ORIGINAL: yallaair
This definitely appears to be compressive overload damage...
Or limited lubrication... Non bushed conrods need better lubrication. The conrod has definitely been overheated. You can see the black varnish from carbonized oil. This overheating can be a result of compressive overload together with bad lubrication. I have never seen carbonized oil on conrods at normal operating temps before.
That is exactly what my MVVS .15 diesel looks like. i ran it quite a bit when I started the hobby. I never thought I ran it over compressed, but it did run it with a tuned pipe on it. Being so long ago I'm not sure. I had black carbon near the small end of the rod. Aluminum gets soft when it gets hot, so I think that is the main cause.