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  • 912 vs 914

    Is there anyone that bought a rotax 912 ULS 100hp engine that later regrets not spending the extra money for the 914 version on a two place? I知 in mid to northern California and I知 considering the 912 but worried slightly that I値l later regret not spending the extra money for the 914.
    Thanks,
    Paul
    (925) 481-4304

  • #2
    Originally posted by Spank View Post
    Is there anyone that bought a rotax 912 ULS 100hp engine that later regrets not spending the extra money for the 914 version on a two place? I知 in mid to northern California and I知 considering the 912 but worried slightly that I値l later regret not spending the extra money for the 914.
    As everyone knows, extra power is always welcome in gyros, but -吠n my opinion- the 912 is perfectly acceptable for a two-place, provided 1) the altitude of your airfield is near sea level, and 2) most of the time you'll fly alone. I'm flying now an ELA fitted with a 912, my airfield is at 3000 ft., and the performance is very good when flying alone. I have never tried with a passenger, because I believe that the take-off will be slow and risky with the 912 at 3000ft.
    Last edited by XXavier; 12-05-2017, 11:48 PM.

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    • #3
      Another option is going with a big bore kit, more hp without the complication of a turbo. That has worked out great on this ELA G8 flown down here in Texas.

      https://www.youtube.com/watch?v=qGNuDANOjuU

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      • #4
        If you have any desire to head into the Sierra Nevada Mountains you can get high very quickly.

        I fly high when I go to Georgetown because the trees reduce the available landing zones and the approach is somewhat restricted.

        Truckee-Tahoe Airport is at 5,901 feet.

        They are both lovely places to fly.

        If you stay in the flat lands and have long runways you will probably be just fine even with two big people on board.

        Remember the power listed is takeoff power and is for a limited time.

        Continuous power is less.
        Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

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        • #5
          I avoided the turbo on my 2-place Dominator because of cost (of course) but also because complexity, and hot-rodding small engines, both bother me. The underlying 1300 cc engine was designed for 80 hp. The old VW 1300 cc made about 40 hp.

          I built my 2-place as light as possible and used 28-foot blades in place of the 27's often used on this model. I flew passengers up to 250 lb. (I'm 180) but that was admittedly near sea level and with half fuel (the bird had two 8-gallon seat tanks). I did not fly it solo all that much but, boy, what a rocket it was when I did.

          I've never regretted skipping the 914.

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          • #6
            I flew my MT03 solo but with baggage across the Ratton pass at an altitude above 10,000 feet (don't know density altitude but it was in summer).

            -- Chris.
            Read about my trip across the USA in an MT03 gyro here.

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            • #7
              Actually turbochargers are very simple provided the engine is injected.The turbo is easy to install and is trouble free,I don't think

              having a turbo using low boost is over working the engine, with low boost 7 lbs or less there is no need for a intercooler or any other changes

              to the engine in most cases you are just bringing the boost up to sea level pressure.

              I think rotax has there computer control the pressure output and have had problems with that setup and they use a lot of boost

              which I think would reduce reliability.Keeping things simple works best and there is no reason to make a turbo system complicated.

              My engine makes 230 hp on takeoff but for most of the time I probably I'm using considerabely less,by making more HP I can use

              a lower rpm setting which increases longevity, less fuel burn, and a good cruise speed, and when I need to go up I use the up lever

              (the throttle ). I have more than 750 hrs on my engine with no turbo related issues at all.
              Best Regards,
              Eddie Sigman,Polvadera,nm
              (575) 835-4921

              Comment


              • #8
                Hi Eddie
                rotax uses 6 lbs of boost only and allows full boost for only 5 minutes max. The Turbo Control Unit will not allow longer duration and default to lower boost after that.
                The system is very simple. TCU senses Air box pressure runs servo that is attached to waste gate.
                the weakest part in Rotax 9 series engine is the way crank is made. It痴 pressed together like in 2 strokes. If you go more than 124 HP, it痴 likely to slip in time. To go higher you need a welded or something else. 914 is 115 HP.

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                • #9
                  Fara I did not know that, with only 6 lbs of boost it should have a good reliability record.

                  I remember reading about early engines that came back on power during takeoff,because of computer issues with the wastegate.
                  Best Regards,
                  Eddie Sigman,Polvadera,nm
                  (575) 835-4921

                  Comment


                  • #10
                    Originally posted by eddie View Post
                    Fara I did not know that, with only 6 lbs of boost it should have a good reliability record.

                    I remember reading about early engines that came back on power during takeoff,because of computer issues with the wastegate.
                    Yes it does. I have friends like Russell Brown here who have 5000 hours on a their fleet of 914s (multiple engines) with just top ends done at each 2000 hours.

                    I am not sure about older engines. You could be completely right.

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                    • #11
                      How much would each of you say that turbos reduce engine oil life? This is a really great topic. Thanks.
                      Regards

                      Frank

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                      • #12
                        The last time I looked Rotax listed the same time to overhaul on the 914 and 912.

                        The 914 is a smaller displacement engine than the 912 with a reasonable combustion chamber and they go to a lot of trouble to keep the boost down.
                        Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

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                        • #13
                          I use mobil one 15-50 synthetic it takes the higher temps just fine,I don't think the turbocharger affect its lubrication ability at all. I change oil every 30 hours.

                          My engine uses zero oil between changes,but it only has 750 hrs on it.
                          Best Regards,
                          Eddie Sigman,Polvadera,nm
                          (575) 835-4921

                          Comment


                          • #14
                            Originally posted by eutrophicated1 View Post
                            How much would each of you say that turbos reduce engine oil life? This is a really great topic. Thanks.
                            I was in a hurry and didn稚 read your question correctly.

                            If people don't let their turbos cool down properly they can have a challenge with oil in the floating sleeve bearing.

                            In my opinion changing the oil more often won稚 help; having the engine at low power for five minutes before shut down will.

                            I changed the mineral oil and filter every twenty five hours in the Rotax 914 I was taking care of because I was running 100 LL. In my opinion full synthetic doesn't work well with 100LL.

                            If I were using synthetic oil and motor fuel I might have changed the oil and filter every fifty hours.
                            Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

                            Comment


                            • #15
                              Originally posted by Spank View Post
                              Is there anyone that bought a rotax 912 ULS 100hp engine that later regrets not spending the extra money for the 914 version on a two place? I知 in mid to northern California and I知 considering the 912 but worried slightly that I値l later regret not spending the extra money for the 914.
                              I have flown a Cavalon with a 912 and in my opinion spending the extra money on a 914 would be the smartest thing you will ever do.

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