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I just repowered my 20 deg. deep V - 23' w/a, about 5000#, with a 350 magnum mercruiser (300hp). I reused my alpha 1 gen II outdrive. Does your boat use a small block V-8 also? If so, with 300hp you can expect it to plane easily and cruise at just over 30mph getting 3mpg. WOT will be in low 40's but a 300hp V-8 will absolutely drink fuel at those rpm's. Plus they are designed to cruise around at 3000-3400rpm's, that is the way they will last, not running all out.
I have a 233 an if i were to repower with a new package I would go with a mercuiser 496 with a Bravo 2, our boats are heavy and need some power to get moving effeciently. the bravo 3 is nice but you will lose some top end but gain fuel effeciency.
__________________ "I love you and respect you very much. But I will kill you dead before this day ends"
Injected 454 with Vortech marine supercharger. Ridiculous gobs of power for about the same price as half a Verado.
not the best idea, 454 blocks are becoming harder to find since they are out of production. our formula's have a hook in the hull, once you hit 55-60 the power required to go faster becomes exponetial. then you are looking at racing drives and fairing the hull bottom.
the OP did not mention the intended use of the boat, but if you wanna go faster than 45 MPH, look at different hulls. the beauty of the 233 is how heavy they are, throw some chop at em and they go faster, when everyone is slowing down through a squall on the way home the 233 is at home in the squall.
I have a 1980 233FS w/ 350 Alpha propped @ 14.5 x 18 it does real well and I have no complaints however if and when I repower I plan on a big block probably 502 with bravo 1. The most cost efficient is to rebuild what you have but if you choose to replace then go for the big block (it does'nt cost that much more). This will give you much better performance #'s as well as better mpg #'s if you go easy on the throttle. As inferred earlier "the OP did not mention the intended use of the boat" and the top end is limited by the hull design.
not the best idea, 454 blocks are becoming harder to find since they are out of production. our formula's have a hook in the hull, once you hit 55-60 the power required to go faster becomes exponetial.
OK then how about a 502. The vortech supercharger kit for that engine makes up to 720 horsepower. I should think that hook or no hook in the hull that boat will fly. http://www.vortechmarine.com/products_01.php
__________________ Bill Adams
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93 LWB
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not the best idea, 454 blocks are becoming harder to find since they are out of production. our formula's have a hook in the hull, once you hit 55-60 the power required to go faster becomes exponetial.
OK then how about a 502. The vortech supercharger kit for that engine makes up to 720 horsepower. I should think that hook or no hook in the hull that boat will fly. http://www.vortechmarine.com/products_01.php
where ya gonna put the fuel? you gonna run a standard bravo and pick the parts up from the ocean floor? no?
then spend the money on a fastec and actually go fast.
720 HP is worthless if you cant put it to the water.
I doubt the OP wants to spend $60,000 on an old hull
Yeah, sounds like a good idea to invest all that coin for a 700+HP motor to get the absolute top speed out of a 35 year old hull. Don't leave anything on the table and get all you can out of it.
I just repowered my 20 deg. deep V - 23' w/a, about 5000#, with a 350 magnum mercruiser (300hp). I reused my alpha 1 gen II outdrive. Does your boat use a small block V-8 also? If so, with 300hp you can expect it to plane easily and cruise at just over 30mph getting 3mpg. WOT will be in low 40's but a 300hp V-8 will absolutely drink fuel at those rpm's. Plus they are designed to cruise around at 3000-3400rpm's, that is the way they will last, not running all out.
michiganmotorz.com has some good motors
not to put you down but the #s for your trophy and a 233 formula will be quite different. the formula has more deadrise and is considerably heavier. ive been in smallblock powered 233's(260 hp) and they arent quite a dog, but the little smallblock and alpha are working overtime pushing her through the water at speed.
big block chevy would do better but an alpha will grenade under that pressure,plus finding big block parts is not gonna get any easier.
again, best bet is a 496 with a bravo hands down. and a 233 is a most worthy project for a $20K + power package
I just repowered my 20 deg. deep V - 23' w/a, about 5000#, with a 350 magnum mercruiser (300hp). I reused my alpha 1 gen II outdrive. Does your boat use a small block V-8 also? If so, with 300hp you can expect it to plane easily and cruise at just over 30mph getting 3mpg. WOT will be in low 40's but a 300hp V-8 will absolutely drink fuel at those rpm's. Plus they are designed to cruise around at 3000-3400rpm's, that is the way they will last, not running all out.
michiganmotorz.com has some good motors
not to put you down but the #s for your trophy and a 233 formula will be quite different. the formula has more deadrise and is considerably heavier. ive been in smallblock powered 233's(260 hp) and they arent quite a dog, but the little smallblock and alpha are working overtime pushing her through the water at speed.
big block chevy would do better but an alpha will grenade under that pressure,plus finding big block parts is not gonna get any easier.
again, best bet is a 496 with a bravo hands down. and a 233 is a most worthy project for a $20K + power package
I'm not familiar with the Formula 233 so I was giving my specs for comparison. Remember though, I was talking about a new 5.7 Vortec Marine engine. They are roller cam engines with lots more torque, rev to 5000, and typically have 315-325hp. I don't suggest anyone use an Alpha drive with higher hp, I'm reusing mine because it's not broke. I'm not gunna subject it to 300hp. Luckily my boat now planes easily with 1/2 throttle and I will be cruising from 3000-3300 which doesn't come close to 300hp.
thats a super package for your trophy no doubt. in the late 80's mercruiser offered an alpha with a big block and they hardened all the parts in the drive but have since stopped production. that is the drive to get your hands on.
personally I have 2 inline 6 cyl. 165 HP chevy's in my formula and love the redundancy, only issue is this motor is not made anymor either so when it is time.................................hello496/bravo 2/3.
__________________ "I love you and respect you very much. But I will kill you dead before this day ends"
It's also the same hull as my 24' Blackfin. From my experience, it would be hard to overpower this hull with a single engine. It would be easy to underpower it, though.
Horsepower ratings at full throttle top rpm are meaningless if you intend to cruise all the time. Whatever you get, make sure it has roller lifters because of the oil issue.
Repower a 1974 thunderbird formula 233 
He started the same thread a year ago and did not reply. 
