Max Advance

[Dave Edge]

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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