[solarguy]

I had a 1962 VW beetle, the original air-cool horizontally opposed 4 cylinder boxer engine. It had a lot of miles. One day I'm driving along, and the engine suddenly makes this horrendous banging sound for about ten seconds. Then the horrible noise quits, but the engine runs very rough.

The top of the piston basically broke off at the ring groove, and the main part of the piston, hammered the piston crown up into the chamber until it couldn't hit it any more. This had several effects:

1. No pumping losses, since the top of the piston is effectively missing.
2. Less balance problems than the OP is considering. Just the top of one piston is "missing", not entire pistons and rods.
3. In 1962, there were no monitoring electronics or computers, just a carburator.


The original engine made some pathetic low number of horsepower, like 50, and with the one cylinder deactivated, it could barely get out of it's own way. And the vibration, particularly at certain speed was...ominous.

I drove it that way for a couple months while I built a new engine. I don't recall any improvement in FE.

troy