Results 1 to 4 of 4

Thread: Supercharging with AFM

  1. #1
    Lifetime Member
    Join Date
    Sep 2007
    Posts
    214

    Default Supercharging with AFM

    Can anyone tell me how this works? Not finding information on it anywhere. I'm having a problem understanding how a positive displacement supercharger works with AFM, considering the supercharger pushes X amount of air into the intake with each revolution of the engine. When AFM cuts the engine in half, it seems to me like the active cylinders are now taking the same air meant for 8 cylinders, which should increase those cylinder's compression by quite a bit. GM sells the LT4 with AFM active, and they seem to make it work.

    So, how are they making AFM work without screwing the engine up? I'm in the initial planning stages for a 5th gen LT1 based 427, and I may at some point want to supercharge it and if I do I plan to keep AFM active. I know a lot of folks don't like the system but I do.
    Last edited by Telco; November 18th, 2019 at 03:01 PM. Reason: Corrected a mistype

  2. #2
    Lifetime Member
    Join Date
    Mar 2009
    Posts
    746

    Default

    If you're light enough on the throttle to be in 4 cylinder mode, you're surely light enough for the supercharger to be bypassing. I'm guessing this is enough?
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

  3. #3
    Lifetime Member
    Join Date
    Sep 2007
    Posts
    214

    Default

    I guess that could be. Wish I knew more about forced induction. But, I was under the assumption that a PDSC displaces X amount of air per revolution regardless of how many cylinders are opened, so cutting them in half would mean that double the air is being forced into each cylinder.

  4. #4
    Lifetime Member
    Join Date
    Mar 2009
    Posts
    746

    Default

    Quote Originally Posted by Telco View Post
    I guess that could be. Wish I knew more about forced induction. But, I was under the assumption that a PDSC displaces X amount of air per revolution regardless of how many cylinders are opened, so cutting them in half would mean that double the air is being forced into each cylinder.
    The amount of air the blower would be pushing is nil for 2 reasons: 1 the throttle is barely opened at all and 2 the bpv would be open.
    1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
    1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
    2004 Corvette Z06 with longtubes.

Similar Threads

  1. Help tuning out AFM?
    By horsehaulin in forum Gen IV V8 Specific
    Replies: 60
    Last Post: June 29th, 2017, 09:11 AM
  2. stupid afm engines
    By turbo in forum Gen IV V8 Specific
    Replies: 5
    Last Post: January 26th, 2013, 07:35 PM
  3. E38 Tune, help with AFM
    By Brads_rs in forum E37, E38 & E67 PFI ECM's
    Replies: 2
    Last Post: January 25th, 2012, 01:23 AM
  4. 2010 5.3 AFM tuning
    By CDN SS in forum Petrol / Gas
    Replies: 0
    Last Post: April 7th, 2011, 06:31 AM
  5. 07 Tahoe with AFM
    By kkmboise in forum E37, E38 & E67 PFI ECM's
    Replies: 0
    Last Post: February 18th, 2011, 03:35 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
  •