Talk:Hemispherical combustion chamber/Archive 1

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.

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

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. --SFoskett 14:41, Aug 8, 2004 (UTC)

Compression ratio

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. —User:Mulad (talk) 18:53, Sep 2, 2004 (UTC)

Hemi engined cars had domed pistons to compensate. One of the ways to vary compression ratio is to dome or dish the piston top. —Morven 20:48, Sep 2, 2004 (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 —Morven 20:51, Sep 2, 2004 (UTC)

hemispherical vs. Chrysler Hemi

I think we need to split this article. Chrysler Hemi engine should refer to those models that Chrysler called "Hemi" and the regular Hemi engine article should be a general overview of the design with links and information on Porsche, Mitsubishi, Chrysler, and other Hemis. Thoughts? --SFoskett 16:29, Jun 1, 2005 (UTC)

Yes, agreed. Chrysler Hemi engine 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. Hemi engine should be a general page about the concept.

Dr_gonzo should learn to be less gonzo, at least in terms of using a spell-checker. —Morven 18:40, Jun 1, 2005 (UTC)

spell checkers cramp my style. Dr-Gonzo.

crossflow

or "crossflow cylinder head"??? the Crossflow cylinder head article says nothing about hemis. --Gbleem 05:45, 27 July 2006 (UTC)

It certainly doesn't, just like an article about animals may not mention ring tailed lemurs 202.27.209.71 08:21, 25 February 2007 (UTC)

All engines are hemispherical

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.

I think this is all a bit confusing, as

From what I've heard "Hemi" means:

1. to have two valves per cylinder
2. these valves must be in a strait line, and obviously, in the head
3. the spark plug will be between them
4. perhaps the engine will have to use push rods?

And although these engines are supposed to be "the sex", as they won nascar, nascar is restricted to ancient, 2 valve engines.

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) 202.27.209.71 08:21, 25 February 2007 (UTC)

I see we don't have an article on Wedge head. 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. Gzuckier 19:00, 26 February 2007 (UTC)

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

[1] This page seems to suggest that the only advantage is larger valves

Page cleaning?

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.--— Typ932^{T | C}  20:47, 23 January 2008 (UTC)

Why do you keep making the pictures smaller? Why not do some link checking or actually take away the Porsche/Mitsubishi stuff?

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? —Preceding unsigned comment added by 64.107.159.130 (talk) 21:30, 1 February 2008 (UTC)

Do you want to discuss your reasoning before you hack away at someone else's vision? —Preceding unsigned comment added by 64.107.159.130 (talk) 21:24, 1 February 2008 (UTC)

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.. --— Typ932^{T | C}  21:36, 1 February 2008 (UTC)

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?

On my monitor, it is too big a block of text. For the 1903 engine, size is needed to see the details. —Preceding unsigned comment added by 64.107.159.130 (talk) 21:39, 1 February 2008 (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... Wikipedia:Picture tutorial --— Typ932^{T | C}  21:45, 1 February 2008 (UTC)

Image size

The thumbnail feature of Wikipedia allows each user to set, in his own preferences, the default display size for thumbnails in an article. It's best, per the Wikipedia Manual of Style, 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...! ;-) --Scheinwerfermann (talk) 02:35, 2 February 2008 (UTC)

WikiStalking and being UNCLEAR on the concepts of this article

A hemispherical head is one in which the combustion chambers are spherical in shape. Obviously, there are no completely spherical combustion chambers, only chambers made up of some portion of a sphere. That portion of a sphere may range from 1/2 to 3/8 to less of a complete sphere. It doesn't matter, as long as the combustion chamber is indeed, some portion of a sphere. The Australian hemi-6 chambers are spherical, something less of a sphere's volume than the 426's chamber, but spherical in shape none-the-less. You apparently do not know this, do not understand the concept of a hemispherical chamber, or are just being willfully dense. Whatever the real reasons, stop following my I.P. from article to article and messing them up. —Preceding unsigned comment added by 64.107.58.130 (talk) 22:50, 12 February 2008 (UTC)

64.107.58.130, it appears you and I have overlapping areas of interest. That does not mean I am "WikiStalking" you. There is one area, however, in which our interests do not appear to match: I have an interest in improving articles on Wikipedia in accordance with Wikipedia protocol, procedure, and standards ( WP:MOS, WP:V, WP:RS, WP:NPOV, WP:NOR, WP:NOT, WP:OWN, WP:VAN, WP:CITE, WP:SIGN, WP:NPA, and WP:CIVIL, amongst others), while you have made it amply clear you regard Wikipedia's protocols and standards as irrelevant. I derive no particular joy from cleaning up messes made by editors who willfully refuse to behave coöperatively; it's just work that needs doing on Wikipedia. It's baffling to see your repeated reinsertion of text that is clearly ungrammatical and syntactically problematic, not to mention unencyclopædic (OR, POV, essays, dead links, improperly formatted references, etc.); one is left to conclude that you are primarily interested in seeing your text in the articles you edit, rather than being interested in the quality of the articles themselves. That isn't how Wikipedia works. We also do not engage in personal attacks and other uncivil behaviour here, as has been pointed out to you repeatedly. I have no interest in a pissing contest with you, nor do I relish the extra work you are creating for coöperative Wikipedians; if you carry on behaving disruptively I will have to report you for administrative action. Please choose instead to learn and follow the rules. Thanks. —Scheinwerfermann (talk) 23:41, 12 February 2008 (UTC)

you have been stalking me so much I recognize the above for what it is...it is NOT an answer on point regarding the Australian 6. It IS a cut-and-paste page-filler.

I notice that there is STILL no article for the 426 hemi. That the Chrysler hemi article still has the errors present that I pointed out weeks ago. There seem to be articles for the Plymouth LA engine, in addition to the Chrysler/Dodge LA engine, which have to be duplicates or at least redundant. —Preceding unsigned comment added by 64.107.58.130 (talk) 02:12, 13 February 2008 (UTC)

I also see there is no article about Wedge heads either. If you want to actually contribute some well-researched and documented articles. —Preceding unsigned comment added by 64.107.58.130 (talk) 02:19, 13 February 2008 (UTC)

You're right, there's no article specific to the 426 Hemi, nor is there an article on wedge-shaped combustion chambers. Both are worthy topics, for sure. If you have the interest, the time, and the reliable sources, you should be bold and start one or both of those articles. —Scheinwerfermann (talk) 05:01, 13 February 2008 (UTC)

Other hemi engines — List or not?

Seems that you put back those hemi tables/list, I think those are totally unnecessary here, if we collect all car brands/engines here we got quite a large article...hemis are so used/popular that almost every brand uses those...the Porsche engine table should be some Porsche engine page--— Typ932^{T | C}  23:48, 12 February 2008 (UTC)

You've got a good point. Significantly popular hemi engines other than the most familiar (Chrysler) units do merit mention in the article, but the details of those engines belong in their own articles. Take a look at the short few Wikilinked sentences I left in regarding the Mitsubishi hemi-head engines. I think a similar short few wikilinked sentences would do nicely for the Porsche engines, as well; if the specificity currently contained here is not presently contained in the relevant Porsche articles, it can easily be cut from here and pasted there. What do you think? —Scheinwerfermann (talk) 00:31, 13 February 2008 (UTC)

Yep there is already some lines about Porsche in main text, here is one page about Porsche engines List_of_Porsche_engines --— Typ932^{T | C}  00:40, 13 February 2008 (UTC)

Done! All relevant links have been left here, but the extended language about Porsches has been pruned; it's readily available in the Porsche articles. The table of Porsche hemi-head engines been moved to List of Porsche engines. —Scheinwerfermann (talk) 01:36, 13 February 2008 (UTC)

Second round of edits. I've incorporated the stub "other hemi engines" section (which contained info only on Porsche + Mitsubishi) into the new heading structure. —Scheinwerfermann (talk) 04:51, 13 February 2008 (UTC)

What makes a Hemi better?

In what way is a hemispherical combustion chamber superior to a non-hemispherical chamber? The article makes reference to the notion that they create more power, but it doesn't explain how. Instead, the list of "benefits and drawbacks" makes it sound like the hemi engine would only be less powerful than a normal engine. Could someone please clarify this for those of us who are not car experts? --207.47.0.242 (talk) 17:27, 5 May 2008 (UTC)

You're right, the "benefits" section was very confusing due to a large number of variously dubious unsupported assertions that had been tagged as such without amelioration for months. I've removed these statements, and the section is now much clearer. If somebody has reliable support for the deleted assertions, of course, they can be added back into the article with suitable citations. —Scheinwerfermann (talk) 18:17, 5 May 2008 (UTC)