Rotax 135 HP Engine

[TROOPER]

Bert Flood also shared our stand at Avalon and from memory didn't have a lot to say about the modified 912.....

Rick, were you thinking that the blokes at Bert Flood thought that the modified aftermarket turboed 912 was a 'good thing' or 'not so good'?

[RickE]

The core engine is the 80 hp model. My understanding is that you can't turbo the 100 HP 912 due to the high compression ratio. The 80 HP model is a low compression engine. Please correct me if my info is wrong.

Waddles.

At Avalon Airshow this year there was a TAG on display that had a Turbo charged 912. It boasted having 146hp and I believe the turbo conversion was done by Steve Paulette in Melbourne. I do recall a modification was required to the head of the 912 to address the compression issue.
Bert Flood also shared our stand at Avalon and from memory didn't have a lot to say about the modified 912.....
As a matter of interest for all you mechanically minded folk, we were also told there is a way to "trick" a 914 into providing an extra 20 or so hp for a limited time.

[Brian]

After having a factory suby turbo & having lot of trouble with it my advice would be to make sure you thoroughly research the project from start to finish as a turbo will add extra heat .
I love horsepower as well & it seems it's something you can't have too much of, particularly when the situation gets extremely tight!

[Waddles]

The core engine is the 80 hp model. My understanding is that you can't turbo the 100 HP 912 due to the high compression ratio. The 80 HP model is a low compression engine. Please correct me if my info is wrong.

Waddles.

[deandob]

I think the bearings in the turbo would fail before any heat damage to the engine (and higher performance turbos have an oil cooler to help). Agree exhaust temp sensor would be sensible for a higher boosting turbo.

One disadvantage of the rotax 914 system is the extra complexity of monitoring the engine and electronic wastegate control - more things to go wrong compared to the simpler mechanical system of an aftermarket turbo. However you trust that the manufacturers have got it right especially after a couple of years (I see rotax are regularly releasing service bulletins based on field experience - a good sign).

Probably not a whole lot to worry about (safety / maintenance wise) if the aftermarket turbo is done by a reputable firm and there are lots of aircraft flying around with the modifications and no issues being raised especially after many hours use. A boost, EGT gauge & oil cooler should be mandatory for models with higher boost and for a used gyro the previous owner should be aware about not operating the motor outside safe parameters (like high boost for too long, not enough time to cool down before boosting again). Is this a reasonable summary of what to consider when buying a used gyro with an aftermarket turbo?

[WEST OZ FLYER]

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.

[Brian]

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 !

[deandob]

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.

[tonydenton]

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

[RickE]

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?

[deandob]

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.

[WEST OZ FLYER]

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 (sdsefi.com) 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.

[deandob]

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.

[chook]

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.

Regards.........Chook.

[RickE]

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