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  1. #1
    Join Date
    Dec 2003

    Totally wrong prop in a Donzi?


    Anyone who has some experiance of Donzi 25 Ragazza?

    Me and a guy has put a chevy 350 with a blower, Holley 850cfm and all the right stuff in that boat. It stopped at 500hp and 700nm in the dyno. We have a Volvo SP drive with 1,61:1 gear ratio and a 3blade Turbo stainless steel prop. We are having problems with the speed, it does 48knots with 23 pitch and revs 5400rpm, 46knots with 25 pitch and 5000rpm. We are thinking of speeding up the blower so it will rev more because it feels like the prop are going to slow. It´s the lowest ratio to that outdrive. Maybe we should speeding up the blower a bit and try a prop with 5blades? Yeah.. the chargepressure is 0,4bar with the 25pitch and 0,6bar with the 23pitch..almost forgot that. The acceleration is extremely good but at 46knots it feels like going into a wall, its totally stop.

    Does anyone has some idea?

    /Björn from Sweden

  2. #2
    Platinum Member Platinum Member johnnyboatman's Avatar
    My Boats:
    Join Date
    May 2001

    Re: Totally wrong prop in a Donzi?

    maybe it needs more fuel?

  3. #3
    Join Date
    Dec 2003

    Re: Totally wrong prop in a Donzi?

    Maybe, dont know. Dont think so.

    Do anyone knows something about the hull? Maybe it doesnt want to go any faster? Or do we just need more power? Like 800hp and 30 pitch?

    Im full of questions heh ;D The needle stops att 55mph with the 23 prop, i want it to continue much longer ofcourse =D

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