Talk:Variable valve timing

message: 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)
thread_title: Untitled

message: *This article is a little off base.  VVT or variable valve timing simply changes the timing of the camshaft, using cam phasers.  It does NOT change the actual profile of the camshaft.  Vtec, on the other hand, utilizes a camshaft that has multiple profiles, and can select which profile to use based on current operating perameters.*  —Preceding unsigned comment added by 12.28.232.10 (talk) 16:28, 12 December 2007 (UTC)
replies: text: The Z31 and Z32 were not powered by the same engines, all models of the Z31 were powered by variations of the VG30E SOHC engine, all models of the Z32 were powered by variations of the VG30DE DOHC engine. The VG30DE was not produced until 1990. Also I have located the earliest US patent for the Nissan VVT system (4,960,084), it shows that the earliest date that Nissan applied for a patent in Japan was in September of 1988. The reference you provided is pretty far from definitive proof that Nissan produced a VVT system in 1986. Are there any other references that you can provide? IJB TA 19:30, 13 August 2006 (UTC)

text: Still nothing on a VVT system. Here's a reference stating that the VG30DE went through extensive development after it was shown in the Mid-4: http://www.zccw.org/History/Z32_part1.htm . The VG30DE with VVT was developed for the Z32 which did not enter into production until 1990 (model year). One obscure reference is simply not enough to disprove what is a very widely accepted fact, so unless you have something a little more concrete I think the article should be reverted to my previous edit. IJB TA 05:20, 14 August 2006 (UTC)

text: Well, most of what has been presented here is not really solid proof. But Nissan had been developing VVT systems as early as the mid 1970s (and maybe even earlier) so it is much more plausible that Nissan did produce the first VVT systems. I have also found it difficult to locate information on Nissan production engine technology so I can't say for sure either way. So I suppose the article will stay as is, unless someone else presents information to say otherwise. IJB TA 07:34, 14 August 2006 (UTC)
thread_title:  Nissan VVT 

message: I am considering incorporating some new information into the History section such as the following:
*Lycoming (not Fiat) would develop the worlds first functional VVT system in 1944 for the R-7755, the largest piston aircraft engine developed in the US. Anyone know if this system was patented?
*Nissan had developed a VVT system that used "3d" cam lobes which could alter timing, duration and lift. It would later inspire a similar system currently used by Ferrari. US patent numbers 4,182,289 and 4,352,344.
If anyone has anything that they would like to add please present it. Thanx, IJB TA 02:06, 26 October 2006 (UTC)
thread_title:  Revisions to the History section 

message: 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
:There are no exaggerations. I changed race cam to high lift, long duration, which is essentially a race cam. VTEC cams in V6 engines have an intake cam profile which is aggressive, maybe not comparable to race cams but fairly aggressive for a mass production vehicle. The high rpm cams in high output DOHC VTEC engines do have profiles comparable to that of a race cam, the ability to use these types of profiles is why the VTEC system was developed in the first place. VTEC engines do not produce less power at low rpm when compared to non-VTEC engines, again, this is the main reason the VTEC system was developed, to allow for an aggressive, high rpm cam to be used without sacrificing low rpm output. DOHC i-VTEC engines do not have an "added lift device", the VTEC system already varies lift. Advanced VTEC will have a device which will allow the system to vary lift continuously like the BMW Valvetronic system. DOHC i-VTEC engines do have continuously variable timing for the intake cam. Fully operate does not apply, that would be like saying a door latch does not fully operate until the door is closed. Please research your edits properly before making them, there is a huge amount of information about these systems on the web. I should not have to teach anyone who edits this article about this subject. IJB TA 05:25, 31 October 2006 (UTC)
replies: text: I will add something about Advanced VTEC to the list. I did read the TOV article but there is still only speculation as to how the Advanced VTEC system affects the exhaust valves, if it does at all. If someone finds more detailed information they can change it. IJB TA (talk) 15:54, 30 June 2009 (UTC)
thread_title: Honda exaggerations

message: 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)
replies: text: Wikipedia does not publish original research or anything that is not publicly available. One of Wikipedia's 5 Pillars is Verifiability. This means it must be possible for others, with reasonable effort, to find the same sources you used and verify what you said. Please carefully read the pages I linked to, and revise your contribution using only verifiable sources, and then please cite your sources to make it possible to check them. --Dennis Bratland (talk) 16:39, 12 January 2012 (UTC)

text: Deleted again. Please read WP:NOTWEBHOST. Wikipedia is not your free web host. You could create a blog and publish your research there. Or you could apporach a magazine, journal, or other reputable publication and ask them to publish your work. If that happened, then you could add it to Wikipedia and cite it. It would have to be pass a bona fide editor, though, and not be self-published. See WP:SPS.<P>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.<P>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)
thread_title: Variable Valve Actuation

message: 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)
replies: text: Wikipedia does not publish original research or anything that is not publicly available. One of Wikipedia's 5 Pillars is Verifiability. This means it must be possible for others, with reasonable effort, to find the same sources you used and verify what you said. Please carefully read the pages I linked to, and revise your contribution using only verifiable sources, and then please cite your sources to make it possible to check them. --Dennis Bratland (talk) 16:39, 12 January 2012 (UTC)

text: Deleted again. Please read WP:NOTWEBHOST. Wikipedia is not your free web host. You could create a blog and publish your research there. Or you could apporach a magazine, journal, or other reputable publication and ask them to publish your work. If that happened, then you could add it to Wikipedia and cite it. It would have to be pass a bona fide editor, though, and not be self-published. See WP:SPS.<P>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.<P>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)
thread_title: New Section On Mechanical Types

message: Article as I found it  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.
:On reflection this seems to be not only WP:OR about the history of the steam engine but, more important, WP:POV about the merits of VVT. The author doesn't like VVT! We've had such problems before with automotive articles, notably that one editor doesn't like extractor manifolds. And their opinions may be valid for all I know, it's just that Wikipedia is not the place to express them. Andrewa (talk) 20:53, 27 September 2012 (UTC)
thread_title: Citations needed regarding steam engines

message: 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)
thread_title:  Information out of date? 

message: 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)
thread_title:  Challenges Section