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Rotax 135 HP Engine

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  • Rotax 135 HP Engine

    I'm posting on behalf of a newbie who has registered on this forum and been issued with a password but hasn't been given access to post. I've sent a PM to Dan, but no response and still no fix. Any clues out there please?

    Now. This guy is interested in a gyro with a Rotax 912 that has upgraded with an aftermarket turbo giving a nominal output of 135 HP. He been getting various bits of conflicting information and was hoping that someone out there can clear this up.

    What are the service intervals on the 135. He's heard 25 hours and compares this with a 914 with intervals of 100 hours. Any advance on these figures.
    Also, what is the serviceability of the 135 like compared to other turbo models? Any major problems?
    The gyro does not have a boost or MAP gauge fitted. Is this necessary for safe operation?Any other thoughts and facts appreciated.



    In aviation, the only stupid question is the one you don't ask!

  • #2
    I will send Dan a PM as well in regard to posters timing out too early, we will see how we go.....
    in regard to aftermarket turbos on 912 Rotax engines, Neil from TAG is using that modified engine a bit and should be able to help. Xenon and Brako also use the 912 with an aftermarket Mitsubishi turbo. Any owners of these aircraft should be able to help.
    i can pass on some names if that helps.
    Most fellows I know with 914 engines change the oil and filters every 50 hours unless using Avgas which then reduces service intervals to 20 hours or in my case as soon as I get home.


    • #3
      I have just noticed that Rotorute are also working with a turbocharged 912.


      • #4
        Thanks Rick,

        I've found a Rotax Maintenance Schedule (MS) which specifies exactly that. Also, perusal of a Xenon MS does not have specific engine maintenance requirements for the RST model (135 HP), so I'm guessing that the Rotax Schedule (914) is the applicable one.

        It appears that the time out problem may have been fixed as I had no trouble posting the original on this thread, even with my two fingered expertise.

        Thanks for the input.


        In aviation, the only stupid question is the one you don't ask!


        • #5
          Thanks guys. My forum registration has finally come through so I can now post. Allan thank you especially for going out of your way to help me with research. Being new to aviation and gyros I'm trying to assess the safety risks of flying with a gyro with an aftermarket turbo.

          I'm looking at a second hand Xenon 2 to purchase as my first gyro and am a bit concerned about both the reliability & the additional maintenance due to the aftermarket turbo on the 912. I have quite a bit of experience with automotive turbos and am aware of the extra stresses (heat & compression) that it puts on the engine, especially when boosting for long periods of time which is hard to do in a vehicle (without breaking the law) but easy to do in a plane. As this particular gyro doesn't have a boost gauge (that I could locate) the possibilities for running the engine in boost for longer than you should may mean the motor had high stresses / wear.

          However it does seem that aftermarket turbos in the rotax 912 are common although a poster on rotaryforum warns about potential crankshaft damage due to the extra torque

          and I can see a turbocharged motor would be better for a heavier gyro and also provide extra thrust when needed in difficult situations. So given the number of gyros that have similar aftermarket turbos on the 912 it can be assumed there aren't any significant issues although no warranty on the motor. There is even a company that sells the rotax with the aftermarket turbo

          Failure modes for a turbo motor due to the extra power would be compression loss (eg. turbine blades broken / not spinning, blown gaskets/hoses) which you could limp home on, but there is also possibility of severe engine damage (eg. crankshaft, bent rods) which would shut an engine down, potentially crashing the gyro.

          Am I worrying too much about the risks with flying a gyro with an aftermarket turbo?


          • #6
            I have sent you a PM Deandob with the contact details of a guy in Melbourne that does the 912 turbo conversion.


            • #7
              Deandob you are flying one of the most forgiving aircraft types available (I've tested their ability on at least 2 occasions). Concentrate on your ability to land with engine out practice which is easy because you can practice on every 3rd or 4th landing without upsetting anyone. Remember that you can still fly these machines if the life critical stuff is still intact, that being your blades are still spinning, you are still connected to the mast in your seat, your hand is still connected to the rotor head (via cables or rods), you are not over tiger country and you have some altitude. With those basics you should still be able to get down safely.

              There has not been an engine developed which is not going to fail at some stage - plenty of certified aviation engines continue to do it on a regular basis (Air Asia just north of Exmouth in Western Australia 3 weeks ago) so keep a keen eye on the life critical components described above - its still fun.

              And remember - we've never left one up there.



              • #8
                Thanks Chook and RIck for the tips.

                Agree that practice and proper training is the key to safety and I won't be taking any shortcuts. Regarding engine out practice landings upsetting people, is that because people on the ground freak out if they see a gyro with no prop motion?

                I'm probably over-thinking this, as long as the modifications are done to a proper standard with quality parts, inspected regularly all will be OK.


                • #9
                  Hi deandob, was the engine originally a 100 hp or 80 hp engine? The 135 hp engine should be a 100 hp base engine with mods if it is the one I am thinking of. I personally would definitely run a boost gauge and 4 egt's on this turbo rotax with Bing carbs. With the 914 you are either on or off boost but with this 135 hp engine I believe that you are on boost all the time varying depending on the load of the engine thus varying your boost pressure.

                  There is a reason Rotax put a computer turbo controller on the 914. Every parameter has to be right before it will allow boost to your engine.

                  135 hp from a 100 hp is less of a hp percentage increase than what Rotax did for the 914 (80 to 115 hp) in regards to extra load on your crank. The Rotax crank albeit pressed together has one piece conrods. As there are no bolts to break they are stronger by design. This engine I am thinking of does run at 154 hp too if that makes you feel any better. 😂😁 Some people choose to weld the crank to make them stronger.

                  If I were to do this I would use a efi system like simple digital systems ( I have a spare engine and turbo to do this but I don't need that much hp. 😎 There is more to flying gyrocopters than having excessive amounts of hp. It's good to have but if you need it you should reconsider your aeronautical decision making process that got you in that situation.

                  Yes if it is all done properly it should be ok if it isn't abused.


                  • #10
                    Not sure about the original engine, its from an older Xenon 2 (2007) so I assume the manufacturer had thought about the long term reliability of the aftermarket changes.


                    • #11
                      Originally posted by deandob View Post
                      Not sure about the original engine, its from an older Xenon 2 (2007) so I assume the manufacturer had thought about the long term reliability of the aftermarket changes.
                      Is this engine out of a Xenon that use to fly out of Cessnock in NSW?


                      • #12
                        who would of thought a good old ROTAX 4 banger causing so much kaffle on the forum. what do you recon about that brian ????.


                        • #13
                          Not sure of the history except it was one of the first in the country - and I don't have any specific concerns with the condition of this particular Gyro, my questions were more general in relation to the wear / tear / reliability of the rotax with an aftermarket turbo.

                          From what West Oz Flyer mentioned about the 914 and the boost controller only active when the conditions are right makes perfect sense and will ensure the long term reliability of the engine. The aftermarket turbos should also be OK if used within similar parameters, however it relies on the pilot to ensure the engine isn't overboosted or on high boost for long periods of time, and without a boost gauge or MAP it is hard to judge (although the oil temp gauge could be used as a rough proxy for turbo use), especially if the pilot isn't aware of these things.


                          • #14
                            Yeah, surprising what these guys will talk about Tony . Goes to show how quiet things are when a 912 is the conversation piece of the day !


                            • #15
                              Your pistons will melt long before you notice a rise in oil temp or a dramatic rise in cht's for that matter. Aluminum melts just after 1200 degrees F or 650 degrees C. A few moments at that temp and it is all over. Molten aluminium and cylinder pressures will blow out the top of your piston in no time.

                              Your oil has to complete it's path through the engine into the tank, mix with cooler oil and then gets sucked through the oil cooler before reaching the temp gauge sender. EGT's are the only reliable way as long as the probe is located close to the exhaust port.

                              If that engine is from a Xenon 2 it should have come from Edge Performance in Norway and based on the 100 hp. Have a look at their stuff. I have been watching them for a few years now.