RPM Related knock

[Mad_Trbo]

I've been experiencing knock that I think is actually phantom knock. Based on the logs I have been running over the past year I note it comes on @ 5500 RPM.


RPM: 5500 - 6000
Fuel: 93 octane
Boost: 18lbs
Timing: 21 degrees

I think it is phantom knock because I retard timing and I still see the knock. I have retarded timing to as low as 15 degrees and I still see the knock. I am using XFI and the knock count is as high as 10 for whatever that means to most. In my book this to high.

Question, where should I start to look for my issue.

 

[ijames]

The best way to prove the knock is mechanical is to put in some 104 octane unleaded. What valve springs, how old are they, what rocker arms - any chance they are just touching a valve cover at peak rpm? Anyway, valvetrain is where I would start looking, from lifters to valves and everything in between. Hmm, any chance the timing chain is touching something inside the front cover when you wind it up?

 

[Mad_Trbo]

James -

Thanks for the reply - turns out like an idiot I was making a change to my spark map and for some reason it wasn't uploading.

I found the knock was coming on to excessive timing advancement @ 6k RPM. What I did was I retarded timing to 18 degrees from 5700 RPM through 6500 rpm .

FRI Rockers are Harland Sharps and the springs are a heavy duty comp series provided by Weber Racing with no more than 3k in miles on them and not severe duty.

Thanks again for the reply!