Misplaced Pages

Talk:Hemispherical combustion chamber: Difference between revisions

Article snapshot taken from Wikipedia with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.
Browse history interactively← Previous editContent deleted Content addedVisualWikitext
Revision as of 02:35, 2 February 2008 editScheinwerfermann (talk | contribs)Extended confirmed users, Pending changes reviewers, Rollbackers10,205 edits Page cleaning?← Previous edit Latest revision as of 01:28, 2 February 2024 edit undoQwerfjkl (bot) (talk | contribs)Bots, Mass message senders4,011,969 edits Implementing WP:PIQA (Task 26)Tag: Talk banner shell conversion 
(69 intermediate revisions by 34 users not shown)
Line 1: Line 1:
{{talkheader}} {{Talk header}}
{{Not a forum|Hemi engines or engines in general}}
{{WikiProject Automobiles|class=start|importance=mid}}
{{WikiProject banner shell|class=Start|
{{WikiProject Automobiles|importance=mid}}
}}


==Archives of past discussion==
''']'''
==Cars==
Wich car models used the hemi engine?


==French hemi?==
I think we should make this page a summary of Chrysler's Hemi technology and fully split out the 426 Hemi and new Hemi. It's a bit confusing.
I recall reading (somewhere...) of a French-built, Chrysler-designed hemi, around 130ci, intended for armored cars or something in France in the '40s, being sold in SAm (Brazil?) into the '70s... Can anybody substantiate? ] ] 02:48, 7 February 2009 (UTC)


Should ] just point here, or should it explain hemispherical heads in general? ] 04:37, Aug 8, 2004 (UTC)


==Factually inaccurate disaster==
:I think we should have a page for hemispherical heads, pointing here and at other hemi (small h) engines like the Jaguar XK6 and Mitsubishi V6 and Chrysler Australian straight 6. The new Hemi and old Hemi and "early" Hemi are all different enough that each could have its own page, I'm sure. I'm going to split out the Mazda engines like this too. --] 14:41, Aug 8, 2004 (UTC)
Why all the pent-roof content? A pent-roof combustion chamber is by definition NOT hemispherical. And ironically, Aston Martin engines that actually do have hemispherical combustion chambers aren't mentioned at all. Benefits/drawbacks is incomplete, "Supersession in modern engines" is flawed, many historically/technologically significant hemi engines aren't mentioned, the Lotus section doesn't actually say anything about Lotus's engines, Alfa's 4-cyl hemi (second only to the Jag engine for longevity of production, 1953-1993) isn't mentioned, and the Porsche section erroneously claims that recent 911s utilized hemispherical combustion chambers! And why do these Mitsubishi engines warrant inclusion (has anyone verified that they actually have hemispherical combustion chambers?) when inexpensive 4-cyl pushrod hemis from Renault and Toyota (both of which are arguably of more historical/technological significance on account of racing victories) are omitted? Good grief.
] (]) 15:10, 14 November 2010 (UTC)


::::<!-- begin Template:Uw-sofixit -->Thank you for your suggestion{{#if:|&#32;regarding ]}}. When you believe an article needs improvement, please feel free to make those changes. Misplaced Pages is a ], so anyone can edit almost any article by simply following the '''{{lcfirst:{{int:edit}}}}''' link at the top. The Misplaced Pages community encourages you to ]. Don't worry too much about making honest mistakes—they're likely to be found and corrected quickly. If you're not sure how editing works, check out ], or use the ] to try out your editing skills. ]. You don't even need to ] (although there are ]).<!-- end Template:Uw-sofixit --> Misplaced Pages has this cool idea...if you see a problem, fix it. As to pentroof chambers being hemis or not; when Mopar was developing its DOHC "hemi", it called the four valve pentroofed heads "hemi pentroof" chambers (according to a 1967 "Mopar Muscle" article)
== Compression ratio ==


::::::I did find some time to make a couple such minor improvements in June 2012, but it appears that they were promptly undone by people who preferred the less accurate prior versions. (This is sort of what I suspected might happen if I went ahead and started investing time in improving this article without running it by the ′Talk′ page first...) ] (]) 00:14, 28 October 2014 (UTC)
I'm curious how the compression ratio of a hemi-head engine compares with other gasoline engines. It would seem to me that a full hemisphere would take up a lot more space (of course, I suppose "hemi" doesn't necessarily mean a full hemisphere is in there), and the piston wouldn't be able to rise far enough to compress the gas/air mixture to the level you see in other engines. Anyway, just something I don't know much about. ] &mdash;] ] 18:53, Sep 2, 2004 (UTC)


::I don't know that a sentence and a picture is all that much content. And it shows the evolution of the hemi chamber. A pentroof is a cross-flow head, just like a hemi and the only reason it isn't a true hemispherical combustion chamber is because it has 4 flat-headed valves in each ""corner"".
:Hemi engined cars had domed pistons to compensate. One of the ways to vary compression ratio is to dome or dish the piston top. ] 20:48, Sep 2, 2004 (UTC)


::::::It could be said of any cross-flow combustion chamber design that ″the only reason it isn't a true hemispherical combustion chamber is because .″ So what? I don't understand the apparent desire to confuse the meaning of a technical term like this. If you're going to stray from the long-established and very specific meaning of such a term, the term loses essentially all technical value; why maintain an encyclopedia entry at all? ] (]) 00:14, 28 October 2014 (UTC)
:P.S. the "New Hemi" isn't a full half sphere; it's shallower, so that domed pistons are not needed. Domed pistons make the combustion flame-front have to go further, which means pollution-causing incomplete combustion ] 20:51, Sep 2, 2004 (UTC)


::If you think benefits/drawbacks is incomplete, complete it to your satisfaction. Same goes for fleshing out the Lotus, Alfa and any other manufacturers you may want to add to the list.


::::::The ′Benefits and drawbacks′ section does appear to have been substantially improved over the last two years. That said, I'd still be inclined to remove much of the second paragraph (since it erroneously discusses drawbacks associated with large valves in general ) and the entire fourth paragraph (since it erroneously discusses drawbacks associated with adapting a pushrod valvetrain to work with hemispherical combustion chamber design ). But if I went ahead and did any of that today, I wouldn't have much confidence that my revisions wouldn't be undone tomorrow. ] (]) 00:14, 28 October 2014 (UTC)


::I believe the concept here is for everyone to add their bit. It sounds like you have some bits to add, so go to it.] (]) 01:03, 30 November 2010 (UTC)
== hemispherical vs. Chrysler Hemi ==


"Today,"hemi" is more of a trademark than a description of a combustion chamber." It's either a trademark, or it's not. Let's not use the term 'trademark', which has a particular legal meaning, to mean 'characteristic term'. <span style="font-size: smaller;" class="autosigned">— Preceding ] comment added by ] (]) 17:36, 15 June 2012 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->
I think we need to split this article. ] should refer to those models that Chrysler called "Hemi" and the regular ] article should be a general overview of the design with links and information on Porsche, Mitsubishi, Chrysler, and other Hemis. Thoughts? --] 16:29, Jun 1, 2005 (UTC)


::::::It's true that Chrysler has somehow registered ″Hemi″ as a trademark in the USA, despite the fact that this clearly contravenes the legal prohibitions on the registration of descriptive and/or generic terms as trademarks. That they got away with it was probably just a matter of no one objecting (note that other car manufacturers have typically not made a big marketing deal out of the shape of their combustion chambers); if I were an intellectual property attorney with time on my hands, I suspect I could get Chrysler's trademark registration thrown out under section 706.01 of the USPTO's Trademark Manual of Examinging Procedure. But I'm not an attorney, I'm a mechanical engineer, so I'll just refer you to ] to draw your own conclusions. (And I would love to see a section of this article dedicated to Chrysler's spurious trademark of ″Hemi,″ but I'm really not the one to write it.) Never mind that the current crop of Chrysler ″Hemi″ engines arguably aren't hemis at all, since their combustion chamber design is only slightly concave... ] (]) 00:14, 28 October 2014 (UTC)
:Yes, agreed. ] should refer to the three different Chrysler hemi designs. We are currently lacking a page on the 426 Hemi, I believe; one should be created. ] should be a general page about the concept.


== Possible improve to lead section ==
:Dr_gonzo should learn to be less gonzo, at least in terms of using a spell-checker. ] 18:40, Jun 1, 2005 (UTC)


I am not knowledgeable enough about this subject to write about it, but I would like to suggest how the lead section could be improved. I think that is should mention what the hemi design is an alternative to . It should also explain if it is a relatively uncommon design; maybe something like "In 2012 hemi engines were used in only 2% of new cars". Some of these things may be covered in more detail later on in the article, but I think the lead should provide some basic context for the casual reader. ] (]) 15:38, 23 July 2012 (UTC)


== Benefits and drawbacks improvements ==
spell checkers cramp my style.
Dr-Gonzo.


As the Hemi is talking about a specific type of engine which is used in specific cars and advertised as a recognizable name, I expected the benefits and drawbacks section to discuss the benefits and drawbacks of the hemisphere design compared to other, more conventional designs. Instead, it only talks about the pros and cons of variants on the engine, with a slight section talking about weight and how they have fallen out of favor. However, the new Dodge Durango is advertised as having a HEMI option so it still seems to have some favor.
==crossflow==
::Whoever wrote the Benefits and Drawbacks section studied English as a 47th language. I'd clean it up, but I have no idea what meaning it intends to convey. --] (]) 19:00, 27 September 2014 (UTC)
or "crossflow cylinder head"??? the ] article says nothing about hemis. --] 05:45, 27 July 2006 (UTC)
:::if a hemispherical combustion chamber can't have four vpc then the examples cited such as the 1912 GP Peugeot can't have had hemispeherical combustion chambers. Either than or there CAN be 4-valve hemispherical combustion chambers, coz they can't both be right. ] (]) 12:53, 13 October 2014 (UTC)
:It certainly doesn't, just like an article about animals may not mention ring tailed lemurs ] 08:21, 25 February 2007 (UTC)


::::::Well, strictly speaking, you ''could'' develop a true 4-valve hemi, but (to my knowledge) no one has done so (due to the valvetrain complexity that would be required). The 4-valve examples cited in the ′History′ section do not have hemispherical combustion chambers, and their inclusion there is egregiously misleading—but it looks like last time someone tried to correct that, their correction was almost immediately undone. ] (]) 00:14, 28 October 2014 (UTC)
==All engines are hemispherical==


==Requested move 20 May 2015==
Aren't all engines more or less hemispherical (as opposed to the archaic flat head design), given that the head is usually cone shaped to a large degree.
<div class="boilerplate" style="background-color: #efe; margin: 2em 0 0 0; padding: 0 10px 0 10px; border: 1px dotted #aaa;"><!-- Template:RM top -->
:''The following is a closed discussion of a ]. <span style="color:red">'''Please do not modify it.'''</span> Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a ]. No further edits should be made to this section. ''


The result of the move request was: '''moved.''' ] ]] 17:57, 21 June 2015 (UTC)
I think this is all a bit confusing, as


----
From what I've heard "Hemi" means:
# to have two valves per cylinder
# these valves must be in a strait line, and obviously, in the head
# the spark plug will be between them
# perhaps the engine will have to use push rods?


] → {{no redirect|Hemispherical combustion chamber}} – This is what the article is about. "Hemispherical combustion chamber" would be a more accurate and more general title, while remaining perfectly understandable. Hemi is a Chrysler trademark and closely associated with ]; hemispherical combustion chamber engines were used a wealth of different manufacturers. <small>--'''Relisted.''' ] (]) 05:52, 30 May 2015 (UTC)</small> ] (]) 11:58, 20 May 2015 (UTC)
And although these engines are supposed to be "the sex", as they won nascar, nascar is restricted to ancient, 2 valve engines.
:'''Keep at current page'''. Hemi engine is the ]. That some one owns a trademark on the name is not sufficient reason for a move. : About 27,500 results, : About 16,800 results. ] (]) 13:38, 20 May 2015 (UTC)
::You've proved my point! Almost all of are about the ], not hemispherical combustion chamber engines. That demonstrates "Hemi engine" is the common name of a Chrysler V8, ''not'' that it is the common name of the technology discussed in this article. —] (]) 16:58, 20 May 2015 (UTC)
:::No, I do not. The first book indicates on page 9 that he uses "hemi" as the generic term and "Hemi" when refering to Chrysler's. refers to "Hemi clone cars" on page 11. Chrysler originally used Firepower name in 1950's for Hemi engine (Hemi Muscle] (Page 9). Other early books are Chrysler manuals. --] (]) 19:51, 20 May 2015 (UTC)
::::Books (and some newspapers) that use the word this way exist, but aren't they outnumbered more than 10 to one by those that use Hemi for Chrysler and hemispherical for other brands? When I search books for "hemispherical head engine" I get book after book about non-Chrysler engines, but search for "Hemi engine" and it's Chrysler, Chrysler, Chrysler, with only one or two exceptions. --] (]) 20:04, 20 May 2015 (UTC)
*'''Move''' ] should redirect to ] (or vice versa). The shorthand "Hemi" refers to Chrysler's engine. A general article about all hemispherical combustion chamber engines needs a different title. "Hemi" is not the common name of all such engines, only the Chryslers. It's true that sometimes the term is used figuratively, as a ]: someone will say the name of Chrysler's engine, "Hemi", intending it to stand for all such engines, like saying "a Coke" to refer to any soft drink. But we shouldn't use such imprecise figures of speech in article titles. --] (]) 17:46, 20 May 2015 (UTC)
::'''Comment:''' however that is precisely how WP handles article titles per ] and ], as it is ] not William Jefferson Clinton, as it is how people would search for the info. Redirects can be used for official names or other common names (using the most common). Chysler's engine could just be a section at Hemi engine. ] (]) 19:32, 20 May 2015 (UTC)
:::I'm sorry, but I can't follow your reasoning at all. If your argument were inverted, then it would make sense to me. Bill Clinton is not relevant because nobody ever refers to ex-presidents as Bill Clintons. They do refer to Pepsi, Sprite and Coke as Cokes, but that figurative use would break the encyclopedia badly. Maybe someone else can read what you're saying and explain it to me. --] (]) 19:46, 20 May 2015 (UTC)
::::In other words you don't know what your reason is for moving as I followed your reasoning: "But we shouldn't use such imprecise figures of speech in article titles." Bill Clinton is not precise as it isn't his official name (William Jefferson Clinton) and as there are ]. You are mixing "ex-president" with "Bill Clinton". ] (]) 21:23, 20 May 2015 (UTC)
:::::Nope, but I can see there is a great deal of misunderstanding here. ] simply isn't a relevant example. You're saying we should redirect ] to ] or ] to ]. At least in those case you could at least show a substantial number of uses of the words that way. In the case of Hemi, the overwhelming majority refer only to Chrysler engines, so there is even less reason to to use the genericized trademark as a a title of a generic article. The next best alternative to the move proposal here would be to make ] a dab page, similar to ]. --] (]) 21:33, 20 May 2015 (UTC)
*'''Support'''. I'm getting Google Books hits for "hemispherical combustion chamber" compared to for "hemi engine". The latter does appear to be closely associated with the ], which has its own article.--] ]/] 14:53, 9 June 2015 (UTC)
*'''Support move''' - At this time, "Hemi" means Chrysler, and doesn't reflect the technology itself. Make this a redirect, put a hat note on the Chrysler Hemi article pointing to the full, proper name. ] - ] 00:53, 14 June 2015 (UTC)
----
:''The above discussion is preserved as an archive of a ]. <span style="color:red">'''Please do not modify it.'''</span> Subsequent comments should be made in a new section on this talk page or in a ]. No further edits should be made to this section.''</div><!-- Template:RM bottom -->


== 2 valve - 4 valve innacuracy ==
Also, it doesn't take a genius to realise that, at 10:1 compression, by sliding a piston in a cylinder, having anything really resembling a hemisphere at the end is going to take a stroke so long when the piston is at the bottom, the space in the cylinder will resemble a saussage (which certainly isn't a good shape in terms of thermal efficiency) ] 08:21, 25 February 2007 (UTC)


The article states that the design of a hemispherical combustion chamber only allows 2 valves per chamber, but in the history there is mention of a 4 valve engine.
:I see we don't have an article on ]. In fact, valves "in a straight line" is a funny concept; obviously, any two valves will be in a straight line, but if you mean the valves are parallel, that's kind of the opposite of a hemi, that's a wedge head. Imagine a triangle with two long sides and one short side; one long side is the top of the piston, the other long side is where the valves are in the head, the short side is the other side of the chamber in the head; often where the spark plug goes. A hemi is more likely to have valves canted in different directions, ''i.e.'' on opposite sides of an isoceles triangle, if not an actual hemisphere. Variations such as the old chevy "semi-hemi" 427, where the valves were definitely canted apart, but not a true hemi, etc. ] 19:00, 26 February 2007 (UTC)


One of these statements is inaccurate. <small class="autosigned">—&nbsp;Preceding ] comment added by ] (]) 18:50, 1 June 2015 (UTC)</small><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->
::I'm not really up with the play on different engine configurations, my 86 suzuki swift single overhead cam pushing intake and exhaust valves via rockers had a hemispherical head. I'm not sure about how single overhead cam engines that push the valves directly (no rockers) work (I can only assume the valves would be parallel with a spark plug between them) or dual overhead cams, but it was my understanding that all (non-archaic) rocker engines had non-parallel valves and a moderately


The BMW Apfelbeck ] engine was a 4 valve hemispherical engine. Certainly 2 valves are easier but 4 vales can be done (with great effort). My German doesn't exist but the engine is mentioned on the German hemi page ]. I suspect there are others but most would be 2 valve engines. I think many SOHC and DOHC 2 valve motors were also hemi in shape. Ironically the current HEMI V8 does not have a hemispherical combustion chamber. ] (]) 03:28, 28 July 2015 (UTC)


== External links modified ==
This page seems to suggest that the only advantage is larger valves


Hello fellow Wikipedians,
== Page cleaning? ==


I have just modified {{plural:4|one external link|4 external links}} on ]. Please take a moment to review . If you have any questions, or need the bot to ignore the links, or the page altogether, please visit ] for additional information. I made the following changes:
I don think its relevant to have here list of Porsche or Mitsubishi engines...If we put all hemi engines here this page will grow quite large...This page needs more sources also.--&mdash; ]<sup>] | ]</sup>&nbsp; 20:47, 23 January 2008 (UTC)
*Corrected formatting/usage for http://www.allpar.com/mopar/hemi/ardun.html
*Corrected formatting/usage for http://phystutor.tripod.com/stang/engines/427sohc.html
*Corrected formatting/usage for http://www.jagweb.com/aj6eng/xk-engine/page2.php
*Corrected formatting/usage for http://www.davidandjemma.com/mazda/FAQ/quench.htm


When you have finished reviewing my changes, please set the ''checked'' parameter below to '''true''' or '''failed''' to let others know (documentation at {{tlx|Sourcecheck}}).


{{sourcecheck|checked=false}}
Why do you keep making the pictures smaller?
Why not do some link checking or actually take away the Porsche/Mitsubishi stuff?


Cheers.—]<small><sub style="margin-left:-14.9ex;color:green;font-family:Comic Sans MS">]:Online</sub></small> 11:06, 4 July 2016 (UTC)
Saab 95 and Volvo 300 were just edited by you and they have pictures just as big, and bigger. Can you explain your objections in this article? <small>—Preceding ] comment added by ] (]) 21:30, 1 February 2008 (UTC)</small><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->


== Aircraft? ==
Do you want to discuss your reasoning before you hack away at someone else's vision? <small>—Preceding ] comment added by ] (]) 21:24, 1 February 2008 (UTC)</small><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
:::No they have not so big pictures, those pic you put are so big they cover over half of the text area, really too big. Automobile infobox has standard size 250 pixels, if you follow the rules those thumbs should have no size defined. Now this page looks really ridiculous.. --&mdash; ]<sup>] | ]</sup>&nbsp; 21:36, 1 February 2008 (UTC)


Why are only autos mentioned here? Hemis have been used in recip aircraft emgines almost from day one. They are essential for high power to weight.
:::: Sorry, but I disagree with you. On my screen they are the right size. What kind of monitor do you have? What resolution are you using? The Voyager article you just edited also has images this size. Again, why is that ok, but not here?
Also, all motorcycles use a hemi or pentroof (derivation.) Harley since 1937; almost all makes at least since the 'thirties. Indian was only notable exception. Harley stopped producing flatheads in what 1964 I believe.
Also Boats. Many use Hemis in 4 stroke applications--PT boats used 3 V12 Allison aircraft engines, again, hemis. <!-- Template:Unsigned IP --><small class="autosigned">—&nbsp;Preceding ] comment added by ] (]) 13:53, 26 April 2017 (UTC)</small> <!--Autosigned by SineBot-->


== A Simca plan ==
:::: On my monitor, it is too big a block of text. For the 1903 engine, size is needed to see the details. <small>—Preceding ] comment added by ] (]) 21:39, 1 February 2008 (UTC)</small><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
Why aren't the 136ci Brazilian SIMCA hemis (based on the ]) mentioned? ] ] 05:25, 11 December 2017 (UTC)

::::: I have 17 inch TFT (1280 x 1024), but 300 pixel is way too big, Voyager article has 250 px image in infobox if you leave it without pixel definiton the viewer can decide the size... ] --&mdash; ]<sup>] | ]</sup>&nbsp; 21:45, 1 February 2008 (UTC)

===Image size===
The thumbnail feature of Misplaced Pages allows each user to set, in his own preferences, the default display size for thumbnails in an article. It's best, per ], to avoid explicitly specifying a size for thumbnails in an article. Remember, all it takes is one easy click to see the full-size image. The thumbnail doesn't have to (and isn't meant to) do the whole job of illustration. Its job is to serve as a marker and say "Hey, there's an image here!". Of course it shouldn't be so small as to be invisible, but just using the thumb tag ''without'' an explicit size callout usually doesn't result in an invisibly-small image. If you think the images are too small or too large, go in ''your'' user prefs and change ''your'' default view. I've removed the size-forcing callouts from the thumbs in this article; that minimises the number of users who'll see them as too large or too small. It also nullifies any reason to bicker over what size they should be...! ;-) --] (]) 02:35, 2 February 2008 (UTC)

Latest revision as of 01:28, 2 February 2024

This is the talk page for discussing improvements to the Hemispherical combustion chamber article.
This is not a forum for general discussion of the article's subject.
Article policies
Find sources: Google (books · news · scholar · free images · WP refs· FENS · JSTOR · TWL
Archives: 1
This page is not a forum for general discussion about Hemi engines or engines in general. Any such comments may be removed or refactored. Please limit discussion to improvement of this article. You may wish to ask factual questions about Hemi engines or engines in general at the Reference desk.
This article is rated Start-class on Misplaced Pages's content assessment scale.
It is of interest to the following WikiProjects:
WikiProject iconAutomobiles Mid‑importance
WikiProject iconThis article is within the scope of WikiProject Automobiles, a collaborative effort to improve the coverage of automobiles on Misplaced Pages. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.AutomobilesWikipedia:WikiProject AutomobilesTemplate:WikiProject AutomobilesAutomobile
MidThis article has been rated as Mid-importance on the project's importance scale.

Archives of past discussion

Archive 1

Cars

Wich car models used the hemi engine?

French hemi?

I recall reading (somewhere...) of a French-built, Chrysler-designed hemi, around 130ci, intended for armored cars or something in France in the '40s, being sold in SAm (Brazil?) into the '70s... Can anybody substantiate? TREKphiler 02:48, 7 February 2009 (UTC)


Factually inaccurate disaster

Why all the pent-roof content? A pent-roof combustion chamber is by definition NOT hemispherical. And ironically, Aston Martin engines that actually do have hemispherical combustion chambers aren't mentioned at all. Benefits/drawbacks is incomplete, "Supersession in modern engines" is flawed, many historically/technologically significant hemi engines aren't mentioned, the Lotus section doesn't actually say anything about Lotus's engines, Alfa's 4-cyl hemi (second only to the Jag engine for longevity of production, 1953-1993) isn't mentioned, and the Porsche section erroneously claims that recent 911s utilized hemispherical combustion chambers! And why do these Mitsubishi engines warrant inclusion (has anyone verified that they actually have hemispherical combustion chambers?) when inexpensive 4-cyl pushrod hemis from Renault and Toyota (both of which are arguably of more historical/technological significance on account of racing victories) are omitted? Good grief. Jelliott4 (talk) 15:10, 14 November 2010 (UTC)

Thank you for your suggestion. When you believe an article needs improvement, please feel free to make those changes. Misplaced Pages is a wiki, so anyone can edit almost any article by simply following the edit this page link at the top. The Misplaced Pages community encourages you to be bold in updating pages. Don't worry too much about making honest mistakes—they're likely to be found and corrected quickly. If you're not sure how editing works, check out how to edit a page, or use the sandbox to try out your editing skills. New contributors are always welcome. You don't even need to log in (although there are many reasons why you might want to). Misplaced Pages has this cool idea...if you see a problem, fix it. As to pentroof chambers being hemis or not; when Mopar was developing its DOHC "hemi", it called the four valve pentroofed heads "hemi pentroof" chambers (according to a 1967 "Mopar Muscle" article)
I did find some time to make a couple such minor improvements in June 2012, but it appears that they were promptly undone by people who preferred the less accurate prior versions. (This is sort of what I suspected might happen if I went ahead and started investing time in improving this article without running it by the ′Talk′ page first...) Jelliott4 (talk) 00:14, 28 October 2014 (UTC)
I don't know that a sentence and a picture is all that much content. And it shows the evolution of the hemi chamber. A pentroof is a cross-flow head, just like a hemi and the only reason it isn't a true hemispherical combustion chamber is because it has 4 flat-headed valves in each ""corner"".
It could be said of any cross-flow combustion chamber design that ″the only reason it isn't a true hemispherical combustion chamber is because .″ So what? I don't understand the apparent desire to confuse the meaning of a technical term like this. If you're going to stray from the long-established and very specific meaning of such a term, the term loses essentially all technical value; why maintain an encyclopedia entry at all? Jelliott4 (talk) 00:14, 28 October 2014 (UTC)
If you think benefits/drawbacks is incomplete, complete it to your satisfaction. Same goes for fleshing out the Lotus, Alfa and any other manufacturers you may want to add to the list.
The ′Benefits and drawbacks′ section does appear to have been substantially improved over the last two years. That said, I'd still be inclined to remove much of the second paragraph (since it erroneously discusses drawbacks associated with large valves in general ) and the entire fourth paragraph (since it erroneously discusses drawbacks associated with adapting a pushrod valvetrain to work with hemispherical combustion chamber design ). But if I went ahead and did any of that today, I wouldn't have much confidence that my revisions wouldn't be undone tomorrow. Jelliott4 (talk) 00:14, 28 October 2014 (UTC)
I believe the concept here is for everyone to add their bit. It sounds like you have some bits to add, so go to it.Marshmallowbunnywabbit (talk) 01:03, 30 November 2010 (UTC)

"Today,"hemi" is more of a trademark than a description of a combustion chamber." It's either a trademark, or it's not. Let's not use the term 'trademark', which has a particular legal meaning, to mean 'characteristic term'. — Preceding unsigned comment added by 207.189.106.4 (talk) 17:36, 15 June 2012 (UTC)

It's true that Chrysler has somehow registered ″Hemi″ as a trademark in the USA, despite the fact that this clearly contravenes the legal prohibitions on the registration of descriptive and/or generic terms as trademarks. That they got away with it was probably just a matter of no one objecting (note that other car manufacturers have typically not made a big marketing deal out of the shape of their combustion chambers); if I were an intellectual property attorney with time on my hands, I suspect I could get Chrysler's trademark registration thrown out under section 706.01 of the USPTO's Trademark Manual of Examinging Procedure. But I'm not an attorney, I'm a mechanical engineer, so I'll just refer you to Trademark distinctiveness to draw your own conclusions. (And I would love to see a section of this article dedicated to Chrysler's spurious trademark of ″Hemi,″ but I'm really not the one to write it.) Never mind that the current crop of Chrysler ″Hemi″ engines arguably aren't hemis at all, since their combustion chamber design is only slightly concave... Jelliott4 (talk) 00:14, 28 October 2014 (UTC)

Possible improve to lead section

I am not knowledgeable enough about this subject to write about it, but I would like to suggest how the lead section could be improved. I think that is should mention what the hemi design is an alternative to . It should also explain if it is a relatively uncommon design; maybe something like "In 2012 hemi engines were used in only 2% of new cars". Some of these things may be covered in more detail later on in the article, but I think the lead should provide some basic context for the casual reader. ike9898 (talk) 15:38, 23 July 2012 (UTC)

Benefits and drawbacks improvements

As the Hemi is talking about a specific type of engine which is used in specific cars and advertised as a recognizable name, I expected the benefits and drawbacks section to discuss the benefits and drawbacks of the hemisphere design compared to other, more conventional designs. Instead, it only talks about the pros and cons of variants on the engine, with a slight section talking about weight and how they have fallen out of favor. However, the new Dodge Durango is advertised as having a HEMI option so it still seems to have some favor.

Whoever wrote the Benefits and Drawbacks section studied English as a 47th language. I'd clean it up, but I have no idea what meaning it intends to convey. --76.21.157.203 (talk) 19:00, 27 September 2014 (UTC)
if a hemispherical combustion chamber can't have four vpc then the examples cited such as the 1912 GP Peugeot can't have had hemispeherical combustion chambers. Either than or there CAN be 4-valve hemispherical combustion chambers, coz they can't both be right. Mr Larrington (talk) 12:53, 13 October 2014 (UTC)
Well, strictly speaking, you could develop a true 4-valve hemi, but (to my knowledge) no one has done so (due to the valvetrain complexity that would be required). The 4-valve examples cited in the ′History′ section do not have hemispherical combustion chambers, and their inclusion there is egregiously misleading—but it looks like last time someone tried to correct that, their correction was almost immediately undone. Jelliott4 (talk) 00:14, 28 October 2014 (UTC)

Requested move 20 May 2015

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section.

The result of the move request was: moved. Number 57 17:57, 21 June 2015 (UTC)


Hemi engineHemispherical combustion chamber – This is what the article is about. "Hemispherical combustion chamber" would be a more accurate and more general title, while remaining perfectly understandable. Hemi is a Chrysler trademark and closely associated with Chrysler engines; hemispherical combustion chamber engines were used a wealth of different manufacturers. --Relisted. George Ho (talk) 05:52, 30 May 2015 (UTC) Cloverleaf II (talk) 11:58, 20 May 2015 (UTC)

Keep at current page. Hemi engine is the common name. That some one owns a trademark on the name is not sufficient reason for a move. Google books search for Hemi engine: About 27,500 results, Google books search for Hemispherical combustion chamber: About 16,800 results. Spshu (talk) 13:38, 20 May 2015 (UTC)
You've proved my point! Almost all of these books (Google books search for Hemi engine) are about the Chrysler Hemi engine, not hemispherical combustion chamber engines. That demonstrates "Hemi engine" is the common name of a Chrysler V8, not that it is the common name of the technology discussed in this article. —Cloverleaf II (talk) 16:58, 20 May 2015 (UTC)
No, I do not. The first book (Page 9). Other early books are Chrysler manuals. --Spshu (talk) 19:51, 20 May 2015 (UTC)
Books (and some newspapers) that use the word this way exist, but aren't they outnumbered more than 10 to one by those that use Hemi for Chrysler and hemispherical for other brands? When I search books for "hemispherical head engine" I get book after book about non-Chrysler engines, but search for "Hemi engine" and it's Chrysler, Chrysler, Chrysler, with only one or two exceptions. --Dennis Bratland (talk) 20:04, 20 May 2015 (UTC)
  • Move Hemi engine should redirect to Chrysler Hemi engine (or vice versa). The shorthand "Hemi" refers to Chrysler's engine. A general article about all hemispherical combustion chamber engines needs a different title. "Hemi" is not the common name of all such engines, only the Chryslers. It's true that sometimes the term is used figuratively, as a synecdoche: someone will say the name of Chrysler's engine, "Hemi", intending it to stand for all such engines, like saying "a Coke" to refer to any soft drink. But we shouldn't use such imprecise figures of speech in article titles. --Dennis Bratland (talk) 17:46, 20 May 2015 (UTC)
Comment: however that is precisely how WP handles article titles per Misplaced Pages:Official names and common name, as it is Bill Clinton not William Jefferson Clinton, as it is how people would search for the info. Redirects can be used for official names or other common names (using the most common). Chysler's engine could just be a section at Hemi engine. Spshu (talk) 19:32, 20 May 2015 (UTC)
I'm sorry, but I can't follow your reasoning at all. If your argument were inverted, then it would make sense to me. Bill Clinton is not relevant because nobody ever refers to ex-presidents as Bill Clintons. They do refer to Pepsi, Sprite and Coke as Cokes, but that figurative use would break the encyclopedia badly. Maybe someone else can read what you're saying and explain it to me. --Dennis Bratland (talk) 19:46, 20 May 2015 (UTC)
In other words you don't know what your reason is for moving as I followed your reasoning: "But we shouldn't use such imprecise figures of speech in article titles." Bill Clinton is not precise as it isn't his official name (William Jefferson Clinton) and as there are other Bill/William Clintons. You are mixing "ex-president" with "Bill Clinton". Spshu (talk) 21:23, 20 May 2015 (UTC)
Nope, but I can see there is a great deal of misunderstanding here. Bill Clinton simply isn't a relevant example. You're saying we should redirect Coke to Soft drink or Xerox to Photocopier. At least in those case you could at least show a substantial number of uses of the words that way. In the case of Hemi, the overwhelming majority refer only to Chrysler engines, so there is even less reason to to use the genericized trademark as a a title of a generic article. The next best alternative to the move proposal here would be to make Hemi engine a dab page, similar to Coke. --Dennis Bratland (talk) 21:33, 20 May 2015 (UTC)

The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

2 valve - 4 valve innacuracy

The article states that the design of a hemispherical combustion chamber only allows 2 valves per chamber, but in the history there is mention of a 4 valve engine.

One of these statements is inaccurate. — Preceding unsigned comment added by 50.121.72.11 (talk) 18:50, 1 June 2015 (UTC)

The BMW Apfelbeck ] engine was a 4 valve hemispherical engine. Certainly 2 valves are easier but 4 vales can be done (with great effort). My German doesn't exist but the engine is mentioned on the German hemi page ]. I suspect there are others but most would be 2 valve engines. I think many SOHC and DOHC 2 valve motors were also hemi in shape. Ironically the current HEMI V8 does not have a hemispherical combustion chamber. Springee (talk) 03:28, 28 July 2015 (UTC)

External links modified

Hello fellow Wikipedians,

I have just modified 4 external links on Hemispherical combustion chamber. 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:

When you have finished reviewing my changes, please set the checked parameter below to true or failed to let others know (documentation at {{Sourcecheck}}).

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 5 June 2024).

  • If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
  • If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—Talk to my owner:Online 11:06, 4 July 2016 (UTC)

Aircraft?

Why are only autos mentioned here? Hemis have been used in recip aircraft emgines almost from day one. They are essential for high power to weight. Also, all motorcycles use a hemi or pentroof (derivation.) Harley since 1937; almost all makes at least since the 'thirties. Indian was only notable exception. Harley stopped producing flatheads in what 1964 I believe. Also Boats. Many use Hemis in 4 stroke applications--PT boats used 3 V12 Allison aircraft engines, again, hemis. — Preceding unsigned comment added by 184.99.135.215 (talk) 13:53, 26 April 2017 (UTC)

A Simca plan

Why aren't the 136ci Brazilian SIMCA hemis (based on the flatty) mentioned? TREKphiler 05:25, 11 December 2017 (UTC)

Categories: