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  1. #1
    Join Date
    Dec 2004
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    36

    Default Horsepower 383 Sbc?

    How much hp do you think my soon to be finished 383 actually 384.5 cu.in will make?
    Edelbrock Rpm 64cc straight plug heads, Air-gap intake, Holley 750 vacuum sec, Comp cams Xe268r solid roller, 1.52 roller rockers, fully balanced engine, static compression 9.89

    All under 6.27 litres is a starter.


  2. #2
    Join Date
    Feb 2005
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    mo
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    1,343

    Default

    400-430.

  3. #3
    Join Date
    Dec 2004
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    unknown
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    319

    Default

    Quote Originally Posted by 383
    How much hp do you think my soon to be finished 383 will make?
    Edelbrock Rpm 64cc straight plug heads, Air-gap intake, Holley 750 vacuum sec, Comp cams Xe274r solid roller, roller rockers, fully balanced engine, static compression 9.7

    Hmm, I would say 445 to 455 HP. I admit that my 383 solid roller just made a little bit more.. 612 hp with dyno sheet. It is a little more radical than your build, but I had another 383 that had similar specs and it made around 455 hp on the dyno.

    Jeff

  4. #4
    Join Date
    Sep 2004
    Location
    Santa Barbara, Ca
    Posts
    977

    Default

    The dyno in my head says 450 hp

  5. #5
    Join Date
    Sep 2002
    Location
    San Jose, CA
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    1,795

    Default

    I'm guessing in the mid 400's. That is really low compression for that engine setup.
    Are you using dished pistons to get compression that low? With flattop pistons your comrpession should be in the mid 10's
    1971 Camaro, 383 stroker ~500HP,M21 Trans with lightened flywheel. All Sorts of Auto-x Goodness in the Suspension. 12" Brakes ->SOLD

    But ask me about my 2004 STi Auto-x car...

    Just call me Brett

  6. #6
    Join Date
    Dec 2004
    Posts
    36

    Default

    -18cc pistons are used, but the compression is a unknown for me because the engine block has been machined and i dont know by how much. The smallest number possible is 9.7 my is guess: 9.8 - 9.9
    All under 6.27 litres is a starter.

  7. #7
    Join Date
    Dec 2004
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    36

    Default

    The engine made 233 rwhp and 260hp @ flywheel everything is new or in very good condition.

    What´s wrong?
    All under 6.27 litres is a starter.

  8. #8
    Join Date
    Sep 2006
    Location
    New York, NY
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    so you dynoed it in the car and dynoed it on a stand?

    was the carb tuned at the dyno?
    was timing set correctly, does it bog when you drive it?

    need more info on the problem to start guessing.

    Jerome

  9. #9
    Join Date
    Nov 2005
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    RI
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    Somethings wrong. My 388 made 318 rwhp with my crappy exhaust, and I have old school type heads.
    Frank M
    1970 lemans sport
    2004 silverado 4x4 lowered
    http://www.youtube.com/watch?v=SER1gBLn2N0

  10. #10
    Join Date
    Dec 2006
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    346

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    seems off i would of guessed 440 fwhp....????? something isnt right!
    71 nova ss
    was..355 6 speed, in process of 6.0/ls3 head build
    411's
    always under construction....

  11. #11
    Join Date
    May 2005
    Location
    Fontana, CA
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    5,161
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    That thing has some serious issues. Are the springs correct to the cam? What about timing? Carb adjustment? Check the ignition system including full 14 volts to the coil (this is VERY important). What size exhaust and headers are you running?
    Nick R.
    69 Camaro - 383, 700R4, 12 bolt 3.55, Hotchkis, Bilstein, Global West, Morris Classic
    08 HHR SS - Still Stock for now
    Do you still believe in all the things that you stood by before? Are you out there on the front lines, or at home keeping score?
    Do you care to be the layer of the bricks that seal your fate? Would you rather be the architect of what we might create?

  12. #12
    Join Date
    Jul 2007
    Location
    ventura ca..
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    37

    Default

    yo ponch i think your heads are robbin ya..

  13. #13
    Join Date
    Jul 2007
    Location
    ventura ca..
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    37

    Default

    and for 383 , is vacuum secondarys workin go double pump 750

  14. #14
    Join Date
    Nov 2005
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    RI
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    Josh they are prob hurting a little but they have been ported and polished by a very good machinist. I just bought 1-3/4 headers and 3" oval x-pipe, my exhaust is def killing it. I'll dyno it in a month or so but at least I'm in the 12's (on street tires) Hey 383 I would check your timing and if your vacuum secondries are opening like others have said.
    Frank M
    1970 lemans sport
    2004 silverado 4x4 lowered
    http://www.youtube.com/watch?v=SER1gBLn2N0

  15. #15
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    Jan 2003
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    Jacksonville
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    Quote Originally Posted by 383
    The engine made 233 rwhp and 260hp @ flywheel everything is new or in very good condition.

    What´s wrong?
    I'm sorry to hear that. Never guess at compression. Start here:
    http://www.rosspistons.com/calculator.php?Units=English

    If you don't have all the answers to fill in the blanks--get them from your piston manufacturer/engine builder.

    From there check the stupid stuff first--starting with a check for wide open throttle. At 9:1 with a good hydraulic cam and a 170cc runner head (which is what you have), you should be able to generate 1 HP per cube. 10:1 (which I don't think you have), 200cc heads and a roller, you should be able to generate 1.15-1.2 HP per cube.

    At 260HP something should have appeared very wrong on the dyno if you have a problem such as ignition timing, ring seal, bad cam lobe. Lazy, "popping/farting/banging", smoking, nosing over, etc. Any of that happen?
    _____________________
    Steve Chryssos
    Twist Machine

  16. #16
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    Jul 2005
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    Mountain View, CA
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    Another thing to check would be the degreeing of the cam.
    True T.

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  17. #17
    Join Date
    Dec 2004
    Posts
    36

    Default

    Nope, the car and engine runs like a dream and the carburator is tuned with broadbandslambda. The valvetrain is the correct one for the cam, exhaust size: 1.5/8 to a dual 2.5" pipes. 13.5volts to the Hei distributer.

    So probably there must have been something wrong with the dyno itself.
    All under 6.27 litres is a starter.

  18. #18
    Join Date
    Dec 2006
    Location
    Massachusetts
    Posts
    193

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    Your engine specs are not too far off from mine and I made 502 HP on pump gas at 5900 RPM. Also made 495 Ft Lbs at 3400 RPM.

    You can see the dyno printouts on my website if you are interested.
    -Morgan
    www.hwimotorsports.com
    '68 Camaro SS vert
    '10 Camaro SS/RS
    '91 GMC Syclone
    '60 Impala

  19. #19
    Join Date
    Dec 2004
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    36

    Default

    The printouts looks exactly like mine, strange. My peaktorque was at 3300 and peakpower at 4930 but with totally different numbers.
    All under 6.27 litres is a starter.

  20. #20
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    Jan 2003
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    Jacksonville
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    Well if it's running smooth, then I'm concerned that your compression is way off. Maybe they shipped you a set of 72cc heads? Should be easy enough to confirm based on part number. Might be cast into the head under the valve cover. 72cc plus -18cc dish plus your healthly cam would give you very low static compression and dismal dynamic compression.

    If the heads are right then worst, worst case scenario, you have 9:1 which should still make 100HP more at the flywheel. Your engine and chassis numbers are in line for the most part, so I would keep digging for an answer.
    _____________________
    Steve Chryssos
    Twist Machine

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