Talk:Multi-valve

message: what's the record for most valves per cylinder?  —Preceding unsigned comment added by 18.228.1.49 (talk) 07:53, 9 January 2008 (UTC)
thread_title: Untitled

message: Didn't Suzuki develop the 1st 7v moto engine? (With oval pistons.)  TREKphiler any time you're ready, Uhura  21:31, 28 October 2010 (UTC)
thread_title:  Lucky 7 

message: I have undone your reversion on parallel valve stems.  I think it is incorrect to say that parallel valve stems are "rare" in four-valve heads.  Particularly in car engines, parallel stems are the norm.  A notable exemption (that perhaps proves the rule) is the "RFVC" (Radial Four Valve Combustion) head used (inter alia) in the Honda XR series single-cylinder bikes.  But the RFVC layout was not easily adaptable to multi-cylinder engines.  And the cost of valve-gear complication was one of the reasons that Yamaha fell out of love with five-valve heads. Arrivisto (talk) 11:09, 27 April 2014 (UTC)
thread_title:  Parallel valve stems 

message: Recent additions put forward the thesis that <=4 valve heads can use parallel valve stems, whilst >4 valves must use angled valve stems. This is both incorrect, misleading and of course unsourced.  Parallel valve stems are unusual as, first and foremost, they lead to poorly placed valve heads and an inefficient combustion chamber shape. Secondly, >4 valve heads have (subject to the same proviso) used parallel valves. When such engines first appeared, as large capacity high-speed engines, such as 1930s airship engines and 1950s high speed locomotive engines, parallel stems were not uncommon for those 5 & 6 valve engines.
The statements as they stand are uncited. The implication of the statements, that parallel valve stems is dependent on the number of valves (rather than being a compromise for simplifying machining at the cost of a less efficient chamber design) is additionally misleading. Andy Dingley (talk) 11:27, 27 April 2014 (UTC)
replies: text: The edits you reverted should be taken in context: they were a comparison between four-valve and five-valve heads, and were made partly to show why (implicitly, in cars and motorcycles) the five-valve head is now uncommon.  Ignoring the mathematical symbols, you say the edits, "put forward the thesis that 4-valve heads can use parallel valve stems, whilst 5-valves must use angled valve stems", but that is a misreading. You make the point that the edits are uncited (true, as yet): so why not add a citation needed rather than instant reversion?  You say, possibly wrongly, that parallel stems are "rare" in four-valve engines, but provide no evidence.  You say that parallel stems alead to poorly placed valve heads and an inefficient combustion chamber shape, but, again, provide no evidence.  To then allege that the reverted edits were "misleading" is unjustifiable semantics.  Arrivisto (talk) 12:03, 27 April 2014 (UTC)
thread_title:  4 valves parallel stems, >4 valves angled stems 

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thread_title:  External links modified (February 2018) 

message: I notice this article has power per cubic inch, this does not follow the guidelines in the Wikipedia Manual of Style regarding Units to display, completely missing is the power per litre in either horsepower or kilowatts. Does any country presently use cubic inches for engine capacity? Even the USA now uses liters on the manufacturer web page. https://www.ford.com/suvs-crossovers/ecosport/models/ecosport-s/ Avi8tor (talk) 07:33, 18 April 2021 (UTC)
thread_title:  Power per cubic inch