would bring it up to at least 24 or 25. 

Remember that your FF meter in your airplane is not calibrated (unless you have put it through a fine calibration process). Equally so, make sure the mechanic's gauges have been recently calibrated. So what he sees on his gauges and what you see on FF may differ slightly. However from a relative point of view, I believe you would benefit from an increase to at least 24 gph. He will likely see pressures above the Continental charts to get there.

[Mooney 217RN]

The higher fuel flow is for the 310HP conversion...you then have 27-28 gph on departure from sea level.

[Alan Maurer]

Hi Everyone, thanks for the notes. annual shortly...will plan to get FF on T/O up to 24 gal/hr 

[Rmag]

8 page thread on this topic from 2010 on BeechTalk https://www.beechtalk.com/forums/viewtopic.php?f=37&t=44453 for an IO 550. 

[A64Pilot]

Bottom line is if your a little rich, you can lean it some, if your lean you can’t go richer than full rich. At least on some other aircraft they go to high boost to get more fuel, not the correct way, but it does work. I assume a Mooney has a two speed boost pump, never flown a 550 Mooney myself.

I can tell you that getting the fuel flow right on a 500 on other aircraft isn’t a trivial thing, either follow directions fully or better take it to someone with experience, that does it frequently.

Edited May 17, 2022 by A64Pilot

[FlyingScot]

On 5/15/2022 at 10:25 PM, M20Doc said:

A few documents for you from Mooney and Continental.  However many people will raise the maximum power fuel flow higher than book for lower EGTs.

https://www.mooney.com/wp-content/uploads/2020/12/SIM20-107.pdf

Clarence

 

Clarence - Thank you for this - could you tell me what is the source of this table? I cannot find it in any of Continental's docs - Thanks - Bob

 

[Guest]

8 hours ago, FlyingScot said:

 

Clarence - Thank you for this - could you tell me what is the source of this table? I cannot find it in any of Continental's docs - Thanks - Bob

 

It’s from Continental’s maintenance manual for spark ignition engines publication M-O .

Clarence 

[EricShr]

Hi fellow M20R pilots, Took off Friday at 109 degrees in Mesa, AZ. 

I answered my own question. This time, I used the low boost after takeoff. The cylinder temps rose to 425* on cylinder #3 at 500 ft. prior to the boost pump.  I then engaged the boost pump.  Immediately, the EGTs all dropped 200 degrees, but the cylinder head temps did not budge, even after reducing the manifold pressure to 21" and RPM to 2300. So obviously adding boost DOES add fuel, but just not enough fuel! Climb was a miserable 200 FPM. It ran smooth. All baffles are sealed, chafe seal is tight, timing is correct. Slowly the temps began to drop upon reaching 4500 ft. Time to turn up the fuel flow to 31 gal/hr like the "N".

PS, the old stock cylinder temp gauge never exceeded 400 *

Also, the Switch Cap Housing on the Left side of the pilots yoke containing the A/P disconnect and trim FRACTURED in half - I HATE the heat!

So, anybody who has made that cap housing from the 3D printed file and has the capability - I am interested.

[EricShr]

The engine monitor is a JPI 700 FYI.

 

[LANCECASPER]

52 minutes ago, EricShr said:

So, anybody who has made that cap housing from the 3D printed file and has the capability - I am interested.

I've never done this but I think this might be what you're looking for: https://www.thingiverse.com/thing:4340751

 

 

[Marc_B]

Since this thread resurrected and links broken.  Here is the Continental M-0 Standard Practice Maintenance Manual Table 6-4 Fuel System Adjustment chart in a PDF.  According to Mike Busch & Savvy, they like to see fuel flow of 0.5 - 1 GPH over the standard full power fuel GPH recommended by Continental.  As mentioned before this would need calibrated equipment to make sure the numbers you see on monitor are accurate.

Continental M-0 Table 6-4 Fuel System Adjustment.pdf

[Will.iam]

On 9/30/2024 at 7:21 AM, EricShr said:

Hi fellow M20R pilots, Took off Friday at 109 degrees in Mesa, AZ. 

I answered my own question. This time, I used the low boost after takeoff. The cylinder temps rose to 425* on cylinder #3 at 500 ft. prior to the boost pump.  I then engaged the boost pump.  Immediately, the EGTs all dropped 200 degrees, but the cylinder head temps did not budge, even after reducing the manifold pressure to 21" and RPM to 2300. So obviously adding boost DOES add fuel, but just not enough fuel! Climb was a miserable 200 FPM. It ran smooth. All baffles are sealed, chafe seal is tight, timing is correct. Slowly the temps began to drop upon reaching 4500 ft. Time to turn up the fuel flow to 31 gal/hr like the "N".

PS, the old stock cylinder temp gauge never exceeded 400 *

Also, the Switch Cap Housing on the Left side of the pilots yoke containing the A/P disconnect and trim FRACTURED in half - I HATE the heat!

So, anybody who has made that cap housing from the 3D printed file and has the capability - I am interested.

And this right here is why I use the manual trim wheel even though I have a trim switch on the yoke that trim switch and casing is unobtainaium so I use it very very rarely. Same with using the AP button on the kc-150 instead of the button on the yoke.