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Discussion Starter #1
Need to improve or replace the 330hp 454.
The boat is a 1991 21' Conquest with the 7.4/Bravo One. Not looking to go cazy just need 100 or so more horses. Any suggestions?
IMG00078-20110610-1758.jpg
 

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Keep it simple

Hyd. roller cam, roller rockers, better heads, upgrade exhaust. all can add power and 450hp is a really ez number to get to. got pics of the motor? what type of exhaust does it have now? every improvement you do to get more air/fuel in and exhaust out will make more power.:|err
 

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steelcomp was here
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Need to improve or replace the 330hp 454.
The boat is a 1991 21' Conquest with the 7.4/Bravo One. Not looking to go cazy just need 100 or so more horses. Any suggestions?
View attachment 125366
Easiest thing is a little more compression, performance cyl. head rebuild, camshaft upgrade, and intake/exhaust upgrades.
 

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Or Seth, either one
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As above, not hard to do at all. You can do a bunch of research and order piece by piece, or the really easy option is to get a proven package. I like the process of researching and creating the combination, but if you just want the easy answer...
Edelbrock Performance Package
 

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Discussion Starter #5
Hyd. roller cam, roller rockers, better heads, upgrade exhaust. all can add power and 450hp is a really ez number to get to. got pics of the motor? what type of exhaust does it have now? every improvement you do to get more air/fuel in and exhaust out will make more power.:|err
Poor picture but here it is...

Boat Motor.jpg

Only thing not stock is the carb.
 

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Discussion Starter #6
Easiest thing is a little more compression, performance cyl. head rebuild, camshaft upgrade, and intake/exhaust upgrades.
I've got the basics down, I guess I'm really looking for what combos work with a bravo one. Or what combos yield the best bang for the buck. Never messed with a outdrive boat before. Don't want a boat that is not reliable. Not interested in making big horepower and tearing up the outdrive.
 

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Easy. Cam,carb, intake and exhaust. Easy 100-150 there. Let us know what you do.
 

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Discussion Starter #8
As above, not hard to do at all. You can do a bunch of research and order piece by piece, or the really easy option is to get a proven package. I like the process of researching and creating the combination, but if you just want the easy answer...
Edelbrock Performance Package
Never had any issues with edelrock stuff. Chevy trusts them, why shouldn't I ??? Anyone ever used a set of their marine heads?


Side note... Launched out of Del's and skied Victoria for years, I miss cold delta mornings!
Delta people are great people!
 

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As above, not hard to do at all. You can do a bunch of research and order piece by piece, or the really easy option is to get a proven package. I like the process of researching and creating the combination, but if you just want the easy answer...
Edelbrock Performance Package
Have you ever installed that kit on a low compression 330hp/454 I/O with wet exhaust ?

Here are the cam specs:

Cam Style Hydraulic flat tappet
Basic Operating RPM Range 1,500-6,500
Intake Duration at 050 inch Lift 240
Exhaust Duration at 050 inch Lift 246
Duration at 050 inch Lift 240 int./246 exh.
Advertised Intake Duration 300
Advertised Exhaust Duration 306
Advertised Duration 300 int./306 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.560 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.573 in.
Valve Lift with Factory Rocker Arm Ratio 0.560 int./0.573 exh.
Lobe Separation (degrees) 112
 

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I'd step up the compression a wee bit, drop in a 1/4" stroker crank, and go up a step or two on the cam lift (mild increase). This won't kill the outdrive, but give you noticeable improvement in pulling power. It's amazing what a little more lift and a stroker crank can do to wake up a big block.

Essentially you go from a 454 t a 496 which is "smooth" power, not rpm crazy...

OK Bob, Steel, give him the part numbers!

Ps. I have used Edlebrock combo's on street cars and they were very effective. I used their cam, intake, carb combo and had my guy do the heads. If you are in the Bellflower area, I know someone who can help you with your project and keep it "under control".
 

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Or Seth, either one
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Have you ever installed that kit on a low compression 330hp/454 I/O with wet exhaust ?

Here are the cam specs:

Cam Style Hydraulic flat tappet
Basic Operating RPM Range 1,500-6,500
Intake Duration at 050 inch Lift 240
Exhaust Duration at 050 inch Lift 246
Duration at 050 inch Lift 240 int./246 exh.
Advertised Intake Duration 300
Advertised Exhaust Duration 306
Advertised Duration 300 int./306 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.560 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.573 in.
Valve Lift with Factory Rocker Arm Ratio 0.560 int./0.573 exh.
Lobe Separation (degrees) 112
No, I never have. I'm certainly not as experienced as many of you guys here and I'd personally put a combination together part by part after researching and consulting you guys. Although, a package like that will offer results with little or no research time if that's what the guy is looking for. The trade off for convenience is it may not be absolutely optimum. IMO that cam is aimed a little too high in the RPM range to provide optimum performance on a I/O boat. But again, there are very very knowledgeable people here that are able to verify or disprove my opinion. And I'm very OK with it. I have learned more here on the boards than I knew to begin with... and I thought I knew it all! LOL:happy:
 

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Or Seth, either one
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Or...
Just put a ProCharger on it. 4-5psi should get you the 100hp your looking for. Bolt it on and take it off if you decide to sell the boat and put it on the next.

Keeping your target rpm in the 5000 to 5500 range will simply require more air in the engine. Without forced induction, your biggest restrictions are your heads (assuming they're peanut port heads) and the stock exhaust.

Options options options, which to choose?
 

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I'd step up the compression a wee bit, drop in a 1/4" stroker crank, and go up a step or two on the cam lift (mild increase). This won't kill the outdrive, but give you noticeable improvement in pulling power. It's amazing what a little more lift and a stroker crank can do to wake up a big block.

Essentially you go from a 454 t a 496 which is "smooth" power, not rpm crazy...
"essentially", a 1/4" additional stroke would make it a 482. it would have to be bored .060 over to make it a 496, which isn't always necessary.
 

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Discussion Starter #14
I'd step up the compression a wee bit, drop in a 1/4" stroker crank, and go up a step or two on the cam lift (mild increase). This won't kill the outdrive, but give you noticeable improvement in pulling power. It's amazing what a little more lift and a stroker crank can do to wake up a big block.

Essentially you go from a 454 t a 496 which is "smooth" power, not rpm crazy...

OK Bob, Steel, give him the part numbers!

Ps. I have used Edlebrock combo's on street cars and they were very effective. I used their cam, intake, carb combo and had my guy do the heads. If you are in the Bellflower area, I know someone who can help you with your project and keep it "under control".
I work at LAX, who's the guy in Bellflower?
 

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I work at LAX, who's the guy in Bellflower?
Dont know of any builders in bellflower, used to live there?

You can also start off easy and work your way up and see what small thing will do for power improvements. I replaced the intake with a edelbrock air gap intake, a stock 750 double pump, t-stat, and a crossover bypass kit, and I think one step colder plugs and wires, in a 89 carrera with a stock 454.
stock before adding parts it went 53-54 at about 46-4800 rpms. after doing these small bolt on's and adjusting the carb, it went 5600rpms at 69mph, that I saww and the customer said he say 70-71mph. It also had through hull exhaust already but stock iron manifolds.
 
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