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O360-A1A high fuel flow ?

T

tturner

Well Known Member
I have a o360-A1A with Hartzell constant speed prop in an RV6. At max power the fuel flow is 19 to 20 gph which I think is too high. This is a new certified Lycoming engine that was purchased in 2002, stored for 9 years and run for the first time this summer. The engine runs smooth and I can lean it back and it will run LOP ( has one p-mag ). It has a MA4-5 carb p/n 10-4164-1 and the main jet is p/n 47-755 which has an orifice diameter of .125. I replaced the float per the SB and this had no effect on the FF. I believe the FF indication is accurate as the totalizer matches the fuel consumed. I was not the original purchaser but I do believe this carb is just as it came from the factory.

Does anyone else have this high a fuel flow with this setup?
 
Hi Tommy,
Have you verified that your fuel flow meter is correct? Stupid question, but you never know. I believe you need to calibrate it in most systems.
 
Sonny

The refuel amount matches up with the indicated fuel burn and when the engine is leaned in cruse the FF indication seem correct. I think the indication is accurate.
 
I havn't seen anything near that high. On the other hand, I haven't been scientific about it either. Looking at cockpit pics, I see 8.8 gph at 188 mph GPS ground speed. Could be some tail wind there. I don't remember going over 10 gph in level flight, and 11-14 at the most, in a climb. Usually, I pull the throttle back a bit, where I'll be running in the upper 7's.

This is for an RV6A, 0360A1A, Hartzell C/S prop...............and was stored from 1996 (new) to 2008 before first run. In fact, I have it apart at the moment due to a prop strike. It's still like new....in there. I do live a lower humidity climate, though.

edit: most of my flying is between 8500 & 11500' around the mountain west.

L.Adamson
 
I have a 180 hp IO360, same hp as yours, and it will burn 18+ gph at full rich.

When doing the WOT break in, I leaned it to 1300 EGT to get off the high fuel flow. It ran around 16 gph.

A Lycoming sucks up a lot of fuel at full rich. The metering system must provide enough fuel no matter what the temp and there is quite a bit required at 10F verses 90F. It could easily be 18-20 gph, the air is mighty dense at SL when it is that cold. I've tried to lean at 15F and the engine goes into rough almost immediately due to the lean F/A ratio. My engine will not run LOP when it is very cold.
 
From experience, I have had one Lycoming O-360 A1A with a Hartzell constant speed prop in a Cessna 170 and it used 10 gallons per hour or a bit less block to block on cross countries. You could put it in the bank. I leaned it to peak and backed off a bit to save valves and engine. I have a Superior XP 360 in my RV-8 with the same prop and it's fuel consumption is about the same. In cruise I get it down into the high eights, but overall it is just shy of ten gallons per hour. Most of my RV-8 time is cross country and the fuel consumption is very consistent at 2450 RPM and 22 inches at nine to ten thousand. Naturally, on full power climb I will burn more fuel. You have a problem, something is very wrong if your figures are accurate. the Suggest you verify the carb, jet size etc and check your timing one more time.
 
Correct fuel flow would be 18ish, if cold and dense a bit more. So it's all
Good:)

Tom,
I leaned it to peak and backed off a bit to save valves and engine.
Click to expand...

Please tell me that you leaned and backed it off leaner. If you meant richer, with that logic in mind I would recommend some remedial engine training to you.
 
At sea level, boost pump on, WOT, full rich, the max I see is 16GPH ( 60 LPH ) I have a dynon red cube, same engine and carb as you have.
What numbers do you get when running LOP ?
The best LOP for me is 7.5 GPH ( 28 LPH ) if you are getting higher than 7.5 GPH, I would say your fuel flow computer may need an adjustment.
 
Remember Jamie you have a fixed pitch prop, and at takeoff power you are getting around 150-160 HP so that is correct.

Different with CSU as the engine will be at full rated rpm and power ;)
 
tturner said:
At max power the fuel flow is 19 to 20 gph which I think is too high.
Click to expand...

Maybe just a wee bit too high (1 GPH).

The RV-8 in my avatar has an ECI Titan IO-360 (w/cold air, forward induction, ECI fuel injection, etc) and on full power takeoffs/climbouts, I see between 18-19 GPH.
 
Last edited:
IO-360B1B w/ Precision EX

Aerosport told me I should see somewhere between 16.5 and 18 gal/hr full rich WOT. I'm running a fixed pitch so I test this flying level at less than 3K. Currently I can't get much over 15 gal/hr. Red cube fuel flow calibration seems to be very close.

Precision can adjust it to whatever I want, I just don't want to rush into anything. Increasing the fuel flow would probably would help with my high CHTs though.
 
Thanks for all the replies. The 19 to 20 GPH is at WOT takeoff, 800 ft MSL. Based on the replies it may only be a little high. I have a Skyview with Fowscan transmitter and LOP in cruse I can get down to 7 to 8 GPH.
 
tturner said:
Thanks for all the replies. The 19 to 20 GPH is at WOT takeoff, 800 ft MSL. Based on the replies it may only be a little high. I have a Skyview with Fowscan transmitter and LOP in cruse I can get down to 7 to 8 GPH.
Click to expand...

I'm at 4600' MSL for takeoff. That would explain some of the difference.

L.Adamson
 
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