Talk:Wankel engine

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Disadvantages?

The page contains an advanatages section, i was just wondering if there are any disadvantages to the engine? Zephyr 12:30, 1 February 2007 (UTC)

Sure. Wankel engines have traditionally consumed a little more fuel, though that gap has been closing over the years. Errm, I think there are some slightly higher emissions because of the oil they consume at combustion for lubrication. Dunno if there's enough there to be of use in the article, and it'd need sourcing of course. - CHAIRBOY (☎) 13:37, 1 February 2007 (UTC)

Well, having an advantages section without a disadvantages section seems very bizarre, especially as the article then goes on to describe how wankels aren't used for many road cars, and how this number has been decreasing to the point where only one is available (and that's a sports car anyway) Modest Genius ^talk 15:54, 1 February 2007 (UTC)

Based on grounds of increased fuel consumption, I feel a Disadvantages section is warranted. I don't feel I am qualified enough in the subject to break the ground, but I think there is enough support to start a Disadvantages section even if it start with a lacking "increased fuel consumption" statement. -- ViaBest 18:11, 1 February 2007 (UTC)

Under "Pistonless rotary engine" there is a discussion of the disadvantages - primarily sealing problems, perhaps that could be incorporated here, or the pages could be merged.

What is the weakness? The only wankel engine who has problems with the apex seals is the NSU Ro80. Constructional defect, wrong material choice and unsatisfactory testing.

"Worse still, these two sets of seals must somehow join at sharp corners at the ends of the apex seals. " Yeah, therefor invented Felix Wankel the Sealing pin.

"An additional problem is that the seals at the Wankel rotor apexes meet the chamber walls at an angle that varies plus and minus ~26 deg; during the cycle, while a piston ring meets the cylinder walls at a constant angle.

That is probably the largest imbecility. First, without varies angels work no apex seal. This is a function of the k-factor and the aequidistante.

As well as making the seal design itself more difficult, this means that while multiple rings are easily fitted to a piston, a corresponding approach is impossible with the Wankel apex seals.

Completely wrong.

"Another disadvantage of the Wankel engine in particular is the large surface area of the combustion chamber which reperesents a large heat transfer and quench area, combined with an unfavorably long and rather thin stretched combustion space, which means a long flame travel. The combustion is less complete than in, for example, an RPE, which has a more compact chamber shape with smaller area per unit of chamber volume. The Quasiturbine has similar disadvantages with its concave combustion chamber, and in the AC design the sharp angles of the carriers hamper the propagation of the flame front, leading to incomplete combustion"

The geratest myth for ever: The large surface area. An Wankel with a camber volumen of 1,3ltr has a displacment of 2,6ltr. But I have only the losses as 1,3ltr engine. And completely different heat transfer and isolating oil film. Therfore need a Wankel a smaller cooler per kW engine power!!!--90.186.119.176 22:39, 29 March 2007 (UTC)--90.186.119.176 22:38, 29 March 2007 (UTC)

I don't know who wrote the latest disadvantages section, but it was utterly incomprehensible. Due to that reason (it was doing more harm than good to the article, in my opinion), I tried to clean up the grammar and structure a bit, whilst retaining the salient points. Some of the deep technical detail was lost, but if anyone wants to try and explain some of the disadvantages to that level of detail, they should really try to make sure the explanation is excellent. (Sev, 10 Apr 07)

Then should you make correct and not wrong statements. A Four stroke exaust has only 180° opening time!! For a Wankel engine 270° this is 50% more opening time! Four stroke reciprocating engine 720° (2 rotations or 4 x 180° ) for a complet Otto cycle. A Wankel engine 1080° (3 rotations or 4 x 270°) per flank for a complet Otto cycle and this at the same time for 3 flanks. The intake time is 50% longer for Wankel and not shorter. A wankel engine can suck in therefore more air! The only problem you can't pre-store the mixture! Why? No valves!!! The exaust time is 50% longer for a Wankel engine and not shorter! Then I would see this comparison natural aspirated four stroke engine with 1,3ltr displacement and 238HP! To compare combustion engines needs we the specific fuelconsumption and not MPG or hypothetical four stroke reciprocating engines!!!--90.186.252.183 08:51, 11 April 2007 (UTC)

Well, I guess that shows how much sense the previous description made :P Personally, I think talking about ° of opening time for the intake valves is well beyond the scope of this article, and beyond the interest of most. However, a third opinion would be appreciated on this. (Sev, 11 Apr 07)

I'd say speaking about "Duration of admission and expansion strokes", both in terms of degrees of a circle, is a better wording than "duration of intake and exhaust", the Wankel cycle is a four stroke cycle, but is different to the Otto cycle the reciprocating engine uses, and thus its thermodynamic features, advantages and disadvantages come from different sources than in reciprocating piston engines, they're close but never the same.--Jgrosay (talk) 22:17, 29 January 2013 (UTC)

Even after Sev's grammatical corrections this section is still incomprehensible. The intelligible parts send mixed messages at best; the uncited claim that the Wankel's engine is less efficient in general conflicts with Mazda's results. 206.55.189.90 (talk) 05:10, 17 March 2008 (UTC)

Does it really give smooth power at high RPM and low torque, as stated in the opening? The wording ('and' instead of 'but') implies smooth high-rpm power and low torque are either both advantages or both disadvantages. Is low torque an advantage or disadvantage? I would think that for an engine used in sports cars, low torque would be a disadvantage. 206.53.197.24 (talk) 22:53, 11 December 2008 (UTC)

Then must a Forml-1 engine be a loser, torque around 185 NM. When you need torque then must you drive a Diesel truck and not a sports car! HP is HP! The engine torque is uninteresting. Only the torque on the wheel interested, 300HP is always 300HP! P= 2*Pi*n*m!!! High engine torque caused excessive wheigt, make a heavy engine, heavy gerabox, heavy cardan shaft, heavy transfer gearbox etc. Then is only the eccentric shaft high revving, the rotor revving with 1/3 of the eccentric shaft revs. --HDP (talk) 18:12, 12 December 2008 (UTC)

The section marked "disadvantages" does not discuss disadvantages, and principally contains a technical discussion that belongs elsewhere. The information in this discussion is helpful but is not present in the disadvantages section of the article.Andyberks (talk) 21:07, 16 June 2010 (UTC)

Cite #30 hardly seems scientific, and is used to validate the following claim:

"Comparison tests have shown that the Mazda's rotary powered RX-8 uses more fuel than heavier V-8 powered vehicles with over four times the displacement for similar performance results."

I feel that unless you take a vehicle, drop the engine, put in a modern rotary, then put in a V8, and perform tests on both (so everything else but the engine is the same) you are comparing apples and oranges. I think the above claim should be reworded to clarify this, or a better, more scientific, source found. —Preceding unsigned comment added by 72.33.0.163 (talk) 15:04, 16 July 2010 (UTC)

You have to compare power/weight ratio. The clear disadvantage of the Wankel is the poor fuel consumption at low revs. This is not a problem at high revs. The Wankel is not suited for direct drive in normal driving condition. The best application is constant speed high revving in range-extender applications, then it sings. The low weight and small size then makes this unit the obvious choice. Audi have it in the future A188.109.15.29 (talk) 17:28, 28 August 2010 (UTC)

If looks like fans of this engine are trying to say there are no disadvantages. If so, it's had over 50 years to catch on and take over the internal combustion engine market but there are no, or almost no, cars using it??? foobar (talk) 10:01, 29 January 2016 (UTC)

There are few disadvantages of a rotary if all the advances are rolled into one engine. Usage in cars does not determine the viability of an engine. 94.6.57.104 (talk) 19:11, 8 December 2016 (UTC)

I agree with foobar. The disadvantage statements are followed by carefully-worded qualifiers and theoretical technical solutions which allegedly eliminate the cited disadvantage. This makes it sound like there are no disadvantages. Obviously this cannot be true as the rotary vehicle has gone extinct, primarily due to emissions and fuel consumption concerns. The disadvantage section needs to actually reflect the reality of the currently and previously implemented rotary engines, otherwise it is hopelessly irrelevant. See: http://www.roadandtrack.com/car-culture/videos/a27893/how-a-rotary-engine-works/ . Booksacool1 (talk) 01:00, 8 December 2016 (UTC)

The disadvantage does state the disadvantages in production rotary engines. However it does mention advances in R&D that overcome disadvantage putting it into perspective, which are referenced. This is not a rotary vs piston engine article. It is to explain how it works, the history, advantages, disadvantages, R&D and other advances, to give the reader a balanced view. This is not a mine is bigger than yours article.94.6.57.104 (talk) 19:03, 8 December 2016 (UTC)

The disadvantages sections states.."Many of the disadvantages are in ongoing research with some advances greatly reducing negative aspects of the engine. However, the current disadvantages of the Wankel engine in production are the following:" I see nothing wrong with that. It does state, "the current disadvantages of the Wankel engine in production are the following". It is stating there are disadvantages. It goes on to list them: Rotor sealing, Apex seal lifting, Slow combustion, Bad fuel economy and Poor emissions. The points are then expanded. There is nothing wrong with the section. It is very informative. 94.6.57.104 (talk) 07:16, 11 December 2016 (UTC)

Diesel

Not much is mentioned about using diesel wankel engines. Does the generally low compression ratio make wankels unviable modern vehicles? Should it be mentioned if that's true? Scott Paeth 03:07, 22 August 2007 (UTC)

I don't think compression ratio is a problem because the diesel version uses two stages of compression. I suspect the problem, as with the petrol version, is the short life of the seals. Biscuittin (talk) 23:56, 1 February 2010 (UTC)

Modern petrol versions have improved seals but I think work on the diesel stopped before they became available. Perhaps it's time for another try with the diesel. Biscuittin (talk) 00:03, 2 February 2010 (UTC)

There were also single stage compression ignition Wankel engines, but it seems it proved difficult to start and tune; regarding the issue of Specific Fuel Consumption of RCEs and reciprocating engines, early RCEs reached SFCs of around 280 gr/hp/hr, not too different from series engines in common cars, but somehow higher than in the best reciprocating piston engines ever, the engines with distribution by Single Sleeve Valve, that in the hands of Harry Ricardo and Mike Hewland gave SFCs of around 190 gr/hp/hr; but SFC has been improving constantly over time in RCEs, and the SFC at the rpm zone of best Volumetric Efficiency and best torque that is where good SFC figures for reciprocating engines are obtained, may differ in an important proportion to the fuel economy in actual conditions of use, and in a not so favorable rpm regime, also, it's not the same an engine designed for a constant or near constant rpm range, such as for an electric generator or an airplane, that is going to run most of time at the cruise speed, than an engine intended for an street car use.--Jgrosay (talk) 22:33, 29 January 2013 (UTC)

Specific power

"Wankel engines have several major advantages over reciprocating piston designs, in addition to having higher output for similar displacement and physical size"

I've heard, in both aviation and automotive articles, that the Wankel can be characterized as having "one third less power, but one half the weight". The statement above suggests otherwise. Can someone explain why the specific power is higher, and perhaps give a characterization like the one I had heard before?

Maury —Preceding unsigned comment added by Maury Markowitz (talk • contribs) 12:38, August 27, 2007 (UTC)

How these articles come to that conclusion is unclear. The power-per-displacement and power-per-weight ratios are incredibly high (check the List of automotive superlatives). I imagine that they must be confusing applications of the engine with properties of them? Mazda's wankel engines are all relatively small and light compared to other sports car engines that have more power at disproportionate weight and size gains, could this be the basis of those statements? Scott Paeth 22:53, 4 September 2007 (UTC)

Note that power to weight varies greatly with engine design and the expense of the materials. For example the Ford polymotor (plastic block) had a very good power/weight, and the Ducati desmodici (800cc NA 250hp@ 17000rpm) has an great power/weight. —Preceding unsigned comment added by EdEveridge (talk • contribs) 18:21, 3 February 2010 (UTC)

Doubts may come from the way engine displacement in Wankel RCEs is stated; some used the displacement of a single chamber multiplied by the number of rotors, other used the displacement of a single chamber multiplied by 3 and multiplied by the number of rotors, the most widespread approach would be 2 times the displacement of one chamber multiplied by the number of rotors, and the Japanese taxation authorities seem using the displacement of one chamber multiplied by 1.5 and multiplied by the number of rotors to rate taxes in Wankel RCEs, the way you use to express the displacement of a Wankel RCE may have a big influence in the image people gets about the RCE performance compared to a reciprocating piston engine, where total engine displacement is displacement of one cylinder multiplied by the number of cylinders; the 2 times the chamber volume multiplied by the number of rotors looks like a reasonable approach to the subject of RCE displacement calculations.--Jgrosay (talk) 22:43, 29 January 2013 (UTC)

Animation

Just a nit to pick on the animation. The ignition cycle does not show red in all cases. Jokem (talk) 17:29, 20 July 2009 (UTC)

Perhaps you didn't notice but the colouration is only shown for one cavity and matches the highlighted cycle caption around the outside. 109.156.49.202 (talk) 17:11, 13 October 2011 (UTC)

New application: range extender for plug-in hybrids

At the eCarTec in Munich October 13 to 15th 2009 in Munich, the first international fair for electric mobility was a Fiat 500 converted to a plug-in hybrid shown. Small cars like this are expected to drive 90% in electric only mode. So for the few usage of the range extender, the little less efficiency of the wankel is not so important. Important is low weight and small size. Here a photo --Pege.founder (talk) 10:16, 24 October 2009 (UTC)

A Wankel run at the optimum speed continuously turning an alternator will be quite efficient. The small size and smoothness is a great bonus in car packaging. Audi used one in their A1 concept car. It was so small it was under te boot floor. The car is to be produced. 81.178.168.233 (talk) 17:28, 26 August 2010 (UTC)

I think Audi have dropped the Wankel range extender idea. However others are taking it up, like Mazda When revving up and down the efficiency of Wankle drops seriously. A constant speed at it its most efficient speed makes the unit a winner. 94.194.18.103 (talk) 09:14, 30 August 2013 (UTC)

Displacement figures shenanigans.

The absence of any mention of the debate about the displacement of a Wankel engine destroys any notion that this article has a neutral POV. For example: the 1.3 figure for mazda's 13B engines only counts one side of each rotor. When i was first learned this i was awestruck that they would say such a thing because i assumed (naively) that they wound count all three sides of each rotor since all three sides are simultaneously producing power. Other people I've spoken to about this have compared it to only counting two cylinders of a V8.

I realize that the displacement calculation makes no difference as to the actual size or weight of the engine or on the output of the engine. Wikipedia should include this in the interest clarity. If figures are given that include a "Rotary Equivalence" or "conversion" factor, that should be noted. But just saying "1.3 liters" is carrying on deliberate obtuseness that is inappropriate for Wikipedia. see http://www.hemmings.com/hsx/stories/2008/04/01/hmn_feature11.html Grabba (talk) 16:50, 1 February 2010 (UTC)

There are a couple paragraphs under "disadvantages" that discuss displacement measurement. It could be better written and probably shouldn't be listed as a disadvantage, but those paragraphs are basically correct. The method in the link you provided is not mentioned because it's wrong :-) Further, there's nothing inappropriate or POV about using the displacement figures that almost all of the cited sources use.ColinClark (talk) 08:05, 15 February 2010 (UTC)

Comparing displacement of a Wankel to a piston engine is meaningless. You have to compare the power to weight ratio. The Wankel gives near 200 HP per litre, while the best BMWs give 100 HP per litre. Wankels are at the most efficient running at high revs. Using them as range extenders is the best application for them. The promise to take over this market as series-hybrid will be the norm in a few years time.81.178.168.233 (talk) 17:24, 26 August 2010 (UTC)

You say Wankels should be compared on a power to weight basis. Then go to quote horsepower per liter numbers. Anyone familiar with the various designs and material makeups of an engine will know that the displacement of an engine does not reflect its weight. 5.7-7.0 liter Aluminum block and head 3rd and 4th generation Small Block Chevy's weigh approximately 458lbs and produce anywhere from 310-505hp, a late model Wankel (series 6, 7, or 8 RX-7 13b-rew, aluminum and iron housings) weighs approximately 410lbs and produces anywhere from 255 to 280hp. The 2.6 liter RB26DETT and 3.0 liter 2jz-det both weigh around 600-700lbs and produce 280-320hp. Clearly engine type (V8, rotary, Inline six) and material (aluminum, iron) has more bearing on the total weight of the engine than its swept displacement. Also, by inciting hp per liter you are simply taking the discussion back to what formula should be used to calculate the displacement of a rotary. 280hp/1.3 liters (~215hp/l) is clearly an incorrect comparison measure, as is 255hp/3.9 liters (~65hp/l). If compared simply by power to weight, clearly the chevy pushrod V8's come out on top regardless of what displacement measure you us for the rotary. —Preceding unsigned comment added by Li7in6 (talk • contribs) 00:05, 9 November 2010 (UTC)

Displacement is near meaningless. It was used as a means to tax engines well over 100 years ago, as it was the only figure they could nail down. Take a large V8 lump car and a Wankle with equal power output in car designed around the Wankel taking full advantage of the small size, less weight and great power/eight ratio and using a series hybrid (electric transmission) - playing to the strengths of the Wankel, and the Wankel will outperform it in performance, mpg, etc, etc. 94.194.18.103 (talk) 09:25, 30 August 2013 (UTC)

Wrong. Look below. But what is really important is fuel efficiency, BSFC. The few strenghts of Wankel engines are unimportant. The Mazda RX-8 with 231 hp has the performance of sporty cars with 200 hp piston engines (compare the acceleration times 0-200 km/h), but the fuel consumption of 400 ci V8. And furthermore, Mazda engines loose their power sooner than piston engines, one of the untold/secret reasons for sale ... Minzoblate (talk) 19:05, 12 May 2022 (UTC)

Look: Mazda RX-8 won "engine of the year award 2003" in the category 2.5 - 3 litre displacement. --Minzoblate (talk) 15:32, 25 November 2020 (UTC)

Drop the discussion of surface to volume ratio

The article mentions surface to volume ratio without any mention of why it is an important consideration either as a positive or as a negative. This is confusing. EdEveridge (talk) 18:25, 3 February 2010 (UTC)

So expand and clarify it. It's the #2-#3 reason (behind seals and maybe flamepath lengths) why Wankels haven't been a success. Andy Dingley (talk) 20:51, 3 February 2010 (UTC)

Wankels have great advantages. They are not a success because the have not been used for the correct application - constant running range-extending - a generator. Also, a license fee had to be paid.88.109.15.29 (talk) 16:59, 28 August 2010 (UTC)

People are trying to make a direct comparison to a piston engine, which is ludicrous. It is like attempting to compare a V8 with a turbojet. 94.194.18.103 (talk) 09:39, 30 August 2013 (UTC)

This is completely wrong. Even Felix Wankel did it. A comparison is explained in R.F. Ansdale "The Wankel RC Engine", english version from 1968, page 56. You must compare a single-rotor (=three chamber) four stroke (there is no two stroke of course) Wankel engine with a two cylinder four stroke piston engine, where one chamber has the same volume size of one (of two existing) cylinder. Then you have same rotation speed of excentric shaft and crankshaft, same "number" or "counts" of iginitions of shaft/crankshaft revolutions and same throughput of air-fuel mix. And additional to that, there is no need for "corrections" of the volume/surface ratio, because if those engines are running, then always one chamber (with bad v/s ratio) ignites parallel to one cylinder (with good v/s ratio). at the same time. If you compare a single rotor Wankel engine with only one cylinder piston engine, then this piston engine has half the counts of ignitions of crankshaft revolutions and half the throughput of air-fuel mix. Minzoblate (talk) 18:56, 12 May 2022 (UTC)

One thing is clear is that the Wankel has a superior power/weight ratio, which leads to vastly superior packaging of the engine in a car. Head of Mazda research said is is best suited to a constant speed generator application. The emissions problem is eliminated with hydrogen running which also improves efficiency a massive 25%. Japan is moving to a hydrogen society.

Mazda are introducing the Mazda MX-30 hybrid next month with a rotary range extender. So we shall see. Wisdom-inc (talk) 14:24, 11 December 2022 (UTC)

Motorcycle engines since the 80s

One sentence says that wankels have not been used for racing since the 80s. Next we are told that norton raced (and won) with one at the IOM TT in 1991. can someone with more time correct the first staement? —Preceding unsigned comment added by 213.122.161.179 (talk) 12:47, 12 August 2010 (UTC)

Apparent numerical error

There is something wrong with a "1 mm" diameter wankel engine with a displacement of "0.1 cc". Possibly it should be 1 cm diameter and 0.1 cm displacement?

Mike Halling, [email protected] —Preceding unsigned comment added by 68.8.12.40 (talk) 10:33, 31 August 2010 (UTC)

date error

top says Wankel got first patent in 1929, then a little later the article says he first had the idea around 1951-54. —Preceding unsigned comment added by 173.69.30.47 (talk) 13:56, 15 February 2011 (UTC)

new developments

the new approaches to use wankel engine might be mentioned

http://www.autozone99.com/2011/06/mazda-develop-laser-ignition-system-for-future-rotary-engine/

laser ignition for engine ( which, btw effectivly resolves 'size' problem - allowing bigger wankel engines, than ever were built )

another is a ceramic variant which is described here http://www.ultrahardmaterials.co.uk/ceramic_rotary_engine.htm and here http://ceramicrotaryengines.com/ ( I checked - the team of people is the same, though registration is different UK and US respectivly ) they just produced experimental engine - no more, but noneless - something new. SergeyKurdakov (talk) 18:05, 15 July 2011 (UTC)

Kyocera advertisement

I removed the following piece of text 'cause it seems like an advertisement:

Ceramic piston rings are available from Kyocera together with ceramic liners and ceramic pistons and are a special (expensive and low-production series) car parts.<ref>Kyocera ceramic car parts (silicon nidride){{cite web|url=http://americas.kyocera.com/kicc/automotive/engines.html |title=Kyocera's advanced ceramic materials }}</ref>

--TiagoTiago (talk) 15:46, 21 March 2012 (UTC)

Revising the Definition of the Wankel Engine

The Wankel engine is a type of internal combustion engine. In which it uses 3 main components rotors, housings/plates, and an eccentric shaft. The eccentric shaft or lobe goes straight thru the middle of the rotors, which rotate the rotors, which look like triangles. The two rotors are separated by plates and enclosed by housings, which basically closes up the internals to the motor. As the eccentric shaft moves the rotors a four-stroke cycle takes place inside the enclosed motor. As the rotors spin, each chamber on the 3 sides of the “triangle” spinning inside the motor has their own task. Air/fuel mixture is inhaled into the engine by the intake port as the rotor keeps spinning. The next phase is the mixture gets compressed and when it finally makes its way to the spark plugs and the spark plugs spark it ignites the compressed mixture, which builds up pressure quickly forcing the rotor to move even faster which creates power. Just after the spark plugs ignites and moves the rotor the next phase it lets the combustion gases out the exhaust port, which is basically the end of the cycle since the exhaust ports lead to your exhaust, and out the vehicle. So basically each phase is happening at the same time one right after another however the shaft spins three times for every complete revolution for the rotor. • On a side note if you want a better idea to see how the engine works visually you can grab a straw and loop it so that its enclosed looking like a circle/oval shape. Then grab a Dorito chip, since it looks like a triangle, and put it in the closed looped straw and rotate the Dorito and that’s how the internal of the Wankel engine works. — Preceding unsigned comment added by JEV7-NJITWILL (talk • contribs) 22:26, 12 December 2012 (UTC)

this has been amended, although not exactly to this text. 78.105.234.189 (talk) 02:11, 16 October 2013 (UTC)

Interesting data coming

SAE seems about to publish two papers with a promising title, in both one of the authors is Mr. Ming-June Hsieh, one is: "The intake and exhaust pipe effect on a Rotary Engine performance", the other: "The numerical investigation on the performance of Rotary Engine with leakage, different fuels and recess sizes". Hope they arrive sooner than later.--Jgrosay (talk) 16:44, 2 January 2013 (UTC)

When the data comes, give a source and it will be inserted.188.223.115.193 (talk) 11:49, 29 August 2013 (UTC)

Question mark

What is a "No loss" way of lubrication of apex seals and of stator surface in a Wankel engine? Some recent developments, such as the Austro Engines (heirs of MidWest Aeroengines, the company that produced the first aviation engines designed by the Norton team), single rotor 294 cc per chamber engine intended for ultra-light aircraft use and giving 80 HP, uses this approach of "no loss" lubrication.--Jgrosay (talk) 22:06, 29 January 2013 (UTC)

Give a source and it will be inserted.188.223.115.193 (talk) 11:48, 29 August 2013 (UTC)

Future or imminent R&D section

Many people perceive the Wankel engine as finished and a curio. The Wankel engine is still ongoing in R&D and is being taken up more in specialized aircraft applications. A section may be needed to gather all the advances, confirmed R&D and proposed applications and indicate to the reader what may come in the nears future. Most of the info is in the article, which is scattered about. It needs bringing into one section. 94.193.161.81 (talk) 06:34, 31 August 2013 (UTC)

By "specialized" aircraft application you mean EXPERIMENTAL aircraft, where pretty much anything goes because experimental aircraft are severely limited in power, altitude, capacity, weight and performance. All to keep them from getting into airspace where certified aircraft fly in civil and commercial aviation. You could use a giant rubber band to power the prop on an experimental aircraft and it would be "legal" if it met a few other basic requirements. Of course even THOSE requirements are just to make it "airworthy" enough to operate from public airfields, etc. If you fly from a private airstrip, stay out of controlled airspace and don't bother with insurance and such, you don't even need a pilot license of any kind to fly in the U.S. Those that go for "experimental aircraft" acceptance are those that want to show off their new toys at the local airport or don't have access to a private airstrip. So being "accepted" for use in "experimental aircraft" is not a big accomplishment or achievement for Wankel engines. Neither are "proposed applications" which are literally pure speculation about replacing existing piston engines with Wankels. Which is something Wankels have been unable to achieve on any sort of SUCCESSFUL and "mainstream" level throughout their history.

The "near future" for Wankels is about what it was 50 - 60 years ago. A tomorrow that doesn't come. — Preceding unsigned comment added by 68.234.100.60 (talk) 11:54, 30 May 2017 (UTC)

Mazda announced a hybrid using a rotary with maybe using the innovative SPCCI ign.

The Holy Grail Of Rotary Engines - SkyActiv-X

https://www.youtube.com/watch?v=vEMuOi0N2fQ&t=1s

the VP of R&D for Mazda said there was a chance SkyActiv-X strategies could be applied to future rotary engines. In this video, we'll look at what changes to the rotary engine could result in great efficiency. This includes changes to the compression ratio, fuel injection, SPCCI lean-style combustion, superchargers, and using a pressure sensor to optimize ignition timing.

2A01:4B00:881D:3700:CAA:6491:D375:C8BC (talk) 14:48, 23 April 2019 (UTC)

Factual errors and POV issues

I like Wankel engines and I feel the article editor does too. However fact remains that, even though some poorly designed conventional engines need extensive maintenance below 50,000, Most reciprocating engines continue to function adequately for three times that. Also the Mazda statement is incorrect as Mazda does not currently offer a mass market Rotary engined vehicle. Mazda.com no longer offers a rotary engine option. Fact is that rotary engines are only useful for short lifetime power, like torpedoes. Shjacks45 (talk) 08:00, 26 April 2014 (UTC)

You wrote "fact", then what you wrote after was pure opinion. 94.193.157.145 (talk) 17:37, 1 August 2014 (UTC)

Wankel engines can easily run into 100,000 miles of use before a rebuild. Also to rebuild a Wankle is a simple, cheap and quick task to a piston engine, mainly requiring replacement apex seals. Small Wankle engines can be lifted out of a car by one man. If the Wankle was taken up en-mass, an engine exchange system of a quick replacement taking about a hour is easily implemented. The Wankel is still under development and the new Austro Engine model has a non-loss lubrication system. 78.105.8.41 (talk) 09:13, 4 August 2014 (UTC)

How "rebuildable" a Wankel engine is relies completely on the definition of "rebuild". A piston engine can often be "rebuilt" with just replacing seals and gaskets, too. But that doesn't remove wear and it doesn't return the engine to factory new specifications and performance, which is the standard most PROFESSIONALS demand from an engine "rebuild". You're talking about light-duty engines any time there aren't replaceable cylinder sleeves involved and its a spark-ignition engine. Medium-duty engines have parent-bore cylinders that can be bored and honed and fitted with oversize pistons without affecting cylinder wall thickness enough that flexing and ring seal issues become a problem. Heavy-duty engines have replaceable cylinder liners that are completely replaceable so the engine can literally be RENEWED rather than "rebuilt".

None of the above are possible with a Wankel and 100,000 miles is a long ways from an accomplishment these days when even relatively "cheap" piston engines in the same "displacement" and "power" categories with Wankels will run 200,000 or more. Even then, many "modern" engines aren't even designed to be "rebuilt" at all, because by the time the vehicle and engine reach their designed service life "expectations", they're not worth the time and money to "rebuild". Many have torque-to-yield fasteners for the cylinder head and occasionally the main bearings and connecting rods, they have cylinder bores that can't be bored a useful oversize and the manufacturer doesn't offer oversize pistons, rings, etc.

That's how you determine if the MANUFACTURER thinks its engines are worth "rebuilding". The aftermarket doesn't matter much if you're interested in restoring "like new" performance and reliability. But even the cheapest "throwaway" engines can typically be sleeved back to standard IF someone wants to put the time and money into them. Nothing of the kind is possible with a Wankel and replacing those seals just results in new seals that want a NEW SURFACE FINISH to seat in and seal against in contact with USED and WORN and GLAZED surfaces that are out of spec and where worn will no longer provide proper TENSION for the seals, much less proper sealing. Which is why things like "apex seal lift-off" are a PROBLEM for Wankels to begin with, both worn out AND "rebuilt".

Unless and until somebody comes up with a cost-effective way to return a rotor housing to its new dimensions, tolerances and surface finish and hardness, Wankels can't be "rebuilt" using any PROFESSIONAL definition of the word. Until then its find "good used" parts, machine worn out parts to get a "new" surface finish and used "oversize" seals or do some other Band-Aid repair to "rebuild" them that still doesn't result in like-new performance and efficiency. Until Wankels go 100,000+, can be "rebuilt" by the local machine shop or auto shop and then go back into the vehicle to run ANOTHER 100,000+ with similar or IMPROVED fuel economy, oil consumption, power, etc. they're just throwaway engines.

There's a reason — Preceding unsigned comment added by 68.234.100.60 (talk) 12:09, 30 May 2017 (UTC)

Tree Dimentional Spinning Wankel Engine

The totally round Wankel design-based motor cycle has 3 intake/exhaust sets, compression is achieved by closing with caps 2 sets at a time in a rotary serial sequence, also we have 3 ignition sets. [totally round is not the official Wankel engine but an lab version of it]

The problems? The engine usually exploads because the ignition sets might get mixed with more fuel than are supposed to, also caps break of.

It doesn't work really well yet. It is a great idea though.

Some scientists tried to used a double Boomerang shape at the beginning with 2D motion, but now we know that we must build the firts 3d motion rotary engine.

A 3d motion rotary engine is like a quantum mechanical particle. You cannot make a simple 2d animation to explain it but a 3d.

It is the best thing we know have in mind, we can trap that 3d moving central part with gears, but many times it breaks. It is a way more complex and delicate design, not so great for simplicity but for academic research that might help simpler engines. A 3d rotary engine does not complet a spin in one period but in 2 or three, it depends on the design.

It is really fun though!

This is really a diamond to look, a rotary engine disigned with spins - like quantum mechanics, so the 3d motion does not return to the same position at once, it has to follow a 3d path.

It breaks and it does not work well. But academic engine research, always allow us understand more stuff, and keep the parts that work well. — Preceding unsigned comment added by 2.84.206.14 (talk) 05:21, 2 July 2014 (UTC)

Copyvio ??

Much of the section titled 'Design' is lifted word-for-word from this YouTube video:

http://www.youtube.com/watch?v=Z7kj9rO8CgI

posted by ADP Training.

http://www.autodiagnosticsandpublishing.com/

They deserve at least a credit!

109.145.110.160 (talk) 02:06, 7 July 2014 (UTC)

This is an interesting situation because the section of the text being read by a computer generated voice in the video (thus the "word-for-word" transcription) has been in this Wikipedia article long before the video was posted by ADP. Therefore, it seems that ADP Training is using parts of this article from 2010 in their 2011 video without giving credit to Wikipedia? CZmarlin (talk) 02:59, 7 July 2014 (UTC)

Yes. Thanks for pointing out my mistake. Much of this section is now as it was at the end of 2005 in the section then headed 'How it Works'.

109.145.110.160 (talk) 09:32, 7 July 2014 (UTC)

External links modified

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User ScrapIronIV

This user has a problem with me. He is deliberately following me. He has no idea of the workings of a Wankel engine (clearly non-technical) and will revert anything I add, getting into a needless edit war. He is adding no value and stopping the article from progressing. He has a problem with me over the Mustang plane article. I intend to change the Mustang article with references. He doesn't like that. He appears to be an American who thinks the Mustang was a 100% US plane. He is quite odd. 2.126.207.30 (talk) 17:23, 24 February 2016 (UTC)

Your "adjustments" to the article were problematic, and certainly not an improvement. Please read WP:NPA and comment on content, not contributors. Scr★pIron^IV 17:27, 24 February 2016 (UTC)

Please expand and comment on content here. I doubt you can as you know nothing technical about this. It is against wiki to stalk users like you are doing. 2.126.207.30 (talk) 17:36, 24 February 2016 (UTC)

Also user ScrapIronIV has threatened me with a banning if I enter into an edit war. He is the one initiating an edit war. He has never once contributed to the Wankel engine article, just come here to stalk and cause an edit war. 2.126.207.30 (talk) 17:40, 24 February 2016 (UTC)

ANI is over there >, and ANEW is up here ^ You won't get another meal from me. Scr★pIron^IV 17:43, 24 February 2016 (UTC)

Stop stalking me and go away. OK? 2.126.207.30 (talk) 18:08, 24 February 2016 (UTC)

HCCI

A section on this advance in rotary research has been added. 90.213.129.219 (talk) 10:15, 7 August 2016 (UTC)

Temperature conversion problem

I see a problem with the page; it says that something causes a "7 °C (45 °F) reduction" in temperature. This unit conversion is wrong. While it is true that when you look at the thermometer it will read 7 and 45 at the same time, that is for absolute measurements. When the temperature changes by 7C, it changes by 9/5 that amount in F, or 12.6 degrees. I have not applied any edit though because I am not sure which value is correct, C or F. 173.48.141.58 (talk) 13:28, 14 September 2016 (UTC)

Uh, you're making this too complicated at the same time you're oversimplifying it. First of all, the conversion is already done and its correct. 7 degrees C IS 45 degrees F, or very close to it. There's no error to correct. Second, whether its different scales on the same thermometer or different thermometers or outside temp or a DIFFERENCE in temps, 7 celcius is always going to be 45 degrees F. You're getting 12.6 because you're "oversimplifying" the formula by leaving a big part of it out. Fahrenheit IS determined by multiplying Celsius by "9/5" (dividing 9 by 5 results in 1.8 so the use of the fraction is pointless) but you then have to add 32 to the result. Which is why O degrees C is 32 degrees F. And it's why 7 x 1.8 = 12.6 and 12.6 + 32 = 44.6. Which rounds up to 45 degrees F. — Preceding unsigned comment added by 68.234.100.60 (talk) 11:46, 30 May 2017 (UTC)

No, the original complaint was correct. You are confusing absolute measurements with differences. The *absolute* temperature 7 °C is 45 °F, but a *difference* of 7 °C is 12.6 °F. The constant 32 is present in both measurements and is therefore subtracted out when forming the difference. An easy way to show this is to compare the differences between freezing and boiling points of water in C and F scales. 100 °C - 0 °C = 100 °C 212 °F - 32 °F = 180 °F Ratio = 1.8 = 9/5 (and ≠ 9/5 + 32)

Therefore, your comment that "...whether its different scales on the same thermometer or different thermometers or outside temp or a DIFFERENCE in temps, 7 celcius is always going to be 45 degrees F..." is completely false.

Proper use of the "convert" function gives the correct answers. See https://en.wikipedia.org/wiki/Template:Convert#Units_of_difference:_10.C2.A0.C2.B0C_higher.3B_how_much_in_.C2.B0F for correct usage for differences. Article text was edited using method in above link.4.14.62.246 (talk) 13:39, 9 August 2017 (UTC)

I supposed it would be "WP:OR"...

To have a section in the article simply stating the truth about Wankel engines in one simple sentence instead of a long list of "advantages" and "disadvantages". That truth is that despite decades and decades of "development", Wankel engines are still right where they began. In "niche" applications that are a tiny percentage of theorized possible "viable" applications and uses for them. That could be summed up simply by saying "Wankel engines are no closer to "mainstream" acceptance and use today than they were several decades ago when first designed and constructed. Plenty of "manufacturers" have plenty of "plans" and "ideas", but to date only one manufacturer (Mazda) has been even remotely "serious" about advancing the technology, and even that manufacturer uses the Wankel "design" in a small fraction of its engine and vehicle production.

Unlike gas turbines, which were similarly promoted and propagandized as panaceas of internal combustion performance, Wankels and their promoters and supporters haven't gotten their reality check yet, and continue to be not only a "solution" to an existing problem, but an increasingly LESS PRACTICAL "solution" to ANY problem. Emission, fuel-economy and noise requirements, limits, regulations, standards and laws are increasingly present in nearly all areas of internal-combustion engine use, as are increased expectations for performance and longevity, which ALSO figure prominently in "sustainability" and "environmental responsibility". And those are all things Wankels, like gas turbines, do very POORLY. It's no one's fault and it's not "hate" or being "close-minded" to acknowledge and discuss that. In fact, being close-minded is IGNORING that reality and letting go of the Wankel dream.

The one thing that is absolutely required for modern engines to meet the goals and expectations and requirements they meet is "tuneability". That means being able to accurately and precisely control what goes INTO the engine, what happens INSIDE the engine and what COMES OUT so that OTHER technologies can be "tuned" to deal with the emissions that invariably result and accessory systems and other components and parts can also be designed and developed and "tuned" to create a holistic "system approach" to getting to those goals, expectations and requirements. Wankels just don't cut it, and tons of resources and BRAIN POWER are wasted trying to "prove" what the free markets AND government intervention in economies and industries have already proved impractical and have cast aside. Let Mazda come out with yet another "generation" of low-production, "high-performance" sports cars with rotary engines that either skirt or barely meet emissions requirements or use "smog credits" and various "loopholes" to be exempt from them and let other "manufacturers" produce THEIR "Wankel miracles". That won't change the fact that as a "mainstream" technology, Wankels are a flop. — Preceding unsigned comment added by 68.234.100.60 (talk) 11:31, 30 May 2017 (UTC)

That was biased opinion. The rotary is used in many applications with about 5 companies making them world-wide. Mazda have just announced a rotary hybrid to be sold in 2019. There is R&D on electric planes with a hybrid generator for range in some models. The rotary is favourite for this role for obvious reasons.

Advances like HCCI and laser ignition are also in R&D. The engine is not dead as you mistakenly think it is.2.221.197.152 (talk) 10:56, 30 October 2017 (UTC)

I don't know what you have against gas turbines, but they're almost maintenance-free and work quite efficiently, particularly compound and/or with coolant heat use (crops heating, for example). As for the wankel, it's quite safe to say that, commercially viable or not, any research done on it will have positive effects on any ICE. To me, the 13B-MSP was absolutely viable, even if not exactly "outstanding" in the good way (moderately high fuel consumption not adequate for its performance level, but still... that would fit a ND MX-5 quite nicely, just a bit over the 160HP 2000cc as essentially a more exclusive "high tune" version which cost would mainly be due to... taxes because of regulations requiring a target emission level for the whole vehicles mix, measured with a flawed protocol), it wasn't really worse than the recent downsizing trend with stupid people proud of a TC 1000cc engine burning exactly the same amount of fuel as a NA 2000cc engine for the same work done (but advertised a good 30% lower because of the said flawed emission protocol, noting even the 2000cc one can't match its advertised fuel consumption derived from the same test), while being marginally more compact and heavier than a 1400cc engine with 1 or even 2 more cylinders (because of the added weight of the turbo, intercooler, additional fluids and possibly even heavier flywheel to compensate for the spikier torque distribution). By the way, emissions are responsible for part of the increase in fuel consumption... you feel quite bad when a good'ol' 80's carbureted engine doesn't burn more fuel than a "top notch" almost-2020 DI engine of similar power in a similar chassis despite its considerably shorter gear ratios (you could almost remove the 2 last gears of contemporary 6-speed gearboxes to be fair). — Preceding unsigned comment added by 2A01:CB11:13:D700:3C4D:8FAC:C381:225C (talk) 01:27, 10 June 2017 (UTC)

"Three power strokes per revolution" etc

The intro goes on about how the Wankel is "Smooth because there are three power strokes per revolution". No, it's smooth because there are no reciprocating parts. This is totally misleading. Yes, there are three power strokes per ROTOR rev, but since the actual OUTPUT spins three times this rate, for each ECCENTRIC SHAFT (ie crank) revolution, there is only ONE power stroke, as can be seen in the animation on this very page. Look at "A", the rotor, and "B", the eccentric: B completes three revs for each rev of the rotor. Each time a face goes "bang", the output shaft spins once, one full 360deg revolution. Simple. This is why you only measure ONE face as the displacement, otherwise you'd be including the 2/3rds of the engine that aren't working for each eccentric rev (something like calling a 2.0L 4-stroke a "2.0L" even though only one liter is actually creating output for each rev. A 1.3L Wankel is roughly the same as a 1.3L 2-stroke. I'm kind of shocked the intro to the article has it so wrong, or very misleading at least. There is a REASON they only chose to measure rotaries as the size of ONE face, and it' not because there was some big conspiracy, its because it was the way that made sense! AnnaGoFast (talk) 02:24, 29 August 2017 (UTC)

The engine is smooth because it all moves one way for sure, but having three power strokes per revolution, does help, not the main reason but it assists. 2.221.196.156 (talk) 15:08, 5 February 2018 (UTC)

Nice theory, but it doesn't have three power strokes per revolution, as AnnaGoFast explained above. --Guy Macon (talk) 02:03, 6 February 2018 (UTC)

Three power pulses, (not a stroke), per rev of the rotor or shaft? The rotor creates the power and turning motion, not the output shaft.

Look at Jason. https://www.youtube.com/watch?v=Ny4-Jc_qW60.

He uses 1,000 rpm. At 1,000 rpm at the output shaft, the rotor spins at one third of that, 333.3 rpm. There are three combustion pulses for every rotation of the rotor. The rotor is spinning at 333.33 rpm. Multiply that by three and we have 1,000 power pulses at 1,000 rpm.

So, at 1,000 rpm you have 1,000 power pulses.

The engine does have three power pulse per rev of the engine, when the output shaft running inside the rotor is regarded as a part of the gearbox, which it is as it is a part of the transmission taking power out to the load (wheels). A Wankel could run without out an output shaft. One was proposed to run like this using electrical coils in the housing and rotor to be a simple generator.

The gearing between the rotor and the output shaft can be one to one, in other words, three power pulses per rev of the output shaft.

To get three power pulses per rev of an output shaft (crank) in a 4-stroke engine you would need six cylinders, whereas a Wankel does it with one rotor when geared on a one to one ratio between rotor and output shaft. Have three rotors firing at 120 degrees of each other (evenly heating the engine housing), then a highly smooth and vibrationless engine emerges, which would be the equiv of an 18 cylinder 4-stroke engine. This will give enough torque indeed. An engine could have three rotors of small physical sizes, eliminating a gearbox for direct drive, when using SPCCI ign on gasoline or hydrogen. Alas direct drive IC engines appear to be a thing of the past, being predicated to be used only for range extending (constant speed generators), in the near future.

In a four-stroke piston engine you get 500 power strokes (pulses) for 1,000 rpm. With complete combustion, say using hydrogen fuel, the rotary will need less gearbox gearing for the output to the wheels, making the whole setup simpler even again. In a small runabout hatchback, the gearbox could be eliminated altogether, giving knock-on benefits of amazing packaging in a small car.

So, having three power pulses per rev of the rotor does add to smoothness of the Wankel. 2A01:4B00:881D:3700:F581:7D0F:ADCE:E437 (talk) 09:43, 29 April 2019 (UTC)

The output shaft is a part of the engine, not the transmission (gearbox), as a crankshaft is a part of a piston engine. A transmission (gearbox) is bolted onto the end of a rotary engine. Yes the rotary does have 3 power pulses per revolution of the output shaft. That vid by Jason does explain it very well.

From what I know of the new Mazda MX-30 that will have the rotary turning only a generator, is that there will be no gearing between the engine and electrical generator, which means less drag giving higher efficiency. We shall see. Constant speed engines turning electrical generators do not need flywheels, which reduces weight and improves efficiency. Wisdom-inc (talk) 15:18, 22 November 2022 (UTC)

Cooling sub-section

A section for Cooling is needed. It needs to be a sub-section in Engineering. The info is there it just needs organising. I will do this within the next few weeks. 90.195.174.67 (talk) 11:15, 7 May 2018 (UTC)

Article quality review (ifs201)

Each fact is not necessarily referenced with an appropriate citation, many facts could use addition references. Yes the entire article is relevant. All information revolves around the engine and it’s concepts, advantages and disadvantages, and history/applications. The article is current as far as I am aware, outside searching seems to return similar information as the article. The most recent addition to article was most likely the engines use as a rotary/hybrid, and is discussed on the talk page.

Kkuffelroy1 (talk) 06:21, 28 March 2019 (UTC)

Added a section on SPCCI

Added a new section on SPCCI advances being adopted by rotary engines. 2A01:4B00:881D:3700:F581:7D0F:ADCE:E437 (talk) 11:33, 24 April 2019 (UTC)

Added section on hydrogen fuel

All passages put into one section 2A01:4B00:881D:3700:F581:7D0F:ADCE:E437 (talk) 16:14, 24 April 2019 (UTC)

Misinformation about oil changes

Article suggests that because some Wankel Engines don’t expose their oil to the combustion chamber there is no need for an oil change. This is misleading because oil breaks down with heat and oxidation so that even in ideal conditions it is still going to require oil changes as that oil breaks down with time. 174.246.130.111 (talk) 17:25, 29 March 2022 (UTC)

An example an Audi NSU RO80 need no oil change. The oil is only topped up and the oil filter is changed from time to time.--HDP (talk) 12:00, 16 May 2022 (UTC)

Depending on which oil. Fully synthetics last and last if not contaminated. Wisdom-inc (talk) 16:31, 25 November 2022 (UTC)

Balance in lead

For some reason, this article reads like Popular Mechanics back in the 1970s, which I still vividly recall. This was the engine of eternal promise, set to toss the piston engine onto the junk heap. All of those glowing articles spoke at length about the reduced complexity and the other conceptual assets, before doing a deep dive on the perplexing and nonintuitive mechanical geometry. Just now, on YouTube, I revisited this topic, and in the space of 30 minutes learned more about the real trade-offs than every darn thing I read from the mid-1970s to the mid-1980s combined (it was covered regularly). Without even getting into the perpetual thermal gradient while requiring such tight tolerances, we could at least be honest that this engine poses some deep challenges which factored into its failure to unseat the traditional piston engine in the promised timeframe, pretty much over its entire existence.

Perhaps we could have rolled up our sleeves long ago and invested a billion dollars to make this the perfect replacement engine for all applications. But that's not how technology works. What happens is that something good enough becomes established, and is then polished relentlessly over many decades, which is why novel technologies often need to outperform incumbent technologies by an decimal order of magnitude (10×) on some key figure of merit to gain enough capital investment to make the grade.

Here's a quick pass to bring balance back into the lead:

Compared to the reciprocating piston engine, the Wankel engine has more uniform torque; less vibration; and, for a given power, is more compact and weighs less—though combining high power with long service life often entails poor fuel efficiency and a problematic emissions profile, especially when running on gasoline. Ongoing research seeks to mitigate these disadvantages. The most direct solution appears to be switching from gasoline to a faster burning, cleaner fuel such as hydrogen. For hydrogen, designs would need to target applications where low volumetric density of the fuel tanks is not a problem. For specialized applications, such as loitering munitions, the reduced complexity, compact size, and high power of gasoline-powered Wankel engines easily outweighs concerns over fuel conversion efficiency (more than repaid by improved aerodynamics), service life, or emissions profile.

Then it continues on with the Popular Mechanics version of the world, as before. The sad thing here is that the lead obsesses over the internals because the design has never achieved huge success, and so there isn't a long list of rave accomplishments to forestall the deep technical dive.

I'm sure my quick cut could be improved immensely, but that's my two cents, and now I'm off to other pastures. — MaxEnt 08:13, 14 October 2022 (UTC)

Just about all the negative aspects of the engine have been solved. The article points out the improvements. Patents and the likes acts as a barrier to the merging of the improvements into one engine package. What has emerged is that the engine is best suited to constant speed generator applications and running on hydrogen. The article does cover these two points, although it does not throw it into your face.

Japan is moving to a hydrogen society (few 100% battery EVs come from Japan), aiming to produce hydrogen in gas cooled nuclear reactors (helium as it reaches 1,000C which ideal and efficient for cracking water into hydrogen). Info on Youtube on this advance - two bit de vinci. Mazda are 100% certain to introduce in March 2023 the Mazda MX-30 rotary hybrid with the rotary turning only a generator, running at a constant speed. The rumour is that it is easily converted to hydrogen then being 100% clean in emissions. So, the rotary may have met its niche after all this time. Once more info on Mazda's hybrid rotary is available on hydrogen running, the article should present this, highlighting a new role of the rotary on road vehicles. Wisdom-inc (talk) 15:21, 19 November 2022 (UTC)

Restructured article

Information was scattered about. for example, motorcycles was in two separate sections. I restructured the article added sections and merged text from differing sections. Now it is more readable. Wisdom-inc (talk) 15:07, 19 November 2022 (UTC)

Wankel or rotary

@Wisdom-inc: I've reverted (most of) your recent changes of "Wankel" to the more vague "rotary", as "Wankel" is used purposefully in this article to avoid confusion with other types of rotary engines. While you're welcome to disagree with me, this has long been this way in the article, and really needs to be discussed before being changed again. Thanks. BilCat (talk) 01:52, 21 November 2022 (UTC)

I have no problems with that. But the manufacturers do call the engine a rotary. Wisdom-inc (talk) 02:02, 21 November 2022 (UTC)

And so do the myriad fan-people who occasionally show up at Rotary engine or its talk page to tell us that the article is incorrect! BilCat (talk) 02:05, 21 November 2022 (UTC)

Article re-structured

After years of additions and deletions the article was all over the place. I greatly re-restructured and tidied it up, making it easier to read an navigate thru. The contents page shows it is now easier to navigate. The disadvantages appear to have been largely eradicated on the engine, with some disadvantages now largely myth, so this may need some work. Wisdom-inc (talk) 13:48, 4 December 2022 (UTC)

Splitting article

I has been suggested that the Cars section be split off into a separate article. Parts of the car section does provide tech info and history. Also most of the applications of the engine has been in cars. I think it should stay. Wisdom-inc (talk) 14:29, 4 December 2022 (UTC)

Special:Diff/1128297522

This article was (and still is) in need for a decent overhaul, which I began with a couple of days ago. My recent efforts have been reverted so I feel the urge to explain my actions in some more detail. While this is (or should be) obvious to the experienced Wikipedian, I still think that it's reasonable to say that Wikipedia is not a hearsay compilation, instead, it is an encyclopedia which depicts what is (considered to be) established knowledge. In my personal experience, internal combustion engines are machines that are very difficult to comprehend which has lead to a lot of conspiracy theories, so one needs to be careful not to include any "information" that is false. Therefore, I mainly base my edits on Bensinger's 1972 book "Rotationskolben-Verbrennungsmotoren", which is the "bible" of the Wankel engine. Springer has not released a new edition of that work and I have recently (a couple of years ago) used it in a scientific context, so we can presume that this book is accurate and among the best sources one could possibly base this article on. Also keep in mind that any unreferenced claims in Wikipedia articles may be removed with a good reason, and that a lot of the material that I have removed was indeed unfererenced hearsay. I shall try to summarise key points of my recent edits in chronological order:

• The complexity and inefficiency of the 4-stroke piston engine contrasts with the rotational simplicity of the Wankel engine – this is just wrong and contradicts all reliable sources. The Wankel engine is the inefficient engine, the reciprocating piston engine is much more efficient because of its superior design.
• Wankel has invented the Wankel engine, and Paschke has designed it. This is actually a summarization of what the article had previously described in the "Early Developments" section. Now, Bensinger does not describe this in his book, but the currently cited sources are sufficient for this claim.
• The Wankel engine suffers from poor thermodynamics – this should be obvious to any knowledgable ICE engineer, but in case there's still someone who disputes this, Bensinger writes about this on page 85: "Zweifellos ist der Wankelmotor in der Thermodynamik den Hubkolbenmotoren unterlegen, wie die Form des Verbrennungsraumes und die großen wärmeabführenden Flächen sofort erkennen lassen". (Undoubtably, the Wankel engine is, seen from a thermodynamics perspective, inferior to reciprocating piston engines, which is immediately obvious because of the combustion chamber shape and the huge surface area, which causes heat losses).
• Usage: The Wankel engines does not give advantages in "automobiles, motorcycles and racing cars", quite the opposite is true. The ridiculous fuel consumption and bad exhaust gas behaviour make the Wankel engine unsuited for these applications. There is not a single advantage that the Wankel engine has that is useful for any of these applications. Back in the 1960s, engineers thought that the low mass and small size would give Wankel-powered cars a lower mass and better aerodynamics, which would ultimately reduce fuel consumption, but in practice, the Wankel engine's awful thermal efficiency outweighed these advantages.
• The Wankel engine's problems are being eradicated – frankly, this is impossible, because it would require reshaping the combustion chamber and reducing the surface by converting the Wankel engine into a reciprocating piston engine. There is not a single source that describes how the Wankel engine can be designed to have a decent fuel consumption of, let's say 190 g/(kW·h). Practical Wankel engines can compete with the first Diesel engine, but that is not an achievement. Any 1950s naturally IDI Diesel outperforms a bog-standard Wankel engine with ease.
• The Wankel engine is returing to cars – well, it has been announced. In practice, there has not been a Wankel car since the Mazda RX-8, which was effectively discontinued with the Euro 5 emissions standard taking into effect in 2011. Also note that all internal combustion engines have a BSFC, this does not only apply to Wankel engines, so "the efficiency of the engine rises when run at a constant speed" is true for all internal combustion engines (when assuming an ideal load).
• Hydrogen fuel increases thermal efficiency by 23 per cent – that is very misleading. Any internal combustion engine has a high efficiency if run at (decently) high epsilon and high lambda values; now, hydrogen has a very wide ignition range and thus favourable ignition limits. Of course one may choose lambda = 4 when using hydrogen, which obviously increases efficiency. But that is not a feature of the Wankel engine – it is a feature of the fuel. An Otto engine will also have the exact same benefits from running on hydrogen. While the Wankel engine is better suited for hydrogen due to its design, the overall problems of hydrogen operation have still not been solved (hydrogen is the first element in the first group and the first period of the periodic table of the chemical elements – it reacts with virtually anything). More interestingly though is that an increase in efficiency by 23 per cent would require an efficiency of >37 per cent to be a significant achievement. That is, because practical (lorry) Diesel engines would still outperform a Wankel engine with a "23 per cent increase in efficiency" if it had a base efficiency of less than 37 per cent. The problem is, however, that practical Wankel engines are not that efficient. So even if the efficiency is significantly increased in a prototype engine running on hydrogen, that particular engine would still be inferior to a bog-standard, mass production Diesel engine.
• The description of the design should be moved up; the "more uniform torque" is due to the short ignition interval – this is an advantage that is especially useful for hand-held devices such as chainsaws; this advantage doesn't need to be explained twice in the lead section.
• The taxing of automotive engines is not particularly interesting for Wankel engines, because they are not particularly well-suited for automobiles.
• The section on chamber volume and displacement is self-explanatory I reckon – the article previously didn't explain this and I think it is very helpful to include it. Everything is based on Bensinger, and even the example of the KKM 612 is taken from Bensinger's book; the specs for the Mazda R26B are taken from Shimizu et al. (1992).
• The torque delivery section was previously placed in the disadvantages section, and the torque delivery of a Wankel engine is much more uniform, which is an advantage over a conventional reciprocating piston engine (Bensinger, p. 72).
• The first part of the "Fuel economy and emissions" section was again very misleading. Yes, Wankel engines have a poor fuel consumption and emissions behaviour, but, as previously mentioned, hydrogen does not magically solve the Wankel engine's problem. The source was also poorly cited, and the alleged "near zero emissions" are, according to the source, high NOx emissions that are so high that the engine would fail emissions testing. Calling that "near zero emissions" is technically the same as calling a Volkswagen 2.0 TDI a "Clean Diesel".
• Attempts to produce a compression ignition Wankel have failed, and in practice, no such engines exist. The problem is that the design doesn't really allow high epsilon values without having a ridiculously unfavourable surface to volume ratio (cf. Bensinger, p. 60, 67, 86), which means that all attempts that have been made either rely on precompression, or spark igintion. Bensinger also argues that a Wankel Diesel is "not promising" (Bensinger, p. 86). This is a pretty strong argument and I doubt that present engineers can magically eradicate this "feature" of the Wankel engine. Anyone may cite a source that is equivalent in quality to Bensinger (i.e., a source that is a scientific journal or monograph) that describes a functioning Wankel Diesel. Ignore the usual suspects (e.g., Wankel Supertec engines hardly outperform the Mazda R26B, and are outperformed by any IDI Diesel).
• Speaking of Wankel Supertec: a BSFC of 270 g/(kW·h) for a stationary engine is very poor (a Diesel can do <190 g/(kW·h), and also nothing particulary interesting given the fact that the exact same engine has a BSFC of 290 g/(kW·h) when used as a vehicular engine, which the aforementioned Mazda R26B outperforms (286 g/(kW·h)).
• The claim that the Curtiss-Wright RC2-47 has a BSFC of 226 g/(kW·h) is very likely a false claim (such a figure is outright unrealistic), and it is also unreferenced. Given the fact that whoever wrote this compares it with the MTU MB 873-Ka 501, and makes the MTU MB engine a common-rail engine while it is an old-fashioned IDI Diesel, completely destroys that comparision. It's like comparing the first Diesel engine with a 21st century Wankel engine design that was made using computer technology and then arguing that the Wankel slightly outperforms the very first Diesel, by 14 grams per kilowatt hour. That is obviously unreasonable, and that comparision is made up.
• Again another section on hydrogen use; the claim that Otto engines are not well suited for hydrogen operation is "false" if one argues that a Wankel engine is well suited for hydrogen operation. The Wankel engine does have the advantage of lacking exhaust valves, but the major problem of hydrogen operation still applies to Wankel engines. Thus, I have rewritten that section to explain better why hydrogen is a good fuel for a Wankel engine; I have already explained the part on that "23 per cent increase in efficiency".
• A homogeneous mixture of hydrogen and air is avoided in a Wankel engine, according to the cited source. There is no reason to explain things in a contradicting fashion.
• The surface-to-volume ratio of Diesel engines is not poorer than that of Otto engines. In IDI Diesels that is true, but IDI Diesels have always been a stopgap solution, and since the 1960s, IDI Diesels have largely fallen out of favour in good engine design.
• A reciprocating piston engine with equal power to a Wankel will be approximately twice the displacement is wrong, because there is no significant difference. Let's compare the KKM 612 (cf. Bensinger, p. 133) with the BMW M10: Both engines perform virtually identically: p_me= 1.02 MPa (KKM 612) / 1.04 MPa (BMW M10); P=85 kW, V_h= 1.99 dm³. The major difference is that the KKM 612 Wankel engine has a significantly worse fuel efficiency than the BMW M10. The BMW E12 has a rated fuel consumption (DIN 70030) of 7.6 l/100 km at 90 km/h, while the NSU Ro80 has a rated fuel consumption (DIN 70030) of 11.2 l/100 km at 90 km/h. Some of that is definitely due to the hydrodynamic torque converter and the three-speed gearbox, but still, that difference is significant, and shows how bad the Wankel engine really is (the NSU Ro80 is much better designed than the BMW E12, it even outperforms the BMW E28).
• Bensinger does not describe pumping losses in his book, and the surface-to-volume ratio of the reciprocating piston engine is smaller than the Wankel engine's, according to Bensinger.
• GM tested and enhanced safety: There is no reference for that section, and it is quite obviously original research. The claims, as well this entire section are very misleading. Turboshaft engines also don't have valves – are they not as safe as Wankel engines? And what about aircraft noses: What about aircraft with the engines installed in the wings? Wankel engines operating within their original design parameters are almost immune to catastrophic failure – isn't that true for any engine designed with reasonable design paramters, and isn't it false for any engine designed with unreasonable design parameters? The KKM 612 for instance, was very prone to catastrophic failure because it shared its oil system with the gearbox.
• The entire disadvantages section was bloated and didn't focus on the key points (i.e., poor thermodynamics).
• The Mazda R26B engine did not outperform its competitors in terms of fuel economy (b_e=286 g/(kW·h), I mean, that is not exactly fuel efficient, it is quite the opposite); the cited source doesn't make that claim.
• The picture of the Žiguli is quite obvious I hope (the depicted car is a bog-standard 2106, and doesn't have a Wankel engine); also, the claims (even stating that little specific information has surfaced) are unsourced and dubious.

I hope that this is a better explanation and helps with understanding. Again, keep in mind that most claims that I have removed were unsourced and outright false, or the cited sources didn't support the claims. In Wikipedia, the editor who makes a claim needs to cite sources that support that claim. Best regards, --Johannes (Talk) (Contribs) (Articles) 15:22, 19 December 2022 (UTC)