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Toymods » Tech & Conversions » Head flow and flame propegation issues in turbocharged cars Show: Today's Posts  :: Show Polls  Email to friend

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earlyrolla Regular Location: Perth Registered: May 2003	Re: Head flow and flame propegation issues in turbocharged cars Mon, 01 November 2004 14:38 I might be wrong, but after reading this thread there might be some confusion of squish area with some. Squish is created by having a small gap between the piston top and head surface(for all those who haven't read Bill's Page). In closed chamber heads (Holden 6, 3K Toyota etc) there tends to be a large squish area created due to combustion chamber design. In open chamber heads the squish area tends to be smaller. (I will leave the 4AG heads to those that know about them). For the hemispherical combustion chamber of the 18RG the squish area is the area around the very outside of the piston that surrounds the outside of the combustion chamber in the head. (I.e. the bore is slightly larger than the diameter of the combustion chamber, creating a ring of squish area around the combustion chamber). An even squish area around the outside of the combustion chamber coupled with a centrally mounted spark plug and flat top piston should theoretically provide the best combustion process. I know the 2TG 88260 head uses a slight modification on the perfectly circular combustion chamber. The head surface has more area on the inlet side in order to create more squish, obviously to create more turbulence on that side of the head in order to 1) mix the gases better and 2) to force the mixture across the piston top (as the air/fuel mix would tend to be slightly more concentrated on the inlet side of the head). As stated by many previously, the squish effect causes the in rush (in towards the centre of the cylinder) of gases as the piston reaches TDC. Too large a squish gap and the squish effect is next to nothing (no benefits), too small a squish gap and the velocity of gases can become too high and there is also the possibility at high RPM the piston will kiss the head. A point worth mentioning, one problem with why decreasing an engines compression (for turbo/supercharging) by using a head spacer is classed as a bad idea is because it kills all chance of making use of the squish effect. Squish gap can be dictated a little by rod choice (especially in drag engines) where using aluminium rods a larger gap is needed due to expansion of the rods due to heat and high rpm stresses (this is Stewarts field) cause the rod to lengthen substantially compared to forged steel rods. Stewart, that article was an interesting read. Here is some more: http://www.speedomotive.com/Building%20Tips.htm Well thats my 2c [Updated on: Mon, 01 November 2004 14:41] [Report message to a moderator]

	Subject	Poster	Date
	Head flow and flame propegation issues in turbocharged cars	Shraka	Wed, 27 October 2004 02:14
	Re: Head flow and flame propegation issues in turbocharged cars	Bill Sherwood	Wed, 27 October 2004 02:21
	Re: Head flow and flame propegation issues in turbocharged cars	Shraka	Wed, 27 October 2004 02:30
	Re: Head flow and flame propegation issues in turbocharged cars	oldcorollas	Wed, 27 October 2004 02:44
	Re: Head flow and flame propegation issues in turbocharged cars	oldcorollas	Wed, 27 October 2004 02:50
	Re: Head flow and flame propegation issues in turbocharged cars	Bill Sherwood	Wed, 27 October 2004 02:56
	Re: Head flow and flame propegation issues in turbocharged cars	oldcorollas	Wed, 27 October 2004 02:58
	Re: Head flow and flame propegation issues in turbocharged cars	Bill Sherwood	Wed, 27 October 2004 02:43
	Re: Head flow and flame propegation issues in turbocharged cars	Shraka	Wed, 27 October 2004 02:57
	Re: Head flow and flame propegation issues in turbocharged cars	Bill Sherwood	Wed, 27 October 2004 03:06
	Re: Head flow and flame propegation issues in turbocharged cars	Bill Sherwood	Wed, 27 October 2004 02:49
	Re: Head flow and flame propegation issues in turbocharged cars	Shraka	Wed, 27 October 2004 03:39
	Re: Head flow and flame propegation issues in turbocharged cars	oldcorollas	Wed, 27 October 2004 03:49
	Re: Head flow and flame propegation issues in turbocharged cars	Bill Sherwood	Wed, 27 October 2004 04:00
	Re: Head flow and flame propegation issues in turbocharged cars	Shraka	Wed, 27 October 2004 04:20
	Re: Head flow and flame propegation issues in turbocharged cars	Joshstix	Wed, 27 October 2004 04:28
	Re: Head flow and flame propegation issues in turbocharged cars	Shraka	Wed, 27 October 2004 06:29
	Re: Head flow and flame propegation issues in turbocharged cars	indigoid	Thu, 28 October 2004 11:40
	Re: Head flow and flame propegation issues in turbocharged cars	Shraka	Fri, 29 October 2004 03:23
	Re: Head flow and flame propegation issues in turbocharged cars	da_horse	Wed, 27 October 2004 20:34
	Re: Head flow and flame propegation issues in turbocharged cars	Norbie	Thu, 28 October 2004 01:49
	Re: Head flow and flame propegation issues in turbocharged cars	da_horse	Thu, 28 October 2004 11:24
	Re: Head flow and flame propegation issues in turbocharged cars	rokusan	Thu, 28 October 2004 12:04
	Re: Head flow and flame propegation issues in turbocharged cars	takai	Fri, 29 October 2004 12:41
	Re: Head flow and flame propegation issues in turbocharged cars	indigoid	Fri, 29 October 2004 12:44
	Re: Head flow and flame propegation issues in turbocharged cars	RWDboy	Fri, 29 October 2004 14:25
	Re: Head flow and flame propegation issues in turbocharged cars	M.W.P.	Fri, 29 October 2004 16:44
	Re: Head flow and flame propegation issues in turbocharged cars	RWDboy	Sat, 30 October 2004 03:59
	Re: Head flow and flame propegation issues in turbocharged cars	Shraka	Mon, 01 November 2004 03:15
	Re: Head flow and flame propegation issues in turbocharged cars	RWDboy	Mon, 01 November 2004 03:54
	Re: Head flow and flame propegation issues in turbocharged cars	Joshstix	Mon, 01 November 2004 06:04
	Re: Head flow and flame propegation issues in turbocharged cars	Shraka	Mon, 01 November 2004 06:15
	Re: Head flow and flame propegation issues in turbocharged cars	oldcorollas	Mon, 01 November 2004 06:18
	Re: Head flow and flame propegation issues in turbocharged cars	justcallmefrank	Mon, 01 November 2004 06:19
	Re: Head flow and flame propegation issues in turbocharged cars	Joshstix	Mon, 01 November 2004 06:21
	Re: Head flow and flame propegation issues in turbocharged cars	oldcorollas	Mon, 01 November 2004 06:48
	Re: Head flow and flame propegation issues in turbocharged cars	justcallmefrank	Mon, 01 November 2004 07:34
	Re: Head flow and flame propegation issues in turbocharged cars	Mr DOHC	Mon, 01 November 2004 08:28
	Re: Head flow and flame propegation issues in turbocharged cars	Shraka	Mon, 01 November 2004 09:26
	Re: Head flow and flame propegation issues in turbocharged cars	oldcorollas	Mon, 01 November 2004 09:04
	Re: Head flow and flame propegation issues in turbocharged cars	justcallmefrank	Mon, 01 November 2004 09:07
	Re: Head flow and flame propegation issues in turbocharged cars	Shraka	Mon, 01 November 2004 09:27
	Re: Head flow and flame propegation issues in turbocharged cars	justcallmefrank	Mon, 01 November 2004 09:32
	Re: Head flow and flame propegation issues in turbocharged cars	RWDboy	Mon, 01 November 2004 13:08
	Re: Head flow and flame propegation issues in turbocharged cars	Shraka	Mon, 01 November 2004 13:13
	Re: Head flow and flame propegation issues in turbocharged cars	earlyrolla	Mon, 01 November 2004 14:38

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