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1967 383 'Commando' vs 'Super Commando'

Discussion in 'Mopar General Discussions' started by 69 Cuda 440, Feb 8, 2013.

  1. 69 Cuda 440

    69 Cuda 440 Legandary Member Legendary Member

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    1967 Mopar 383 'H-Code'

    Plymouth Barracuda - 383/280 HP 'Commando 383'
    Plymouth Satellite and Belvedere - 383/325 HP 'Super Commando 383'

    Also,
    Dodge Dart GTS - 383/280 HP - '383 4-Barrel'
    Dodge Charger and Coronet - 383/325 HP - '383 4-Barrel'

    One in the same, except for Exhaust Manifolds and Exhaust Piping.

    All engine specifications were the same,
    * Piston Compression
    * Cylinder Head and Valve Size
    * Camshaft
    * Valve Train
    * Intake Manifold
    * Carburetor
    * Ignition

    The only difference was in the exhaust system. Was that truly a 45 Horsepower variation.

    Based on tests on the 1967 A-Body exhaust system, it was obvious that the restriction in both
    exhaust manifolds, and bends in the small diameter exhaust piping limited flow, resulted in
    a 'net loss' of approximately 15 Horsepower and 400 RPM's compared to the 383 in the B-Body.


    Barracuda...........Satellite & Belvedere...Dart GTS & Coronet
    [​IMG] [​IMG] [​IMG]
     
  2. 1970Duster

    1970Duster Well-Known Member

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    Yes the original exhaust was restrictive, nothing a set of good headers and bigger (oh say 3") exhaust pipes can't fix :twisted:
     
  3. 69 Cuda 440

    69 Cuda 440 Legandary Member Legendary Member

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    Yes, definitely restrictive, but -45 HP less than the 383/325 HP
    Big-Body 'Super Commando'.

    No, Chrysler overrated the 383/325 HP 'H-Code' by a big amount.

    Here is what the NHRA 're-factored' the 383 engines to back in the 1990's,
    with the stock exhaust system.

    A-Body
    1967 - 383/280 HP...........255 HP
    1968 - 383/300 HP...........280 HP
    1969 - 383/330 HP...........294 HP

    B-Body
    1967 - 383/325 HP...........270 HP
    1968 - 383/330 HP...........283 HP
    1969 - 383/330 HP...........283 HP

    Road Runner, Super Bee & Charger
    1968 - 383/335 HP...........302 HP
    1969 - 383/335 HP...........302 HP
     
  4. 69 Cuda 440

    69 Cuda 440 Legandary Member Legendary Member

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    Teak,

    NHRA calculated the 1967 383/280 HP in an A-Body with 'stock exhaust' and de-jetted
    Carter AFB (575 CFM) - to a correct 255 Horsepower at 4200 RPM's.

    The same 383 in the B-Body, with the better flowing exhaust manifolds and
    'intermediate' exhaust pipe system was calculated to come in at 270 HP at 4600 RPM's.

    1967 383 B-Body, Right Side Exhaust Manifold #2532464
    [​IMG]

    1967 383 A-Body, Right Side Exhaust Manifold #2863900
    [​IMG]

    1967 383 B-Body, Left {Driver} Side Exhaust Manifold #2532626
    [​IMG]

    1967 383 A-Body, Left {Driver} Side Exhaust Manifold #2899002
    [​IMG]
     
  5. 69 Cuda 440

    69 Cuda 440 Legandary Member Legendary Member

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    Teak,

    Found the 'performance results'

    March 1967

    1967 Plymouth Barracuda 'Fastback' 383/280 HP 'Commando 383'
    3.23 Gears, w/Automatic Transmission
    #3202 lbs ~ 280 HP = 11.44 Wt/Hp
    Performance = 15.40 @ 92 MPH

    1967 Plymouth Satellite 383/325 HP '383 Super Commando'
    3.23 Gears, 4-Speed
    #3480 lbs. ~ 325 HP = 10.71 Wt/Hp
    Performance = 15.70 @ 91 MPH
     
  6. kerryike

    kerryike Active Member

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    Any idea how the A-Body could be rated higher in 1969?
     
  7. 69 Cuda 440

    69 Cuda 440 Legandary Member Legendary Member

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    Yes,

    The 1969 A-Body 383/330 HP came through with,
    * Improved Exhaust Manifolds
    * Improved Exhaust Piping
    * The 68' and 69' 383 Engines had a positive piston deck height
    * #2843906 Cylinder Heads with 2.08" Intake and 1.74" Exhaust
    * Improved Intake Manifold
    * Carter AVS Carburetor (625 CFM)
    * The 440 Camshaft and Valve Train

    The 1969 B-Body 383 Engine (non Road Runner, Super Bee and Charger) had all of the
    above, except did not have the 440 Camshaft or Valve Train.

    Yet, the Horsepower ratings from the factory were both the same 330 HP, yet the
    NHRA did not agree with their adjusted numbers.

    If you look at the numbers, the 1967 B-Body exhaust system was a +15 HP improvement over the 1967
    A-Body exhaust system.

    In 1968, with exhaust system improvements - the A-Body was still -3 HP short of the B-Body 383
    exhaust system output.

    In 1969, the A-Body 383 was now equipped with the 440 Camshaft and Valve Train, which increased
    Horsepower by +14 HP over the Stock 383 Camshaft and Valve Train.

    383 Camshaft and Valve Train
    .425 Intake /.437 Exhaust ~ 256/260 Duration ~ 32* Overlap
    Valve Springs = #134 lbs. Valve Closed / #208 lbs. Valve Open

    440 Camshaft and Valve Train
    .450 Intake / .458 Exhaust ~ 268/284 Duration ~ 46* Overlap
    Valve Springs = #129 lbs. Valve Closed / #280 lbs. Valve Open

    Note; The NHRA lists the 440 Camshaft at .455 Intake / .470 Exhaust
     
  8. 69 Cuda 440

    69 Cuda 440 Legandary Member Legendary Member

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    Teak,

    The exhaust piping for the 1967 383 B-Body.

    Primary piping................2.25"
    No flat spots in piping
    Tail Pipe.......................1.88""
     
  9. 69 Cuda 440

    69 Cuda 440 Legandary Member Legendary Member

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    Teak,

    If you look closely at the undercarriage of a 1967 383 'A-Body' exhaust system, you can see
    the bends in the 'L-Angle' coming down from the exhaust manifolds.

    The primary exhaust pipe had a listed size of 2.25", but those bends 'crushed' exhaust flow.

    It was like jamming a 'half-a-potato' into the primary exhaust pipe.

    [​IMG]
     
  10. 69 Cuda 440

    69 Cuda 440 Legandary Member Legendary Member

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    Teak,

    A better view of the 1967 A-Body 383 exhaust piping.

    [​IMG]