AW: [Diy_efi] Timing Advance Curve?

[Schaffer Klaus Maria]

> -----Urspr=FCngliche Nachricht-----
> Von: Geddes, Brian J [mailto:brian.j.geddes at intel.com]
> Gesendet: Montag, 16. Dezember 2002 19:11
> An: diy_efi at diy-efi.org
> Betreff: RE: [Diy_efi] Timing Advance Curve?
>=20
> Any other advice on this?  If a dyno is not readily available=20
> (I have an all-wheel drive car), could one infer a increase=20
> in torque from a decrease in EGTs? =20
>=20
> > 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.
> >=20

The way which professionals are going:

An engine cycle has his highest efficiency (best torque) when the timing =
of MBF50% (time when 50% of the fuel is burnt) is set to 8deg-ATDC. =
Sounds easy, you only need a device that tells you when 50% of the fuel =
is burnt ;-)

The only way to get the information, is to calculate the heat release =
rate. Therefor you need at least information about the incylinder =
pressure. You need a incylinder pressure sensor and a trigger device =
(resolution of 0.5deg works good enough). A good incylinder pressure =
transducer costs ~$2000,-, bad one ~$1000,-. Low cost sensors are in =
development since years, but not available today. Equations for =
calculating the heat release rate can be found in the Heywood book and =
in many SAE-papers.

There are some indicating system on the market that will do this for =
you. Best will come from a company located at my hometown www.avl.com =
;-). But don't ask for prices or better: before you get a price: fasten =
your seat belts.

Further a few words to timing advance. Engines of newer conception (4V, =
central spark plug, CR~11) will have at loads lower than 50-70% their =
best advance before "pinging". At full load, knock limit is always the =
best.

		--- so long ---, klaus.

--=20
************************************************************
 dipl. ing. klaus maria schaffer
 Institute of Internal Combustion Engines & Thermodynamics
 University of Technology, Graz - Austria
 A-8010 GRAZ, Kopernikusgasse 24/II
------------------------------------------------------------=20
 email: schaffer at vkma.tu-graz.ac.at
 phone: +43-316-873-7724
 fax:   +43-316-873-7712
************************************************************
=20

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