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Lycoming io390 max fuel consumption

Dennis Harm

Active Member
Hi everyone, just did my fuel flow test today as was wondering what the maximum fuel flow is at full rated power? Thanks Dennis Engine is lycoming io-390 EXP
 
Hi everyone, just did my fuel flow test today as was wondering what the maximum fuel flow is at full rated power? Thanks Dennis Engine is lycoming io-390 EXP

For the IO-390A I used the following:

Lycoming YIO-390 manual states a minimum flow rate of 17.3 USG/hr is required at full power. Using max fuel rate by HP calculation results in a 18.5 USG/hr.

I used the higher rate of 18.5 gal/hr.
 
Fuel flow

At 2500 ft elevation and 40 degrees F, my red cube shows a burn of 18.5 gph during my full throttle takeoff run. I have a YIO-390, 210 HP. aa
 
Last edited:
I see 17.5gph +/-.3 on my 390 on takeoff power.

I am running the (standard) Silverhawk fuel servo and not the larger version of the AFP on the EXP engines (fM-200) which I assume would make a noticeable difference at full throttle
 
This is the statement I included in my airworthiness package. I0 390 Exp 210 hp.

The L/H tank was filled with 5 gallons of 100LL and the fuel line was disconnected at the Fuel Servo inlet. The electric fuel pump was run briefly to verify flow. The nose of the aircraft was then elevated to the maximum take off angle plus 5 degrees, which equaled approximately 17 degrees. The pump was then run continuously for 1 minute with the fuel collected in a gas can with a known weight. The collection tank was weighed and the net weight was 3.45 lbs. This was in turn correlated to gallons per hour, which equaled 34.4 GPH. Fuel consumption of the IO-390 at full rated power is approximately 17.5 GPH. The available flow is approximated twice the amount required for a max power take-off at sea level.

Test done by builder and witnessed by xxxxxx, DAR.
 
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