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. Blueone

    Blueone Well-Known Member SILVER Sponsor

    Jan 24, 2007
    Lake Erie, Ohio
    2004 420 Sundancer
    Cummins 6CTA 450's
    @WetPleasure … I like the look of that drive shower…especially if it cools the top cap and just doesn’t run down the sides…. Haven’t seen that before
     
    WetPleasure and Nater Potater like this.
  2. WetPleasure

    WetPleasure Member

    91
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    Nope, what I'm talking about isn't reversion though that is an issue with these. It's the exhaust pulses, a similar but separate issue. They have resonators that go online when using thru transom exhaust that help break up the harmonics that cause this. I'll try to search and find the link to the article. It's not just a simple case of water getting sucked back when both valves are open.
     
  3. WetPleasure

    WetPleasure Member

    91
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    The water comes up and comes out of the top and runs down the side. Super easy install, remove the 4 top cap bolts and replace Roth the ones in the kit and then drill 2 small holes in the cav plate.

    Here is link to the drive shower. https://www.hardin-marine.com/p-11567-sport-tech-outdrive-cooling-shower.aspx
     
    Last edited: Dec 1, 2021
  4. WetPleasure

    WetPleasure Member

    91
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    I don't know why you are acting like a dickhead. Thought you had a serious question and I gave you a serious answer. Not on my third engine, thank you very much. Bought boat with a locked up motor.
    I took a chance on a used motor, it didn't pay off, now rebuilding it. As I already explained, I had to buy new Pistons and a new camshaft anyways so why not buy ones that improve performance when there is minimal price difference???

    Anyone that worries about the price of gas ever shouldn't even own a boat. Plain and simple. A boat is a luxury liability. It costs you money, plain and simple
     
    Last edited: Dec 1, 2021
  5. Pirate Lady

    Pirate Lady Well-Known Member

    Jun 2, 2020
    Middle River, Chesapeake
    Pirate Lady
    1991 250 Sundancer
    MMSI 338377928
    7.4 carb, Bravo 1
    Sorry if i came off as rude. On my sixth Sea Ray so I know just a little about boats.
    My point was simply why are you trying to make a 260 run like a Cigarette Boat?
    Merc recommends rpm range of about 4400+~. You want to make it run 5 - 6k. Will the outdrive take it?
     
  6. WetPleasure

    WetPleasure Member

    91
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    You have to understand why Recommended rpm.ranges are what they are. The STOCK motor had a range between 4200-4600. That is largely due to the fact that we are dealing with cast crank, cast rods, cast Pistons. Since you have owned 6 sea rays you should already know that the 454 Magnum is actually rated for 4600-5000 rpm. Reason being? It has forged internals not cast.

    So all that I'm doing is essentially making some upgrades that are more inline with what a stock magnum motor would have been but increasing compression slightly with the domed pistons . Again, the engine had to be bored .030 over, that meant the old pistons couldn't be reused, had to start with new ones. I could have bought hypereutectic flat Pistons for $350 or the forged dome Pistons for $550. That's a small price to pay for a nice upgrade. Likewise, a stock camshaft would cost me $300. For $500 I got the entire cam shaft kit with upgraded springs and timing chain. No idylis trying to make a cigarette boat lol. Why would t you want more horsepower? My f150 has 400+ ho and almost 600 lbs of torque. Doesnt mean I use all of it all the time. What it does mean is that I get 20mpg around town.

    Someone overseas made similar upgrades to me and made a YouTube video. I'll try to find it. By making these changes he greatly improved his fuel economy. So as you say, run the boat at 3400rpm. Well your motor .at be making 450lbs of torque at that rpm and 300 horsepower, I am going to be making more so I will be going faster using the same fuel amount. "But who wants to go fast, it's a cruiser?" Fine, then I will dial down to 3000rpm and probably get the same output you get at 3400 using LESS fuel.

    Go look at performance bulletins for outboards. I used to have a 23' center console that came with either a 200 or 250 outboard. They always try to sell people that the smaller motor is more fuel efficient. But it's really not because the performance isn't equal.
     
  7. WetPleasure

    WetPleasure Member

    91
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    Screenshot_20211201-082315.png Screenshot_20211201-082305.png This person simply made the cam change. They are running fuel injection, I am carbureted but the numbers speak for themselves. They are running same cruise speed at lower rpm which means less fuel consumption. And also significant top end increase for when a storm is rolling in and you gotta haul ass.

     
    Last edited: Dec 1, 2021
  8. 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 have upgraded your exhaust, not only would it have given you more power but the water exits further down stream to avoid reversion. Dry to the tip is another option.

    Your missing the point about dry-joint exhaust and what it does. Has nothing to do with reversion, it solved the corrosion problem where the elbow or riser meets the manifold. The exhaust and water passage are only separated by a 1/4" of metal, like the BB exhaust. The SB and BB elbow are similar and water dumps at the end
     
    OllieC likes this.
  9. WetPleasure

    WetPleasure Member

    91
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    This is a 260 sundancer. To my knowledge not much can be done in the way of exhaust upgrade. I thought I came across something saying 502 or 496 exhaust works but then I looked at price and it was outrageous.
     
  10. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Oh ya pricey, thought you had money to burn? Freeing up exhaust flow is the first thing a gear-head does. right? So if your reversion continues you'll have to go to plan B
     
  11. WetPleasure

    WetPleasure Member

    91
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    Not sure why everyone has such dickhead attitudes over this? Quite frankly, I have plenty of money but the rich don't get rich by throwing money away right?

    No freeing up exhaust flow is NOT the first thing gear heads do. Many times stock exhaust systems can support more upgrades. For example, my old 2.7 f150 Ecoboost made 70 more HP and 90 more lbs of torque off of a simple tune. No exhaust improvements needed.
    The only exhaust improvements I want are ones that fix reversion issues and condensation dripping back into manifold issues and it doesn't appear that there are any off the shelf options for fixing reversion. Apparently I could install turbulator plate which will fix the condensation problem at low rpms but greatly restrict the exhaust flow.
     
  12. WetPleasure

    WetPleasure Member

    91
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    So you were questioning this back in September. At the time I didn't know the answer. I did research and got the answer. Cam upgrade with valve job and forged dome.pistons keeping 750 cfm carb and dual plane intake.
     
  13. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Doubt it with that exhaust, but hey. Notice what exhaust he uses in the video ?:rolleyes:
     
  14. WetPleasure

    WetPleasure Member

    91
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    Which video are you referencing? Richard holdener? Yeah he's a car guy so he s using automotive dyno headers. And while we are at it, it's on a dyno right so there is no parasitic draw from accessories either. And no drag from a drivetrain. I get it. I get all of that. His first dynonrun in stock form came out to almost 330 on the button, which is EXACTLY what mercruiser rates this motor at in that form so I think it's safe to say we are at an apples to apples comparison in terms of performance improvements I can expect.
    I don't understand where you are going with your comments. You are either being purposeful vague or you flat out don't know. Again, this is a cruiser not some Miami vice scarab race boat; a performance through the transom exhaust is not a viable option.
     
  15. ttmott

    ttmott PhD in OCD TECHNICAL Contributor GOLD Sponsor

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    Suggest to go back and review the first post... There is a lot of marine related experience pitching in but then rather rudely dismissed on what appears an epiphany of new found expertise from Youtube and web sites. We are telling you the boat has an exhaust system problem with respect to reversion but yet a larger duration cam is installed; it defies logic. But it's your boat; please keep us all posted on how it turns out.
     
    scoflaw likes this.
  16. WetPleasure

    WetPleasure Member

    91
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    Now you are just totally making things up. No ify pitched in ANYTHING of specific substance for the rebuild so I spent weeks doing additional research on my own.
    I know the motor has reversion issues. Everyone keeps saying that but guess what? Nobody has presented a single solution!!!! As for you proclaiming that I'm putting in a larger duration cam inspire of it like I'm a total dumbass is totally false. Obviously my internet research has made me far more knowledgeable on this topic than many.

    So for those that find this thread in the future while researching similar issues let the record show the following:
    Merceuiser had 2 different gm based 454 engines. One was called the "7.4L Performance tuned" and the other was known as the "454 Magnum". The 7.4L had a rating of 330 HP while the rating of the Magnum was 385hp. If you look at the cam specs from the Magnum you will see that it is nearly identical to the comp cams marine cam. So no, im not putting some wild and crazy cam in when I know there are reversion problems.

    Last and certainly not least, REVERSION DUE TO CAM OVERLAP IS NOT THE ONLY ISSUE EITH THIS MOTOR AND IS ARGUABLY THE MORE MINOR ISSUE! The bigger issue is the lack of a vaccumn break that allows the exhaust pulse waves to make the water revert. We are talking minor drips of water that are allowed to drip into the cylinder. A proper vaccumn break cast onto the riser would resolve this issue without obstructing the exhaust. Turbulator plates are a solution that allows the drips to land on the hot turbulator plate and immediately turn to steam but again it causes a huge obstruction. The other workaround this is to try to avoid idling as much as possible and prior to shut down run the motor above 1500rpm for a 60-90 seconds and then shut motor down.

    I'm so sick and tired of ignorant old school gesr heads rejecting science and facts but.obviousky that's the world we live in today. You go online and find a million old school gear heads swear up and down that "Peanut head ports can't make any power" "peanut port heads are terrible" and it's all based off some.shit they h are from somewhere or their butt dyno. Then Richard Holdener comes along and literally gives the step by step along with dyno runs to support it and people still refuse to believe it!!!!

    I should really fuck with you guys and throw some aluminum heads on this thing and take the horsepower up over 600!!!!!!
     
  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
    I'm one of those ignorant old school gear heads. So thanks for that... It's not always about what you learned on the innerweb.
    Not all heads that are called peanut ports are peanut ports for starters. ie 290s from an L29. Excellent head with tons of potential, but is still limited.
    Scoflaw helped out alot when I was rebuilding my Gen VI 454 for my boat this past summer. He's not perfect, but who is? Suggest you listen a little more and don't get quite so defensive. That doesn't mean you have to take all the advice, but you don't need to insult guys that are trying to help either. He has a lot of engine knowledge. Go ask the same questions on Offshore Only if you haven't. There is a TON of knowledge out there already if you know where to look.
    Let me know how that B3 works out at 600hp.
     
    Mauler34Rod and scoflaw like this.
  18. Thornton69

    Thornton69 Active Member

    819
    Sep 15, 2014
    Northern BC
    1981 245 SDC
    2021 Solar 420
    '97 5.7 Bravo 2
    '20 Merc 25 EFI Jet
    I think taking her over 600 would f*** with the drive more than anyone here....
     
    HawkX66 likes this.
  19. WetPleasure

    WetPleasure Member

    91
    Jan 30, 2021
    99 260 sundancer
    7.4 bravo3
    Hawk, you may be old school but you are one of the only people that offered any actual information in this thread and then when faced with something you werent' sure about you acknowledged as such and even went so far as to apologize for possibly misconstruing information. I can respect that.
    But the others chimed in questioning me and I thought it was a fair question so i gave an honest answer and still was met with more snideness. I simply don't understand where any of that came from and sorry but I run hot and take kindly to people talking shit and giving me an attitude. The fact is that there is NOT a lot of information on the internet about this stuff. There is a lot of people asking the same questions repeatedly but not getting any actual valid answers. I'm trying to make this thread be a small bit towards adding to the knowledge base.
     
  20. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx
    502 mpi Bravo 1
    Well if you want to add knowledge you going to have to prove it. Build your motor, put on your stock exhaust and dyno it. Would love to see the results. Not sure why you got an attitude.
     

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