Max Advance

[Les Newell]

If you base your ignition timing on revs and manifold/plenum pressure then
you can cover all possibilities. You can't use throttle position because you
can't know how much boost the turbo is providing at any given time.


les

> Can I just throw something else in.
>
> On a normally aspirated engine, VE is known throughout
> the rev range, depending upon ambient temp and
> throttle opening.
>
> On a forced induction engine, VE changes according to
> boost pressure as well as the other values. The theory
> of reducing ignition advance by defined amounts now
> seems incorrect. To achieve max efficiency don't we
> have to modify advance according to revs, boost and
> revs again?
>
> eg, I setup my ECU to provide 1 bar boost = 5 degrees
> less advance. But since the turbo helps the VE of my
> engine at different rpm, I want it to retard the
> ignition by different amounts at different rpm.
>
> I think I have just argued myself into a knot, can
> anyone help. I think that I am trying to say that we
> should have max ignition possible at all times and
> some kind of sensors to pull it down just before
> knock.
>
> hmm
>
> Cheers
> Dave
>
>
> > This objectives can be achieved by running richer
> > fuel
> > air mixtures, increasing turbulence within the
> > cylinder, using higher compression ratios and
> > smaller
> > bore sizes with more cylinders to achieve the
> > required
> > capacity among others.
> >
> > Hope this helps
> >
> >                   thanks Roy ( Spectric's Ltd UK )
> >
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