[Diy_efi] RE: Timing and dyno pulls

[Bernd Felsche]

On Thu, Dec 19, 2002 at 10:56:01PM -0000, William Shurvinton wrote:
> ----- Original Message -----
> From: "Adam Wade" <espresso_doppio at yahoo.com>
> >
> > > Can I also infer that OEM apps ( which run close to
> > > detonation) do this because they are running leaner
> > > than they should?

> > Do what?  Retard timing?  In some cases.  That's
> > usually how a detonation sensor setup works; after
> > detecting knock, it retards the timing.

> No: dave's point: Best power is way off detonation in a race engine. My
> question, why does a modern road car gain 10HP when run on high octane (real
> test, think it was a BMW) when all it has to go on is the knock sensor.
> Inference: it must be running close to knock all the time.

Correct. But it's not just the fuel.

And ambient conditions such as humidity can have dramatic effects on
low-speed and mid-range torque. Something like 4g of water per kg or
air being equivalent to one octane point, IIRC.

-- 
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