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Thread: 8-71 or 6-71?

  1. #1
    PF468Blown
    Hey guys, here is what I got. I have a 525SC (I thought it was), it has a B&M 250 blower in it. The blower was powder coated black. It came out of twin screw boat (original engines). I thought it was a factory mercruiser engine, it came with a single dominator carb. Does mercruiser make a package with this combination?
    The motor was totally rebuilt by Paul Phaff racing. I bought the motor complete oilpan to carburator, never been run. The rebuild was over 3 grand.
    Here is what I want to do. I would like to put a larger blower on it. Is the 8-71 the way to go, or should I run a 6-71? Are these motors strong enough to run high boost, or should I get something else?
    I would like to take the B&M 250 and put it on another BBC that I have laying around and have 2 blower motors to use. Any help/info/comments would be great.
    [ February 05, 2003, 09:39 AM: Message edited by: PF468Blown ]

  2. #2
    Craig
    If it's a true 525 SC, the blower is a 177 Weiand, not a B&M 250.

  3. #3
    Liberator TJ1984
    8/71 would be better , spin it slower and still make good power and boost...

  4. #4
    PF468Blown
    I guess I need to do some research on what I got.
    I thought it was a factory engine package. Since it is a B&M 250 blower/single carb, what should I expect for horsepower with this combo?
    I guess the bottom line is, will this motor be strong enough to put a 8-71 on with 7-10 pounds of boost?
    [ February 05, 2003, 09:43 AM: Message edited by: PF468Blown ]

  5. #5
    PF468Blown
    Who should I call to get some answers to all of these questions?
    [ February 05, 2003, 10:44 AM: Message edited by: PF468Blown ]

  6. #6
    DUCKY
    The factory 525sc was basically a 454 mag under the blower. I wouldn't put a 6 or 8-71 on top of one without pulling it, and dropping the pan for parts inspection. I doubt yours is a factory unit though. The 525 SC had a 177ci Weiand blower and a 850 Holley, not a Dominator, and I think they were powdercoated blue. Or if you have the info, contact the engine builder and find out whats in the bottom end. If you have a choice, go withthe 8-71 and turn it slower.

  7. #7
    PF468Blown
    I there #'s on the block the help me figure out what I got?

  8. #8
    DUCKY
    If it was a Mercruiser system, there will be a small tag on it somewhere with a serial number. I think they are usually on the bell housing flange above the starter boss. It's only about 1" x 1.5" and it's aluminum and riveted to the block.

  9. #9
    paradigm shift
    Go with the 871 if it was me. If it was rebuilt by phaff they will have all the specs on the motor and could help with set up.

  10. #10
    PF468Blown
    I got all the specs, for it 3 pages worth. Thanks for the info.

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