[Diy_efi] Timing Advance Curve?

[Eric Byrd]

The DIY way is to advance until torque drops, or until it pings,
whichever is first.  If it pings first, drop it back a notch, or use
higher octane.

Honda engines, esp. the ones with VTec, tend to have smaller bores and
longer strokes for a given displacement, and a smaller bore is naturally
more ping-resistant, because knock is a function of the paraffins in the
fuel degrading to compounds with a much lower flash point, and this takes
time, and the larger your bore, the longer it takes the fireball to
expand out to the edges.  Therefore, even on low octane pump gas, Hondas
can be advanced to maximum torque at a given RPM before there is danger
of pinging.  Know this from experience.

If you are talking about a programmable chip, where you can set the
numbers at each point, it works the same way, except the process has to
be done for each set point.  But a rule of thumb is, greater VE calls for
less advance, but greater RPM calls for more advance.  The torque curve
of an engine at stock is a good starting place to guess at VE.

On Fri, 13 Dec 2002 10:17:41 +0530 "Sendhil Solai" <sendhil.s at lycos.com>
writes:
> Hello!
> 
> I wanted to know how you can get the Timing Advance Curve for an 
> Engine. That is the minimum advance for maximum torque at diffrent 
> RPM's. 
> How do engine manufacturer's do this? Any method by which we can go 
> the DIY way?
> Your comments will be appreciated! Thank you for your time.
> 
> Stay well.
> Sendhil.
> 
> 
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