Close

Page 3 of 3 FirstFirst 123
Results 51 to 54 of 54
  1. #51
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    117,699
    Rep Points
    31,533.4
    Mentioned
    2064 Post(s)
    Rep Power
    316


    Reputation: Yes | No
    Click here to enlarge Originally Posted by onurleft Click here to enlarge
    The cut off for C-Mod is 3.49 liters. So the guys actually spending more $ on built S54's (there's a bunch of them) than pristine E9x M3 go for "could" go larger with ease but no BMW CCA rule book allows it for what they are using it for
    Very interesting, thanks.

  2. #52
    Join Date
    Mar 2013
    Posts
    68
    Rep Points
    45.6
    Mentioned
    1 Post(s)
    Rep Power
    0


    1 out of 1 members liked this post. Reputation: Yes | No
    Click here to enlarge Originally Posted by PEI330Ci Click here to enlarge
    Mert,

    It's not the block that's the issue really...it's the crank. Running that much stroke with OEM rods would see the wrist pin smashing into the counter-weights. The only way to make it work is to run a longer rod...but then the pistons would smash into the head at the stop of the stroke. Thus my comment about changing the deck height. It's possible... you just need to run a spacer on the top, sleeve the block, and run a custom timing chain.

    FYI, PTG (With BMW Motorsport's involvement) only went to 3.4L. They were running an intake restrictor thanks to the ACO, (Sanctioning body) which from a design perspective favours a bigger engine. Why do you think Chevy went with a lower rev'ing 7.0L V8 for their Le Mans Corvettes.....

    My preference with an FI S54 would be to create more plenum pressure. Once you reach the choke limit of the head with port velocity, the only way to make more power is to change the density of what's flowing through the head. (More boost)
    being an inline 6 surely there is some flexibility in the counterweight radius and still being able to achieve a proper balance?

    for instance i know there is a M52B28 crank with bigger counterweight radii than the M54B30

    also for the NA guys a compression height south of 25mm is possible and there are nice fancy coatings and treatments for pistons which might allow you to sneak below this by a few mm.

  3. #53
    Join Date
    May 2010
    Location
    PEI, Canada
    Posts
    1,123
    Rep Points
    1,665.0
    Mentioned
    30 Post(s)
    Rep Power
    17


    Reputation: Yes | No
    Click here to enlarge Originally Posted by digger Click here to enlarge
    being an inline 6 surely there is some flexibility in the counterweight radius and still being able to achieve a proper balance?

    for instance i know there is a M52B28 crank with bigger counterweight radii than the M54B30

    also for the NA guys a compression height south of 25mm is possible and there are nice fancy coatings and treatments for pistons which might allow you to sneak below this by a few mm.
    I don't dispute any of that, but the question is: Is any of this practical for a street car?
    Rep Points > Posts since 2010

  4. #54
    Join Date
    Mar 2013
    Posts
    68
    Rep Points
    45.6
    Mentioned
    1 Post(s)
    Rep Power
    0


    Reputation: Yes | No
    Click here to enlarge Originally Posted by PEI330Ci Click here to enlarge
    I don't dispute any of that, but the question is: Is any of this practical for a street car?
    which part is not practical? Metric mechanic kits use a compression height of 23.4mm with their 3200 M20 engines many of which are driven on the street for many miles. i have also seen a few people machine the counterweights on the M52 crank to clear stock piston skirts . my comment was more raising the issue as to what can and cant be done realistically if maximum cubic inch is the goal.

Page 3 of 3 FirstFirst 123

Tags for this Thread

Bookmarks

Posting Permissions

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