Talk:Variable valve timing
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Moved to 'Variable valve timing' from 'VVT' because we don't write an article at the contraction, but at the full word, and we don't capitalise except on proper nouns, which I don't think variable valve timing as a concept is. See Wikipedia:Naming conventions. —Morven 17:38, Jul 21, 2004 (UTC)
The GM systems mentioned in the history section were separate, one varied timing and one varied lift, both systems were unsuccessful and never produced. I believe GM did however produce a valve system that was used to deactivate pairs of cylinders on a V8 in the early 80s. I can find no reference to any system with the name Smart Valve. I am considering changing the GM part of the history if anyone has any objections please let me know. IJB TA 01:40, 11 August 2006 (UTC)[reply]
Heres an article stating Nissan did design and implement japans first VVT engine.http://autoweb.drive.com.au/cms/newsarticle.html?&start=90&showall=&id=NIS&doc=nis9810153
"Nissan produced Japans first variable valve timing system in 1986 and, since then, Nissan Valve Timing Control System (NVCS) has been used in many production vehicle applications."
You can do some research on the 300ZR Z31 if you want, it used the same engine as the NA Z32 though with a different intake manifold.
Wrong. In America all Z31s are powered by the VG30E(T) engines. In Austraila and Japan they got the 200Z,200ZR,300ZX,300ZR with VG20E, VG20ETs,VG30E,VG30ETs,RB20DETs, AND VG30DE(300ZR). The VG30DE(TT) engine was originally developed for the Mid-4 in the mid 80s, the naturally aspirated version was first used in the 300ZR in 1986 (87 model year). Heres a bit more info on the DE sereies engines that ALL have VVT.
http://zhome.com/History/MID-4.htm
Also the VH45DE engines used in the Nissan Cederic in Japan (Q45 here) recieved VVT in 1988.
To be quite honest with you, its hard to obtain information on the early VG30DE(TT) engines as they were sold in low #s and only in Japan. Its a pretty widely accepted fact as several sources have mentioned it that Nissan developed the first production VVT system. I know the cederics were using the VG20DET in 87 which also used VVT. Heres the most precise answer I can give you right now:http://www.alljapanesecars.com/specsview.php3?mk=Nissan&md=Cedric&mc=y31&gn=9^Lists the cederic having VVT in 1987
http://www.photodump.com/direct/govaard/DavidZproductionqty.jpg^ and this is when the Z32 began productionThe Z32 was sold as an 89 model in Japan and was actually on sale in 1988. Either way that was still the first mass produced VVT system in Japan and the world.
I am considering incorporating some new information into the History section such as the following:
If anyone has anything that they would like to add please present it. Thanx, IJB TA 02:06, 26 October 2006 (UTC)[reply]
14:44, 5 May 2016 (UTC)14:44, 5 May 2016 (UTC)14:44, 5 May 2016 (UTC)14:44, 5 May 2016 (UTC)14:44, 5 May 2016 (UTC)FifthAgeOfMan (talk) I believe there is an error 14:44, 5 May 2016 (UTC)14:44, 5 May 2016 (UTC)14:44, 5 May 2016 (UTC)14:44, 5 May 2016 (UTC)14:44, 5 May 2016 (UTC)FifthAgeOfMan (talk)Don't know if this is how it's done, however I noted in the article's History section there is no mention that Alfa Romeo had implemented VVT in their Spider Veloce in 1983 and switched to electronic VVT by 1985. Nissan is given credit as first, however, they didn't apply for patent until 1986, three years after Alfa had a system in Production automobiles. There are numerous sources for verification including Alfa's own service advisory updates from 5 May 1990, referring to the means of adjusting the 1983 version, and U.S. Patents, for example [1]There is a great deal more information to be found through the patent office publications alone, however, my job is not to do the correction, for which I do not feel qualified, but to point out what I believe to be "the error." Again, I am unfamiliar with the methods, therefore I hope that this is an acceptable means of calling attention to what may need to be corrected. Thank you for your consideration.[reply]
The exaggerations in the Honda section have to stop. VTEC V-6 is not comparable to a "racing cam." This is a ridiculous assertion along with several other ridiculous assertions removed from the Honda sections. -TP
Separate notation on 10/29/2008: Someone might want to add to Honda's list of VTEC designs, their A-VTEC, which recently debuted with the 2009 Acura TL. This iteration of VTEC has been deployed to bring independent intake & exhaust timing to their J35 & J37, SOHC, V6 motors...functionality similar to VTEC applications to DOHC configurations. Improved low end torque has been cited. Claims are that this is a more elegant design that BMW's Valvtronic. There's a white paper available & a measure of technical discussion re Honda's new A-VTEC off TEMPLE OF VTEC.COM (see Jeff Palmer's article).
Well, I don't think Advanced VTEC is actually in production, but I can't find any information about the VTEC system in use in the 2009 Acura TL. It is a unique system but does not have a specific name. I'll keep looking. IJB TA (talk) 20:42, 1 July 2009 (UTC)[reply]
Why is this page separate from Variable valve actuation? If they are different, there is nothing on either page to explain the differences; If they are the same thing (or closely related), they should be merged. 82.26.227.219 (talk) 09:55, 9 May 2011 (UTC)[reply]
I have added this section as I thought the existing article, although very good, was lacking detail on mechanical only types. In addition to this reason I know that Wiki articles are very often the place both amateur inventors and auto industry researchers alike first turn to when starting a new project. I hope what I have written here will give them some guidance. I know of some researchers who have thought that they had "invented" just about all these types one after another - not knowing that they all ready existed. I have never actually seen anything like the section I have just written on any freely available to the public material - only internal company reports and patent search reports etc.I still have some work to do in finding USPTO numbers as examples, and adding links and references etc. Clivedog (talk) 10:25, 12 January 2012 (UTC)[reply]
This may explain why nothing has been written previously on mechanical types. Basically very little of what I wrote has been published - so I think there is very little point in trying to get this information into the main article. However, as I explained above, I think what I wrote is very useful for amateur inventors and auto industry professionals alike.I will move the "New Section" to the "talk" page and add a link to it on the main article page - I will presume that this is allowable unbder Wiki rules?Clivedog (talk) 02:26, 13 January 2012 (UTC)[reply]
The key is that Wikipedia does not lead. Wikipedia follows. Secondary sources are the main sources used here; well-established, mainstream facts. Nothing cutting edge. Nothing from the fringes. Or next to nothing.
I'm not saying it's not useful. We can agree that it's useful but useful doesn't meet Wikipedia's criteria. Use your expertise to find and cite published sources. Work that breaks new ground goes elsewhere. --Dennis Bratland (talk) 03:13, 13 January 2012 (UTC)[reply]
Dennis - Thank you for your explanation of the situation - which I must admit that I didn't quite understand. However it does seem a slightly odd and paradoxical situation that when something is published by a magazine it then becomes "OK". I know a few editors of motoring-type magazines and, generally speaking, they are so desperate for new and interesting material that they are quite happy to publish pretty much anything within reason - and by Wiki standards this would then make it "kosher"? I will see what I can do about publishing elsewhere - but until then Wiki may have to do without my words of wisdom.Clivedog (talk) 05:07, 13 January 2012 (UTC)[reply]
The Wiki system of referencing turned out to be not as quite as indecipherable as it first appeared to be - so I have added some references and resubmitted the addition to the article.Clivedog (talk) 07:01, 17 January 2012 (UTC)[reply]
Article as I found it [1] read in part Almost all steam engines had some form of variable cut-off. That they are not in wide use is a reflection that they are all lacking in some aspect of variable valve actuation.
I've added some details and wikilinks and two requests fro citations [2], but frankly I'm skeptical of both claims. Our article on cut-off reads in part Smaller stationary steam engines generally have a fixed cutoff point while, in large ones, the speed and power output is generally governed by altering the cutoff... [3] in view of which I think the claim about almost all such engines having cut-off gear needs at least clarification. And I'm guessing that the observation about the reason for the demise of steam is WP:OR but I could be wrong. It certainly needs a citation and probably rephrasing.
It's an interesting comparison and should be kept. Just needs some cleaning up.
Certainly the "Almost all steam engines etc." statement is something of a generalisation. Maybe it should read "Almost all steam engines used for transport had variable cutoff etc." Being able to vary the cutoff makes the steam engine far more economical of fuel at lower power settings. Full throttle (regulator) and the shortest cutoff gave the highest thermal efficiency. If a means of steam transport of any kind had to carry its own fuel it needed the economy gains of variable cutoff. A coal-burning stationary engine at a coal mine would not have the same need for fuel economy. This is an article about internal combustion VVT and I don't think you really need to qualify statements like the contentious "Almost all steam engines etc." too much. I suspect the author was not referring to Stephenson's valve gear (or any of the many other "link" motions) but the more rare varities of steam valve gear such as having selectable differently-shaped cam lobes on a shaft (ancestor of Honda VTEC-type arrangements) or the even more rare "oscillating cam" varities (ancestor of BMW's Valvetronic-type systems). I don't get the impression that he or she doesn't like VVT in general? Although I like the overall article generally there are quite a few "debateable" statements scattered throughout it. I seem to have written this in the middle of Andrewa's comments - sorry. Clivedog (talk) 07:23, 1 January 2013 (UTC)[reply]
Actually the whole article needs cleanup, particularly to sort out the gossip from the information. Andrewa (talk) 20:05, 26 September 2012 (UTC)[reply]
Isn't the Fiat group "multiair" (and twinair) system at least partly camless? IE the intake valve, iirc, is entirely electromechanically actuated? (With a conventional exhaust valve) 87.112.90.182 (talk) 22:22, 31 August 2015 (UTC)[reply]
This section should be deleted or modified. I would argue that according to details listed later in the article under Automotive Nomenclature indicate that VVT implementation has been successful and widespread in production automobiles. — Preceding unsigned comment added by Standard7452 (talk • contribs) 15:35, 5 July 2018 (UTC)[reply]