Move over ROTAX...

[Student Pilot]

Even with all that Nev, gearboxes are still used, every day in every way......

[Student Pilot]

Depends who you talked to about the Go300 Nev, I know 3 people who used to own 175's and speak highly of them. The main problem I have read about with them was operator induced by not running with enough revs. Pilots were used to running low to mid 2000's, the GO300 was made to run harder at low 3000's. Those that thought they knew better ran them too slow causing problems. The only valid complaint I've seen is the cost to overhaul the 6 cyl Continentals. 

 

 

 

[facthunter]

SP in a plane IF you can do without one you are much better off.. Even if the loss is 3% that's a lot of heat. The propeller is like a flywheel and you never run gears between an engine and a flywheel if you can help it.  I've flown the 175 (nice Plane) and I think  the revs used are too high for that engine which is essentially just 2 more cylinders on an 0-200. Very smooth though like most flat 6's.   Nev

[3rd harmonic]

Edge performance in Norway have been doing Yamaha APEX 300 (Jet-ski engine) conversions successfully for some years now. The 300hp EPex300 claims to be the most powerful lightest weight aircraft engines and aircraft powered by them really have smashed it in STOL competitions. BUT unfortunately Yamaha only recently discontinued the production of the APEX engines meaning he can't do any more conversions...

Edited December 1, 2023 by 3rd harmonic

[onetrack]

And this is where the automotive/snowmobile/whatever-your-engine-selection conversion method is, is a dead-end. Not one of these converted engines lasts any more than a few years before it's superseded by a "new, totally redesigned" engine - thus leaving the conversion gurus out on the proverbial limb being sawed, and on the wrong side of the saw.

[3rd harmonic]

Yeah I think the APEX engines were a high end side show. The Edge performance ROTAX 91x engines are pretty bloody awesome. He does seem to know what he's doing with the performance enhancements and the engine dyno test station ect. His latest 917sti has managed a conservative 200hp, I would definitely go with one if I had a spare +20,000€

[skippydiesel]

On 30/11/2023 at 4:53 PM, turboplanner said:

When you're analysing engine reliability and life and you put stroke length into the equation and multiply that by lengths per hour you come up with the total length the piston, rings and bore have/have been travelled. Usually the shorter travel length will win the reliability stakes.

All my adult life I have heard the jib of the big bore enthusiast 'Revs = Rebores"   

 

The logic sounds good BUT  how do you explain the millions of European and now Asian (small) cars that just go & go & go racking up the K's, revving their little hearts out?????

 

My Daihatsu Rocky purchased new in 1985, had 750,000 kms on the clock , engine never opened/worked on (aside from valve clearance checks), never needed oil between services, pulled a double horse float, survived teaching sons to drive, would still be going strong, if a young fella hadn't T boned me, I was hoping for the million K's from that little 4 banger..

[facthunter]

Good oil, good filters, keep the thermostat in and don't do short trips. Lots of taxis do over a million K's and don't do what I've just listed,but they stay hot.   Nev

[spacesailor]

My neighbours " Tesla 3 only gets used for work runs , the rest of the time it sits in the driveway , while they go out in the IC car .

Could be keeping the kilometres down .

spacesailor

[skippydiesel]

15 hours ago, facthunter said:

Good oil, good filters, keep the thermostat in and don't do short trips. Lots of taxis do over a million K's and don't do what I've just listed,but they stay hot.   Nev

Hi Nev,

 

Does this mean that you agree with my observation? ( regarding Turbs comment)

[facthunter]

Without trying to avoid the question, High piston speeds do create a lubrication problem and in the old days did wear rings faster. Likewise very large bearing journals can cause lubricant problems. It's an oilshear issue mainly encountered when racing hotted up basic road engines.

The Daihatsu does seem to be a good engine. My main experience is with the  3 cyl ones.. Not sure they ran the revs that Later motors CAN.. Engines of the 80's -2000 period often experienced Head Gasket problems as the initial reason for spending money on a motor.. Turbo chargers let engines do LOW cruise revs. Plenty do about 2000 at highway speeds. Toyota were one of the first to do things like induction  harden the top of the bores and put iron there for the top compression rings on the pistons. Not sure they do those things now and the Yaris runs the valves direct in the head alloy (and they get away with  it).  Nev

[skippydiesel]

So Nev -  "Revs=Rebores"  is out of step with the technology of , not only today, but probably from about the 1970's onwards ?

 

Does this mean you are coming round to the Rotax boxer ?😄

[facthunter]

Very sceptical about the extra HP models and don't like pressed up crankshafts and I like reduction gears even less than I used to on smaller motors. Sorry.  Nev

[LoonyBob]

Gearboxes? It's the execution, innit? The German review of the WW1 Hisso redrive is priceless... they were scornful of the basic design, the machining, and the housing, but grudgingly had to admit the innovative lubrication solved these problems - but THEY would never adopt such sloppy practice! (It's a NACA Report; No.17 or such...).

The Merlin & Griffon generally worked ok with reduction gears, and some round engines too... Napier used a brilliant load balancing technique on the Sabre reduction gearing, shame about the rest of the engine...

 

Modern gearing and modern engine design has the benefit of FEM, IF the design team knows how to use it and is not constrained by management profiteering.

Edited December 4, 2023 by LoonyBob

[skippydiesel]

3 hours ago, facthunter said:

Very sceptical about the extra HP models and don't like pressed up crankshafts and I like reduction gears even less than I used to on smaller motors. Sorry.  Nev

Nev Nev! you are consistent & a hard man to win over - I do not have the training to argue with you but would once again point to the undeniable success & relative reliability of this so imperfect engine.🙂

[facthunter]

NO engine is PERFECT Skippy. You can find BAD features in ALL of them and I'm a hard critic. The later cranks cannot be serviced by anyone other than Rotax. It's a very critical fit required and every one of them is torque tested. A press fit puts high stresses in a part before it gets loaded due to running.  150 plus HP out of that crank? We will see.. I have plenty of experience with pressed up cranks. A sudden stop and the alignments gone AND how many main bearings has it got?  Everybody wants one each side of a crank throw. The gypsy Major 1-c has it. 100 years ago.   Nev

[skippydiesel]

 "I used to be conceited, now I'm perfect" not sure who said that but have always liked it.

 

Back to engines - Yes! hard to find anything made by man that can be described as perfect. You may be right about the higher hp Rotax's, time will tell. Having great respect for the engineers who developed the 9 range, I will be surprised if there are any serious issues (other than the scary purchase price).

 

I like my 912ULS, its my second, & despite all the aircooled knockers comments on complexity/twin carbs/etc I find it easy to service & work on (did the Sprag Clutch on my last one - that's how I learnt not skimp on battery condition).

[facthunter]

It's a hard choice for people to make at the moment. The way things are looking in the US a lot are going with Rotax .Remember Rotax is NOT essentially an aero engine manufacturer. It has adapted a product from its skidoo line and the same with the 2 strokes I don't know if the bottom end was designed with roller bearings in mind. Unless they planned  for that it's hard to see why the bottom end is done the way it is.. In my opinion they are stacking a lot on it doing the job. The cases have been beefed up a bit and the shaft is now a slight taper fit where it's pressed together Certainly a clone is hardly likely to achieve the tolerances demanded with the later versions. The installations are Very messy.   Nev

[Thruster88]

5 hours ago, facthunter said:

Very sceptical about the extra HP models and don't like pressed up crankshafts and I like reduction gears even less than I used to on smaller motors. Sorry.  Nev

Rotax have progressed the 912 steadily with the 914,915 and now the 916 all on the same basic platform with enhancements were required. Lycoming did a similar thing with the O-235 then O-290,320,360 and finally IO-390.

 

Both engines have flying web crankshafts, 3 main bearings for a four cylinder. Must be a good idea?

 

Rotax 9xx engines have nothing to do with their other BRP products.  

[turboplanner]

1 hour ago, skippydiesel said:

 "I used to be conceited, now I'm perfect" not sure who said that but have always liked it.

 

Back to engines - Yes! hard to find anything made by man that can be described as perfect. You may be right about the higher hp Rotax's, time will tell. Having great respect for the engineers who developed the 9 range, I will be surprised if there are any serious issues (other than the scary purchase price).

 

I like my 912ULS, its my second, & despite all the aircooled knockers comments on complexity/twin carbs/etc I find it easy to service & work on (did the Sprag Clutch on my last one - that's how I learnt not skimp on battery condition).

If it's any help, just pull the numbers making TBO and the numbers that have been sold and the numbers that are still registered for Rotax.

Then do the same for the other engines in the same market.

That will tell the difference between what is actually happening and loaded gossip.

 

[BrendAn]

1 hour ago, facthunter said:

NO engine is PERFECT Skippy. You can find BAD features in ALL of them and I'm a hard critic. The later cranks cannot be serviced by anyone other than Rotax. It's a very critical fit required and every one of them is torque tested. A press fit puts high stresses in a part before it gets loaded due to running.  150 plus HP out of that crank? We will see.. I have plenty of experience with pressed up cranks. A sudden stop and the alignments gone AND how many main bearings has it got?  Everybody wants one each side of a crank throw. The gypsy Major 1-c has it. 100 years ago.   Nev

edge performance weld the crankshafts on their high performance rotaxs

[skippydiesel]

5 minutes ago, turboplanner said:

If it's any help, just pull the numbers making TBO and the numbers that have been sold and the numbers that are still registered for Rotax.

Then do the same for the other engines in the same market.

That will tell the difference between what is actually happening and loaded gossip.

 

"......just pull the numbers making TBO and the numbers that have been sold and the numbers that are still registered for Rotax." If each manufacturer has a different concept for "making TBO"  the statistics will not give you a true result.

 

ie Is it making TBO, if  the engine requires  significant intervention to keep it airworthy, before achieving the claimed TBO  hours?

[facthunter]

Hasn't worked well on many other engines in the past. The weld heat destroys the interference fit. Would you accept a welded crank where it had been cracked in what is now a high performance engine?.  I never said I considered a bearing between every throw essential. Only that it WAS used  a longtime ago in an in line motor so it's not a new proposition..  Nev

[turboplanner]

10 minutes ago, skippydiesel said:

"......just pull the numbers making TBO and the numbers that have been sold and the numbers that are still registered for Rotax." If each manufacturer has a different concept for "making TBO"  the statistics will not give you a true result.

 

ie Is it making TBO, if  the engine requires  significant intervention to keep it airworthy, before achieving the claimed TBO  hours?

My definition for TBO is with scheduled maintenance and perhaps one or two minor unscheduled events with an obvious cause which, when corrected will take it over the line.

 

That's the equivalent of time to an in-frame rebuild in a truck.

Edited December 4, 2023 by turboplanner

[BrendAn]

54 minutes ago, facthunter said:

It's a hard choice for people to make at the moment. The way things are looking in the US a lot are going with Rotax .Remember Rotax is NOT essentially an aero engine manufacturer. It has adapted a product from its skidoo line and the same with the 2 strokes I don't know if the bottom end was designed with roller bearings in mind. Unless they planned  for that it's hard to see why the bottom end is done the way it is.. In my opinion they are stacking a lot on it doing the job. The cases have been beefed up a bit and the shaft is now a slight taper fit where it's pressed together Certainly a clone is hardly likely to achieve the tolerances demanded with the later versions. The installations are Very messy.   Nev

as thruster stated. 9 series are aircraft engines. show me a snow mobile with a 912.