So in a fit of paranoia, I got a spare B20f head from the junkyard. It was cheap, and right there. But dang, heavy! I've never pulled a B20 head before...
And I noticed something right away- where the valves pocket into the edges of the head, the pocket extends right up to the edge of the cylinder.
From working on other engines, I've come to expect a ring around the head, right at the edge of the cylinder. The books call it the 'squish' zone, a ring that almost touches the piston at TDC to push the flame front away from the sharp edge of the cylinder- to- head interface. In fact, they make a pretty big deal about it...

So what's the deal? Where's the squish?

What does this mean for Seb and me, looneys who're turboing our old pushrod lumps? Are we gonna detonate for days?

Inquiring loonies are wondering... maybe the B21FT makes more sense after all...

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