Hey guys I really dont understand where is this sound coming from nor what makes it, I would be more than happy if you guys tell me if this ever happened before also the way to fix it, my car is a 2004 subaru impreza wrx. you can see the video on youtube here is the link.
I've heard it on so many cars and it doesn't make me cringe any less hearing it now. jhmason is right. That's definitely a rod knock. I was hoping to give good news as I was listening to the video at idle, and then you revved it and that solidified it. Before you revved it I was going to ask what it was like above idle, but now I know. You have a good opportunity to build the lower end of the motor now though. I had to do it on my STi for a different reason, but I know how it feels. I'm sorry, but I also am happier with what I have now than I ever had before. See below for the link to my build and the disappointments I faced in doing it. I did all the motor pull labor myself, and sent the block to a machine shop for the internal work. All in, my built motor came to $4K. I know that sounds unimaginable, but it was truly worth it to get the bottom end I always wished it had from the factory.
You can likely re-use some of the parts, if they weren't toasted too. The sad fact is that most engine failures come from oil starvation. People new to turbos don't pay quite as much attention to the oil levels unaware of blow by gasses sucking a little of it through the intake as they drive. It's normal to use 1/2 - 1 quart of oil between oil changes, but check it in the meantime and fill it as necessary. If that was the cause in this case, then I would feel most comfortable with new parts for most of the rotating assembly. WagonRacer will have more insight to the build of a 2.0L, as he's done a ton of them. I also have experience with tearing it all down and putting it back together, and I can just tell you to take it a step at a time, and be ready to be without your car for a while.
Its pretty in depth. Fenders, head lights, hood, bumper, bumper beam, grille, and some other misc. parts (then of course paint for everything) to put it all together. The process has been done across years a few times. I think a search on NASIOC or google search would probably neat you a better answer