500 lb-ft 460 hp HT383 in Hot Rod Magazine!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 71RestoRod, Jan 26, 2002.

  1. 71RestoRod

    71RestoRod 1/2 ton status

    Mar 7, 2001
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    Evergreen, CO
    I always thought that the HT383 would be a killer platform to build from. The March issue of Hot Rod does a step-by-step build-up of the HT383, taking it from the stock 325 hp & 415 lb-ft all the way up to 460 hp and 500 lb-ft w/ little more than a Comp Cams Extreme Energy cam and 1.6:1 rockers. It’s a great article if you are thinking about one of these engines…

    I know that you can play a dyno to get the answer you want…and you have to compare apples to apples… but starting w/ baseline numbers similar to those advertised… check it out…

    Starting w/ stock HT383, 650 cfm Road Demon, budget HEI and Hedman Tork-Step headers: (basically stock out of the crate setup)

    PEAK HP: 338 @ 4,400
    PEAK TORQUE: 444 @ 3,400
    AVG HP 2,500-4,800: 293
    AVG TORQUE 2,500-4,800: 424
    TORQUE @ 2,500: 431 lb-ft

    Then they added 1.6:1 rockers to bump the stick from the stock 0.431/0.451 to 0.459/0.481 and let it breath a little more:

    PEAK HP: 355 @ 4,700
    PEAK TORQUE: 452.5 @ 3,500
    AVG HP 2,500-4,800: 300
    AVG TORQUE 2,500-4,800: 434
    TORQUE @ 2,500: 436 lb-ft

    Swapped in an Edelbrock Air Gap (Vortec):

    PEAK HP: 370 @ 4,600
    PEAK TORQUE: 467 @ 3,700
    AVG HP 2,500-4,800: 310
    AVG TORQUE 2,500-4,800: 447
    TORQUE @ 2,500: 443 lb-ft

    Bumped the carb up to a 750 cfm Speed Demon, jetted it...:

    PEAK HP: 380 @ 4,600 <= yowser
    PEAK TORQUE: 474 @ 3,700 <= yowser
    AVG HP 2,500-4,800: 316
    AVG TORQUE 2,500-4,800: 456
    TORQUE @ 2,500: 450 lb-ft <= yowser

    Ultimately they went further than I would go with it, but very cool for the money nonetheless: Comp Cams XE282HR w/ springs, trimmed the valve guide height & kept the 1.6:1 roller rockers. They swapped the head gaskets to bump the compression ratio a half point (9.6:1):

    PEAK HP: 463 @ 5,600
    PEAK TORQUE: 503 @ 4,200
    AVG HP 2,500-4,800: 335
    AVG TORQUE 2,500-4,800: 478
    TORQUE @ 2,500: 435 lb-ft

    The final combo idled at 950 rpm w/ 12 inches vacuum as opposed to 650 rpm & 19 inches stock, but not bad for a small block if it’s HP you’re looking for…
  2. Hossbaby50

    Hossbaby50 3/4 ton status

    Sep 1, 2001
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    Peoria, AZ
    Being Hot Rod Magazine they are looking for HP's. If they would have put in a cam geared more toward the low end the numbers one the torque side probably would have been higher.

    My Chevy isn't broken, its just out of gas.
  3. Hustler

    Hustler 1/2 ton status

    May 14, 2001
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    St. Peters, MO
    Those #'s are close to mine when I did a 383 for my 90 Jimmy. The guy that built mine, dyno'd it before putting it in the Jimmy and it got around 427 hp and around 517 lb-ft. I forgot the exact #'s, but those are close to what it was. I wanted more torque then hp for towing and off road when I go off road. this is a daily driver, so I have to be carefull taking it off road.
  4. Twiz

    Twiz 1/2 ton status

    Mar 8, 2001
    Likes Received:
    Clearfield Ut.
    Even the stock numbers sound good. I really like that HT383 crate engine. G.M. is really kicking out some great crate engines.

    Is that engine finaly avalible? It's been in and out of production for 3 years...'bout the hell time..

    <font color=white>.</font color=white>Eric
    <font color=white>.</font color=white>Twizted

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