Corsair powerboat need some guidance
10-22-2016, 12:53 PM
#21
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Hey guys bought my first boat which is a 1988 corsair 24ft with a big block 454 330hp engine with a bravo one outdrive. Any info on who helped design corsair and where too get parts for it? I'd also like too upgrade the 454 get some more power out of it. I have a set of old school oval port heads sitting on the shelf waiting too be put on something and thought about putting them on this motor of that would work. Thank you guys
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10-22-2016, 01:00 PM
#22
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Respectfully, unless I missed it, we don't know the gear ratio of the drive here yet, so we don't necessarily know what is too much wheel.
4200 is the bottom of the NORMAL WOT operating range for the 330HP 454. (4200-4600)
Doing 4200 with the 21 suggests that prop has the motor within the normal setup range IF the engine is healthy. Perhaps you'd want to go down as low as 19 to bump up to 4600 RPM when wide open, but that won't jump the speed up from 40 all the way to 50 or 55. Not even close. You might get 2-3 mph out of it if you're lucky. The horsepower at 4200 should be pretty close to the horsepower at 4600. A bit lower, maybe, but very close.
HP is what pushes a boat to a certain speed. (People get very confused about torque, but HP is king. Gearing is how you make use of the horsepower. Gearing takes an available horsepower budget and sets it up for a certain application. If you want to buy a Coke from a vending machine, you need the $2. The $2 are the horsepower. Gearing changes it's application to the task, like having 2 1$ bills versus 8 quarters versus 200 pennies. There are gearing setups that make it impossible. Like 200 pennies. That won't make your $2 work to get the coke. Nor will a $100 bill, even though you have plenty of money. But the 8 quarters, or 2 singles or lots of other things, will. HP = speed. Gearing fits that available HP budget to the task, by getting the torque and RPM where you need them.)
Something is wrong with this boat. The original hull, if intact and not waterlogged with hundreds of pounds of soaked coring, should do more than 40 with a properly set up 330 HP 454. The power must be lower, or load must be higher, or both.
If the measures here are accurate, I'll bet the boat never did 55 with either of those props. Perhaps it did 50. I suspect the motor is sick and perhaps the boat is a good bit heavier than it was when built.
Do you know your drive gear ratio? What type of drive is it?
4200 is the bottom of the NORMAL WOT operating range for the 330HP 454. (4200-4600)
Doing 4200 with the 21 suggests that prop has the motor within the normal setup range IF the engine is healthy. Perhaps you'd want to go down as low as 19 to bump up to 4600 RPM when wide open, but that won't jump the speed up from 40 all the way to 50 or 55. Not even close. You might get 2-3 mph out of it if you're lucky. The horsepower at 4200 should be pretty close to the horsepower at 4600. A bit lower, maybe, but very close.
HP is what pushes a boat to a certain speed. (People get very confused about torque, but HP is king. Gearing is how you make use of the horsepower. Gearing takes an available horsepower budget and sets it up for a certain application. If you want to buy a Coke from a vending machine, you need the $2. The $2 are the horsepower. Gearing changes it's application to the task, like having 2 1$ bills versus 8 quarters versus 200 pennies. There are gearing setups that make it impossible. Like 200 pennies. That won't make your $2 work to get the coke. Nor will a $100 bill, even though you have plenty of money. But the 8 quarters, or 2 singles or lots of other things, will. HP = speed. Gearing fits that available HP budget to the task, by getting the torque and RPM where you need them.)
Something is wrong with this boat. The original hull, if intact and not waterlogged with hundreds of pounds of soaked coring, should do more than 40 with a properly set up 330 HP 454. The power must be lower, or load must be higher, or both.
If the measures here are accurate, I'll bet the boat never did 55 with either of those props. Perhaps it did 50. I suspect the motor is sick and perhaps the boat is a good bit heavier than it was when built.
Do you know your drive gear ratio? What type of drive is it?
