Quiz

[Neal Nurmi]

OK you mechanical types -- what do we have here, and what has happened to it ??

[Pat Carry]

A piston which appears to have become part of an asphalt steet?

[Don Martin]

A little carbon build-up?!

[kmiles]

It is a piston that has gotten a little too hot at some point. The top 2 or 3 rings have been ground down even with the piston, and it looks as if the pieces of ring have been relocated to the top side of the piston.

Would be interesting to see the head/valves from that cylinder.

[Neal Nurmi]

Not quite my understanding of what happened, but I know little...

So what kind of motor, and any more guesses as to what occurred?

[RickH]

Piston that has suffered preignition/detonation. Creates a hi temp piston dome that melts the top of the piston. All that molten aluminum relocates to the cylinder walls which scores the piston, the liner and sticks the rings in the ring grooves. Doesn'take very long to do this once the process has started.

[Neal Nurmi]

Still nobody trying to guess the motor? Here's a "before and after"...

[RickH]

Neal, you have me at a disadvantage as I have never seen a piston out of either an Allison or a Rolls but I would guess that the piston is out of the Merlin.

[Scotty G]

Well, my guess it's a Merlin piston, and part of the valve came off and made a mess of it all. Or some other part got in there to swiss cheese the face of the piston.

[Neal Nurmi]

Rick, it is a Merlin -- destroyed itself during the Gold Race (I think) at Reno 1984. It's from the Mustang racer Mangia Pane (which in Italian apparently means more or less"eats bread" which the owner Tiger Destefani said is what warbirds do).

As I remember after all these years it was explained to me at the time that the motor had essentially swallowed a valve, and that this was the results of the remainder of said valve bouncing around and disintegrating in the combustion chamber.

[Neal Nurmi]

Hello Scotty -- I think we were posting at the same time. Wasn't it on your site that there was a big discussion a couple of years back about Canadian North Star propeller blades being used on Mustang racers? I'd sure like to find and review all that was said about the matter...

[RickH]

Thanks, Neal. I vaguely remember that story.

A piston suffering the effects of the event I described looks a lot like the one in the picture.

[Neal Nurmi]

Well, whatever happened was expensive...

[krlang]

Thats what happens when you put the money into the paint and not the engine!

B-E-R.