[911st]

Asked Steve more about timing at idle and here was his response.

Hi Keith,

No problem. You should be able to idle at 5 degrees btdc, and possibly a little higher. Reason is because with such a low compression, and at vacuum and non boost situations, there is very low cylinder pressure relative to a higher compression normally aspirated motor, so the mixture molecules are farther apart, and will burn slower. Slower burns require more advance. Ideally one wants to achieve peak pressure of combustion by 8 to 12 degrees atdc (like pressing down on a bicycle crank at 1:00 for max torque), and the key is to determine how advanced the spark needs to be for the given combustion conditions so that this peak occurs at the right time.

Off idle, you can go up to around 9-10 degrees, and ramp the timing sharply from there to get best throttle response. Hope this helps.

Steve

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911Chips - Porsche Performance Chips and Accessories
911CHIPS - Performance Chip Tuning for the Porsche 911