Which Engine???

[Jethro Belle]

I'll bite on that, Jethro. We've had a terrific run from our Peugeots. Their Diesel engines are so good they're used in several other brands. When Chas was planning his conversion there was much discussion of diesels on the Jodel forum. One engineer (who must have worked for PSA) placed a TBO of 10,000 hrs on Peugeot Diesel engines, after testing about a dozen of them to destruction. The first one failed at 12,700 hrs with a dropped exhaust valve.

 

Thanks for biting @Old Koreelah My academic theorizing ain't worth squat without backing from actual experience

 

Seeing Theilert ( Thielert Centurion ) seemed to have had significant problems, I was wondering how some-one in NZ can bolt in a pretty stock Peugeot (manual diesel injection swapped in I believe) and happily and safely 'go flying'. Do you have links or references to start researching this install? I must haven't searched right. How many are you are flying these things? Is it a Jodel thing? What are your conclusion based on experience. Do you recommend it? More info please.

 

I note continental are building on their Theilert buy-in Continental expands Diesel Engine Range - Australian Flying (The Chinese are coming!)

At a fraction of 10000 hr TBO estimate, most safety cost minded fliers will be interested:taz:

 

PS: My comment about the Pug reliability was just to get your bite

[Jethro Belle]

The Lycomings /continentals do run large piston clearances but no more than they need. Nev

Thanks Nev, I agree with all you say, but my musing was why they need to when auto-derivatives don't. I picked it up from the Lycoming site discussing why not to use motorcar oils that alerted me to it. Why do hot air-cooled heads require greater clearances on Lycomtinentals and not VW and Jabiru? I don't see your reply answers that. Hot heads would increase the clearance at the top of the piston stroke, not reduce it, which prima facie is opposite to running large clearances. Maybe their 'large clearance' is code for heat expansion caused by hot heads

 

I am interested because the Rotec build water cooled heads for Jabiru engines and the same must apply to them, even though oil burning is not something I read about Jab engines.

 

 

[fly_tornado]

I would never have predicted that. It acts as lubricant/wear coating on exhaust valve seats.

I looked into a rotary conversion and that was feedback that was floating around, the size and shape of the seals means it doesn't take much of a build up to destroy the compression

 

 

[facthunter]

Jabs use an oil ring which I don't like the type for aircooled motors with steel cylinders. They don't burn much oil but they often vent it..... Aero cylinder assemblies are also choked Smaller dia at the top to allow for the hotter parts near the top to become parallel when operating. Jab pistons do have large clearances. Aero heads temps Max allow usually 235 C. They have good material to cope with that. Jabs try to run a lot cooler as they have had temp associated problems... Nev

 

 

[Jethro Belle]

You don't need to go that far for a service life.in a sport plane.. If the engine was capable of a 3,000 hour life RELIABLY that would be enough. Setting a TBO appears to be a lot of guesswork. Once it had some real bearing on what the motor will do. based on reliability in service and approved testing. Today It appears to be a guestimate at best. Nev

 

Off course Chill Nev.

 

@Old Koreelah did indicate

One engineer (who must have worked for PSA) placed a TBO of 10,000 hrs on Peugeot Diesel engines, after testing about a dozen of them to destruction. The first one failed at 12,700 hrs with a dropped exhaust valve.

 

That seems to refer to test dynamo-meters in the Pug test facility, and Peugeot motors (always had a good reputation for reliability (until recent electronic gremlins) could achieve that under those conditions. I doubt it was full noise for that period, but some load cycle representing typical vehicles use (as you keep reminding us ;-).

 

I hope @Old Koreelah will be kind enough to post more so we can get the actual in-plane performance and engine life so far. A very exciting case study.

[facthunter]

Seals on a Wankel are a pretty difficult thing to get right. They can't rely on a springing action like a round piston ring but extra weird springs beneath the strip of seal material. The gas pressure gets behind a conventional ring and helps to force it onto the cylinder wall. all the way around. Nev

 

 

[Jethro Belle]

I looked into a rotary conversion and that was feedback that was floating around, the size and shape of the seals means it doesn't take much of a build up to destroy the compression

I wasn't doubting you FT. Just expressing surprise this was the case as it is counter intuitive to me at least (always learning).

 

I guess you concluded Wankels were not for you in the end? What was your conclusion? You have done the exercise obviously.

 

 

[fly_tornado]

there aren't a lot of rotary engines out there, so every new one is a step into the unknown

 

 

[facthunter]

There's enough out there to be able to adapt one . You don't have to do it on your own. The drive will be up to you. Nev

 

 

[Jethro Belle]

Lead wouldn't be much help as it only works at quite elevated temperatures. That's why it isn't good in the Rotax 912's

Apart from tetra-ethyl lead increasing octane, I understood coating the exhaust valve seat are it key actions (ignoring the exhaust slowly poisoning everyone )

Can you explain your statement please? Why is the Rotax 912's different?

 

 

[facthunter]

They actually run a bit too cool in the heads. The LL100 use permits/causes build up on the valve seats and if part of it separates the compression readings go bad. Mostly they recover once you go back to Mogas but some permanent damage to the valve or seat must be possible if you are unlucky.Nev

 

 

[pmccarthy]

Re the earlier discussion, from Petersen Aviation | Auto Fuel STC

 

When you overhaul your engine use 100LL aviation gasoline until the warranty expires. If there is no warranty, use 100LL for the first 30 hours to insure adequate lead during the break-in period.

 

Radials, Franklins, and Continental engines from the A-65 thru the 0-300 should have lead provided constantly. A mixture of 30% 100LL and 70% unleaded gasoline yields a lead content equivalent to leaded 80/87 octane aviation gasoline. This is enough lead to protect valve seats but not enough to foul the plugs.

 

If a Lycoming engine has been overhauled with factory parts since 2000, then it should have hardened parts requiring no lead.

 

 

[bexrbetter]

The Wankel rotary can rev to astonishing levels (processing air/fuel) to deliver more power than any piston engine of a similar weight - .

Absolute myth.

 

I guess this nonsensical myth came from the original and horrid all aluminium 10A engine of the 1960s. On paper the weight, power and 7000 rpm was quite astounding in comparison to predominately British equivalents of the time, but more astonishing was their failure rate, which caused them to go away from using aluminium to cast iron for the side plates and center section.

 

By today's standards, a Rotary is heavy and underpowered. You can go to Honda and buy a Honda 2000 Sports with a 9000 rpm redline with a 3 year warranty. At 9000 rpm a Rotary lasts as long as a 16 year old with a girly magazine. Plenty of cars have a 7000 or more redline these days.

 

Any modern piston engine today will weigh less, produce more power and use a lot less fuel along the way. Direct injection even more so, and that's before we start comparing turbo versions. Go look up the power and weights of some comparable class engines.

 

Rotary's have a smaller physical size (not lighter, smaller), and their mass center can be more easily placed, about their only advantage.

 

Anyway, I'm just offering factual information, I have no cheese in this pizza, no benefit to me in anyway to pursue it further.

 

 

[Marty_d]

...as long as a 16 year old with a girly magazine.

Showing your age Bex. 16yo's have the internet and sext each other these days - they wouldn't know what a girly magazine was!

 

 

[bexrbetter]

I doubt it was full noise for that period, but some load cycle representing typical vehicles use

This is one of the largest nonsensical myths going, that an automotive engine can't take full noise constantly, let alone 75%.

 

I'm still waiting for someone to explain to me how a connecting rod (whichever component) knows how it's inside an aircraft engine (sic) or a lawnmower.

 

FWIW, Aeromomentum's Suzuki G13Bs have been used for airboats at full noise for many years now, if I remember correctly about 70 running. They recently changed one out of a professional fisherman's airboat at 4000 hrs, and they have numbers over 1000 hours. Oh, and it cost the guy about $3000 to change out for a brand new long engine.

 

 

[turboplanner]

Seals on a Wankel are a pretty difficult thing to get right. They can't rely on a springing action like a round piston ring but extra weird springs beneath the strip of seal material. The gas pressure gets behind a conventional ring and helps to force it onto the cylinder wall. all the way around. Nev

I owned a Mazda RX2.

The seals that failed were the silicone O rings, and they failed because they are open to the combustion chamber flame front.

 

They lasted for months around town, but would burn out in one high speed 190 km/hr run from Melbourne to Albury. O rings are easy to replace, but I got sick of pulling the engine out.

 

The engine had no power under 4000 rpm, so to accelerate in suburban conditions was uncomfortable and noisy, but it would spin the wheels at 160 km/hr.

 

This nopower/fullpower characteristic wouldn't be good for aircraft prop revs, and you'd need a redrive if you set cruise at something like 4750 rpm, so the weight and space advantage would disappear.

 

 

[skippydiesel]

I agree that the Wankel/Mazda has issues but that's what investment/technology was invented for - remember the dreamers who told us the future of the internal combustion engine was ceramic - no need for coolants would operate at such high temperatures that efficiency/power would go through the roof pollution would be eliminated, etc etc.

 

Perhaps the future of the Wankel is ceramic (in whole or part) or some other high tech material(s).

 

Back in the late 60's my best friends father had an NSU RO80 - as you infer it did need an engine replacement at rather short intervals but I now realise that this was because 1. the rotor tip seals had a short life and 2. there were very few technicians around to replace them. The solution was to replace/exchange the whole engine with a reconditioned unit (any 1/2 descent mechanic could do that).

 

My (agree limited) understanding is that the latest generation of Mazda rotaries can expect a similar service life to conventional piston engines.

 

One other teleology that didn't go far (in small aircraft) was the ducted fan - Question if you mated a non/minimal geared rotary with a ducted fan would you have a viable propulsion unit?? (might get over the tip speed limitations of a conventional prop and make use of all that high rpm)

 

 

[Jethro Belle]

This is one of the largest nonsensical myths going, that an automotive engine can't take full noise constantly, let alone 75%.I'm still waiting for someone to explain to me how a connecting rod (whichever component) knows how it's inside an aircraft engine (sic) or a lawnmower.

 

FWIW, Aeromomentum's Suzuki G13Bs have been used for airboats at full noise for many years now, if I remember correctly about 70 running. They recently changed one out of a professional fisherman's airboat at 4000 hrs, and they have numbers over 1000 hours. Oh, and it cost the guy about $3000 to change out for a brand new long engine.

A good data point performance on the Suzuki G13B. Thanks Bex. An exceptional engine.

 

I suspect the 'myth' originates partly comes from British/Australian/US... motors (pre-1980 say) and that it is possible to specify and allow a peak power output much higher than the thermal ability of an engine to deal with for more than a few minutes. Good for sales and quarter-mile drag figures

 

In automotive use engines seldom run WOT and I would never do it, especially on a hot day, as my costly experience is that it results in engine failure. Maybe youngsters haven't experienced that, or ECUs "idiot proof" cars nowadays. A con-rod certainly knows if it is operating at red-line revs (aviation or road). Due to weight restrictions aircraft need to push red-lines to develop enough power to weight. No mystery.

 

Lycomtinentals (all reputable aero-engines) are designed/tested from scratch to be run all day at the power outputs they quote. Ex-motor cycle engine manufactures seem to have an edge in aeroconversions (IMHO).

 

There is usually some origin to myths. I am dubious about any high quoted power output engines unless extensive testing or usage verifies it is possible. It is easy to get extended engine life by 'derating' it. For an unknown engine it is still a 'myth' I am comfortable with, if for no other reason than I will get twice the engine life.

 

 

[Jethro Belle]

One other teleology that didn't go far (in small aircraft) was the ducted fan - Question if you mated a non/minimal geared rotary with a ducted fan would you have a viable propulsion unit?? (might get over the tip speed limitations of a conventional prop and make use of all that high rpm)

Check out the Edgley Optica. I am pretty sure early plans were for it to be rotary driven, but common sense (certification) got in the way when it was built. Even with the Lycoming it suffered some crashes and buyers lost interest.

 

My take is that a ducted fan would only make sense as a styling exercise or to avoid stone chips on normal speed RAA aircraft. Maybe for low noise also. A high speed small diameter fan will not match a low-speed large diameter propeller efficiency and the ducts can add significant weight and drag. They also tend to be more speed specific in my understanding.

 

A mock 'fighter jet' aircraft is the only situation I could see a rotary powered, direct drive, ducted fan makes any 'sense' ! Not efficient, but a more appropriate noise, reliability and fuel consumption

 

 

[Jethro Belle]

This is one of the largest nonsensical myths going, that an automotive engine can't take full noise constantly, let alone 75%..

As an afterthought Bex, do you think the Peugeot diesel would last 10000 hours operating at its redline? My post indicated that to my knowledge auto-engine manufacturers test against a typical load cycle, not at a fixed maximum speed like aero-engine manufacturers.

 

 

[bexrbetter]

A good data point performance on the Suzuki G13B. Thanks Bex. An exceptional engine.

No, it's just an engine, like hundreds of other quite capable of doing the same job. Like the VWs, Honda, Toyota, Ford, Chev, etc, etc engines being widely used today.

 

In automotive use engines seldom run WOT and I would never do it, especially on a hot day,

Another myth, a very strong one in the USA and Australia where you are restrained from WOT by society and law. but not every country is like that. Up until about 20 years ago, you could travel full speed on Europe's freeways, and people did, for hours on end WOT. Note the majority of those cars were around 1100 to 1300cc, and they would sit on around 140kmh screaming their tits off, the same as my Dad would do in the 70's all the way up and down the Newell Hwy WOT in our 1100cc Fiat 128 when the Newell Hwy had no speed limit.

 

They still can/do in Germany, plenty of Youtube videos. You can in China as well, there is a speed limit, but it's more a guide, and if you're doing 200, I will, err I mean, drivers will get a stern phone call telling you to slow down.

 

But maybe someone can point me to an empirical data base of engines that fail at 75% load after some hours? Yeah, nah, there is no such data base because engines (modern) don't fail at those loads, nor WOT.

 

So the people who continually state this absolute B/S myth, could please let me know where your information is coming from ...?

 

Lycomtinentals (all reputable aero-engines) are designed/tested from scratch to be run all day at the power outputs they quote.

The classic statement.

 

Anyone here aware of how an engine is "designed" to accomplish certain parameters, or are you all just parroting previously parroted information over and over?

 

Ex-motor cycle engine manufactures seem to have an edge in aeroconversions (IMHO).

This one makes me chuckle, I can just see the Rotax Engineers, designers of some of the highest specific hp modern production engines in the World, assembled at the meeting after the decision was made to build an aero engine (4 stroke), looking over the design parameters, and one of them puts a hand up: "Excuse me, what exactly is a 'pushrod'?...."

 

Of course the sad side of that is the engines that Aero don't get from them as they are smart enough to build for the Luddites and not what they can actually build.

 

 

[bexrbetter]

As an afterthought Bex, do you think the Peugeot diesel would last 10000 hours operating at its redline? My post indicated that to my knowledge auto-engine manufacturers test against a typical load cycle, not at a fixed maximum speed like aero-engine manufacturers.

It used to be a secret how each manufacturer would or wouldn't test their engines, now it's a promotional gimmick to promote the reliability and endurance of their engines.

 

There are numbers of articles and videos available describing their testing regime and endurance cycles, Ford F150 comes to mind immediately, one of which is where they tow a boat or something around the Indianapolis track WOT for 24 hours.

 

Google is your friend.

 

 

[Old Koreelah]

...I was wondering how some-one in NZ can bolt in a pretty stock Peugeot (manual diesel injection swapped in I believe) and happily and safely 'go flying'. Do you have links or references to start researching this install? I must haven't searched right. How many are you are flying these things? Is it a Jodel thing? What are your conclusion based on experience. Do you recommend it? More info please...

Chas has done the work, Jethro, and he can tell you all about it. In Europe I believe several other Jodels have been fitted with diesels. After a few years research I lost my enthusiasm for diesels after lots of talk about waxing, winter blends, summer fuel and the weight issue.

 

OK. Even at equating each hour with 100 kms ( 60 MPH) which is hardly a serious HP output, that would be equal around a million Kms for your 12,000 hours is a ridiculous life to allocate to any engine that you might want for a plane...

Just repeating what was posted on the Jodel site, Nev. Given our experience with these engines, no reason to doubt the figures.

 

 

[mnewbery]

So the people who continually state this absolute B/S myth, could please let me know where your information is coming from .

My point exactly. Apparently its ok for you to bring it up. When I do it some tosser starts calling me names

 

 

[stol1]

Does anyone know how to take the weight off the ea-81? I recently had someone say that one guy had it down to 165lbs with the 40 lb re-drive on it. That would be in the rotax range.