[Diy_efi] Typical boosted ignition timings

[mrbeau0]

A bit late to the thread, but what sort of EGT did you measure (if you were
measuring that is)?  12 degrees at 1.25 bar with only 0.85 Lamda sounds like
exhaust valve melt-down territory...  And with an air cooled engine, the
heat build-up can lead to pre-ignition a bit more easily than water pumpers.
What sort of CR?

This is all by-the-cuff though as I haven't had the pleasure of playing with
a turbo 911 (yet).  I'm going the high CR/RPM route myself with my '73.

Matt.

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
Behalf Of Marc Reviel
Sent: March 21, 2003 11:58 AM
To: List for general do-it-yourself EFI talk
Subject: Re: [Diy_efi] Typical boosted ignition timings


The distributor was gutted and a simple sensor added for Sync Signal
to the MoTeC. No advance/retard of any kind.  MoTeC also uses the
60-2 factory crank trigger wheel.  Never any issues with the MoTeC
working properly.

I did get some feedback from Todd at ProtoMotive. He did say they had
to retard to 14 degrees @ 1 bar on 91 octane on an engine very
similar to mine to be able to run on street gas.

Experimentally, I was arriving at 12 degrees @ 1.25b and Lambda set
to .85 on 93 octane to get detonation-free on my engine.  That seemed
a little too retarded at first, but considering Todd's experience,
maybe that's just the way it is.

Have you worked much with engines similar to this one?



>You must know the story of ignition distributors then.
>Do you know if there is any mechanical advance system inside
>the factory distributors ?
>
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>Diy_efi mailing list
>Diy_efi at diy-efi.org
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--
Marc J. Reviel

Director of Engineering/CTO
PowerLogix
http://www.powerlogix.com

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