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bored Occasional Poster Location: Sydney Registered: July 2002	Re: Is 5 valve better than 4 valve? Sat, 28 May 2005 10:45 What an interesting thread -- although there seems to be just a little to much pride and emotion for what should ultimately be a technical discussion. A few thoughts... There are other tradeoffs in the 4-valve vs. 5-valve argument which haven't been considered in this thread so far. One of them would be valvetrain packaging and complexity. This is going to influence the design of most production engines considerably. Pointing to whether or not 5 valves are used by various manufacturers is only evidence of an overall cost/benefit decision by a manufacturer, and doesn't really tell you that much about the technical superiority of one design or another. Think of all the pushrod engines still being manufactured for example. The manufacturer's choice to use one system over another is obviously not simply dictated by outright performance. Another issue would be valvetrain mass. 5-valve engines might have an advantage when using regular cams due to lower valve mass. F1 engines have a different set of tradeoffs due to the use of exotic materials and pneumatic valve springs. If you change the valve material in your own car, you'll likely change this tradeoff as well. Actually, there are even more problems with saying that because something is used in F1 it is the best. It just means that it's the best design to use when you are building a car with a massive budget to whichever rules the FIA gave you this year. The discussions about flowbenching are also interesting, but probably more suitable for a different thread. I don't know too much about flowbenching, but from thinking about it it seems to have some inherent limitations. A flowbench seems to generate a continuous vacuum, while a real engine is generating a pulsating vacuum. Clearly this will have different characteristics, as there will be resonance effects due to the mass of the intake charge. So simply comparing flow bench numbers for two different head designs is probably not enough to declare a clear winner. In fact, the tradeoff will be influenced by a lot of factors other than the number of valves... the valve timing, pulse frequency, port diameter, rod/stroke ratio... probably lots more. Engines are dynamic devices, which is what makes them so interesting. Anyway, the point of this message is that the whole 5-valve vs. 4-valve war is a bit silly. Engineering is about tradeoffs, and what works in one situation might not work as well in another. PS. Since when did age have anything to do with having a clue? [Updated on: Sat, 28 May 2005 10:57] [Report message to a moderator]

	Subject	Poster	Date
	Is 5 valve better than 4 valve?	170bhp	Fri, 27 May 2005 12:54
	Re: Is 5 valve better than 4 valve?	Big T	Fri, 27 May 2005 13:39
	Re: Is 5 valve better than 4 valve?	oldcorollas	Fri, 27 May 2005 14:49
	Re: Is 5 valve better than 4 valve?	takai	Fri, 27 May 2005 15:09
	Re: Is 5 valve better than 4 valve?	Jonny2TG	Fri, 27 May 2005 15:34
	Re: Is 5 valve better than 4 valve?	takai	Sat, 28 May 2005 00:26
	Re: Is 5 valve better than 4 valve?	CLG	Sat, 28 May 2005 01:12
	Re: Is 5 valve better than 4 valve?	Jonny2TG	Sat, 28 May 2005 01:42
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 05:16
	Re: Is 5 valve better than 4 valve?	floody	Tue, 31 May 2005 13:06
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sat, 28 May 2005 05:33
	Re: Is 5 valve better than 4 valve?	Henn	Sat, 28 May 2005 05:41
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sat, 28 May 2005 05:48
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sat, 28 May 2005 05:46
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 06:05
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sat, 28 May 2005 06:07
	Re: Is 5 valve better than 4 valve?	Acoustic	Tue, 31 May 2005 16:03
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 06:10
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sat, 28 May 2005 06:15
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 06:14
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sat, 28 May 2005 06:17
	Re: Is 5 valve better than 4 valve?	shinybluesteel	Sat, 28 May 2005 06:40
	Re: Is 5 valve better than 4 valve?	JFAllen	Sat, 28 May 2005 07:28
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 06:39
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sat, 28 May 2005 06:43
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 06:43
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 06:45
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 06:48
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 06:58
	Re: Is 5 valve better than 4 valve?	Jonny2TG	Sat, 28 May 2005 07:52
	Re: Is 5 valve better than 4 valve?	takai	Sat, 28 May 2005 08:24
	Re: Is 5 valve better than 4 valve?	bored	Sat, 28 May 2005 10:45
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sat, 28 May 2005 10:08
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 11:12
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 11:14
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sat, 28 May 2005 11:24
	Re: Is 5 valve better than 4 valve?	takai	Sat, 28 May 2005 11:19
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 11:32
	Re: Is 5 valve better than 4 valve?	bored	Sat, 28 May 2005 11:40
	Re: Is 5 valve better than 4 valve?	takai	Sat, 28 May 2005 11:43
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 11:48
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 11:49
	Re: Is 5 valve better than 4 valve?	takai	Sat, 28 May 2005 11:53
	Re: Is 5 valve better than 4 valve?	IRA11Y	Mon, 06 June 2005 07:26
	Re: Is 5 valve better than 4 valve?	ke382TG	Sat, 28 May 2005 11:50
	Re: Is 5 valve better than 4 valve?	170bhp	Sat, 28 May 2005 11:59
	Re: Is 5 valve better than 4 valve?	ke382TG	Sat, 28 May 2005 12:37
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sat, 28 May 2005 13:58
	Re: Is 5 valve better than 4 valve?	boudan	Sat, 28 May 2005 15:22
	Re: Is 5 valve better than 4 valve?	Acoustic	Tue, 31 May 2005 16:16
	Re: Is 5 valve better than 4 valve?	*rivmasta*	Wed, 01 June 2005 00:38
	Re: Is 5 valve better than 4 valve?	off-road	Sun, 05 June 2005 09:14
	Re: Is 5 valve better than 4 valve?	off-road	Sun, 05 June 2005 09:31
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sun, 29 May 2005 01:29
	Re: Is 5 valve better than 4 valve?	Ben Wilson	Tue, 31 May 2005 00:03
	Re: Is 5 valve better than 4 valve?	Joshstix	Sun, 29 May 2005 02:26
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sun, 29 May 2005 08:14
	Re: Is 5 valve better than 4 valve?	SEXY 16	Sun, 29 May 2005 09:41
	Re: Is 5 valve better than 4 valve?	river	Sun, 29 May 2005 11:53
	Re: Is 5 valve better than 4 valve?	170bhp	Sun, 29 May 2005 12:00
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sun, 29 May 2005 12:08
	Re: Is 5 valve better than 4 valve?	170bhp	Sun, 29 May 2005 12:11
	Re: Is 5 valve better than 4 valve?	Mr Revhead	Sun, 29 May 2005 12:34
	Re: Is 5 valve better than 4 valve?	oldcorollas	Sun, 29 May 2005 13:35
	Re: Is 5 valve better than 4 valve?	ROLLA GTi	Sun, 29 May 2005 13:45
	Re: Is 5 valve better than 4 valve?	Jonny2TG	Sun, 29 May 2005 14:15
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sun, 29 May 2005 14:58
	Re: Is 5 valve better than 4 valve?	THE WITZL	Mon, 30 May 2005 02:34
	Re: Is 5 valve better than 4 valve?	funkdoc	Mon, 30 May 2005 11:02
	Re: Is 5 valve better than 4 valve?	4agte	Mon, 06 June 2005 08:18
	Re: Is 5 valve better than 4 valve?	floody	Mon, 06 June 2005 09:57
	Re: Is 5 valve better than 4 valve?	4agte	Mon, 06 June 2005 10:10
	Re: Is 5 valve better than 4 valve?	floody	Tue, 07 June 2005 04:13
	Re: Is 5 valve better than 4 valve?	170bhp	Mon, 30 May 2005 09:14
	Re: Is 5 valve better than 4 valve?	170bhp	Mon, 30 May 2005 09:18
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Tue, 31 May 2005 10:36
	Re: Is 5 valve better than 4 valve?	Jonny2TG	Mon, 30 May 2005 15:37
	Re: Is 5 valve better than 4 valve?	Johnny	Mon, 30 May 2005 15:55
	Re: Is 5 valve better than 4 valve?	justcallmefrank	Tue, 31 May 2005 02:07
	Re: Is 5 valve better than 4 valve?	takai	Tue, 31 May 2005 00:26
	Re: Is 5 valve better than 4 valve?	Ben Wilson	Tue, 31 May 2005 01:02
	Re: Is 5 valve better than 4 valve?	takai	Tue, 31 May 2005 01:04
	Re: Is 5 valve better than 4 valve?	THE WITZL	Tue, 31 May 2005 07:41
	Re: Is 5 valve better than 4 valve?	Jonny2TG	Tue, 31 May 2005 08:23
	Re: Is 5 valve better than 4 valve?	170bhp	Tue, 31 May 2005 11:40
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Tue, 31 May 2005 11:56
	Re: Is 5 valve better than 4 valve?	Merudo	Tue, 31 May 2005 11:57
	Re: Is 5 valve better than 4 valve?	xolent	Tue, 31 May 2005 12:17
	Re: Is 5 valve better than 4 valve?	170bhp	Tue, 31 May 2005 12:25
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Tue, 31 May 2005 12:43
	Re: Is 5 valve better than 4 valve?	170bhp	Tue, 31 May 2005 12:34
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Tue, 31 May 2005 12:57
	Re: Is 5 valve better than 4 valve?	takai	Tue, 31 May 2005 13:13
	Re: Is 5 valve better than 4 valve?	funkdoc	Wed, 01 June 2005 12:41
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Wed, 01 June 2005 14:04
	Re: Is 5 valve better than 4 valve?	emmac	Wed, 01 June 2005 14:45
	Re: Is 5 valve better than 4 valve?	rx-3 ip	Sat, 04 June 2005 06:26
	Re: Is 5 valve better than 4 valve?	170bhp	Sun, 05 June 2005 13:15
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sun, 05 June 2005 13:47
	Re: Is 5 valve better than 4 valve?	Kr0n1k	Sun, 05 June 2005 17:34
	Re: Is 5 valve better than 4 valve?	170bhp	Sun, 05 June 2005 22:28
	Re: Is 5 valve better than 4 valve?	EMP-2TG	Sun, 05 June 2005 23:50
	Re: Is 5 valve better than 4 valve?	off-road	Sun, 05 June 2005 23:34
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sun, 05 June 2005 23:40
	Re: Is 5 valve better than 4 valve?	jkvsnn	Tue, 07 June 2005 03:19
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Tue, 07 June 2005 03:34
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Sun, 05 June 2005 23:44
	Re: Is 5 valve better than 4 valve?	SEXY 16	Mon, 06 June 2005 01:00
	Re: Is 5 valve better than 4 valve?	oldcorollas	Mon, 06 June 2005 02:01
	Re: Is 5 valve better than 4 valve?	off-road	Mon, 06 June 2005 02:40
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Mon, 06 June 2005 04:02
	Re: Is 5 valve better than 4 valve?	oldcorollas	Mon, 06 June 2005 07:04
	Re: Is 5 valve better than 4 valve?	*rivmasta*	Mon, 06 June 2005 07:29
	Re: Is 5 valve better than 4 valve?	*rivmasta*	Mon, 06 June 2005 07:32
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Mon, 06 June 2005 08:14
	Re: Is 5 valve better than 4 valve?	takai	Mon, 06 June 2005 09:06
	Re: Is 5 valve better than 4 valve?	4agte	Mon, 06 June 2005 09:11
	Re: Is 5 valve better than 4 valve?	takai	Mon, 06 June 2005 11:38
	Re: Is 5 valve better than 4 valve?	Bobski	Mon, 06 June 2005 16:41
	Re: Is 5 valve better than 4 valve?	Blown86	Mon, 06 June 2005 23:30
	Re: Is 5 valve better than 4 valve?	Corona RT142	Mon, 06 June 2005 23:31
	Re: Is 5 valve better than 4 valve?	adamaw11	Tue, 07 June 2005 01:26
	Re: Is 5 valve better than 4 valve?	Bill Sherwood	Tue, 07 June 2005 02:54
	Re: Is 5 valve better than 4 valve?	shinybluesteel	Tue, 07 June 2005 03:03
	Re: Is 5 valve better than 4 valve?	lumpy	Tue, 07 June 2005 05:52
	Re: Is 5 valve better than 4 valve?	oldcorollas	Fri, 10 June 2005 01:50
	Re: Is 5 valve better than 4 valve?	TheStitt	Wed, 08 June 2005 06:24
	Re: Is 5 valve better than 4 valve?	510rob	Thu, 09 June 2005 19:48
	Re: Is 5 valve better than 4 valve?	takai	Fri, 10 June 2005 04:23
	Re: Is 5 valve better than 4 valve?	oldcorollas	Fri, 10 June 2005 04:57
	Re: Is 5 valve better than 4 valve?	Mr Revhead	Fri, 10 June 2005 05:49
	Re: Is 5 valve better than 4 valve?	oldcorollas	Fri, 10 June 2005 06:21
	Re: Is 5 valve better than 4 valve?	Mr Revhead	Fri, 10 June 2005 07:02
	Re: Is 5 valve better than 4 valve?	oldcorollas	Fri, 10 June 2005 07:24

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