Results 1 to 4 of 4

Thread: Knocking in 4th

  1. #1
    Member
    Join Date
    Jan 2008
    Posts
    56

    Default Knocking in 4th

    Anyone have any recommendations for some knock I'm getting in 4th gear? I was at the track last Friday and all four 1/4 mile runs had knock starting at 4900-5000 RPM. Knock varied between 1-4 degrees. Attached is a log from one of the runs. Should I...

    a) Lower base timing (currently at 20 degrees)
    b) Reduce timing based on IAT
    c) Increase fueling (already well under 12:1)
    d) Check for plug fouling and proper gap
    e) Use colder than NGK TR6 plugs
    f) Get water/alcohol injection to reduce IATs
    g) All of the above

    Thanks in advance for any advise!

    Dan
    Attached Files Attached Files
    Last edited by white01ss; June 16th, 2008 at 08:06 AM. Reason: updated base timing
    2001 Camaro SS
    Built 370 LQ9, Ported 243s, D-1SC 14 psi. 691 rwhp, 643 rwtq
    Best time: 11.6@124 on nitto drags with a 2.1 60'
    "if you're gonna build a time machine into a car, why not do it with some style." Dr. Emmett Brown

  2. #2
    Joe (Moderator) joecar's Avatar
    Join Date
    Apr 2003
    Posts
    27,836

    Default

    Also try:
    - reducing plug gap a little,
    - make sure PCV plumbing is not pulling oil.

    I'll be able to view your log when I get home tonite.

  3. #3
    Member
    Join Date
    Jan 2008
    Posts
    56

    Default

    Quote Originally Posted by joecar View Post
    make sure PCV plumbing is not pulling oil.
    Got that one covered already. It was initially installed with PCV going to the inlet hat on the supercharger (per ATI's instructions), but that was sucking in engine oil. Caught it pretty early and now I have all PCV lines going into a single AMW catch can.

    Even after adding the catch can, the dipstick continues to pop up after hard driving which indicates there's still too much crankcase pressure. Maybe I need a can for each side or just a real big one to handle the blow by? Would an LS6 breather setup help?
    2001 Camaro SS
    Built 370 LQ9, Ported 243s, D-1SC 14 psi. 691 rwhp, 643 rwtq
    Best time: 11.6@124 on nitto drags with a 2.1 60'
    "if you're gonna build a time machine into a car, why not do it with some style." Dr. Emmett Brown

  4. #4
    Member
    Join Date
    Jan 2008
    Posts
    56

    Default

    I'm going to try a combo of a, b, and e. I got some colder plugs (TR7IX) because it couldn't hurt and the worse that could happen is they foul a little quicker. Lowered base timing almost a full degree and increased the effect if IAT based retard.

    I talked to a tuner from the shop I bought the kit from and he said to use race fuel and/or back off the timing. Also, adding a alky/meth injection system would also lower combustion chamber temps and raise octane. He says the cause of the knock is a combination of high combustion chamber temps that goes up as you bang though the gears and increased load.
    2001 Camaro SS
    Built 370 LQ9, Ported 243s, D-1SC 14 psi. 691 rwhp, 643 rwtq
    Best time: 11.6@124 on nitto drags with a 2.1 60'
    "if you're gonna build a time machine into a car, why not do it with some style." Dr. Emmett Brown

Similar Threads

  1. Knocking at WOT...is it headers?
    By goldbergv95 in forum LL8 4.2L In-Line 6 - P10 PCM
    Replies: 15
    Last Post: March 28th, 2011, 04:03 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •