O360-A1A high fuel flow ?

tturner · #1 10-25-2011, 07:40 PM

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?

lostpilot28 · #2 10-25-2011, 08:11 PM

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.

tturner · #3 10-25-2011, 08:30 PM

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.

L.Adamson · #4 10-25-2011, 08:38 PM

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

David-aviator · #5 10-25-2011, 09:09 PM

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.

Tom Schad · #6 10-25-2011, 09:10 PM

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.

RV10inOz · #7 10-25-2011, 10:34 PM

Correct fuel flow would be 18ish, if cold and dense a bit more. So it's all
Good

Tom,

Quote:

I leaned it to peak and backed off a bit to save valves and engine.

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.

C-FAH Q · #8 10-26-2011, 04:25 AM

I see 19 gph on full power runs with boost pump on, io-360 A1B6

Jamie Aust · #9 10-26-2011, 02:33 PM

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.

RV10inOz · #10 10-26-2011, 02:50 PM

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