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Good combo?

  1. #1
    Custom user title Big Inch's Avatar
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    Default Good combo?

    Considering buying a fresh motor just curious to get some opinions on whether or not this would be suitable for a 22 daytona/bravo drive. Components look pretty good but if the cam is way off then I have to consider the cost of changing that as well.

    GM Rectangular Port 990 Casting "Hi-Perf" Cylinder Heads
    Cylinders were Bored Over .060"
    Scat 4340 Forged Steel 4.250" Stroke Crankshafts
    Scat 4340 Forged Steel 6.385" H-Beam Connecting Rods
    JE/SRP Forged 18cc Dome 4.310" Bore Pistons - 9.8:1 CR
    Total Seal Classic Race Rings
    Clevite77 HP Main & Rod Bearings
    Durabond HP Cam Bearings
    Manley Severe Duty Valves - 2.250" Intake/1.940" Exhaust
    Comp Cams Xtreme Marine XM298H Hydraulic Cam Kits (254/264 Duration - .575/.578 Lift - 112* Separation)
    Comp Cams Roller Rockers
    Merlin Marine 4150 Intake Manifolds w/Brass Water Jackets
    Claimed power >>613TQ/671HP

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  3. #2
    steelcomp was here
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    Quote Originally Posted by Big Inch View Post
    Considering buying a fresh motor just curious to get some opinions on whether or not this would be suitable for a 22 daytona/bravo drive. Components look pretty good but if the cam is way off then I have to consider the cost of changing that as well.

    GM Rectangular Port 990 Casting "Hi-Perf" Cylinder Heads
    Cylinders were Bored Over .060"
    Scat 4340 Forged Steel 4.250" Stroke Crankshafts
    Scat 4340 Forged Steel 6.385" H-Beam Connecting Rods
    JE/SRP Forged 18cc Dome 4.310" Bore Pistons - 9.8:1 CR
    Total Seal Classic Race Rings
    Clevite77 HP Main & Rod Bearings
    Durabond HP Cam Bearings
    Manley Severe Duty Valves - 2.250" Intake/1.940" Exhaust
    Comp Cams Xtreme Marine XM298H Hydraulic Cam Kits (254/264 Duration - .575/.578 Lift - 112* Separation)
    Comp Cams Roller Rockers
    Merlin Marine 4150 Intake Manifolds w/Brass Water Jackets
    Claimed power >>613TQ/671HP
    That looks like a decent package. I realy like the 496 for that size boat..probably going to ba a tad bit more cam than the Bravo wants, but I'm not that versed on IO cams. I don't like a 1.94 ex valve, but that's just me. Rest of the parts look good. What block? What kind of ex. system are you running? What kind of performance/RPM are you looking for? Your only other issue might be reversion. Same cam in 114* maybe? Where's User?
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

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    Custom user title Big Inch's Avatar
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    Quote Originally Posted by steelcomp View Post
    That looks like a decent package. I realy like the 496 for that size boat..probably going to ba a tad bit more cam than the Bravo wants, but I'm not that versed on IO cams. I don't like a 1.94 ex valve, but that's just me. Rest of the parts look good. What block? What kind of ex. system are you running? What kind of performance/RPM are you looking for? Your only other issue might be reversion. Same cam in 114* maybe? Where's User?
    Block is a MarkIV 4 bolt. Still need to get exhaust. Boat had stock motor/exhaust and that's not going to work. Problem with the exhaust is that it bends and goes under the swim steps so you need to use the real short risers which I would imagine makes reversion a real concern. Want to keep peak rpms at a max of 6k because bravos blow up after that lol so really anything under that is fine. Performance obviously if I'm going to invest the money I want it to be able to run pretty hard on the big end but more then that I want it to idle down low enough to ship and not be so tempermental that it's loading up and burning plugs when it's not at 5k plus. Lost me on the where's user?

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    steelcomp was here
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    Quote Originally Posted by Big Inch View Post
    Block is a MarkIV 4 bolt. Still need to get exhaust. Boat had stock motor/exhaust and that's not going to work. Problem with the exhaust is that it bends and goes under the swim steps so you need to use the real short risers which I would imagine makes reversion a real concern. Want to keep peak rpms at a max of 6k because bravos blow up after that lol so really anything under that is fine. Performance obviously if I'm going to invest the money I want it to be able to run pretty hard on the big end but more then that I want it to idle down low enough to ship and not be so tempermental that it's loading up and burning plugs when it's not at 5k plus. Lost me on the where's user?
    "User" is another board member pretty familiar with IO combinations. My "opinion" is that cam is going to be a little large for what you're doing...duration might put the idle up around 950-1000, depending on other things. The peak power is going to be above 6000. Something in the 240-245* range might be more in order.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

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    Custom user title Big Inch's Avatar
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    Quote Originally Posted by steelcomp View Post
    "User" is another board member pretty familiar with IO combinations. My "opinion" is that cam is going to be a little large for what you're doing...duration might put the idle up around 950-1000, depending on other things. The peak power is going to be above 6000. Something in the 240-245* range might be more in order.
    Appreciate the input. Thanks

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    I agree with Steel on the cam. On the main board that "User" frequents they have done several 496" combos and they have used the Crane 741 cam (234/242 on 112 .610 int / .632 exhaust). This cam is a proven piece with factory HP heads and should work good to 5800 RPM with this combo. The only other comment I may add is the combustion chambers and quench better be right if anything less than 93 octane fuel is used at 9.8:1 with iron heads in my opinion. The safety factor for bad gas or a heavy throttle will be pretty low unless the chambers are preped properly and the quench is in the .040" neighborhood.

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    Quote Originally Posted by WETTE VETTE View Post
    I agree with Steel on the cam. On the main board that "User" frequents they have done several 496" combos and they have used the Crane 741 cam (234/242 on 112 .610 int / .632 exhaust). This cam is a proven piece with factory HP heads and should work good to 5800 RPM with this combo. The only other comment I may add is the combustion chambers and quench better be right if anything less than 93 octane fuel is used at 9.8:1 with iron heads in my opinion. The safety factor for bad gas or a heavy throttle will be pretty low unless the chambers are preped properly and the quench is in the .040" neighborhood.
    Glad you brought that up about the compression. I don't even have 93 octane available so that basically means I would have to mix in some better fuel and I can do that but really was hoping to stay away from it as a necessity.

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    Quote Originally Posted by steelcomp View Post
    I don't like a 1.94 ex valve, but that's just me.
    Agreed, 110%.(scary isn't it) Do what ever you have to do to get back to 1.88. The larger exhaust valve actually hurts performance by shrouding the valve.

    That cam will work, but it is going to like high CR and high RPM. As wette vette said we have done a bunch of 496's at ~ 9-1 or so, with the Crane 741 cam and we get in the 630 HP range at 5800.

    With todays fuel, running 9.8 on less than 93 is asking to break things.

    EDIT:

    I missed the heads you have. Oooops
    That cam with stock heads is not gonna be really happy. Almost every motor we have done with the 741's have had aftermarket heads that flow a lot better than stock do. The cam is going to be asking for fuel/air, and the heads are going to have a hard time giving it what it needs.
    Last edited by 5325user; 01-14-2010 at 10:11 AM.

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    Quote Originally Posted by 5325user View Post
    Agreed, 110%.(scary isn't it) Do what ever you have to do to get back to 1.88. The larger exhaust valve actually hurts performance by shrouding the valve.

    That cam will work, but it is going to like high CR and high RPM. As wette vette said we have done a bunch of 496's at ~ 9-1 or so, with the Crane 741 cam and we get in the 630 HP range at 5800.

    With todays fuel, running 9.8 on less than 93 is asking to break things.

    EDIT:

    I missed the heads you have. Oooops
    That cam with stock heads is not gonna be really happy. Almost every motor we have done with the 741's have had aftermarket heads that flow a lot better than stock do. The cam is going to be asking for fuel/air, and the heads are going to have a hard time giving it what it needs.
    Real glad I asked this here. Some great advice so far. Was really excited about this package for the price but looks like it may not be the right set up for me after I figure in cam change, cr is too high since I don't want to have to mix fuel, exhaust valves are a big no no and the heads are not going to provide sufficient flow.

    630 hp at 5800 at 9/1 that sounds like for me

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    Quote Originally Posted by Big Inch View Post
    Real glad I asked this here. Some great advice so far. Was really excited about this package for the price but looks like it may not be the right set up for me after I figure in cam change, cr is too high since I don't want to have to mix fuel, exhaust valves are a big no no and the heads are not going to provide sufficient flow.

    630 hp at 5800 at 9/1 that sounds like for me
    BB2 heads (Brodix)
    CMI exhaust
    Crane 741
    9.5-1
    1050 Dominator
    Dart/World/Edelbrock single plane

    Thats your 630 HP.
    Last edited by 5325user; 01-14-2010 at 10:49 AM.

  13. #11
    cfm
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    This 22' Eliminator Eagle (not a Daytona like yours) ran 92mph with 665 (east coast) hp.
    Look at the exhaust - sounds like where yours enters the water.

    9.7 to 1 comp 548" that makes 662ft/lbs of torque at 4600 and and 665 hp at 5800, using AFR 305 cnc heads, a victor intake, a 1050 carb, HR cam with some thought, and wet Dana Marine exhaust.

    So, as usual, it can be done (what your looking to do) but it depends on not just $ but who you decide to spend the $ with.

    As a note: the person that owned that boat is very scientific and knowledgeable about how to set up and test boats. Therefore, the same speeds can not be promised without the same set-up.

    5325user (not 'user' by the way) and Wette Vette know the skinny. Their advice is always good when it comes to I/O's and most other things.
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    Last edited by cfm; 01-14-2010 at 11:46 AM.

  14. #12
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    Quote Originally Posted by Big Inch View Post
    Considering buying a fresh motor just curious to get some opinions on whether or not this would be suitable for a 22 daytona/bravo drive. Components look pretty good but if the cam is way off then I have to consider the cost of changing that as well.

    GM Rectangular Port 990 Casting "Hi-Perf" Cylinder Heads
    Cylinders were Bored Over .060"
    Scat 4340 Forged Steel 4.250" Stroke Crankshafts
    Scat 4340 Forged Steel 6.385" H-Beam Connecting Rods
    JE/SRP Forged 18cc Dome 4.310" Bore Pistons - 9.8:1 CR
    Total Seal Classic Race Rings
    Clevite77 HP Main & Rod Bearings
    Durabond HP Cam Bearings
    Manley Severe Duty Valves - 2.250" Intake/1.940" Exhaust
    Comp Cams Xtreme Marine XM298H Hydraulic Cam Kits (254/264 Duration - .575/.578 Lift - 112* Separation)
    Comp Cams Roller Rockers
    Merlin Marine 4150 Intake Manifolds w/Brass Water Jackets
    Claimed power >>613TQ/671HP
    Your going to end up spending to much modifying this bullet to work in the boat. I would keep looking. Winter is only half way over, there will be some deals out there.
    Chris Straub
    Straub Technologies

    3HP is an A$$ Whooping!!! JW

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    Custom user title Big Inch's Avatar
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    Quote Originally Posted by cstraub View Post
    Your going to end up spending to much modifying this bullet to work in the boat. I would keep looking. Winter is only half way over, there will be some deals out there.
    Disappointed about it but I agree with you 100%

    Edit: added a pic of the exhaust for cfm to see.

    See how the exhaust angles outwards away from the motor. From the back my tips are directly under the swim steps.
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    Last edited by Big Inch; 01-14-2010 at 12:28 PM.

  16. #14
    cfm
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    The exhaust is really just like the one in the 22 Eagle.

    BTW: The exhaust in that pic is junk and will ruin your present stock motor. The rust is a tell tale sign water is, or is about to, run down into the motor.

    Expect to pay $2500 or more for a good exhaust. So add that to your budget.

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