Dear collegues, I am interested in this engine, but I am worrying, what can knock there from 0:33 sec. on the video? What it looks like?
Thank you.

 

Well, cranking it up to 7g's isn't helping it...but that reserve tank seems to be showing a sign of a possible head gasket. It appears you had it running awhile prior to making this? ...I'd be wary and find something better.

 

Have you poked at some bits with a stethoscope? I know sometimes the injectors can be a bit loud on these, but I don't think that's the sound in the video

 

Furthermore, revving the engine so high in P or N risks burning one of the gearbox clutches (ZFs are notorious for this). One should stay below 3,000 rpm is such cases and do it briefly only. The supercharged engines with MB gearbox have a limiter at 3,000 rpm when in P or N for this reason. I am surprised that the NA with ZF do not have it.