When is 108 not really 108?

Because in the engine.... its really (2x 108)= 216, and 112 in the engine is really 224,Lobe separation angle, Although its the physical easily visual "cut" of the cam, but in the engine its real definition is the degrees between peak lifts of the Exhaust and Intake lobes.

I was always vexed why are cams described by lobe separation angle, When the cam only turns 1/2 the crank speed.

Everything else on a cam is measured in terms of Crank duration.

This all came about when I was trying to describe how these "Thumper" , or "poser" cams actually work. They have a physically "tight" peak to peak Separation angle...but that specific exhaust ramp opens early off the seat but slowly, or not really enough to impact part throttle drivability.

Also what I think a lot of people might not visualize fully is that with a roller cam...the actual measured "PEAK" lift of the valve can 'Dwell' very close to peak for several degrees. So with asymmetrical ramp design the physical or Mechanical "peak to peak" is not nearly as critical to power and drivability as the intake closing and exhaust opening ramps leading to overlap. so the lobe spread and it's effect on idle and drivability is really more about the flanks of the lobes rather than the nose.

Anyway....I just thought it was interesting to ponder, I for one find it much easier to visualize the intake ramp opening and closing (and it's effect on power) than I do the exhaust, I often have to calculate just to visualize just how far off the seats the valves are during the full duration of overlap. And since overlap is the Closing ramp of the exhaust, I'm intrigued to know more about determining how and when you begin to open the exhaust valve impacts power and cylinder evacuation.