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Fuel Flow @ WOT

rph142

Well Known Member
My IO-320 burns around 12.5gph while running full throttle at sea level. This seems too low according to the Lycoming manual. It has an FM150 airflow performance fuel injector and dual P mags. Is there any way to adjust the airflow injector to increase fuel flow?
 
How are you measuring the flow and is the measuring device calibrated IN your airplane?

Contact Don at Airflow performance for adjustments.

Bevan
 
My IO-320 burns around 12.5gph while running full throttle at sea level. This seems too low according to the Lycoming manual. It has an FM150 airflow performance fuel injector and dual P mags. Is there any way to adjust the airflow injector to increase fuel flow?

If you are running the standard injectors that come with the AFP system (0.028") your engine is already getting more fuel than it can use (at WOT and full rich). This assumes you have no fuel system issue at play like a blockage or clogged filter.

What indications do you have besides your fuel flow measurement that you have a problem?

Carl
 
I calibrated the flow using a stopwatch and bucket and measure via dynon flowmeter. I never gave it much thought until I switched to pmags and developed high cht's during climb. I read somewhere on the forums that running a rich mixture helps cool the cylinders during climb. I confirmed I have .028" injectors and they are all clean.
 
Like Bevan said, contact Don at Airflow. I had the same problem and he suggested changing the main jet to the next bigger one. I did that and everything was fixed.

Dan
 
Dont overlook the Pmags. It is well documented here that PMags can cause high CHT on climb due to unintentionally advanced timing.
 
Actually according to Lycoming calibration specs., an IO-320 (160 HP) at rated power uses 75 to 76 PPH fuel flow that's about 12.5 GPH. Before you cover up a high CHT condition by dumping fuel at it, check the fuel air ratio the fuel control is delivering to the engine to see if it is indeed lean. Fly at 3500 ft, set 24 square, lean until one cylinder peaks EGT and record the peak EGT for that cylinder. put the mixture back full rich, let the EGT stabilize then record the full rich RGT for the same cylinder. If the difference between peak and full rich is 185 to 230 degrees F then the fuel air ratio is in the correct range for your engine. Putting a richer jet in the fuel control will only make the engine loose power, and can actually cause premature wear on the cylinders.
 
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