so i dropped off my truck at the dyno yesterday and today i get a call saying that he cant add more than 13 degrees of timing at WOT because of pinging.

its a ls 383 with prc 5.3 stage 2.5 heads 63cc combustion chambers, cometic .040 gaskets, flat top pistons, fast lsxrt intake, 57 lb/hr injectors, lt headers and thats about it. if im right my compression ratio should be around 11.2-11.5:1 and on 91 octane i should be ok. now i am running a vette filter on a square fuel rail. would the internal regulator have something to do with this? tuner thinks i installed the cam wrong or i have more compression than i think i do. i installed the cam dot to dot. i am about to set this truck on fire. i need ideas to fix this.

 

What are your full cam specs? DCR (dynamic compression ratio) is a big factor.


Strange that they can't get any more than 13 degrees without and I am guessing they actually here it pinging?

 

What plugs are you running? May need a colder plug. Also, are you using the 99-01 operating system? They are prone to false knock. Is it audible knock?

 

Its audible. Im running tr6 plugs with .035 gap.

 

What air fuel ratio are you running?

 

I have no clue. I was not there when he was tuning

 

Im starting to think its the LSXRT.

 

Make sure you are rich enough at wide open throttle. Might have to run that motor a little on the rich side. Cam specs really do need to be posted as well.

 

228/234 @.588 112lsa

 

the one thing i have noticed is that when it started to ping the throttle was over half open and the intake starts to collapse on itself. im wondering if as its collapsing if its causing a lean condition by leaking by the o-ring between the upper and lower intake parts.