110 hp 4 cyl from Taiwan

[skippydiesel]

55 minutes ago, facthunter said:

It wouldn't matter what I say would it? NO evaluation or criticism will be accepted of any odd thing about the ROtax. MY "TONE" ??? You are hypersensitive. You wouldn't know ME from a bar of soap.. Nev

I am sure I would find you to be wonderfully scented.

 

The only point I am trying to make is, that you don't seem to acknowledge the apparent durability, despite your technical misgivings,  of the Rotax 9 range - is it marketing hype? or is it engineering excellence?

[facthunter]

A "Proper" designed exhaust gasket like on an 0-200 will insulate the very hot exhaust pipe from the head so there's no point in running fins way downstream of the exhaust valve.. OHC is also out of the Question where the engine dimensions (width) are needed to be kept as small as possible and cooling is compromised and weight added. Wt/Hp is what counts.  High rpm means lots of load reversals also, and what's wrong with wet sump?  Nev

[facthunter]

Your first response to this thread Skippy, was "Yawn!".  That must have taken a lot of thought but you must admit it's a little dismissive at that stage of the debate.. It seems as if we can't have a respectful discussion based on facts about engines that someone looking here might get some benefit from..   Most Pilots of U/ls just want  something they can afford and cope with in the field and understand. The Latest Rotax offerings would be difficult for the Importer to  be across, let alone the average operator. Nearly doubling the HP of the basic motor is a brave step.   Nev

[skippydiesel]

At first glance (yet to be a second) it seemed very much to be reinvention ie nothing very new/revolutionary - was I wrong?

[facthunter]

Superficially, but EVOLUTION occurs as you even see in the ROtax. and should with any motor. Any lack of quality control  in  either CAN cause a failure. In my view the quality REQUIRED in the 9xx motors is of a very high order just because of the way it's built.. I feel it's unnecessarily COMPLEX. . The crank is NOT serviceable in the higher HP motors. It's a replace item because it has to be to maintain the  stringent requirements the design demands. This is because it's a pressed up assembly.  The con rods are part of the 10 pieces that make up the assembled crank which has 3 Bearings plus one near the drive end... Nev

[RFguy]

OMG. I'll put the opinion  straight for everyone LOL: (ROtax/Lyco)

Rotax , I think is an engineering marvel.

What lets it down  is the variability of installation, probably because it is in so many experimental aircraft category, and thus variability in maintenance , and a lack of adherence to the ICA . 

Installation issues : 

- variation of installed cooling methods of radiator and cooler.

Many installations I have seen are deficient in oil or water or both and would not meet the Rotax IM requirements.

- variation of airflow over the cylinder bores 

The 914 and above - the IM specifies a baffle/ air flow guide over the cylinder bores to cool them. This is rarely fitted and I would expect is a non-zero  importance  for the 912ULS - IE it is required for some conditions and cowls even on a 100hp engine.. .

- Inadequately  plumbed oil system- I would be highly surprised if many installations, especially those on owner-build  would meet the hose  vaccuum test combo of the oil cooler/oil hose/oil tank system per the Rotax IM.

- non adherence to rotax instructions to use a return line for fuel

- incorrect prop loading (pitch too coarse) 

 

Leaving 'accepted' deficiencies of - lack of oil thermostat, use of car plug leads and crappy ignition modules, tendency for 912 to foul front plugs at low idle, lack of user understanding of RPM regions not to run the engine in, lack of fuel pressure  readout, variation of carb heat implementation, 

 

The Lyco has no such issues primarily because certified airplanes have to meet the part91 requirements. I am sure that if Lycos were extensively used in lower end experimental aircraft, you'd find failure rates not dissimilar. But Lycos are usualyl not used in lower end of the aircraft , IE they are less likely to be in a light touch maintenance environment,

-glen

 

 

Edited September 9, 2023 by RFguy

[danny_galaga]

Tell ya what though. I did the oil purge today on my 912. That's when I reminisced about wet sumps 😄

[Area-51]

Sunday.

 

Feeling inspired to level the field again 🤷🏼‍♂️

[facthunter]

Mower distraction. The left side one has a "Hurricane" motor in it and is one of the earliest made.  I have one in good order and an unused POPE engine  as well. .  Nev

[BrendAn]

This thread is f###ed. Need a new 110 hp thread

[facthunter]

Couldn't agree more.. Happens most of the time.   Nev

[facthunter]

110 HP 75 KGs complete. Nev

[Thruster88]

21 minutes ago, facthunter said:

110 HP 75 KGs complete. Nev

This engine is almost identical to a lycoming O-235 in appearance, displacement and horsepower. The lyc O-235 weight is around 110kg. The steel liners on a lycoming actually look thinner than those shown in the first post. The cylinders are of identical construction to the Lyc except the aluminium extends much further down the barrel on this new engine.

 

Not sure I want to know how they white anted 35kg of metal out of the engine.

[facthunter]

White anted?  That's not a loaded concept is it? Weight is important.  That's the trick in all of this. How about we give this thing a bit of a chance? OK? No shortage of armchair experts against people who have been working on this stuff for a lifetime who might think otherwise about a simple(r) and cheaper solution than the Rotax offers.. Those who love it keep buying it OK? There can and should be CHOICES and every new entrant contributes to that to  the benefit of all of US collectively.   Nev

[danny_galaga]

15 hours ago, Thruster88 said:

This engine is almost identical to a lycoming O-235 in appearance, displacement and horsepower. The lyc O-235 weight is around 110kg. The steel liners on a lycoming actually look thinner than those shown in the first post. The cylinders are of identical construction to the Lyc except the aluminium extends much further down the barrel on this new engine.

 

Not sure I want to know how they white anted 35kg of metal out of the engine.

Could be a culmination of dribs and drabs. Maybe more modern alloys here, shorter through bolts due to the heads being cast with the cylinder there. It all adds up. I guess it'll be shown to be good or bad once it has some hours up. 

[Old Koreelah]

There are plenty of stories about how a new racing engine has been gradually developed, with weight being shaved off and yet more power squeezed out.

Aircraft engines are developed for a very different job, but I suspect the much smaller market and strict regulatory regime has stymied progress.

[facthunter]

"Trimmed" might be a better description. Hollow crankshafts are one way and the dehavilland fours had those but their motors were 130 Hp and about 350 lbs despite this. The bronze heads helped make them heavy. It's difficult to get machine drawings of a lot of this stuff, let alone material specs.  An airframe is similar in concept. As light as possible and still getting the required strength and rigidity. 

  The cylinder s are not of identical construction to the Lycoming. The Lyc ones are threaded and shrunk on and to all intents a permanent fit.   These ones are cast into the alloy  for much of their length more like a Franklin which was a pressed in sleeve in an ALL alloy cylinder  but the sleeve can be replaced and is iron . Some rotaries also had iron sleeves press fitted in the machined steel cylinder as it lubricates better. than steel. . IF they are CAST in as the Taiwan motor is they  end up softer as the melt point of aluminium is quite high. A lot of these high quality iron parts  are centrifugally (spun) Cast and very fine grained. Not just your average garden type motor but even some Mower motors are pretty good now. 

  Race and drag motors are not mass produced either nor do they have to last that long or be cheap. A drag motor may only do about 2,000 revs total racing  life.   Nev

Edited September 11, 2023 by facthunter