Gents,

This is one area Lycoming normally do far better than TCM, correct fuel flow at full power full rich.

The correct answer is just a tad under 18 GPH, something around 17.8 USG/hr at ISA and sea level. You can have a bit of latitude, but under 17.5 at ISA would be sub-optimal.

BillL, your data is for around 75-100dF ROP, I suggest that is a very wrong takeoff fuel flow. If you would like, go try it and you will see why.

Jesse, at ISA conditions you should see around 24.5-25 GPH and typically you are in the ball park, whoever has 22.5 assuming sea level 1013 (29.92) and 15dC is in a bad karma zone.

Hey Rags, if you reverse engineer your numbers for the 2000' DA thats about 17.5, so on the money. ;)


Airhead, why are you anticipating? Just for first flight information? If so that is assuming the K factor is set right. But a good idea to be watching for it.

I am not sure why but anyone with an AVSTAR FCU might want to check theirs, I have seen a few far too low.

Bob,
Your Lycoming Operating and Installation Manual IO-360...series should have a Fuel Flow Versus Power chart for your "uninstalled engine." My chart was accurate within 0.5 gph at full power sea level. A fellow builder with a 0-320 observed the same accuracy.

Since I live at sea level and can fly at near standard day conditions it was fairly simple to validate Lycomings numbers. The green run sheet showed a 1.0 gph correlation. As an aside my IO-390 burns 18.5 @ 100% power.

I am seeing 25 gph, 1250F EGT's or about 200F ROP. I keep CHT's under 380F on climbout.

.55-.60 Lbs/hr per HP.

18 or less
 

Jesse had it in the second post. 10% of rated HP is really close. Thats at sea level with standard atmospheric pressure.

Eddy

This post exhibits exactly why I am trying to be specific with my question of fuel flow at full power T/O. Two of the reply's (Paul K & Mehrdad, which I think are both IO 360 M1B Precision FI, C/S prop) are recording fuel flows in the 15 to 16 gph which is what I am experiencing. (I assume Paul and Mehrdad are happy with their numbers). All others are (recording or predicting from charts) higher flows. That is the same spread I have seen in other posts about this subject.

Reason for my investigation: I currently have about 50 hrs on my 7A. At about 20 hours my FF @ T/O full power, started dropping over a period of couple of hours flight time from 18 to closer to 15+. The engine still develops same rpm (2680), is smooth and otherwise performing fine. What brought this to my attention was that I noticed the CHT's were rising to the 430-440 (before reducing power to cruise/climb) range instead of the 400-410 I was recording prior to the mysterious drop in FF (I have the Skyview EMS with red cube FF transducer). This despite the fact that the first 20 hours were in August. I can't see any other engine parameters that have changed. I have checked the mixture control and am getting stop to stop movement. Also checked torque on servo to engine and intake manifolds. The CHT rise (only peaks to over 400 for about 1 minute typically). I can live with that if necessary by adjusting my climb speed and timing for power reductions. But because of the shift in FF over a relatively short period of time I am being cautious, and exploring any possibility. Precision Airmotive has been responsive, and said they will be glad to inspect the servo and adjust if necessary at no cost. But before I go to that time and trouble I wanted to see what others with same installation are experiencing. By the way, I am very happy with the PA system which is giving me a CHT spread of less than 20 degrees and a EGT spread of less than 40 degrees. No GAMI's in my plans.

opps. I was thinkin of the twin big block boat set up....actualy a rough etimate for sea level normaly asp - 1/2 pound of fuel per HP per HR.

I just got a reply from Joe at Van's. He is referencing charts and graphs in Lycoming (or Lyc clones) manuals and interprets 14 to 16 gph. However, my manual has the same charts, and these (the way I interpret them) are for cruise, i.e. "Best Power or Best Economy" settings, not necessarily for full power / full rich WOT T/O conditions where you might want slightly higer flows for cooling. Having said that, the M1B engine seems to be very fuel efficient. I have flight tests recording cruise flows of 8.0/8.5/9.0 GPH at 65/70/75 percent power respectively (peak EGT at 8500 PALT) which is at the very low end of the various charts I have seen. Which is another reason for asking for data from owners of same engine/prop configuration.

I have been meticulously recording (and charting) my fuel tank levels (both stick and guage) and fuel additions after every flight in order to calibrate K value. I have very gradually adjusted it from 68,000 initial (recommended by Dynon) to 74,000 current.

My friend's RV-8 with ECI Titan IO-360 (very similar to IO-360-M1B but has 9.2:1 compression, cold air induction, ~192 hp, etc) and Hartzell BA prop runs around 18-19gph at full takeoff / full rich power. So Jesse's formula is right on for this engine.

My reading on my Dynon's and on the GAMI report I sent in shows 16.1 GPH
at takeoff 2690 RPM MP varies according to alt. 1520 elevation. 45 degrees.

IO360MIB Hartzel blended airfoil prop. Horizontal intake.
Jack

I appreciate all the replies.

Questions if you tune back in to this channel:

1. Do you have Precision Air FI?
2. Do you know your K value setting for your EMS fuel flow monitor?

So far Based on replies, M1B's are indicating significantly less FF at full rich WOT T/O conditions than other 180 hp 360's, ie; 15 to 16 rather than 18+.