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  #1  
Old 05-28-2016, 02:55 AM
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Aiki_Aviator Aiki_Aviator is offline
 
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Default Max Fuel Flow on Takoff/Climb

Hi All,

I was wondering what people are getting out of their IO-540 D series engines for Max Fuel Flow on take-off.

I just want to confirm that mine is running in line with others on the forums.

Thanks guys.
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  #2  
Old 05-28-2016, 06:26 AM
vic syracuse vic syracuse is offline
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Depends on altitude and temp but with the AirFlow performance system I see arounf 25 gph at sea level +1K'.

Vic
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  #3  
Old 05-28-2016, 06:51 AM
N427EF N427EF is offline
 
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25.5 GPH at sea level. (260 HP )
This is a very important number and ensures that your fuel system is
properly set up for maximum performance on take off and in climb.
Some of that fuel is required for cooling to keep the CHTs in an acceptable temperature range.
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  #4  
Old 05-28-2016, 07:11 AM
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Default Documents verifying this number

So looks like consensus is 25.5. Can anyone point to the documentation having this as the Fuel flow for this engine?

All I can validate is the Lycoming Operations Manual setting 21.5 for the D series.

Thanks.
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  #5  
Old 05-28-2016, 10:22 AM
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Aiki: Many of these engines are experimental and don't fit the manual. Mine is an IO540-K1G5 (heavy crank and case) with lightweight ECi parallel valve cylinders, running an AFP 200. With 9.5 to 1 pistons, it pulls 27 to 28 gph on take off. If I leave it at full throttle, I can climb all the way to 10,000' + running plenty cool all the way.

When I spoke with Don Rivera of AFP about it, he said that was not too much fuel at all. I'm cooling with fuel during the climb at full power, of course, but it climbs like crazy and works like a charm. I end up at (say) 10,500' in a big hurry, still burning about 17 gph, leave the throttle wide open and just manage the engine with the mixture. Pull it back to around 2,200 rpm and at or about 13 gph and your doing 190 ktas or just under 220 mph over the ground in still air.

Good luck...


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Old 05-28-2016, 10:29 PM
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For takeoff from sea level you should see about .9-1.0GPH per 10HP. If your engine is a stock 260HP -540, then you should see in the 24-26GPH range. As others have said, this keeps the EGT's low to help keep the CHT's low. I like to see EGT's well under 1300 for takeoff. After I pull back to 25 squared for climb I lean to low 1300's.
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Old 07-05-2016, 08:35 PM
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My rv10 have a fuel flow 25 gallons At take off on a 2700 ft AirPort. Anyone At this altitude to confirm?
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Old 07-05-2016, 11:44 PM
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The excess fuel is not cooling anything. It is merely lowering combustion temperature, and delaying peak pressure, much like retarded timing.

Lycoming data lists what they consider to be the minimum fuel flow for rated power, which includes a detonation margin. Power output is fairly flat in the region richer than optimum, so it is possible to run richer without huge power loss. Setting up the fuel control to be richer than the minimum required for rated power adds additional detonation margin. Recall that best power mixture is about 100F ROP, and we like to see the fuel control set up for 200 ROP at full rich, maybe 250. Some like it even richer, but that's just an expensive way to make less power.

BSFC (pounds of fuel per HP per hour) is a fine guide to fuel flow, IF you know power output with some accuracy. For example, my IO-390 manual says minimum fuel flow is 105 lbs at 210 HP, for a BSFC of 0.50. A 260 HP engine at 0.50 is 130 lbs per hour, or 130/6 = 21.66 GPH. The consensus 25.5 would be a BSFC of 0.588.

Here's a useful chart from the FAA dyno, an IO-540-K. Lots of interesting things to observe, but in the context of this discussion, note the BSFC and fuel flow at max power mixture; 245 HP at 112 lbs per hour, for a BSFC of 0.46, or 18.6 GPH.

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  #9  
Old 07-06-2016, 02:45 PM
jfrank71 jfrank71 is offline
 
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I have the IO-540 as well. Do not recall the exact number, but it seems like its around 22gph on take off. 500MSL airport in south texas. KCOT
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  #10  
Old 07-06-2016, 06:27 PM
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Ok, my servo in the bench has 132 pph in 26". But in my airplane it has 25 gal at 26" manifold and full power. For that I send my gauge for a check, but it was ok.
My engine seens to be rich, at 2000 rpm leaning misture knob I have a rise of 100 rpm. Checking mags with this leaned misture at 2000 rpm, drop is 120 - 110 rpm.
Here the problem, at 2000 rpm and misture full rich it drops 190-200 rpm....
Mags with 500hs inspection, new sparkplugs (rem40e) and cables.
That's why I m asking about gallons; I m thinking my engine is very rich and this is the cause of excess of drop in my mags.

Opinions ?
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