volvo penta 280 hp rating?

[clancy72]

My boat is equipped with a '78 v/p 280 outdrive. Can anyone tell me the horsepower rating? I am pushing 400 hp through it right now with no damage(yet) regular oil changes and such. Any recommends on sturdier outdrives if this one fails would be appreciated... I plan on running 500 hp....

 

[Maclin]

Re: volvo penta 280 hp rating?

I was thinking the number of the drive was the HP it was designed to not stress under, anything over and you need to rethink.

But...torque is the killer. For example, Volvo always has different props for diesel applications because of the elevated amounts of torque the props can feel at the lower rpms.

What I am saying is if your engine's torque curve is typical of a mildly warmed-over gasoline V8 and the extra HP comes from higher RPM then your drive may be able to stand the 400HP. A typical 350 c.i. engine will have 320-360 ft lbs of torque at 3,000 rpm, and the HP will come in later at 5,000rpm or so. But if you have a big block with 500 ft lbs of torque at 1,000 rpm (slight exaggeration maybe) then the drive will not last long after a few AVL's (Aggressive Vehicle Launches).

Also the weight of the boat, hull design, final drive ratio, prop pitch, etc... will be a factor. On a lighter boat with a quick-planing hull designed for speed the 400hp may not stress it at all. If the boat is heavier, or you over-prop for speed, then the drive will be the weak point during an aggressive launch.

Now I am curious, What are you working on?

 

[clancy72]

Re: volvo penta 280 hp rating?

I am working on a 24ft '78 Cobia/Robalo Caribbean (3950 lbs). I just bought it from a dealer who had it on consignment. I'm the second owner. It has a chevy 350 that is "supposed" to be putting out 400 hp. I will be contacting the original owner ASAP to find out what he did to modify the motor to get 400 horse out of it. I know it has a hi-rise edelbrock intake with a double pumper carb, stainless(i think) edelbrock exhaust manifolds. The boat is run at 4500-5000 ft elevation and Lake Powell. the engine starts and runs smoothly and doesn't die when throttled down. It starts quickly hot and cold also, (i've had fuel injected boats that wouldn't do that). The boat is rated for 500hp per the iboat directory, but i'd be hesisant to run that much HP without substantial fiberglass reinforcement. The torque to weight ratio you mentioned is a good point....Any replacement ideas if i do go with a big block?

 

[jastacey]

Re: volvo penta 280 hp rating?

I wouldn't worry about running 400 HP through a 280 drive, just keep the RPM's below 4800, volvo mounted diesel engines infront of this drive and didn't have to do hardly any mods, they can take the torque, most drive don't like RPM's above 4800, they tend to gernade, if you really want a drive that can take that high output, go to a Konrad drive or an Imco drive, but be prepaired to part with some very serious cash

 

[clancy72]

Re: volvo penta 280 hp rating?

Thanks for the advice, while we're on the subject. The original owner was running a 17' prop and achieving 43 at powell with a load (9 people and 70 gallons), he couldn't remember the rpm's he was running at, but he mentioned he took it to WOT then backed off a bit....LOL! I'm anxious to see if a higher pitched prop would get some more top end out of it.... I'm really not sure what a 3950# boat with 400 hp should be running lite.....

 

[whywhyzed]

Re: volvo penta 280 hp rating?

The reason the drive is lasting is because it's an engine that was dynoed at 6500 rpm and made 400HP.
Now it's turning 4600rpm in the boat and making 260HP just like every other 350 Chevy in a boat.
The boat might be running a little bit lighter because of the guy's wallet.

 

[clancy72]

Re: volvo penta 280 hp rating?

True, but is there any way to optimize different gearing in the outdrive or prop pitch to use more of the higher rpm power? Without shelling the outdrive of course...