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16-18 degree after TDC

EFI Tuning Fundamentals

Discussion and questions related to the course EFI Tuning Fundamentals

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Yiu said on recap is 16-18 degree after TDC is the maximum torque?

16-18* AFTER TDC is where you want the combustion cycle to finish. ie. The fuel/air mixture in the cylinder is burnt off completely. I believe this number has been formulated as when you go past 18* ATDC the forces from combustion are no longer putting enough force on the piston to provide torque.

You need to start ignition before TDC to try and achieve this.

This is my first time responding on the forum, hopefully this is what you were asking and I was able to explain it properly.

If you are referring to the position of peak cylinder pressure, then the answer is, it depends on a lot of different factors and is only a generalisation. Cam timing, Rod to Stroke ratio, combustion speed and many other things come into play that affect the torque generated.

This is why you are learning to tune on a dyno, where you can measure the torque directly produced at the wheels, and and adjust ignition timing to produce the best possible torque.



You can't measure the actual location of peak pressure without cylinder pressure sensors, and they cost a lot of money.