Very Strange Knock

Hi everybody, I am facing to a problem since 2 days. I am tuning an engine with 8.1:1 Compression ratio with decent duel. On the car we have a gTX3071r 0.63 a/r. Actually we run 1.4 bar of boost 10.5 afr and -2* of spark advance and we heard very loud metal ping in engine bay and even at 30/40m out of the car we can hear it.. We stop accelerating because we think it's knock. But can knock be as loud as this? As the more so as the engine produce a good amount of torque so I'm a bit confuse. I tried to go leaner and richer nothing to do. When I remove more timing the car seem's to have misfire so it doesn't make the noise.

Do you think it's knock or something else?

Thank you very much. May I ask you what lead you to think it's a bearing failure? And can engine knock be so loud?

It's hard to diagnose specifically given the limited information we have to work with. What do you class as 'decent fuel'? What is the octane rating?

Most turbocharged engines I've dealt with that have a low CR such as yours, should be able to handle 1.4 bar boost with reasonable timing (perhaps in the 10-16 degree vicinity), so the fact you're running -2 degrees is worrying for a start. If you advance the timing are you picking up power?

I'd suggest that the noise you're hearing may be something else mechanical inside the engine and I'd recommend you have a thorough examination to find the source before continuing. If you can post an audio clip of the noise then we may be able to help more.

Thank for your answer. Here we have bad fuel but we run with additives to compensate it. So I think we run 95 RON and 85 MON. When we tuned it without additives I thought it was normal to have knock so I retard timing a lot to try to stop this noise. And it seem's that the noise stop If I severely retard it. But when we put some additives I did advance the timing to check and I am picking up power wheel start to slip in 3rd gear even with the noise. I keep thinking that is a bit uncommon that I'm not able to run decent timing with low boost and low CR,t his is why I am having some doubts about knock or not. I am currently trying to make sure that my wideband sensor is not cheating on me (and maybe am I running very lean). If you need more detail I will give it to you with pleasure don't hesitate to ask.

PS: we did compression test on the engine and we have 10.5bar for each cylinder*

PS2: When this knock happen I don't have exessive EGT I am running maybe 700-800°C