[Diy_efi] Timing Advance Curve?

[Hugh Keir]

My understanding is that as you advance ignition timing you will reduce the
exhaust gas temperature by creating a more complete burn of the air / fuel
mix in the cylinder.

The limitation is that at the onset of detonation EGT will rise sharply.

Is maximum torque found just before detonation? I am fairly sure this is
correct on high load acceleration but I am not certain on low load. I read
an SAE paper about in-cylinder pressures that discussed this subject and
concluded the above to be true, but as far I remember most of the tests were
carried out at 3000RPM.

Santa can I please have an ION sensing kit for Christmas!

Cheers

Hugh




----- Original Message -----
From: "Geddes, Brian J" <brian.j.geddes at intel.com>
To: <diy_efi at diy-efi.org>
Sent: Monday, December 16, 2002 6:10 PM
Subject: RE: [Diy_efi] Timing Advance Curve?


Any other advice on this?  If a dyno is not readily available (I have an
all-wheel drive car), could one infer a increase in torque from a decrease
in EGTs?


>
>
> 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.
>
> 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.

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