400 small block horsepower limit

Discussion in 'High Performance Modifications' started by Kermit Compeau, May 26, 2012.

  1. Kermit Compeau

    Kermit Compeau Member

    Jun 28, 2008
    I've got a 400 SBC with what looks like a stock bottom end. I'm looking to pep it up a little bit. Right now its got what sounds like a mild cam, Weiand manifold, shorty headers and a 750 Holley on it. Bought it used so exact specs are unknown.
    What ever, its too mild. I'm thinking of stuffing a few turbos on it, maybe some better heads, and so on. Any ideas on what sort of abuse the short block might take? I'd like to coax 600 hp or so out of it, but I'd hate to grenade it right away.
    I figure 600 hp will be fast enough to make things interesting, but maybe not explosive. Any suggestions for other mods or guesstimates on what the short block might take would be appreciated--Thanks!
  2. hhott71

    hhott71 Veteran Member Lifetime Gold Member

    Mar 30, 2001
    Joplin Mo. 64801
    If you can afford to mess with turbos, you can afford to buy the right parts first.
    Go with a DART block
    Forged crank and H-beam car screw rods
    D-shaped Forged Pistons.
    Roller valvetrain
    AFR large chamber heads
  3. F-Bodypilot

    F-Bodypilot Veteran Member

    ^^ At that HP level,.... what he said ^^
  4. red78z

    red78z Veteran Member

    Sep 12, 2009
    you do realize that you wouldnt really notice the difference between 400 and 600 horses unless youre on a track. Just cruising and driving around town isnt going to give you the time to tell the difference .

    CNC BLOCKS Veteran Member

    Oct 11, 2004
    OEM 400 blocks are a crap shoot at 600 and even at 450 horse.

    I would go with the Dart SHP or the SHP Pro block both are good choices over any 400 block.

    Here is a link to look over.
  6. 5spd540

    5spd540 Veteran Member Lifetime Gold Member

    Sep 19, 2009
    Guyton, GA
    Cant go wrong with a dart block:) :) :)
  7. 71camaroz27

    71camaroz27 Veteran Member

    Jun 23, 2011
    SW Ontario
    How fast do you want to go?
    My stock bottom end 400 (yes short rods) went 11.70 on the motor, and 10.40 on 2 stages of nitrous.
    Dart II sportsman II cast iron heads and a Vic Jr. in my 80 street/strip Malibu.
    Thinking back, I did stud the mains, but it was a cast GM crank, and SPS (ya old school) rod bolts.

    It was alway in the back of my mind... "One day i'm going to scatter this thing", but it ran strong for 3 years.:cool:
  8. Rich Schmidt

    Rich Schmidt Veteran Member

    Mar 27, 2010
    Denville NJ
    I have run stock 400 blocks,cranks and rods making some serious power,like a little over 500 on motor plus a 200 shot. All without fail for hundreds of runs. The down side to 400's is head gasket sealing. With turbos,that will be your downfall. I am talking those power levels with freshly machined/deck blocks and new iron Dart heads,not junky yard stuff.

    So aside from the engine needing to be fresh,or at least in very good condtion,the head gasket seal is going to be the dealbreaker for your turbo setup. You should be able to get a 50% power increase with 8 psi of boost,and thats really pushing it on stock 400 decks and gaskets.
  9. warped

    warped Veteran Member Lifetime Gold Member

    You can get a reliable 500+ hp a lot easier and cheaper if you go with a big block. Depends on what you want to do, but putting together a twin turbo setup will be $$$! Good luck.
  10. strstk71

    strstk71 Veteran Member

    Aug 12, 2005
    Surrey BC Canada
    at the very least O-ring the block to improve the head gasket sealing like you would for nitrous.

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