Why has my engine let go?

[dangerous dave]

I wasnt suggesting that the "spirited" drives had anything to do with it. I was just stating that it happen 2 weeks after the work was done and after little use.

You should be able to do 5 years of track days and 70k or some sh1t...

Not 2 months..

Sounds like you got turned.

 

[MicKPM]

The crank will only slip the position if:

• The fixing tension is incorrect (eg. Bolt stretches and fatigues due to over tightening OR isn't capable of holding due to not enough torque).
• The rotation of the engine components is in someway halted (Foreign object in the belt run or valve/piston interference).

The same is true for the camshaft fixings which is why it is imperative that ALL fixings be replaced and NOT reused... EVER! I know some places that re-use them and get away with it but then others, like in this example, have and didn't. There is no way the crank should've spun thru normal use or even track abuse!