Talk:Flat engine

A new opinion on terminology
Here are definitions which I have always accepted"

A "V Engine" is a piston engine with two cylinder banks (therefore, at least two cylinders) sharing a common crankshaft and arranged in a "V" shape (that is, the included angle between banks is less than 180 degrees).

Note that this definition does not require opposing pistons to share a crank pin, nor does it permit a "180-degree V" engine, which is a contradiction in terms. This seems to go against the prevailing opinion on Wikipedia, but can anyone quote an authoratative source that refutes my definition? I always thought that the definition of a V engine was connected to the name - cylinders in a V shape.

A "Flat Engine" is an engine where all the cylinders lie in the horizontal plane. For common engine designs, this would be synonymous with a "horizontally opposed engine" and also a "boxer engine." The trouble, I suppose, is when one considers exotic designs that have probably never been ever manufactured and then tries to categorize them. For example, if one tried to classify an engine with a single bank of four cylinders, pointing sideways, would it be called a "flat" engine or an "inline four engine laid on its side?" **The Toyota Previa uses a inline 4 cylinder laid flat on its side and mounted in the center of the van.** Personally, I would call it the latter. For all intents and purposes, it behaves like an inline engine, so we should call it that. It would be misleading to call it a "flat" engine because the only automotive engines currently in large-scale production (at least in the US) that are called "flat" are horizontally opposed engines from Porsche and Subaru, and they all have two cylinder banks.

The same thing applies to engines with opposing pistons, sharing a combustion chamber, with two crankshafts. I fully understand these are legitimate designs, but I have never heard of them being recently produced in large quantities anywhere. If there is an inconsistancy in the terminology, we should structure the article so it is consistant with the majority of engines and the biggest engine manufacturers.

My library of engine books is currently at work. My plan is to, sooner or later, go through them to review the terminology and edit the article as necessary. In the mean time, anyone care to respond to this?

--- Didn´t the original beetle had an engine like that?


 * Yes. &mdash;Morven 06:29, 8 Mar 2004 (UTC)

IMHO The Ferrari Testarossa does not have a real flat, but 180°-V-Engine.--217.187.67.229 23:33, 21 Mar 2004 (UTC)


 * In my understanding of things, a 180 degree V is a flat engine, but it is not a boxer engine. &mdash;Morven 06:03, 22 Mar 2004 (UTC)


 * Interesting discussion. The same discussion is currently also on the German version Diskussion:Boxermotor. But due to in German, there doesn't exists a correct translation of flat engine (it translates to Boxermotor, too), the very interesting question about the difference between a flat engine and a boxer engine is missing. I expect "flat engine" to be some more generalized term while boxer engine and 180° V engine include both a statement on the position of the crank pins and pistons on the crankshaft as already explained in the comparision between the boxer engine and 180° V engine in the first paragraph.


 * The big question now is: Shall this page become split into three: Flat engine (some kind of overview page), Boxer engine and 180° V engine? --XTaran | Talk 00:41, 25 Mar 2004 (UTC)


 * @User 217.etc By definition, there is no such thing as a 180 degree V engine, it is a flat engine.  Your issue seems to be in thinking that all flat engines are boxer engines, when this is just not the case.  The boxer style of engine IS a flat engine.  The defining difference being, from what I have found, is that the boxers have separate crank journals for each connecting rod/piston.  Other than that, a boxer engine is STILL a type of flat engine.  You could have shared or separate crank journals on a V (of any even cylinder number), but that doesn't make it somehow a boxer engine now, it is still a V engine.  It is one because of the layout of the cylinders, nothing more.


 * Single cylinder
 * Class all their own


 * Multi cylinder
 * Inline, means that all cylinders are in line with each other
 * Inline 6, inline 4, etc.
 * V means the cylinder banks form a V shape, under this you have 2, 4 6, varying even number of cylinders
 * V-6
 * V-8
 * etc
 * flat engine
 * Boxer engine
 * any other flat, opposing cylinder, horizontally opposed, etc. name with shared crank journal
 * Radial engine
 * Each cylinder is spaced out evenly around the edge of a circle, with the crankshaft in the center, most commonly seen in older piston driven propeller aircraft

There is no such thing as 180 degree V. It is a flat engine. Period. What makes a boxer different from other flat engines (of which it IS a flat engine) is the manner of how the connecting rods join the crank shaft and the pistons. It's really that simple. Not all flat engines are boxer engines, but all boxer engines, so far at least, ARE flat engines. 32.212.104.223 (talk) 18:59, 9 July 2017 (UTC)

Clarification
In a true boxer engine, the pistons are boxing each other, which means there is one looooooong cylinder for one pair of pistons. The two piston heads are facing each other and share one common combustion chamber. These engines have two main crank-shafts, obviously. They are essentially two inline engines made into a siamese twin by merging at the head. Such engine is used in some medium battle tanks (japanese I think) and are usually of the two-stroke principle.

In a flat engine (180 degrees Vee engine) there is one separate cylinder for each piston, because the pistons are boxing away from each other. These engines have a single crankshaft, these engines are siamese twins made of two inline engines "merged by the foot", so to say. These engines are used in Porsche and some 1980's Ferraris.


 * Please sign your posts, user 195.70.48.242.


 * And, I'm afraid I think you have this quite wrong. The Volkswagen Beetle is an example of a boxer engine, probably the most famous yet, as are current Subaru cars and the classic BMW "knee-warmer" motorcycle. What you are describing above as a true boxer is an opposed piston engine, a completely different design to a horizontally opposed engine, which is another name for boxer engine.


 * I mostly agree with the authors above. A boxer engine has (nearly) opposing pairs of cylinders, and each pair is on a pair of crank pins (big-ends) that are 180&deg; out of phase, so that the two pistons of the pair reach TDC similtaneously.


 * A V engine on the other hand has one crank pin per pair of cylinders, so if the V angle is 180&deg; (and there's nothing to say it shouldn't be) then the two pistons will reach TDC 180&deg; apart. This is not a boxer engine, but a 180&deg; V engine.


 * It seems agreed that a boxer engine is a type of flat engine. But is a 180&deg; V engine another type of flat engine, or is the boxer the only type? Some authors definitely say it's not, but I'm not impressed. Many other knowledgable writers describe the Ferrari Berlinetta Boxer and Ferrari Testarossa engines as being flat 12 configuration (but nobody AFAIK calls them boxer).


 * I'm inclined to think that the attempt to say that 180&deg; V engines aren't really flat engines is overly pedantic (which is not uncommon among motoring writers IMO). It might also stem from the difficulty in translating between English and German; It seems that there is no term in German for flat engine apart from Boxermotor, which of course means boxer engine. Andrewa 13:22, 27 September 2005 (UTC)


 * A Flat engine is an engine that lies flat, regardless of whether it is a "180deg V engine" or a horizontally opposed engine. A boxer engine is a completely different thing with two pairs of crankshafts and pistons facing each other. A horizontally opposed engine is an engine which has on crank pin per piston with the pistons facing left, right, left, right etc. The pistons in a horizontally opposed engine move towards each other then away from each other and so on. A 180 degree V engine has two pistons per crank pin and move together in unison. I hope that clears it up for you


 * It is hard to tell in here with little to no difference in spacing between different people's posts, and possibly unsigned posts, so I am just going to address everything here, and hopefully, you will be able to pick out your respective parts.


 * "so if the V angle is 180° (and there's nothing to say it shouldn't be)" Uhm, yes there is.  It is no longer a 'V' if it is at 180 degrees to each other.


 * "But is a 180° V engine another type of flat engine" What you are mistakenly calling a "180 degree V" is a type of flat engine.


 * "This is not a boxer engine, but a 180° V engine." Correct on the first part, but 180 degrees off on the second.  Pardon the phrasing.


 * "I'm inclined to think that the attempt to say that 180° V engines aren't really flat engines" The issue lies with calling it 180 degrees, and V, not with saying it is a flat engine design.


 * What makes it a V or not a V, or a flat engine or not a flat engine, is not the way the connecting rods and the crank shaft are joined, but the alignment of the cylinder banks. Since the cylinder banks on a V engine form a V, THAT is what gives it the V designation, not the sharing of a crank journal.  On a boxer engine, as well as other flat engine designs, the cylinder banks are flat in regards to each other.  As far as Ferrari calling the car a Boxer, that is just the name of the car.  People call cars Mustangs, doesn't automatically mean they are.


 * ":A Flat engine is an engine that lies flat, regardless of whether it is a "180deg V engine" or a horizontally opposed engine. A boxer engine is a completely different thing with two pairs of crankshafts and pistons facing each other. A horizontally opposed engine is an engine which has on crank pin per piston with the pistons facing left, right, left, right etc."


 * Actually, from the reading I have been able to find on this, the two crank shafts is ONE possible configuration of what makes it a boxer engine. The same primary thing, the not shared crank journals, is possible with a single crankshaft, even in a V configuration engine.  I have not seen one thing yet that says the only way it is a boxer engine is that the piston tops face each other.  32.212.104.223 (talk) 19:28, 9 July 2017 (UTC)

Another attempt at standardising terminology
There seems no consistency across Wikipedia on this at present.

A summary of the issues:

V engine
In a V engine, do the corresponding cylinders necessarily share a single crank pin?

In a V engine, can the angle between the cylinder banks be 180°?

If yes in both cases (as I suspect) then all is well.

But if no to the first and yes to the second then we have a problem, in that all flat engines would then become 180° V engines, which I don't think is the case.

Boxer engine
In a boxer engine, do the pistons in corresponding cylinders necessarily reach top dead centre similtaneously?

If yes (as I suspect) then there is a translation problem between German and English, in that the German boxermotor would mean flat engine in English, but the obvious translation of boxer engine would be wrong, as in English boxer engine means something more specific.

If no, then perhaps there is such a thing as an engine that is both a boxer engine and a V engine.

Flat engine
This seems relatively straightforward and general. However the term is defined, any boxer engine is also a flat engine. If there is such a thing as a 180° V engine, then it is also a flat engine.

Comments? Andrewa 12:54, 26 October 2005 (UTC)


 * The Fiat 500 Giardiniera (1960-1976) uses an in-line air-cooled twin lying flat under the rear floor.

Deconstruction 21:39, 8 February 2006 (UTC)


 * Found this definition at https://www.autoevolution.com/news/there-s-a-big-difference-between-a-boxer-and-flat-engine-85305.html
 * "Boxer engines should not be mistaken with flat V engines. Crank journals or crankpins, whatever you want to call them, these small devices attached to the crankshaft's big end bearings make the difference between a boxer and a flat motor. Simply put, the boxer mill employs one crankpin per cylinder, while the flat (horizontal V) engine uses one crankpin per two horizontally opposed cylinders."


 * Now, I don't know enough about engines/motors/whatever to say that this means that the cylinder banks need to be facing each other, and 2 separate crankshafts opposing each other from the outside of the engine, or it means a bigger crankshaft area in the center where the 2 opposing cylinders meet mechanically, or if this would just mean what some are calling a "flat" V. That term, to me anyway, makes no sense, as it was my understanding the V designated the physical layout of the engine, i.e., in a V shape.  But the diagrams in the above linked page seem to show all examples with opposed cylinders, not 2 pistons that share a common combustion area.  32.212.104.223 (talk) 17:37, 9 July 2017 (UTC)


 * That's confusing the opposed piston engine into it, which isn't helpful at all.
 * A boxer engine is a sub-type of the 180º flat V engine. It is characterised by the fairly unusual layout (common enough in 2 cylinders, but not for engines with more cylinders). The block is much the same, but the crankshaft is different: the crankpins are arranged so that pairs of pistons move in and out together, keeping an overall balance. In contrast, the 180º V engine has pairs sharing the same crankpin (see connecting rod for how) and so they move both left and both right together, giving a side-to-side vibration (this is counteracted somewhat by the adjacent pair, but there's still a yawing component left). Andy Dingley (talk) 20:45, 9 July 2017 (UTC)

Cleanup needed
I would like to edit this page and clear up the misinformation and confusion. Here are a few points:

1. A "flat engine" comprises two types: a horizontally-opposed engine (boxer), and the non-boxer type (that the article calls 180 degree V). American car magazines such as Road & Track refer to both boxer and non-boxer types of flat engines as flat engines.

FizzicksPhun (talk) 04:00, 12 May 2012 (UTC) Note: I would be careful about calling it opposed. You might get into another difficulty with confusion between this and the "Opposed-piston engine" like used in tanks. ''((This is the Very 1st Time I have ever made any edits. If I have erred in any way please fix it up and set me on a learning path by letting me know.)''

2. It is not a distinguishing characteristic of V engines that the crank pin is shared. A five-minute search on Google can confirm this. It may be true that all currently-produced flat "180 degree V" engines have this characteristic, but I doubt it's a requirement.

3. This sentence from the article is ambiguous: "Flat engines with more than eight cylinders are most commonly V engines." Does it mean "180 degree V engines" (i.e. non-boxer type) or does it mean V engines with some angle (e.g. 60 degree or 90 degree)?

4. It seems that the true distinguishing characteristic of boxer vs. non-boxer type of flat engines is the "horizontally-opposed" nature of them. If we can get agreement on this item, we'll be closer to a consensus.

It would be nice to gain consensus on this topic so that we can clean up this article. Erikvcl 23:33, 29 January 2007 (UTC)

FizzicksPhun (talk) 04:00, 12 May 2012 (UTC)

5. In the 4th paragraph under "Configuration"; "True boxers have ... while 180° engines, which ... share crankpins," there is a link for "180º engines" (http://en.wikipedia.org/wiki/Flat_engine#180.C2.B0_V-engines) that is broken and needs to be repaired.


 * Hi FizzicksPhun, thanks for your interest in this.
 * Before starting to edit it, I suggest you look at the other related articles too (V engine, V12 engine etc.) Many of these editing issues need as much coverage shifting between articles to file it in the right place as they do changes to it.
 * I'd agree some of your broad points here. However I can't help thinking that we already discussed them some months ago - particularly the flat/boxer confusion, and when crankpins are shared. Can't find which talk page though offhand (one reason why such discussions belong on article talk pages, not user talk pages).
 * This article is also one of those that's "mostly done". That means that any new changes to it really do need to be supported by references, and good references at that - serious texts, not just Hot Car or coffee table books. Andy Dingley (talk) 09:13, 12 May 2012 (UTC)


 * hi FizzicksPhun &othrs, one other talk Andy has mentioned was at there: Talk:Napier Nomad, there might be others.
 * and: i also dislike the ambiguous similarity in english of horizontally opposed ~ and opposed piston ~ but i think this trouble is sort-of unavoidable, so i'd still use the term, only 'being cautious' to mean providing a 'dont confuse!' text, and not the avoidance of the word opposed. --Aaa3-other | Talk | Contribs 21:39, 18 May 2012 (UTC)


 * Thanks for that - I'd forgotten where the thread was, but that's the one.
 * I still see opposed piston engine as a red herring. It's a very clear term with a clear meaning, and it's unrelated to what we're discussing here. Andy Dingley (talk) 01:11, 19 May 2012 (UTC)

Two definitions
If there are two definitions of a V-engine then we should explain that, and then we should just be clear which one we are using in each case. This article and the V-engine article are very confusing. --Gbleem 20:16, 22 August 2007 (UTC)

Standardising
I copied information from the wikipedia page on 180 V engines to further show the difference between, a V engine and a "boxer" flat engine. This also helps the articles be inline with each other in content. —Preceding unsigned comment added by Lossy (talk • contribs) 14:14, 23 October 2007 (UTC)

Engine deficiencies
A mechanic recently explained to me several deficiencies in this engine. These include the oil pooling on one side of the engine and the combustion of the gas, which is injected into the cylinder, occurring primarily on one side of the piston. This results in a slight impact of the piston on the cylinder wall on ever power stroke. Eventually, this causes a decrease in engine life as the piston tends to go through the cylinder wall. I don't even know where to obtain professional verifiable sources for this but would welcome anyone expanding on this or finding sources for this. Andrew M. (talk) 04:18, 18 January 2008 (UTC)

180° V nonsense
Asserting that shared crankpins is the defining characteristic of V-engines is absurd. Where does that leave the various 120° firing angle V6's? Not V's? So what are they? Lancia and VW's narrow angle V's? If bank angle isn't defining, then inline engines are as much 0° V's as flat engines are 180° V's. It is correct to say that the Ferrari flat-12 is not a Boxer, despite what it says on the car, but saying it's therefore a V doesn't make any sense. To the comment at the top of the page, inline 4's laid on their side are inline 4's. Look at the BMW K-series until recently. Zandr (talk) 17:31, 11 September 2008 (UTC)


 * The Ferrari engine is commonly referred to as a 180 V This article does a pretty good job of explaining the difference between the Ferrari engine and a boxer engine. What I do agree with though is that this article mixes up its terminology. A boxer and a 180-degree V12 are both flat engines and that flat does not automatically equal boxer. Look at Flat-12, which is much better written than this article. I'd be in favour of clarifying things. --TimTay (talk) 18:59, 11 September 2008 (UTC)


 * Most of this article is either nonsense or rev-head jargon. I draw to your attention the following paragraph: "The 180° V engine, in which corresponding pistons share a crank pin on the crankshaft, and thus each will reach top dead center half a crankshaft revolution after the other. Flat engines with more than eight cylinders are most commonly V engines,". I ask of you, what the fuck does any of this mean? It's not only jargonical, it's riddled with clumsy grammar. 18:01, 20 September 2008 211.30.122.32 (talk)
 * Makes perfect sense to me. There may be excessive attention paid to something I'd never head of, the 180deg V-twin, but that's a different question. MalcolmMcDonald (talk) 18:32, 2 May 2009 (UTC)
 * The entire engine configuration series is full of CRAP. It uses regional expressions as if they were universal and fails to understand the basics. It even describes the single cylinder as an "inline" engine, can't get more stupid than that. The single cylinder is the most basic piston engine - it stands alone and unique and every other configuration derives from there. Whether it's upright like a B31, laid down like a Guzzi Falcone or sloped like a BSA Sloper doesn't matter - it's a single. Two stroke or 4 stroke doesn't matter. Add another cylinder and everything changes.

Another crankpin and cylinder inline and it can be an inline twin like a Sunbeam or a parallel twin like a Triumph. Add yet another cylinder and you get an inline three like a SAAB or Suzuki auto engine or a triple like Triumph or Yamaha. Add another cylinder and you get an inline four like Indian or an across the frame four like Honda or a "flat" four like the K-series (take one cylinder off that and you can have a "flat" three like the K75). Better to describe them all as inline engines and add that certain specific configurations have other common names.

Add that extra cylinder at 180 deg and you get a horizontally opposed twin. Doesn't matter if the engine is inline with the frame like a Douglas or across the frame like an ABC. Doesnt matter if the conrods have separate or common crankpins, it remains a H-O twin. Add two cylinders to that engine in the same plane and you have a H-O four, etc. While the engine is invariably used in a "flat" configuration it doesn't have to be.

Add that extra cylinder somwhere between O and 180 deg and you get a V-twin. Early twins were usually around 45 deg but Matchless used 18 deg or so on the Silver Hawk and Zündapp 170 deg on the KS750. Once again common or separate crankpins make no difference.203.214.38.164 (talk) 03:01, 26 May 2009 (UTC)

BikerBiker seems incapable of accepting that uncited material can be deleted and ALL of the argument over 180 deg "V engines" is uncited and contrary to the wikipedia definition of a "V engine". I intend to delete this "uncited material" until someone provides a citation and I have hundreds of IP addresses! Get used to it or provide a citation.

Restarting this discussion
A Google Books search actually shows many references to "180 degree V" engines. Just about all of them use this term to describe the position of the cylinder banks relative to each other. None I've seen so far has made any distinction regarding crankshaft configuration. Until someone cites a source for the term "180 degree V" as a flat engine where the opposing cylinders share a crank in the crankshaft, I will assume that an editor or group of editors at Wikipedia made the term up. Sincerely, SamBlob (talk) 02:39, 2 April 2013 (UTC)


 * Not sure I understand what you're trying to say. A quick search shows plenty of books describing flat-6 and flat-4 engines:


 * http://books.google.com.au/books?id=HLEnQwAACAAJ
 * http://books.google.com.au/books?id=OoFcHOLpCskC&pg=PA458&dq=flat+engine&hl=en&sa=X&ei=F6FaUffEFMSriAeirYC4Dg&redir_esc=y#v=onepage&q=flat&f=false
 * http://books.google.com.au/books?id=VOwQ0y-vvOQC&pg=PA45&dq=flat+engine&hl=en&sa=X&ei=F6FaUffEFMSriAeirYC4Dg&redir_esc=y#v=onepage&q=flat%20engine&f=false
 * Or are you talking about whether opposite pairs of pistons share crank pins (ie the old old boxer vs flat engine debate) ?  Stepho  talk 09:23, 2 April 2013 (UTC)


 * I am talking about "the old old boxer vs flat engine debate". The term "180 degree V engine" is being used in the Flat-twin engine article to mean a flat-twin with a shared crankpin.  I have yet to see any cited evidence that the term is supposed to be used as such, not in the specific articles nor in this more general one. Sincerely, SamBlob (talk) 13:45, 2 April 2013 (UTC)


 * I found this book that says all flat engines have 2 banks 180° apart (not contentious) but that they then fall into two groups: 180 V engines with pairs of pistons sharing a common crank pin (with each piston's otto cycle being 180° out of phase with its partner, hence moving left together and right together) and boxer engines which have separate crank pins 180° apart (with the paired pistons always being in the same phase of the otto cycle, hence moving in together and out together like a pair of boxers jabbing at the same time).  Stepho  talk 08:19, 3 April 2013 (UTC)


 * That's useful, but a big sticking point is still the question of whether a 4-stroke engine with 360º firing intervals is a boxer or not. By mass balance it is, but is simultaneous firing also a requirement? Andy Dingley (talk) 09:28, 3 April 2013 (UTC)


 * Hmm, interesting question. The book I pointed out says both pistons reach compression together, so presumably they also fire simultaneously. But since it's almost trivial to change the firing order by altering the cam(s) and distributor, my personal opinion is that simultaneous firing isn't a requirement. Be nice to have that in print though. Not sure which form of firing makes for a nicer engine.  Stepho  talk 13:35, 3 April 2013 (UTC)


 * I am not sure of the extent to which I trust a book, published after this argument began here, by two authors that Google doesn't know of having published anything else. How do we know they didn't get their terminology from here? Sincerely, SamBlob (talk)


 * Here's another book by them according to google. They seem to be a couple of teachers or university professors attached to Project Lead The Way. But here's some more books from different authors.
 * Ferrari which says boxer engine have opposed pistons, ie "back and forth, toward and away from each other, like two boxers sparing"
 * Hillier ́s fundamentals of motor vehicle technology 1 where boxer is equated to 180° banks with opposed pistons.  Stepho  talk 06:35, 7 April 2013 (UTC)
 * Funnily enough, neither of these sources mention the 180° crankshaft, and the Ferrari one does not state clearly that the term "Boxer" is a misnomer as applied to the Berlinetta Boxer. It seems to be the usual 180° V definition, stating that the banks are opposed to each other, with no mention of the opposing pistons going in together and coming out together. Sincerely, SamBlob (talk) 21:06, 8 April 2013 (UTC)

(reset indent) To me, the title of this section says it all, calling it 180°, and "V" is just that, nonsense. By definition, a V is not 180°. At that point, it becomes a flat line. The Ferrari team calling a car a "Boxer" doesn't automatically make it a boxer by definition of the term that I have been able to find. For the record, a boxer engine IS a flat engine design, as is the misnamed "180° V" engines. But all it is is a variation of a flat engine design. Just like a V-6 and a V-8 are both V engine designs, just different variations. What differentiates it is the shared or separate crank shaft journals that the connecting rod uses. You can have a V engine with the same design idea, different crank shaft journals, but that doesn't make it a boxer engine. It is still a V engine. Same thing here, a boxer engine is still a flat engine. But not all flat engines are boxer engines. 32.212.104.223 (talk) 19:55, 9 July 2017 (UTC)

Lancia engines
What is the source for the assertion that Lancia tested a 300bhp flat-4 with 16 valves and turbo, based on the Gamma engine? I can find no other mention of this engine anywhere, and relatively detailed accounts of the Beta Montecarlo Turbo say that its engine was based on the Beta from the start. --Rebollo fr (talk) 16:15, 22 August 2009 (UTC)


 * Sounds like you have good justification for deleting the offending text. --Biker Biker (talk) 16:55, 22 August 2009 (UTC)


 * Lancia also rebuild a new big flat-4 engine in 1976, 2484 cc, for his upper size model Lancia Gamma, this engine was also tested by Squadra Corse Lancia in 1978 with 16 valves and Turbo supercharged, over 300 bhp, for the racing Car Lancia Beta Montecarlo prototype (car after becomes World Champion of Makes in 1979 with a different engine).
 * I moved the sentence here in case someone finds out that this is actually true. --Rebollo fr (talk) 18:42, 24 August 2009 (UTC)

Lycoming and Continental "O" aircraft engines
This article has a huge gap in that it hardly more than mentions in passing the biggest use of horizontally opposed piston engines in general aviation and particularly fails to mention the two biggest manufacturers of these types of engines - Lycoming Engines and Teledyne Continental Motors. The only example of a horizontally opposed aircraft engine in the article is a small ultralight engine from a relatively obscure manufacturer. Roger (talk) 12:05, 26 April 2011 (UTC)
 * I couldn't agree more. WP:BOLD - add it. --Biker Biker (talk) 12:34, 26 April 2011 (UTC)

Animation needs to be redone
The animated gif does not represent even a stylized boxer crankshaft. There is no identifying the center of axis of rotation. The backmost plate of the three doesn't even make sense. Temblast (talk) 14:36, 24 January 2012 (UTC)


 * It could certainly benefit from being re-done, but I'd keep it until there's something better. It does illustrate the piston and con rod movement usefully, even though the pistons have different strokes too. Andy Dingley (talk) 14:43, 24 January 2012 (UTC)

Cars using flat four engines.
This section is incomplete. For example I know that the Citroen GS also used an aircooled flat four engine because we had one. Also I see a category in Wikipedia has a long list of vehicles using flat engines. — Preceding unsigned comment added by Jrvzn (talk • contribs) 19:31, 15 August 2013 (UTC)


 * The section title is ' notable flat engines'. It doesn't have to cover every car with a flat engine. As you found, the category 'Flat engines' is the better place to list every single flat engine known to mankind.  Stepho  talk 22:56, 15 August 2013 (UTC)


 * It shouldn't be "notable" as a section within an article. WP:Notable is a loaded term, and it's not a term that is even relevant here (article topics need to be notable, entries within them don't).
 * As to the Citroen engines, the GS flat four certainly warrants inclusion here. Andy Dingley (talk) 00:48, 16 August 2013 (UTC)


 * Please note that the Citroën GS is mentioned in this article under the "Configuration" section, and is also mentioned in the flat-four engine article. Sincerely, SamBlob (talk) 07:36, 29 August 2013 (UTC)

Truly poor referencing
The following paragraph from the article:

Boxer engines have been used successfully, with up to twelve(1) cylinders in automobiles and up to six cylinders in motorcycles. Multi-cylinder boxer layouts are common for light aircraft engines.(2)(3)

is not referenced well at all:


 * 1) - twelve

Reference #1: I have seen many, many stupid things in my lifetime, but I will have to search hard to find something more stupid than the word "twelve" given as a reference to verify a statement.

Reference #2: Quote from this site: "...the flat boxermotor (the German term for flat engine) has been powering some of the world’s best known automobiles (Porsche, Volkswagen’s Beetle and Kombi f’rinstance), motorcycles (Honda’s Goldwing and BMW’s mainstay Boxer range) and aircraft (Lycoming and Continental) ever since." This statement does not verify anything in the given passage, and no other statement at the site even comes close.

There is, however, another statement at the site that makes one wonder about its reliability: "In 1896, when Karl Benz patented the first internal combustion engine..." By 1896, Benz, Daimler (Cannstatt), Peugeot, and Panhard had all made cars with internal combustion engines in them!

Reference #3: This is a press release about Hirth's line of UAV engines and says nothing at all about the use of boxer engines in motorcycles, automobiles or aircraft.

I am going to remove these citations because they don't verify anything the paragraph says.

Sincerely, SamBlob (talk) 23:43, 21 January 2015 (UTC)

Organization of "Automotive use" section
I propose that the "Automotive use" section be sub-sectioned as follows:

Layouts normally used with flat engines. This would feature the compact layouts (FF and RR) and the four-wheel-drive derivatives of these layouts. Mention would be made of MR (Porsche, Ferrari, Jiotto Capista) and of FR layouts (Tatra, Toyota). (Is there any documentation to show that flat engines are almost universally mounted longitudinally?)
 * Drivetrain layouts

Mention the many examples of air-cooled flat engines in cars.
 * Air cooling

Filter out what's in the list and try to build a coherent history from it. (I've been trying to do that in the "Automotive use" section thus far) A possible further section of this would be a general "Up to World War II" section and a post-war section further divided into countries: France, Germany, Italy, Japan, UK, US, and "Rest of the world". UK (Jowett) and US (Corvair) could probably be lumped into "Rest of the world"; Japan (Toyota and Subaru) probably could too, but the Subaru fans would disagree strongly.
 * History

Porsche and Subaru, with mention of the Lykan HyperSport.
 * Current users

Any objections? Suggestions? Counter-proposals?

Sincerely, SamBlob (talk) 19:19, 3 May 2015 (UTC)

Pancake engine
There are several references to Pancake engines in Wikipedia, e.g. in Tang-class submarine. Is this a nickname for a flat engine? Biscuittin (talk) 19:00, 15 August 2015 (UTC)
 * No, it's a vertical axis radial. The submarine engine is (I think) a GM EMD 16-184 and four rows (of four cylinders). It's taller than it is wide. The layout is an inline radial, like the Armstrong Siddeley Deerhound or else an X like the Rolls-Royce Vulture. I have no idea why this engine was called a pancake.
 * A better known pancake engine are the big Nordberg engines used for pumping. These were huge cylinders in a single row, with (I think) a varying crankcase side and number of cylinders according to size. Some were diesels, but they also notably did a multi-fuel version running on diesel and natural gas from the oil or gas wells they were installed at. Andy Dingley (talk) 19:30, 15 August 2015 (UTC)


 * Thank you. Biscuittin (talk) 19:05, 16 August 2015 (UTC)


 * Interesting Albacore photo set here Andy Dingley (talk) 12:38, 11 July 2017 (UTC)

W Motors
What does this section title mean? 2.121.174.214 (talk) 15:25, 21 December 2016 (UTC)
 * It means nothing. "W Motors" is a brand, nothing more. They have gone to a range of small engineering groups in order to produce the Lykan HyperSport, an exampled of conspicuous consumption for sale around the Gulf. Its purpose is to be the most expensive at anything, not technically innovative. It does have a flat engine (a flat six), but it's of no relevance to this article. Andy Dingley (talk) 15:32, 21 December 2016 (UTC)
 * The sections needs this explanation.

The name "Boxer"
The unofficial name, 'boxer', comes from the engine forming a "box". Then it changed to boxer over time with use. Then people started to give analogies to a fighting boxer. Look at the youtube vid, 'Learn About Subaru Boxer Engine Technology', at 1 min 26 sec. It is really an 'opposed piston flat engine'. 2.121.174.214 (talk) 12:03, 22 December 2016 (UTC)
 * It has nothing to do with boxes. Andy Dingley (talk) 12:11, 22 December 2016 (UTC)
 * Nor does your YouTube video even support this claim. Andy Dingley (talk) 12:13, 22 December 2016 (UTC)
 * Nor do you understand what opposed piston engines are about. Andy Dingley (talk) 12:14, 22 December 2016 (UTC)
 * Cut out the arrogant, condescending attitude. 2.121.174.214 (talk) 13:56, 22 December 2016 (UTC)
 * Cut out repeatedly adding made-up nonsense to articles. Andy Dingley (talk) 14:08, 22 December 2016 (UTC)
 * I wrote, "Cut out the arrogant, condescending attitude." It is continuing. 2.121.174.214 (talk) 14:12, 22 December 2016 (UTC)
 * Made-up nonsense is still made-up nonsense. Andy Dingley (talk) 14:21, 22 December 2016 (UTC)
 * , you need to show some evidence about "forming a box". Without evidence we have no choice but to assume that you made it up. See WP:VERIFY.  Stepho  talk 23:59, 22 December 2016 (UTC)
 * Well "box engines" are a real thing. See Napier Deltic. German WWII developments with opposed piston diesels put four of them into a box shape to make one enormous engine. A clever geometrical realisation at Napiers showed that by reversing one crank's rotation, just three sides could be used in the "Deltic" triangle.
 * But these are incredibly rare. The German aircraft engines (prototypes only) and the Napier Deltic, that's it. Nor do they have anything to do with boxer engines. Andy Dingley (talk) 10:56, 23 December 2016 (UTC)

External links modified
Hello fellow Wikipedians,

I have just modified one external link on Flat engine. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
 * Added archive https://web.archive.org/web/20131219232421/http://fgwcf.org/rever/debut_legende.asp to http://fgwcf.org/rever/debut_legende.asp

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

Cheers.— InternetArchiveBot  (Report bug) 04:11, 2 October 2017 (UTC)

Error in Section 4.3.1
The second sentence of the second paragraph "The flat-twelve in the 917 model is a 180° V 12 engine and later Followed by Ferrari Berlinetta Boxer (BB 512) used 180 degree Flat 12 for Le Mans to compete with Porsche but Ferrari BB 512 used on road going cars unlike Porsche." does not make sense and needs some rephrasing.

Frikdt (talk) 13:32, 2 January 2019 (UTC)

most common
The article originally had "Compared with straight engines— the most common layout for engines with four cylinders or less— flat engines have better ...". In September, an editor removed the "for engines with four cylinders or less" to make it just "Compared with straight engines— the most common layout — flat engines have better". The part about straight engines being the most common is a bold statement that may or may not be true but is totally unsourced. Straight engines are indeed quite common - but are they truly the most common ? As NiD.29 said in his edit summary, it was probably true in the 1930's. Is is still true today? Is it still true if all engines ever made were totalled up? Ships certainly like their straight 6 engines. So do trucks. Trains have been a mix of straights and V's. Planes started with inline engines but flat engines are also very common in non-jet planes. Motorbikes like mostly V-twin's, boxer twins and inline 4's. Cars are all over the place with V-twins, flat twins, inline 3's, inline 4's, flat 4's, VR 5's, inline-6's, V6's, V8's, V10's, ,V12's, V16's, W16's. In other words - it's not obvious and needs a reference. Or, better yet, just delete it because it's not really that important to this article.  Stepho  talk 11:30, 5 January 2022 (UTC)