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Thread: Stainless Marine headers

  1. #1
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    Stainless Marine headers

    I've got an older 22' Donzi Classic, 454 with a Bravo 1 drive. It's stock except it has an Edelbrock intake and carb. The boat probably runs in 60-65 mph range. I've found a set of Stainless Marine Hi-Torque Exhaust System (slightly used but like brand new) that I could buy for half of what a new set would cost. Even at that they are pricey and I wonder if the performance increase would be worth the investment.
    I know that performance increases don't come cheap and it's usually not just ONE thing that makes a boat faster. It's usually a combination of things that makes a real difference. The manufacturer makes claims that tests revealed increases of 3.2 to 6.5 MPH on MerCruiser Big Block powered 22'-24' boats. Now, THAT got my attention. To me, I would be very happy to get a 5 mph increase on just exhaust alone!
    Question: Does anyone run this exhaust and did you experience this kind of increase in performance by just bolting these on or are they just blowing smoke?

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    The gain is very slight with with no other mods, some say barely noticeable on stock applications.
    No matter what your beliefs are "GOD BLESS AMERICA"

    Fully retired marine tech near 60 years in the biz.

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    Angry

    Thanks for the reply MOP. I think you're probably right. I figured they might be exaggerating at 3.2 to 6.5 mph increase.

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    I think the main advantage of the SM products is the reduction in weight and the risers won't ever leak at the joint like stock manifolds can.
    Beside the marginal improvement in performance these other two items are worthwile.
    They will improve the quality of your boat.
    They are a good investment.
    George Carter
    Central Florida
    gcarter763@aol.com
    http://kineticocentralfl.com/


    “If you have to argue your science by using fraud, your science is not valid"
    Professor Ian Plimer, Adilaide and Melbourne Universities

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    It starts with the exhaust then you might think of msd thats good for a few more hp if you still have the points.

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    It's got a stock Thunderbolt pointless distributor. Unfortunately I'm not in a position to trick out the motor right now but thought if I could get 5 mph from the exhaust system alone, it would be worth the investment.

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    Short of a blower, I can't think of much you'd bolt on that would give you 5 mph.

    Still a good exhaust though, and a good starting point should you want to make mods down the road. If it's in the budget I wouldn't hesitate to go for it, just don't expect big gains. Think of it as laying the foundation for future mods. Plus, it should out-last the stock manifolds by a good bit - they just looooove to rust!
    Don
    '01 22 Classic, 502/B1
    And a bunch of other stuff

    "If everything seems under control, you're just not going fast enough" - Mario Andretti

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    machinist ,bore it deeper,ream it bigger, and lap it to a fine finish



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    A- he's got a 454, not a 496/8.1
    B- I question the '48 hp' gain
    C- even if it was a true 48 hp gain, I don't know if that would be enough to go from 60-65 to 65-70

    But they sure are pretty...
    Don
    '01 22 Classic, 502/B1
    And a bunch of other stuff

    "If everything seems under control, you're just not going fast enough" - Mario Andretti

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    48 ain't happenin'.......
    Charter Member - WAFNC, SBBR, KWOSG
    1955 Perfect Mate
    1986 Hornet III, 502-415 TRS

    www.donzi.org


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    Quote Originally Posted by joseph m. hahnl View Post
    Wow, those look nice.

    Been reading on offshoreonly about how a lot of guys had problems with some of the tube design headers cracking welds, but these units look thicker.



    Do any of you have experence with these?

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    One of the magazines many years ago did the SM swap on a 22 and it picked up considerable speed all things considered. That may be where the speeds come from.

    That said, it probably depends mostly on your existing system. If your current exhaust is a rust pile that is about ready to fail it could really help. If it is new or near new, not so much.

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    Quote Originally Posted by BUIZILLA View Post
    48 ain't happenin'.......
    I have to agree. I'm sure they have a dyno sheet somewhere that supports that, but I find it hard to believe Merc would leave that kind of power on the table. If you figure the delta between the stock manifolds and the Danas at a bulk wholesale price I would think Merc would have just upped the engine price by a few hundred bucks and claimed a huge power advantage over their rivals.

    And yet they didn't.

    I don't doubt they're a decent part. I just question the claims.
    Don
    '01 22 Classic, 502/B1
    And a bunch of other stuff

    "If everything seems under control, you're just not going fast enough" - Mario Andretti

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    Ask Carl what he got out of his $5000 CMIs on his old 496...Zero.
    Cheers,
    Pismo
    1996 22 Classic
    Red with Stainless Windshield
    Stock Gen VI 502 Magnum MPI-415hp
    Stock Bravo I
    25" Mirage Plus
    74.5mph best @ 5050rpm GPS (Speedo said 80)
    27" Labbed Mirage Plus
    75.5mph best @ 4800rpm GPS (Speedo said 82)

  15. #15
    mrfixxall Guest

    Fixx

    Quote Originally Posted by IpanemaSports View Post
    Wow, those look nice.

    Been reading on offshoreonly about how a lot of guys had problems with some of the tube design headers cracking welds, but these units look thicker.



    Do any of you have experence with these?
    Howee bolted a set of thease on his 22 and he got 48 +


    Gallons of water in his engine..(reversion)

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