Results 1 to 11 of 11

Thread: Proud of Performance

  1. #1
    Join Date
    Dec 2003
    Posts
    518
    Rep Power
    21

    Proud of Performance

    Happy to say the 1996 22 classic is still pretty quick. I have to admit I've only done routine maintenance on her over the past several years.

    But ---- this weekend she showed how well she still moves. Saturday evening on a hot calm night with 3 aboard and a full tank of gas she ran just shy of 67mph. But then on Sunday, with slightly less gas, hotter then hell, calm, with 6 aboard and a dog she ran just shy of 63mph.

    This boat is amazing. Solid as a rock. 100% stock: 454Mag, bravo 1.

    Still happy to be a donzi owner.

  2. #2
    Join Date
    Sep 2001
    Posts
    1,462
    Rep Power
    24
    T you still running the Sassafras River? Do not get down as much to that area like I did in the past...


    Undertaker

  3. #3
    Join Date
    Dec 2003
    Posts
    518
    Rep Power
    21
    Yes. We almost always hang out at buoy #10. Ordinary point has been covered with a rock sea wall.

  4. #4
    Join Date
    Aug 2003
    Posts
    1,848
    Rep Power
    22
    You are going faster, your speedo is off. For a non-Mag that would be good but you are faster.
    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)

  5. #5
    Join Date
    Dec 2003
    Posts
    518
    Rep Power
    21
    Pismo, You think I am actually going faster then 67mph (loaded)and 62mph (overloaded)?

    I hope you're right. I will calibrate speedo again with my handheld gps.

    Thanks

  6. #6
    Join Date
    Aug 2003
    Posts
    1,848
    Rep Power
    22
    Quote Originally Posted by TBroccoli View Post
    Pismo, You think I am actually going faster then 67mph (loaded)and 62mph (overloaded)?

    I hope you're right. I will calibrate speedo again with my handheld gps.

    Thanks
    Yes, should hit low 70s with lots of trim. What prop? My 1996 22 with a 502Mag MPI, only 30 more hp, has hit 75.5mph(many times) GPS with a labbed 27" Mirage Plus, and 74.5 GPS with a stock 25" Mirage Plus prop. Trim is the key, more than you think.
    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)

  7. #7
    Join Date
    Dec 2003
    Posts
    518
    Rep Power
    21
    I've got a Mirage Plus 23. Trimmed out, at about 4800 - 5000 rpms.

    gotta find a Mirage plus 25 to test.

  8. #8
    Join Date
    Dec 2007
    Posts
    4,279
    Rep Power
    21
    Unless I'm missing something, from the sound of it, your Mirage+ 23 is just right since your RPMs top out at 4800-5000. The 25 should knock down your RPM by 400-500 RPM.

    IF the HP the motor produced was the same with both props and other things were equal, WOT speed would be the same with both props, and the 25 would top out from 4400-4600 RPM. But since peak power for the motor is probably up near 5000 RPM, you won't reach peak power with the 25. As such, I expect you will lose slightly more than 400 RPM, lose a few HP, and lose a little speed.
    "I don't have time to get into it, but he went through a lot." -Pulp Fiction

  9. #9
    Join Date
    Dec 2003
    Posts
    518
    Rep Power
    21
    Is it possible that the motor could turn the 25 mirage plus at the same rpm as the 23 MP? Then the speed should increase???

  10. #10
    Join Date
    Mar 2005
    Posts
    3,291
    Rep Power
    23
    If that were to happen, with both props running to the same max rpm, that would suggest something was out of whack with one, or both of the props. Or there is a rev limiter at work.

    The amount of pitch is what determines the load on the engine. An actual 23" pitch prop loads the engine less than an actual 25" prop. Less load would allow the engine to spin faster, unless there is an arbitrary rpm limit, set by a rev limiter for example.

    If the distributor has a limit set (the MSD in my 16 engine did, and you could set it to whatever you wanted), that would make the engine top out at the same rpms if it was strong enough to spin the 25" prop to that limit. If this were the case, then yes, it is possible to spin the engine to the same rpms and go faster. However, this isn't representing the true top speed of the boat.
    “Oh right, because you walked into strippers discount warehouse and said ‘Help me showcase my intellect.’” - Archer

    Bill
    Grand Rapids, Michigan
    1985 Donzi Criterion SS
    1967 Donzi 16 Ski Sporter, C16-409, Has a new home!
    38' Carver Aft Cabin
    1968 Sea Ray SRV 180 w/1975 70 hp Evinrude
    10" RIB w/15 hp 1984 Evinrude

  11. #11
    Join Date
    Dec 2007
    Posts
    4,279
    Rep Power
    21
    What N2O said.

    Further, I would add that what is needed to push a boat at a given speed is POWER. Not torque, or RPM, or energy, etc. A certain amount of power is needed, period. The motor will produce different amounts of power at different RPM. If you are getting the max power from the motor without some unusual problem with loss due to inefficiency, you're pretty well topped out. Switching to a different pitch of the same sort of prop is only going to shift you to an RPM level that is no longer at the peak power for the motor.

    Now, if you were running a 4 or 5-blade prop and switched to a 3-blade, the DRAG might decrease and thus the existing power might then push the boat faster. And you might be able to turn more pitch at the same RPM. But switching pitches within the same flavor of prop is mostly just changing gears. And those Mirage props are usually the fastest, or close, for the sorts of boats at the speeds where you are.
    "I don't have time to get into it, but he went through a lot." -Pulp Fiction

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •