[Diy_efi] Rich detonation?

[Becker, Damon Damon]

Hi, Joe!  It's Damon (flyboy) from the MR2 community.  
 
Yes, it's totally possible to get rich detonation.  However, you will usually misfire before you hit this point, unless you are pretty careless with the ignition.  
 
Combustion velocity is what dictates spark timing, and it varies with AFR.  The max velocity is around 11.0 mass air/fuel ratio (the exact value is debatable, but the concept still holds).  Therefore, rich of this value, the combustion velocity increases again, necessitating a reduced spark advance.  
 
If you leave the spark static and add fuel, then very rich mixtures will detonate, assuming the detonation propensity was there to begin with.  

	-----Original Message----- 
	From: diy_efi-bounces at diy-efi.org on behalf of Joseph Obernberger 
	Sent: Sat 11/18/2006 3:10 PM 
	To: diy_efi at diy-efi.org 
	Cc: 
	Subject: [Diy_efi] Rich detonation?
	
	

	Hi,
	    I've read in various places that it is possible to run an engine so
	rich that detonation can occur - or at least the knock sensor would pick
	up what sounded like detonation.  Has anyone ever experienced this?  Any
	truth to it?
	Thanks!
	
	-Joe
	http://www.lovehorsepower.com
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