how much power?

J

jlr2384

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I recently purchased a twin powered omc 350 sbc rated at 260hp with cobra out drives. Im not sure the ratio on them. My question is can I build these motors up with cams and a few add ons and the out drives not blow up or am I stuck with the power I have now and need to go to mercruser outdrives?
 
H

HT32BSX115

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Re: how much power?

My question is can I build these motors up with cams
Click to expand...

Howdy,

Absolutely. But understand that the cams you already have are pretty much optimized. If you use camshafts that would give you more power, you may have to "cam" for more RPM.

Sterndrives usually want engines that turn around 5000 or less. Marine camshafts are optimized for that around that RPM. Also, they are set up to minimize reversion so this sort of limits what you can do with the camshaft that you might otherwise do in an automotive application.


Which boat is it?
 
J

jlr2384

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Re: how much power?

The boat I have is an 86 baja force 280. The motors are rated at 260hp and I want to eventually build 400hp or bigger 383 motors. I was told that the omc cobra outdrives an only handle 260 hp. I found a marine cam that has an rpm range of 1300-5300. Im just looking for a mild cam sound now but don't want to blow up my outdrives
 
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sschefer

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Re: how much power?

I did a little research on this a while back for a boat I was building. Essentially you're pretty well matched right now. The marine architect that designed your boat was concerned about the amount of torque the stringers and transom could handle and also the center of balance (cb) for your boat. A torquey 383 stroker or small block 400 might just rip itself loose after a couple of hard hole shots. Most certainly you'll be looking to change outdrives and that could lead to some major transom mods.

Personally, I'd leave well enough alone on this boat and go get yourself a "Go Fast" boat like an 2002 Allison or a STV for the times when you just want to hall arse.
 
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jlr2384

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Re: how much power?

The boat I have also was available with a 454 big block option. Would they change the stringers in the boat or would they just make the same boat and add more power. I looked into changing outdrive and found the holes are different for the transom mount so im prepaired for the mods and expense.
 
Faztbullet

Faztbullet

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Re: how much power?

Would they change the stringers in the boat or would they just make the same boat and add more power.
Click to expand...
Boat and stringers would be the same, the 454 option would have came with Mercruiser drives as OMC only used a 460 in this time frame and a King Cobra drive. Adding hp to these drives will result in "empty pockets" as they will DIE.... If you want to increase hp of engines,covert the cobra set-up to mercruiser as SIE has a kit to do this and use the newer Gen II drive in 1:47 ratio. If you want to go fast find you a pair of Alpha 1 SS drive as they are a short shaft version of a standard drive with a CLE lower unit....
 
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HT32BSX115

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Re: how much power?

jlr2384 said:
The boat I have is an 86 baja force 280. The motors are rated at 260hp and I want to eventually build 400hp or bigger 383 motors. I was told that the omc cobra outdrives an only handle 260 hp. I found a marine cam that has an rpm range of 1300-5300. Im just looking for a mild cam sound now but don't want to blow up my outdrives
Click to expand...

400hp would probably break the little Cobras. You'd be ok if they were King Cobras though (good luck finding 2!)

You should probably consider Bravos if you want put 400hp engines in engines in it.
 
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jlr2384

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Re: how much power?

Thanks for the input from everyone. I was kinda thinking I would need to upgrade to better outdrives.
 
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