Ram VI Range – Not as good as stock 414?

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  • #84851

    My 414 has tip tanks and aux tanks (163 Gal total), and I’m trying to understand how to get the most range out of it.

    Reading thru my Ram Power chart and comparing it to the original Cessna POH.

    Per RAM VI power chart with American Intercoolers:
    20K Feet
    MP 25.5″
    RPM 2300
    FF: 32GPH
    TAS: Not on chart (Ram’s website indicates 188 KTAS)
    Range: 5.09 hours (no reserves)

    Per the Cessna POH
    20K Feet
    MP 26″
    RPM 2300
    FF: 27.5 GPH
    TAS 186 KTAS
    Range: 5.92 hours (no reserves)

    The Stock Cessna 414 goes 1102 NM, but the Ram 414 goes 956 NM.

    Here’s another Scenario

    Per RAM VI power chart with American Intercoolers:
    20K Feet
    MP 28.5″
    RPM 2300
    FF: 37GPH
    TAS: Not on chart (Ram’s website indicates 203 KTAS)
    Range: 4.40 hours (no reserves)

    Per the Cessna POH
    20K Feet
    MP 30″
    RPM 2300
    FF: 31.2 GPH
    TAS: 200 KTAS
    Range: 5.22 hours (no reserves)

    The Stock Cessna 414 goes 1043 NM, but the Ram 414 goes 893 NM.

    Does anyone have a Ram VI or VII? How do you get the most out of the range? The RAM chat is not nearly as detailed as the charts in the 414 POH concerning distance and airspeed. I’m working an example flight plan that I will fly tomorrow. I will be stopping for fuel, but I wish there was a scenario where I didn’t have to.

    842NM total trip distance
    Climb = 56NM, 22 gal, 20 min
    786NM after Climb, Fuel after Climb left = 141
    Cruise Fuel Burn = 32GPH
    Cruise Speed = 188KTAS
    Fuel left after climb: 4.40hrs
    Time to destination: 4.10hrs

    a 30 minute reserve is too close for comfort, and not legal or smart for IFR anyways.

    How about LOP @ 55% power. Anyone doing it?

    #103503

    LOP is the way to get the best range. The Cessna charts are probably at peak or 25-50F ROP (which is bad for the engines), and the RAM settings are at a more ROP setting that’s fine for the engines, but has bad fuel consumption. LOP is the way to go. I wrote an article about it in the September 2013 issue I believe.

    #103524
    rwelsh
    Participant

      First off, you will never make 20K in 20 minutes with a 414; more like 28 to 30 minutes even with the 335 HP engines and AA innercoolers unless you climb at 2600 RPM and 34″ MP and 60 GPH. A good climb would be 2550 RPM and 32″ MP and full rich of 58 GPH until level off and accelerating to cruise IAS of about 155 KIAS. LOP you can cruise at 34″ and 2350 RPM and 31 GPH assuming your engine is baffled tight enough to keep the CHTs below 390 dF, and this should get you around 200KTAS. I am surprised you do not have a 20 gallon nacelle tank as most planes came with them.

      #103582

      On the way down I experimented with power settings

      ROP – 16K Feet
      MP 28.5
      RPM 2300
      FF 18GPH / Side
      EGT: 1458
      CHT: 376
      190 KTAS

      LOP – 16K Feet
      MP 28.5
      RPM 2300
      FF 13.5GPH / Side
      EGT: 1539
      CHT: 394
      Speed: 182 KTAS

      I will increase the MP on the way hope and see if the temps can support it!

      What type of TIT would you say is the max for LOP operation?

      #103585

      I tend to recommend 1550F or below for TIT/EGT, but your CHTs should be 380F or below. If you’re seeing 394, lean it out a hair further and it should drop.

      #103586

      I’ll lean a bit more and see if it drops. IIRC, last flight it had a pretty big power drop with more leaning.

      My TIT was just over 1600 – 1620 but EGT’s were around 1550

      #103588
      quote BHerron1:

      I’ll lean a bit more and see if it drops. IIRC, last flight it had a pretty big power drop with more leaning.

      The mixture control is very sensitive it’s had to pull it back only a touch. On my LH engine I can nudge the MP up an inch or so without effecting fuel flow, this drops the temps.

      quote BHerron1:

      My TIT was just over 1600 – 1620 but EGT’s were around 1550

      My TIT at similar settings sit about the same. However my EGT are about 50F higher then yours. What do they peak at and how far LOP were you?

      Andrew

      #103590
      jltaylor
      Participant

        Just a question here guys. Are any of you comfortable with a TIT indication of 1600? Much less higher than that?

        #103591
        jltaylor
        Participant

          I keep thinking that a temp of 1650 is melt down! Am I wrong here?

          #103592

          1650F won’t melt down your engine. If it would, then it wouldn’t be a certified allowable temperature.

          That said, I’ve always advocated 1550F or cooler for longevity. A number of people on here I’ve noticed run at 1600-1650F and seem to get good service, so maybe my numbers are more conservative than they need to be. On the other hand, I also don’t know what their cylinder service is.

          #103593
          quote :

          Just a question here guys. Are any of you comfortable with a TIT indication of 1600? Much less higher than that?

          The 1650 limitation is because over a long period of time your turbo blades could stretch enough to scrape the turbo housing. Brief excursions past 1650 are not a problem. I fly mine at 1600 all day long. There is no data that I am aware of that proves anything under 1650 causes a problem.
          Pete

          #103594
          quote PVANHELDEN:

          The 1650 limitation is because over a long period of time your turbo blades could stretch enough to scrape the turbo housing. Brief excursions past 1650 are not a problem. I fly mine at 1600 all day long. There is no data that I am aware of that proves anything under 1650 causes a problem.
          Pete

          Cessna didn’t publish a limitation as there was no TIT gauge. Continental have a limit of 1650. Mike B has spoken about his personal limit of 1600. Consider also probe location can have a big effect as well.

          I too run 1600 all day and haven had an issue. I don’t think I could get 1550 LOP without a massive loss of power.

          Andrew

          #103598

          Pete and Andrew. What airplane and engines you have?

          It is not the same thing flying at 6,000 feet or 22,000 feet.

          #103600

          Made another attempt for LOP Cylinder temps were dropping nicely, but TIT went up thru the roof. As soon as I went LOP and watched CHT/EGT fall, TIT climbed up to 1650 within 30 seconds. Going more lean seemed to cause it to climb even faster, and richer cooled it down.

          The JPI only reads to 1650 so once it hit there I had no choice but to push the levers forward and get it back down.

          This is a 74 414 Ram VI, AA intercoolers, and about 15K feet. Anyone else have experience with increasing TIT temps?

          Brian

          #103601

          Brian, we need some more data. What manifold pressure, what RPM, what were temps outside?

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