The car is an Evo 6, with forged internals 2.0L, E9 80 series turbo, RC 750cc injectors.
I had previously tuned the car on 93oct fuel. Using an MBC, boost was set at max of 27psi which would taper down to 21psi. The car ran great & everything was perfectly fine. Then the car suffered thrust bearing damage, & we had to disassemble the engine to install new thrust bearings. We thought it would be better to also install a new crankshaft & also, new sets of main & con rod bearing.
Now, post the above repairs, the car is knocking like it never did before, showing 4-6 consistent counts at peak boost, 5000-6500 rpm. Strangely the knock is very audible from within the cockpit, it's so loud I never heard an Evo knock that loud.
I tried the following to remedy the knock to no avail:
-Decreased ignition timing to stock like figures & then even lower until reaching figures like 1 - 0 - -1
-Enriched AFR, to 11.5 mid range (4000-6000) & 11.3 beyond 6000.
-Got 93 fuel from different gas stations.
-Changed spark plugs.

Now, I'm not sure what to try next! I'd appreciate your suggestions

 

Here is what I suggest Sir.
Check physical timing of cams.
Verify timing with timing light with 10* in the idle to 2000 range of timing map on a warm engine.

Check the part number of your pistons to verify compression

Change oil cooler ( if you have one) if you haven't already, If the bearings went bad it will spread metal contamination into everything. It is impossible to clean.

Gap plugs to .020-.024, one step colder then stock

Check coil/wires for voltage and arching.

Check for exhaust leaks pre 02 sensor. If you have a leak the sensor will read leaner then what is really going on.

Check wideband

Check boost level

If everything checks out you may need to add timing to get it to run clean. Start at stockish levels and add a degree. Some engines need timing to run and not knock.

If your fuel is like US 93oct then it should take 1-3* before 5000rpm and then a degree added a few hundred rpm getting to 11-15 out the top.
You can also try 11.3afr once boost is over 15psi . There isn't much power difference in 11.3-11.5 so the fuel can keep the chamber cooler and help to avoid knock

Good luck with it.

 

balance shafts still in there

 

Balance shafts were removed, but it's no phantom, I could hear knock loud & clear!
The cams are 272 Brian Crower, with new BC valve springs, but with stock cam gears.
Pistons are Wiseco, 9.5:1 CR
Brand new 8-heat Iridium spark plugs, gaped at .020
I don't dare to increase timing at this point as it knocked like crazy when I increased timing to near stock levels!
I will check the following:
timing with a timing light
Coil/wires
valve springs
I can enrich AFR as Abcaus suggested & it's likely to help reduce knock, but the thing is that the car never had this issue prior to replacing the camshaft & bearings!
It's like searching for a needle in a hay stack! I'm also considering replacing the entire wiring harness!
I'd appropriate any further suggestions

 

have you tested a different knock sensor?

 

Assuming the build was done correctly I would put race gas in it and see if the knock disappears. I would also try to locate where the noise is coming from. you could use a 3 foot garden hose to see where it is coming from then open the motor up and see what you find in that area where the noise is coming from.

 

Mine was bad, is why I ask. Start with the simple stuff first.

 

Short of it being the knock sensor, or something in the tune. BC cams are known to be loud..

 

You need to determine if the knock is :


1.) PHYSICAL
2.) Chemical
3.) Phantom.


Since you can HEAR the knock (which is horrible) then we know it isn't #3. If you couldn't hear it we would still do the next step to remove that from the list.


That leaves 1 or 2.
You can remove #2 by draining your tank, and filling with 100+ octane, and pull timing on your map. If the car STILL knocks then it is physical knock What is physical knock? Something is built wrong (set timing) or broke (something slapping loosely) with your engine. So something is making that noise that you and the computer are hearing as knock. Use a LONG thick screwdriver to listen on different parts of the head/block and try to figure out where it is coming from. (if you can recreate without load).
Sounds to me like it is #1, but I am guessing.

 

could it be your downpipe since the build is touching the engine at certain speeds?

 

I missed the part where you said you could hear it. That's odd, but narrows it down.
You most likely have metal hitting metal. Good advice in the posts above.

 

Rod or main bearing?

 

redo the rotating assembly, check clearance of the bearings, piston ring gaps, crank end play. Also with the new crank did you get it balanced?

 

Thanks for all the feedback, the knock is real, I have no doubt about it as it has that distinct sound.
I examined engine compression & found that cylinder #4 has lower comp than the rest, I removed the head & found a leak in one of the valve guides. I'm now replacing that guide. The question is: would such variation in engine compression cause such abnormal knock as I described in my first post?

 

you won't hear knock from low compression. and it's not rod knock? no metal in the oil pan?