400 HP 350 in a 1950 capri-gctid360883

[Guest]

Gent's I would like to know if any of you have attempted this much horsepower in a 1950 cuddy, I will be installing the engine this month with the help of a good friend, specs bores 0.010 over, scatt high output crank, scatt flat top pistons, competition cam 275 h series, comp roller rockers, comp pushrods, lifters and rockers, external oil cooling system with stainless steeel red. calculated horsepower at 375 to 400 horse. would like to know what kind of prop I should order for this type setup, I will be able to turn 5000 rpm without any problem to the rotating assembly but I would like to get the boat up out of the water as quick as possable and I expect with this much horsepower that wot is a bad idea with this little boat. I just had anough of the new jet boats coming up beside me and then opening up the throttle to leave me behind, hope this gives them a bit of a wake up call this summer.

[Guest]

My first question- why?

That hull is not designed to handle that much power and speed. Professionally speaking, that modification is irresponsible, as the boat hull cannot be modified to accept the greater speeds you desire.

Get a boat designed to handle that type of power and speed, and keep yourself alive.

[Guest]

I am in a similar situation. I have an 86 1950 and am going to repower the original 305 with w 350... but my 350 will only have 260hp... 400 seems a bit excessive imho. I'm not sure you could insure that boat since it will exceed the coast guard capacity plate. Maybe stick with a 300 hp engine? Good luck on your project!!!

[Guest]

what are the heads and manifold and carb?

[yachtman]

I see a couple of problems with what you propose.

#1...the cam is too big for an out drive boat. A comp cams 262#12-236-3 cam is the biggest cam that should ever.go it an out drive boat. With the cam you propose you risk water inversion and pounding the drive gears to pieces from duration slap.

#2...no mater what you do you will never realize that much hp with a through outdrive exhaust. Outdrive exhaust is really restrictive

#3... the hull is not designed to handle that much power. Im not talking about handling although that would na a problem with that much power. What im talking about is after a time the engine coming out of the boat or transom damage.

#4...the out drive can't take that much hp unless you have up graded or modified the out drive. You don't say what it is but im guessing a alpha drive or a volvo. Either one will be toast in a short period.

Yes it has been done im just telling you what you can expect. You are better off getting some thing like this and putting it in

[Guest]

Jerry Atkinson wrote:
Gent's I would like to know if any of you have attempted this much horsepower in a 1950 cuddy, I will be installing the engine this month with the help of a good friend, specs bores 0.010 over, scatt high output crank, scatt flat top pistons, competition cam 275 h series, comp roller rockers, comp pushrods, lifters and rockers, external oil cooling system with stainless steeel red. calculated horsepower at 375 to 400 horse. would like to know what kind of prop I should order for this type setup, I will be able to turn 5000 rpm without any problem to the rotating assembly but I would like to get the boat up out of the water as quick as possable and I expect with this much horsepower that wot is a bad idea with this little boat. I just had anough of the new jet boats coming up beside me and then opening up the throttle to leave me behind, hope this gives them a bit of a wake up call this summer.

Sounds idiotic, no offense

That hull won't handle 400hp. No concerns about it falling apart like yachtman, the transom will hold it fine. But it will be a dangerous mess to operate. This is not like a car with too big an engine where it's still safe and fun to go fast in a straight line but it won't handle, boats get on plane and it can easily become a danger just giving it gas going straight.

Your build seems to be an automotive build and not a marine build. Asking for trouble.

Also, as yachtsman said either drive the boat came with (OMC or Alpha, looks like OMC originally) will likely not survive, you'll need a Volvo upgrade to make things happen. The v8 Volvos will handle 400hp just fine.

[Guest]

You should be able to launch and get on plane very quick.

I wouldn't go WOT for fear of the engine/drive ripping the boat apart.

Im guessing that you will have at least 150hp more tha that hull was designed to handle.

Well I probably would, once or twice, alone, just to see what it would do.

Have a kill switch tether attached to your vest in case the fecal material hits the fan. Maybe even wear a helmet.

[2850Bounty]

Ditto Dave's comments.... and ditto the comments re; insuring this boat with those modifications. And you don't want to be out there un-insured!!!!!

I think that what you would be attempting is rather impractical for this hull and drive (assuming Alpha).

Could it be done???? Possibly......, but you'd need to dig more deeply into this in order to understand just what it requires to make 400 "Marine" HP from the SBC 5.7L. Then if you make 400 hp, your drive ratio is likely incorrect, and would need to be a taller ratio.

Is a taller Alpha drive ratio even available???

Now..... if you want to impress your Jet Boat buddies, here's the way to do it.... but you'll need to get your check book out.

Courtesy of Bill L (aka Billbayliner) .

http://www.baylinerownersclub.org/fo...lking-on-water

.

[Guest]

250HP is all that hull would be controllable with, imo

Jerry Atkinson wrote:
calculated horsepower at 375 to 400 horse.

...

I will be able to turn 5000 rpm

400 HP at the 4200-4600 recommended Alpha WOT rpm is tough to get from 350 cubic inches.

That's 450 ft. pounds of torque... can't imagine that without a blower

I also can't imagine the Alpha's U-joints living for long at that torque, especially if you ever forgot you were trimmed up and gunned the throttle

Alpha drives are good for 300HP in the 1.32:1 ratio ...but I'm not sure they're produced in that ratio anymore.

[Chief_Alen]

I surmise your not going to listen to advice here, but maybe you will heed this little tidbit from me.

Make sure you have a chase boat following you. Wear a life preserver, and have the kill switch hooked up to you.

[2850Bounty]

whywhyzed wrote:


400 hp at the 4200-4600 recommended alpha wot rpm is tough to get from 350 cubic inches.

That's 450 ft. Pounds of torque... Can't imagine that without a blower

1.... i also can't imagine the alpha's u-joints living for long at that torque,

2.... especially if you ever forgot you were trimmed up and gunned the throttle

3.... alpha drives are good for 300hp in the 1.32:1 ratio ...but i'm not sure they're produced in that ratio anymore.

1.... Believe it or not, this same bearing cross (or a close equivilent) will take much more torque. The Spicer 5-1306 also shares a home with the early Alpha drive, as it does with the Volvo drives that are found behind BBC power.

I doubt that this alone is an issue.

2.... Fully agree!

3.... That is a good tid bit of info!

I was wondering what the over-all ratio would be, and was pretty sure that a taller ratio would work much better.

chief alen wrote:
i surmise your not going to listen to advice here, but maybe you will heed this little tidbit from me.

make sure you have a chase boat following you. Wear a life preserver, and have the kill switch hooked up to you.

[size]4 wrote:
[/size]+ 1

[yachtman]

I will answer one of your questions about what prop you should have.

In a boat that small with that hp and if you dohave have an alpha drive( you didn't say what drive you have) you wont be able to get a prop with enough pitch and diameter to keep it with in the 5000 rpm range unless you have it modified with more pitch. You will also need.it cupped because a standard one will cavitate when you get up on plane and the drive is nearly the only thing in the water.

[itsabowtime2]

Here is a thought, with the money you plan on investing is this boat, purchase one that has a motor with HP closer to what you want. You will be looking at more of a "go fast" type of boat like a Baja.

As others have said, the Alpha is rated for 300hp max. You would need to invest in a B drive and transom. You are looking at 5-6K for the hardware alone then you will need to glass over the transom and do fresh cut outs.

[Guest]

I had a 2050 with a 305 in it. That was the upgraded engine for the 50th anniversary edition. that carbed 305 would run over 57 mph at 6000' elevation. That was too fast for anything other than calm water. Even the smallest wake would launch the boat completely out if the water. The hull is not designed and there is no use for that speed. Even those guys that run those fast bass boats have the hulls restraked for that speed, and those are designed for 100mph. I wouldn't want you pulling me up on a wake board! That big cam will have a lousy low end IMHO and starts less than 40% throttle will be jerky.

[2850Bounty]

If you really want to impress your Jet Boat buddies......

a properly built GM SBC ........ + this



= this..........



And he's probably going faster than any of us would ever want to ski behind.

Remove the prop set for skiing, and install a high speed set, and...........................