Quote Originally Posted by nullset View Post
Easier to ignite has nothing to do with the voltage required to break down the air gap of the spark plug.

The plug will spark at whatever voltage is sufficient to bridge the gap, no matter what the 'maximum output' voltage of your coil is, no matter what your compression ratio is, and no matter what your A/F is.
Easier to ignite has everything to do with how wide you set the gap. If you set the gap too narrow on a low compression engine (harder to ignite), you risk misfiring not only because the spark voltage will be too low, but because the flame front will be too small.

It's no historical coincidence that American manufacturers widened their plug gaps at the same time they were dropping compression ratios.

Bill Robertson
#5939