Baby boy boat question
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Baby boy boat question

  1. #1
    Member MSCobalt220's Avatar
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    Default Baby boy boat question

    Hey guys, I'm new to the site and may not be in the right company to ask this , but here goes . I've been reading some of the posts and see there is a lot of BBC knowledge here . I have a '95 Cobalt 220 bow rider, 7.4 GL , Volvo penta Duo Prop O/D . It's a 330 horse peanut port engine with cast iron intake and Holley vac. carb . 440 hrs and in mint condition. Ran a comp. test and all were 145-150 psi . motor is still strong and runs clean. Now for the 64 dollar question. This winter I want to build a bit more power for the main reason that I keep a good number of people onboard , plus I just like to pump things up .

    How much increase can be expected going to a set of 049(large oval) open chamber heads , opened up to 2.19/1.88 valves with pocket porting and a Weiand/Edelbrock intake with a better carb . I would like to start with a good set of exhaust manifolds or headers for this mild combo that could be used on a hotter 468 in the future . I've already got the through hull exhaust . I'd like to see 360-380 out of it at around 4800 . I don't know the cam specs for the 330 horse , but I believe it is an 8:1 CR engine , so it can't be very hot . Where can I find the specs on this cam ? Would there be any benefit going to a different hydraulic grind marine type camshaft ? Roller rockers? What exhaust system is good for this type boat?

    I run timing at 10 initial , 34 total using a stock HEI with no vac. adv.. This seems to be a bread and butter engine with plenty of potential for some gain. Any tips for a new boat owner would be great. I've been rodding since I was a kid , so I know plenty of street antics , just don't know how much I can get away with in the boat before I have a slug that won't pull an inner tube . At the moment this rig runs just over 60 @42-4300 with two people in it and jumps on plane with no problem.

    Question #2 , and I am leaning this way for some reason. I have a 2 bolt 454 truck engine ready to be bored .060 for a set of TRW L2349 LS6 pistons . These are listed to bump 10:1 with the open chamber head . I already have a new set of these pistons , so that's all I'm considering , other than a set of cast flat tops . Gotta stay on budget here.

    Using this marine camshaft :
    E-1117-P
    INT.323 .549 293° 232° 12° BTC 40° ABC 88°HYD104°8

    EXH.328 .558 310° 239° 56° BBC 3° ATC 116°
    <<Back




    Or a Comp Cams 292 magnum hydraulic camshaft . I already have this camshaft and new lifters, so no more money spent on that.


    FLAT TAPPET: Street/strip applications. 10:1+ compression, 3000+ stall or 4 speed. 4.10 or lower gears & aftermarket intake. Very rough idle.
    2500-6500
    11-213-3
    292H

    244
    244
    .550
    .550
    110°


    My thoughts would be to leave the 330 horse intact, stored tight with MMO inside her and just build the 10:1 468 for playing with. When it's time to sell the boat , drop the 330 back in it and put the 468 in one of my Chevelles .

    What's the best option of these two ? Sorry for the book . Thanks for any help in advance .

    Here's my rig .



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  3. #2
    Senior Member gregb's Avatar
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    I think in 95 that engine would have come with hydraulic roller lifters. You would probably be in the power range you want by just swapping the heads and intake. Not sure what kind of risers and such Volvo used but they make many aftermarket HP versions for Mercruiser which would probably be very easy to adapt to your current setup. They arent cheap though. If you are going to swap the exhaust I'd start with that and the intake and see if that does what you are looking for, if not, then get into the heads. That would be the easiest, you could have it done in a few hours. What size is the carb? If it's a 600 I'd step up to a 750. Cam would definitely help, even without doing the heads I think you could come up with an easy 400 HP.

  4. #3
    No Sandbar To Far sanger rat's Avatar
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    I would leave that thing alone and buy a flattie to play with.
    Quote Originally Posted by One More Year View Post
    The only blab's I will even be a part of is just when it is me they are talking about. Aaaah yes I can see a few good looking shiny tall deck motors on the beach, with barely enough fuel to get back to the launch saying, "Holy crap how fast you think that Daytona was going man? That's like the 20th time he's gone by today?"

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  6. #4
    Member MSCobalt220's Avatar
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    Quote Originally Posted by gregb View Post
    I think in 95 that engine would have come with hydraulic roller lifters. You would probably be in the power range you want by just swapping the heads and intake. Not sure what kind of risers and such Volvo used but they make many aftermarket HP versions for Mercruiser which would probably be very easy to adapt to your current setup. They arent cheap though. If you are going to swap the exhaust I'd start with that and the intake and see if that does what you are looking for, if not, then get into the heads. That would be the easiest, you could have it done in a few hours. What size is the carb? If it's a 600 I'd step up to a 750. Cam would definitely help, even without doing the heads I think you could come up with an easy 400 HP.
    Greg, you're probably correct about the roller cam . 400 HP sounds ideal . I've read different stories about the peanut port heads ability to get up to 400 ponies . Some say without doing some good pocket work they won't do it. Lingenfelter Performance did some real wonders on these castings and got some fat torque curves , which would be ideal in this type of application. Can you give me a safe RPM limit for the 7.4 Vovlo ? Any idea what comp. ratio ?

    Would the CMI E Top headers be overkill for this boat/engine combination? I'm all for losing some weight with the factory cast intake and exhaust systems .

    Quote Originally Posted by sanger rat View Post
    I would leave that thing alone and buy a flattie to play with.
    Ahh, you've prolly got something there , s rat . I can't leave well enough alone sometimes.

  7. #5
    Senior Member gregb's Avatar
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    I think those headers would be just fine, the stockers are not the most effiicient thing out there, Lightning also makes a water jacketed header, GLM makes some free flowing cast aluminum manifolds for Mercruiser engines also might be a bit cheaper, ok a lot cheaper (some folks have posted on other forums that GLM machine work isn't all that, but I put some on my 4.3 powered runabout and they are fine), as for a safe RPM I'd say keep it a 5000 or below and it should last a long time. Can't help with the compression but you're probably close, I'd guess 8.3 to 8.5. If you change the cam don't go overboard, if you get something that's idling above 7-800 it might get hard to get in and out of gear. I hear you about not leaving well enough alone, but since this is the family boat I wouldn't go overboard. Pun intended. Lingenfelter was a genius, IMO, but those fat curves were probably the result of more than just porting, I'll bet the cam had a lot to do with it.

  8. #6
    Member MSCobalt220's Avatar
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    Thanks greg. The CMIs give me a warm fuzzy feeling . Yup, a good exhaust with some pocket port work with a better intake would be ideal for up to 5,000 . That is what I am looking for , around 4,800 to stay out of trouble . Lingenfelter was a genius , he could have had this peanut engine making some good numbers at 5,000 . me grinning the whole time I'm pulling my skiers with no worries.

    I do have an Eldelbrock Performer intake with peanut ports . Weight savings alone would be significant . What can I coat the water jackets with for corrosion resistance? Techline coatings thermal barrier or Cerma chrome? The marine thing is all new , but I am catching on .

  9. #7
    Senior Member CK7684's Avatar
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    If it was mine, I would keep the factory engine wrapped up and build the second one to LS6 specs and see how it performs. Even with 049 heads...
    Those peanut ports might not be barnstormers, but they are good for low RPM torque and decent response. If that package works well, I'd leave it alone, especially when you have another mill laying around. Hold off on exhaust until you find a good deal as it can be spendy...

  10. #8
    No Longer Recovering 454Rocket's Avatar
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    I see scattered volvo drive parts in your future... you really need a better platform. Not to mention trying to prop it right etc...

  11. #9
    Senior Member GT Jets's Avatar
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    Just my opinion.

    The Volvo Penta DP is a horrible drive to try and build in more performance, the drive can handle more power, but you will have a difficult time seeing tremendous gains in overall performance.

    Volvo has out some good running diesels in the DP platform and they do pretty well, but they are not worth a damn at over about 65 MPH because of the poor hydrodynamic properties, not to mention it'll handle like a Puffer fish.

    Your boat should be an honest 65 MPH boat with proper tuning and props...

    I dont know about you potential cam choice either. That drive requires and idle speed of say 850 max. to be able to get it out of gear, may tear things up just getting into the docks..

    Just my opinions, nothing personal, nice boat BTW...

    I have been a marine service technician for over 15 years over the last 25 years and am very familiar with the Volvo Penta's, Yamaha stern drives, Mercruisers, and Volvo SX and the OMC Cobra.

    Good luck with whatever you decide...

    GT
    Last edited by GT Jets; 09-05-2009 at 01:25 PM.
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

  12. #10
    Senior Member GT Jets's Avatar
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    Quote Originally Posted by MSCobalt220 View Post
    At the moment this rig runs just over 60 @42-4300 with two people in it and jumps on plane with no problem.
    You need to go down one prop pitch, get it into the 4600 RPM range and you will be much happier....You can run that motor package to 4800 without issues, try to find someone to loan you a smaller set of wheels.

    You are lugging it down too hard.

    I gurantee you will be very surprised.

    GT
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

  13. #11
    Senior Member OLD MAN ON THE LAKE's Avatar
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    Quote Originally Posted by GT Jets View Post
    You need to go down one prop pitch, get it into the 4600 RPM range and you will be much happier....You can run that motor package to 4800 without issues, try to find someone to loan you a smaller set of wheels.

    You are lugging it down too hard.

    I gurantee you will be very surprised.

    GT

    This is the ticket.
    If you want a fast boat,get a fast boat.Your Cobalt is a great water Caddy not a performance boat.The drive is great but was never intended for speed.Put a smaller prop on it and the hole shot will be awesome.
    The problem with boats is you need more than one.Keep the Cobalt and get something fast.
    Nothing like something small with lots of HP to keep the woman busy with laundry.

  14. #12
    Member bennyb's Avatar
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    Quote Originally Posted by sanger rat View Post
    I would leave that thing alone and buy a flattie to play with.
    That's the best advice right there.
    20'5 Advantage classic cruiser
    Go on get your ass outa here

  15. #13
    Senior Member Uncle Dave's Avatar
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    Dude I get where you are coming from, but dont do it.

    The guys are giving you sound advice- you have a decent running family boat- resist the urge to f with this one.

    You are about to enter "the circle jerk of speed" - sure you could put a bit more power into that mill, but you'll have to start swapping lots of parts out.

    Id seriously recommend sticking with exhaust as the only actual change out (maybe a carb rejet after as it will use a bit more jet) until the engine is totally worn out/wasted. Imco, Dana, Stainless Marine all have nice high perf manifold systems. This is the only engine type mod I think Id ever do to this rig and it will buy you a bit of power everywhere.

    My advice is to take the other guys advice on just running what you got with prop changes - The step the prop pitch down a bit is good advice.

    Buy a project boat to mod, or you risk ending up with a poor running non reliable cobalt. This one will carry your wife around and tow your experiments back to the dock.

    Uncle Dave

  16. #14
    Member MSCobalt220's Avatar
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    Good advice guys . You're right OMOTL , this is a great water Caddy . I love this boat. But I have already found a flattie to play with, just going to wait till the middle of winter before I hit him up with an offer .

    Some of the things I have heard about the Volvo DP drive is that they will hold up all day to the BBC torque , but they are not intended for speed drives(fast boats) . The dual props is for getting the boat to plane quicker , not for a high speed boat . Makes a lot of since to me . Less prop cavitation means instant bite for launching .

    I hear from a lot of boat guys that the exhaust headers really make one snappy out of the hole and all around response , not much more on top speed . My main goals are to make a more efficient running engine for torque across the board and to take some weight off of that puppy . Not wanting to go 70+ with this boat . 60-65 is plenty . My family consists of 5 members , and we are all fairly large at a total of 925 lbs. Myself , I'm 6'3" @ 240 lbs. , daughter is 6' , son is right at 6' 175 , 13 years old . Two coolers , two inner tubes , a grill and all the safety gear adds up to a big payload . I took the family out this weekend and it will do 50 on the clock at 44-4500 on the tach . That's in the river going up stream . Didn't try it down river going back in, hell I ran out of gas going in , DOH !!! Lol. I felt like hiding . Heh heh . It wasn't that bad , my bud towed me in , wasn't but a couple miles .

    Ok, this is great , I'm getting concrete advice now . This is a plan I have . I want to replace the valve springs , just because of the age on them , not necessarily the hours or operation . Lightening or CMI headers , and an Edelbrock Perfromer intake . That's got to knock enough weight off the rear to help make up for the killer swim platform that I'm building for it. Not to mention the new 6 channel amp , six speakers and extra battery .
    Man , I love this boat .

    Now I'm beginning to unnerstand what boat really stands for.
    Break
    Out
    Another
    Thousand
    Last edited by MSCobalt220; 09-06-2009 at 06:07 PM.

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