Where can I get ignition map sample ?

[Axel Rietschin]

With 8.8:1 CR and 98 RON fuel, the timing is like 16 to 18 degrees BTDC -
depending on engine speed - at 15 psi, and 14 to 16 degrees at 20 psi
(numbers taken from an actual engine). This is just to give you ballpark
numbers. Using a lower CR and/or higher octane fuel will usually let you use
a few more degrees of spark advance. As said already, the ignition map is
completely engine-dependant. You must put your engine on an engine dyno to
properly map the ignition as high speed knock can absolutely not be heard
from inside the car and will destroy your engine within seconds, as you
unfortunately found out already. Also, your fuelling has to be on the rich
side, like 0.88 at 15 psi and 0.86 at 20 psi and up, your air charge
temperature must stay below 40 degrees C, possibly with the help of a bigger
intercooler, and you may want to consider using a water injection system to
help eliminate knock.

HTH,
--Axel

----- Original Message -----
From: "Axel Rietschin" <axel_rietschin at compuserve.com>
To: <diy_efi at diy-efi.org>
Sent: Monday, January 15, 2001 6:16 PM
Subject: Re: Where can I get ignition map sample ?


Tyson,

What is your compression ratio?
What fuel are you using (octane ratio)?

--Axel



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