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170bhp Regular Registered: January 2004	Is 5 valve better than 4 valve? Fri, 27 May 2005 12:54 I have got my hands on an SAE technical paper titled 'Optimization of multi valve, four cycle engine design-the benefit of 5 valve technology' research done by Yamaha.Basically what Yamaha did was test head designs from 4 valve to 7 valve, throught their research they found 5 valve to be the best (I suppose their R1 motorbike is testiment to that!), some of the technical aspects gleaned from this paper include;(this is all compared to 4,6,7 valve heads, most test data was between a 4 valve and 5 valve motor with identical, comp ratio, bore/stroke etc, so basically they are comparing apples with apples, the only difference is the number of valves) They found 5 valve to give the best intake valve opening area. Intake valve opening area at maximum lift was greater by 25%. 5 valve allowed better placement of spark plug position. Higher combustion efficiency. Higher volumetric efficiency through all rev range (high speed AND low speed). Higher engine flow rates at all valve lifts, up 25% at lower lifts. Lighter valve train due to smaller valves resulting in higher rpm, therefore more power. Higher intake and exhaust inertial tuning(scavenging) Higher BMEP(brake mean effective pressure) through the whole rev range. They found that if the 4 and 5 valve engines had the same valve opening area that the five valve had significantly higher volumetric efficiency which would give a broader power curve. Being the owner of a 5 valve 4age and comparing my ride to 4 valvers I can see why mine performs so much better than any 4 valve I've been in, it will be interesting to see what the 'Arm chair experts(read 5 valve knockers)' think!!!! But I suppose all these arm chair experts spend more money on R&D than Yamaha [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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