[Diy_efi] A/F mixture, EGT and engine damage

[David Cooley]

WOT you want to be 12.0-12.5:1 for peak power... Part throttle as close to
14.7:1 will give the best economy. 

> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org 
> [mailto:diy_efi-bounces at diy-efi.org] On Behalf Of Tim Marsteiner
> Sent: Monday, May 16, 2005 4:26 PM
> To: diy_efi at diy-efi.org
> Subject: Re: [Diy_efi] A/F mixture, EGT and engine damage
> 
> Both EGT probes are exactly 3" from the cylinder heads.
> 
> http://www.superxtune.com/images/EGT.JPG
> 
> I have heard that going too rich can damage the engine by 
> "washing" the oil film off the cylinder walls. Is there a 
> safe lower limit on A/F or EGT ? 
> 
> Thanks,
> Tim
> 
> --- Michael Richards <michael at fastmail.ca> wrote:
> > Your EGTs do sound a little high but I don't know where 
> your probe is 
> > and I don't have a lot of motorcycle engine experience. If I had to 
> > guess I'd say that maybe you aren't running enough ignition advance.
> > That mixture isn't what I'd characterise as too lean or too 
> rich for 
> > an NA engine.
> > 
> > -Michael
> > 
> > > Some owners of my type of motorcyle have reported burnt exhaust 
> > > valves and cracked cylinder heads. I have logged data 
> running one of 
> > > the standard
> > factory
> > > tunes showing peak EGTs >1500 F and A/F > 13.2:1
> > at
> > > WOT. I have also recorded even higher EGTs (1663
> > F) at
> > > mid to low engine loads.
> > > 
> > > This page shows Avg EGT, Peak EGT and the number
> > of
> > > samples at each operating "cell" in the map (TPS
> > vs
> > > RPMs).
> > > 
> > > http://www.superxtune.com/images/8320Cyl2_egt.jpg
> > > 
> > > 
> > > Any opinions on which of the above conditions is
> > doing
> > > the most (if any) damage?
> > > 
> > > At mid to low engine loads do you need to be
> > concerned
> > > with high EGT or should I just focus on richening
> > up
> > > the higher engine load points?
> > 
> >
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