In Turtlekid95's thread some mention LSPI/detonation. This is not correct IMO.
1. Getting detonation/LSPI on high-forced aluminium engines like N55/N20/N63 kills them in a minute. Have an example with a friend of mine that got a piston totally cracked after just one ride on bad gasoline in combination with custom-tuned N20.
2. The sound doesn't come from the engine itself.
Quote:
Originally Posted by stocktree
I say exhaust leak. Put a gopro underneath or near exhaust manifold and go for a ride.
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We were trying to catch it from different points when revving, and it's almost unaudible from around the engine (top, front, sides). The sound is VERY clear from the bottom-right (where the engine mount bracket/turbo/catalytic converter/exhaust are). Initially, we were thinking the sound goes from the right engine mount bracket or so (like catalytic converter gets hot and thicker due to thermal expansion and thus touches the bracket causing this sound). We even wrapped all around the bracket with heat-resistant wrap, that could prevent the ticking - with no luck.
At the moment I'm 99.9% sure that the sound comes from wastegate flap inside of turbocharger.