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Rotax 4 cylinder opposed engine

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Posted

Seem to be having problems....?

I loved they developed the engine, but a local guy lost his... Started making metal....???

And look on YouTube and you'll see plenty of rod spitting.

NO THANKS!!!

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Posted

Boring day??  hahahaha   and here come the folks to tell ya how great the overpriced engine is no matter what the costs.  

I do gotta agree with them.  From the flight reports I have gotten, it is an engine that has yet to be rivaled.  The Yamaha is probably going to surpass it with time, but IMO the flight times and flight reports are just getting going on the Yamaha and the data is not there like it is for the 912 series.

:BC:

 

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Posted

I like four strokes, and I like 2 strokes. Properly installed and maintained they CAN rival each other in reliability. Most 2 strokes don't fail, they are murdered by their owners!  Got to admit though, lately the price of new two strokes are getting pricy. I know some think I am nuts, but somewhere out there is a common 4 stroke waiting for someone to try in an airframe and just might be what we are needing. May be a Yamaha, Can-Am, ATV engine, boat motor, or whatever, but its out there somewhere.

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Posted

Boring day??  hahahaha   and here come the folks to tell ya how great the overpriced engine is no matter what the costs.  

I do gotta agree with them.  From the flight reports I have gotten, it is an engine that has yet to be rivaled.  The Yamaha is probably going to surpass it with time, but IMO the flight times and flight reports are just getting going on the Yamaha and the data is not there like it is for the 912 series.

:BC:

 

Is it that obvious? :rolleyes: No I was serious. I like the motors, it just seems that some of them don't last to TBO. But then like Allen said, maybe it was partially due to owner abuse?

The new turbo EFI motor is sweet. Not sure I want to bite off that much though.

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Posted (edited)

Seem to be having problems....?

I loved they developed the engine, but a local guy lost his... Started making metal....???

And look on YouTube and you'll see plenty of rod spitting.

NO THANKS!!!

In a subsequent video, the engine failure guy (friend of Trent) owns up to the fact that he built an uprated 912, but he "used an 80 horsepower crank" because he didn't have time to put the higher rated crankshaft into it.

Less a damnation of an engine type than an admission that some experimental guys just screw up. Check out his discussion of the cause of the failure at time 1:20 here:  https://youtu.be/j7uMgxXwfmY

Edited by nlappos
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Posted

There are numerous cases of 912's going to 1000 hours, 2000 hours, and I've read reports of some going over 4000 hours. I don't believe you will EVER, get an air cooled engine to go that far without cylinder work.  

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Posted

Most 912's will make TBO with regular oil changes, and a decent level of maintenance (replacing rubber and so forth as required). Most 912's that fail have either not been properly maintained or have been modified to produce more horsepower. Oil analysis performed at every oil change will usually provide an indication of something starting to go wrong before it bites you in the ass. At least this is my limited experience with the 912.

Two strokes are a lot the same from my perspective. left stock AND properly maintained they are very reliable. The only difference to me is I had to fly the engine as well as the plane because it is pretty instinctive to start a decent and pull back a little on the throttle at the same time which can be disastrous.

That's my experience anyway.

 

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Posted

nlappos, I wasn't completely damming an engine, more like questioning it and open up a dialog. Like I said, I have seen one make metal locally that wasn't even close to TBO. Thanks for the video though. That clears some things up.

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Posted

Another "problem" with 912's (really the operator) is running too heavy a prop and/or idling them too slowly (or with carbs way out of sync or not starting them with a good full capacity fully charged battery, but those things fall under maintenance). I have no experience with the newer engines with soft start but that sure sounds like a good idea. The S can really shake when starting if I don't get everything just right and when shutting down if i don't fully retard the throttle while killing the engine.

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Posted

Another "problem" with 912's (really the operator) is running too heavy a prop and/or idling them too slowly (or with carbs way out of sync or not starting them with a good full capacity fully charged battery, but those things fall under maintenance). I have no experience with the newer engines with soft start but that sure sounds like a good idea. The S can really shake when starting if I don't get everything just right and when shutting down if i don't fully retard the throttle while killing the engine.

Idling too slowly will destroy the gearbox as well as cause other issues.  Also they like to be revved, like run them at 5,500 all day revved. When I would demo the Europa Monowheel with a 914 people would always ask "what's a good economy cruise?" I would reply either "your looking at it (as I was pulling 5,5/5,600RPM) or I have no idea, I've never tried it".  We ran them solely on 100LL with TCP additive, did oil at 25 hours (914) and 50 hours (912S) plugs around 100/150 hours and never had issues except lead staining behind the exhaust and a layer of it in the oil tank at each change. We had one of the first converted 914's from Kodiak that started life as a 912 in our first demonstrator, that plane was thrashed, flown in acro displays by Pete Clark from the UK, and raced in the Sun 60 race a few times by Ivan Shaw which was done the whole route wide open in boost!  Years later a buddy from Kodiak came up to swap the pistons/cylinders on the engine as they were not standard 914 parts and I looked at them all on the bench. Still had a nice cross-hatch, very mild ridge on the top, no galling, scrapes, blow-by marks and very little carbon. I believe they were 80hp 912 heads and milled pistons to lower the compression and had over 500 hours on them.  And still held up to that nonsense. 

I would take that plane off on a cool morning at Lakeland at full boost and leave it that way until I leveled off at 10k about six minutes later. Nice thing about liquid cooling is I could split-S, pull back to idle and dive for the deck at VNE and not worry about shock cooling.  And did just that many times.  Great fun.

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