[Diy_efi] RE: Timing and dyno pulls

[William Shurvinton]

----- Original Message -----
From: "Dave Dahlgren" <ddahlgren at snet.net>
To: <diy_efi at diy-efi.org>
Sent: Thursday, December 19, 2002 6:12 PM
Subject: Re: [Diy_efi] RE: Timing and dyno pulls


> Air temperature increases need less timing yes but it is
 >not air density related at all.

Hotter air is less dense though.

<snip>
> Detonation is so far removed from tuning racing engines that if you get to
that
> point you have truly lost the rabbit so to speak. Peak power +- 0.5% is
quite a
> ways from detonation. There is also no rule I have ever heard about
keeping heat
> out of the cylinder heads. It is a heat engine. more heat more power.

Re: timing vs detonation on race engines, how come so many people get it
wrong? Can I also infer that OEM apps ( which run close to detonation) do
this because they are running leaner than they should?

On the temperature issue that has me confused. I had always thought that
cooler was more powerful and race cars (F1 in particular) only ran so hot
because the aero package demanded a limited rad area and air flow. Hotter
was more efficient. Still I am guessing on your engine dyno you can set any
coolant temp you want so can do real empirical measurements.

Can you also confirm on the cylinder head temp issue that you accepting that
way too hot will cause pre-ignition? I can understand why heating the heads
takes heat out the reaction, but after a point aren't you starting from a
hotter charge and so reducing the available heat increase from combustion?

Sorry for all these questions, but I just don't have the toys to test this
for myself :-)

Bill


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