Why does the spark advance value only increase by maybe 10 degs from idle to 3000 (even on stock setups) when actual distributors have 15-24 degs of advance?
Required spark advance is a complicated subject, especially when you the program tries to predict when detonation will occur. A/F distribution, thermal gradients (differences) across the heads, pistons, etc, combustion chamber design, are just a couple of things the program must make assumptions about. Then we have the factory, which has many different things to consider than just detonation and best power, things like: lighting off the catalysts fast, max catalyst temperatures, transient response, knock sensor calibration, cold start strategies, warranty, transmission durability, etc, etc. That the program does not match the factory calibration is not surprising. Just a note, idle at 700 RPM is a very different condition than full throttle at 700 RPM, both requiring very different spark advance. Idle or some part throttle conditions may want up to 50 degrees of spark advance. Because of the light load and possibly EGR it may not detonate. But the same RPM at full throttle may only be
