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Thread: 355ci 8/71, How bad Inefficient is 25% UNDERdriven at 8 to 10lbs of boost????

  1. #1
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    355ci 8/71, How bad Inefficient is 25% UNDERdriven at 8 to 10lbs of boost????

    This is/was a old SBC NOS motor at 10.1cr that I just bolted on a old blower set up I had on my Offshore powerboat that s was 494ci bigblock

    the motor is a 355ci,dart 215 pro1, littlefield stage2 hardanodized 8/71 with 2 1050 dominators,roller,ls 112,236at .050,636lift, I assume this blower is pretty tight at this boost being underdriven.


    I was wondering when you underdrive a blower so much, Would there a fuel distribution problem? maybe lazy? loss of HP? the blower doesent even have any wine to it.

    What do youall think??

    Thanks
    Rob

    before and after picks


    The car is running pretty good, as 7.5lbs of boost it ran better than the car did on a 200hp of NOS. I am build a dedicated blower motor for this blower set up
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  2. #2
    Senior SCH Member vinces427bb's Avatar
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    that has an intercooler between the blower & intake - functional ??
    how much timing are you using to help keep the combo together ??

  3. #3
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    Quote Originally Posted by vinces427bb View Post
    that has an intercooler between the blower & intake - functional ??
    how much timing are you using to help keep the combo together ??

    its just a spacer, the blower was off my bbc boat, it has the full rear set back, i at that time didnt want to change out the ignition, crank trigger etc. might on new motor, just be a pain making the crank trigger wheel work with my pully set up.

    Its still running,im surprised.its at 18% under and 10psi, running 112oct only, build heat quick. but its been responding to jetting and car still picked up after turning boost up, it still has good leak down, but is putting some metal in filter,stock gm 350 block crank and rods

    Its done pretty much we want , test mule for new motor, sorting out car,broke trans,rear gears, and now has all new suspension. new motor will take alot of boost. Might end up taken spacer and scoop off and make the lexan scoop. not able to tell how much diff it is air going down the scooop or air blowing across top of carbs no scoop.no scoop it would put gas on glass

    I did find out the airscoop and my adapter box, with k&N filter change afr. filter was 1 number and scoop was 1 #, right now i running with no filter.

    should be interesting what the diff is in the 2 motors, drive ratio and carb tuning


    Thanks
    Rob



    house of grudge.jpg

  4. #4
    Senior SCH Member vinces427bb's Avatar
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    so it broke a lot of parts
    its good to find the weak links, and get them out of play...
    what engine has been build for the boost???

  5. #5
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    Quote Originally Posted by vinces427bb View Post
    so it broke a lot of parts
    its good to find the weak links, and get them out of play...
    what engine has been build for the boost???
    70Chevelle
    Engine specs
    New SBC 400ci,24502503 Chevy CNC Bowtie block. 4.125 ,standard deck
    New Crower 4340 3.750 stroke,sb snout,double keyway
    New Crower 4340 6in ML93006b5
    New JE 8.4cr comp dist 1.125, 64th ring, .927 pin
    Felpro MLS 1144
    Littlefield 8/71,stage 2,hard anodized,full rear setback case,
    2 BLP 1050cfm, 90 jets SQ
    Blower Shop intake
    BDS blower crank hub
    3v belt pulley
    Canton oil pan.w/ 3/4 kickout
    New Dart 230 w/ 72 cc 2.100i -1.600ex ,larry Meaux max port for blower
    Milodon gear drive
    Car is 4000lbs,
    TH400,2.75 first gear
    4.56 rear gear changing to 4.10
    29.5-10.5
    PTC 4500rpm
    MSD 6a1
    MSD dist




  6. #6
    Senior SCH Member vinces427bb's Avatar
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    that should be stout enough to break more parts
    what cam is that geardrive going to turn??

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