Fuel Flow RAM VI 1977 414

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  • #84711

    Hi, I have a question.. recently I have noticed that my right engine #2 is running about 1.5 GPH leaner at full throttle full rich than is the left.

    When I purchased the plane about 6 months ago they were both running about 29gph full rich on take off at 37″ and 2700. I’m now seeing less on the right.

    Is there any info out there from RAM or other about the fuel flow full rich full throttle settings?

    Thanks

    #102412

    Your RAM VI pilot’s handbook supplement should provide the full throttle / takeoff power fuel flows and there should be a placard on the instrument panel as well. The instrument panel placard for a RAM VII states: ” T.O. AND M.C. POWER FUEL FLOW 35.9-35.5 GPH / 210 – 208 PPH”. Since they both produce 335 HP at takeoff I would expect yours to be ~36 GPH at takeoff power. 29 GPH is approximately climb power for me. If the pilot’s handbook supplement is missing you can find the recommended value in the RAM VI STC documentation.

    Geoff

    #102413
    quote khouseholder1:

    When I purchased the plane about 6 months ago they were both running about 29gph full rich on take off at 37″ and 2700. I’m now seeing less on the right.

    That’s seems too low to me. In my standard TSIO520 non-ram I have take off flows at 32gph. I’d imagine with the 335hp engines it should be more.

    I have to adjust my fuel flows fairly often for T/O. They just seem to wobble around a bit. It’s very easy to do and is just a single adjustment screw on the fuel pump with a locking screw – out to increase.

    Andrew

    #102418

    Great info all.. Wow I’m way out of line and too lean for sure given this. I don’t have the placard so going to address that one.

    I did find the STC so looking at that for tomorrows’ adjustment for sure. 29 is way off for what should be well over 32 in Take off.

    #102427

    Kelly, what were your EGT readings at full power with these fuel flows?

    Make sure they do the full fuel system setup – not just the top end. Your idle and part throttle mixture may be lean too.

    Eric

    #102437
    rwelsh
    Participant

      You are way too lean. The 335 HP should be closer to 37 GPH. Your EGTs should be in the 1250 to 1300 dF range. Actually you could be approaching detonation if it was a hot day. I use 38 GPH for my 310 HP engines which put out about 330 HP with AA intercoolers and an extra inch of boost. Better to have too much then too little at TO power.

      #102463
      quote EPANNING:

      Kelly, what were your EGT readings at full power with these fuel flows?

      Make sure they do the full fuel system setup – not just the top end. Your idle and part throttle mixture may be lean too.

      As Eric points out check where you are with EGTs and flows first. I’ve found you can chase your tail a bit when adjusting everything, maybe that’s particular to my plane.

      Andrew

      #102469
      quote RWELSH:

      You are way too lean. The 335 HP should be closer to 37 GPH. Your EGTs should be in the 1250 to 1300 dF range. Actually you could be approaching detonation if it was a hot day. I use 38 GPH for my 310 HP engines which put out about 330 HP with AA intercoolers and an extra inch of boost. Better to have too much then too little at TO power.

      For the 375 HP GTSIO-520, take off fuel flow should be 47 GPH (280 lbs/hrs). As Dick has pointed out, watching EGT’s is critical. An injector partially clogged will spike the EGT’s to peak putting you at much higher risk for detonation at take off power.

      One trap is some of the older twin cessna’s use a pressure based fuel flow meter. It measures pressure and shows flow. However, this is based on all injectors being fully open. If you have a partially clogged injector it will falsely show the fuel flow as too high (the pressure will rise with only 5 injectors flowing). Don’t pull back on the mixture and make things worse.

      #102486

      Ok so found all my info on the STC and we adjusted the Fuel Flow to match the required 34-35gph on MCP.

      It was for sure about 1.5gph light on the right side. The numbers I gave in the 20’s was at 35″ vs 39″.

      We have only flown it once as of the flow change but for the short flight it all seemed in line now.

      Thanks for the help.

      Weird thing is that EGT were not even really showing anything much beyond normal.

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