(Teacherjh) wrote
Thanks... now why are separate cylinders a disaster?

Because the engine comes out either too heavy or not rigid enough.
The engine block provides rigidity. Separate cylinders provide none -
they just hang out there by themselves.

Insufficient rigidity is the cause of many ills. For example, if you
manage to crack the block on an engine, it will still continue to make
some power for at least a few minutes. Crack a cylinder, and you can
easily jam the piston/rod and seize the engine. Does that really
happen? Yes, I've lost friends that way.

Insufficient rigidity also contributes to valve/seat/guide problems.

Note that NONE of the new aviation engines (Orenda, Thielert, Honda,
Bombadier) have separate cylinders. No automotive engines do this
either. In fact, ONLY obsolete aviation engines do this.

The reason? It's a rare aviation cylinder, especially on a big
engine, that is built well enough to make TBO. The quality assurance
process mandated by the FAA is a bad joke, and in fact keeps
manufacturers from being able to improve the process.

Michael