If not for bad luck I'd have none....finally got boat working and Big block goes boom

Discussion in 'Gas Engines/Drives/Transmissions/Props' started by WetPleasure, Sep 21, 2021.

  1. WetPleasure

    WetPleasure Member

    101
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    That's kinda what I was thinking. More power can push bigger prop at 4200 rpm or wouldn't more power mean my current props end up spinning to higher RPM so as long as the engine internals can handle it I'd be okay. I agree, I know it's a cruiser but it should be able to cruise at 30-35 and too out in the 40s
     
  2. HawkX66

    HawkX66 Well-Known Member

    Jul 27, 2020
    SE Virginia and NH
    "Tread Knot"
    1997 Sea Ray Sundancer 290DA

    2020 F350 6.7L
    454 L29 Carb w/ Bravo III
    I have plenty of power, but the throttle doesn't allow me to exceed 4,200 rpms. There's no more throttle. There's no reason to exceed it either if you look where the power range is on a boats cam. All you'd be doing is making noise , burning fuel and not producing any more power.
    If you want to go faster, you change the gear/props. If you increase the power in the motor, you can make up for the power loss you'll lose by going with a taller gear ratio/prop which increases your top speed.
     
  3. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Absolutely, my 2006 280 did 50mph with 520 hp. The 280 with the single 425hp 8.1 was mid 40's. Your smaller boat should make that speed
     
    Phil S and WetPleasure like this.
  4. HawkX66

    HawkX66 Well-Known Member

    Jul 27, 2020
    SE Virginia and NH
    "Tread Knot"
    1997 Sea Ray Sundancer 290DA

    2020 F350 6.7L
    454 L29 Carb w/ Bravo III
    You changed your props though right?
     
  5. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    No stock set up. B3 2.2ratio 24pitch
     
  6. WetPleasure

    WetPleasure Member

    101
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    I'm getting confused lol.. and yes I apologize for being all over the place. Ultimately just trying to understand what parts need to go back into the new motor. If there are some aftermarket parts that don't cost an arm and a leg I want to put them in. I keep reading that even with cast internals a 454 can easily make 400hp. If I currently have 330 hp and that got me 35mph at WOT than hell yeah I want another 70hp!

    It is important to note that it's very likely something was wrong and that is why I was only getting those specs.. I do need to empty holding tanks and freshwater tank that is a lot of weight and we had 4 adult males on board but still, if the torque is what it's supposed to be ona big block it should still move that load well.
     
  7. HawkX66

    HawkX66 Well-Known Member

    Jul 27, 2020
    SE Virginia and NH
    "Tread Knot"
    1997 Sea Ray Sundancer 290DA

    2020 F350 6.7L
    454 L29 Carb w/ Bravo III
    How did you get it up to those speeds? Higher rpms? How did you increase the rpms? I don't have anymore throttle. I have 22p
    I apologize to the op. Sounds like I may have been passing some bad info. Scoflaw knows what he's talking about.
     
  8. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    I had a pair of 260hp 5.0's with a 5000rpm redline. That 260 usually comes with a 300hp 350 mag.with a 5k redline.
     
  9. WetPleasure

    WetPleasure Member

    101
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    yes. seems like most 260s came with the 5.7. 5.0 was an option and i haven't seen many in my research and then 7.4 was an option and also dont seem to see or hear about many of them. the 7.4 is obviously a heavier motor but when you look up the specs, man it is WAYYYYYYY more torque even if it is only rated 30hp more.

    Does Sea Ray foam fill their hulls? Honestly, I'm getting scared that i've got some sort of saturated foam situation going on. Also, the boat was so tippy which seems to be reported by many owners because it's a top heavy boat for such a narrow beam but man I'm wondering if i've gotten something bad going on !!!!! I have no experience running this hull, bought from a friend for $5000 as a fun project to flip. now ive got 31k into it and no motor. I'm pretty fucked. Cruisers just dont hold value like center consoles do. For the amount of restoration that I have done all around on this boat as a center console it would be selling for 100k.
     
  10. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Those heads are inferior compared to the 350 vortec heads, there're all grunt with no revs. So if you want speed you need to increase rpm.
     
  11. WetPleasure

    WetPleasure Member

    101
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    not that i doubt you but at some point HP is HP. there is just no way that a 454 should be slower than the 5.7 hindsight being 20/20 i would have handled this all quite differently. now i just gotta eat the shit sandwich. It's only money, I'll make more. What this probably means is i'm going to be stuck keeping this boat for a couple years instead of buying the new center console i was planning to put profits of this boat towards lol. There are FAR worse problems to have in life than not getting to run the desired boat. I'm just annoyed because I've really been trying to do things right on this thing and just want a safe, properly working boat and it's just major shit one after the other lol.

    Regarding the heads, i keep coming across a LOT of threads on varying forums that say people give the peanut port heads a bad rap. Are they going to make 600hp? no. But can you build a solid, reliable, torquey motor to 400+ hp with those heads, yes. That is what i'm trying to figure out how best to do.
     
  12. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    OK then, what parts do you need to get the PP to 400hp with a 5k redline?
     
  13. WetPleasure

    WetPleasure Member

    101
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    Lol. That's what I'm trying to find out!
     
  14. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Google says it's a 42.9mph boat with the 350 mag. Couldn't find any info on the BB
     
    WetPleasure likes this.
  15. WetPleasure

    WetPleasure Member

    101
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    Yep and I'm sure that's with a captain that weighs 140lbs 1/4 tank of fuel and empty freshwater and holding tanks so maybe I'm not that far off but I am having a hard time believing it.

    Are these sea rays foam filled? That is next set of googling
     
  16. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    You should take it to the scale, that will tell a story. What's your max rpm?
     
  17. HawkX66

    HawkX66 Well-Known Member

    Jul 27, 2020
    SE Virginia and NH
    "Tread Knot"
    1997 Sea Ray Sundancer 290DA

    2020 F350 6.7L
    454 L29 Carb w/ Bravo III
    Parts aside for keeping the motor from grenading, how would you physically get the rpms up higher? New throttle? Throttle adjustment to be able to open the carb up more? If the carb is wide open already at 4,200 rpms, the only thing I can think of to get to 4,500 is changing the pitch of the prop or the gears in the outdrive. No? You know I'm not a pro boat guy. I'm just looking at how engines and gearing works.
     
  18. WetPleasure

    WetPleasure Member

    101
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    i took it to the scale and it came in at 14,660. my truck i know was right at 5000 and i estimate 1500 for the trailer which would put this boat at 8000lbs. I had just gone to the gas station and filled the tank and pretty sure the freshwater tank was full and i don't know status of the shitter tank other than the light on it says 1/2 when key turned on. I haven't had a chance to go get it pumped out. I think published dry weight is 6200lbs so full tank of fuel is 500 and then freshwater full tank another 250 and possibly another 250 in full holding tank so that would get me to 7200 lbs. Dry weight is probably with 5.7, how much more does 454 weigh? 2-300 lbs so now i'm at 7500 lbs. hmmmmmm
     
  19. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Simple test to see if your T Body or carb is too small for your motor is hooking up a vacuum gauge and it should read 0 at WOT.
     
    HawkX66 likes this.
  20. WetPleasure

    WetPleasure Member

    101
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    you certainly know a lot more than i do. I just keep reading and trying to understand and i'm hearing things like "domed pistons to increase compression ratio" and other things that supposedly increase power but i'm really getting lost now. you keep reiterating that rpm is rpm. I guess i'm expecting that if i increase the horsepower of a motor and keep the same drivetrain that i would see more rpm


    My head is spinning. There is just no fucking way this boat with that big of a motor can only do 35mph. I wish i had been out on it solo to see how much loading the boat affects it but i'm sorry my center console with a 250 yamaha would top out at 50mph with me running solo at 5900 rpm. When i loaded that boat with my wife, 3 year old, mother and father in law and sister in law we could still top out at 46mph. 23' center console so lighter weight but bigger 103 gallon gastank . not truly apples to apples but i'm just saying this 454 should be a torque monster so no matter how many people on board she should still get up and go. the torque curve for the peanut port heads on a dyno is pretty impressive. it holds that torque through a pretty wide range and its something like 450lb ft
     

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