Volvo Penta Cobra 4.3 to 5.0 or 5.7 swap

[Kyle3590]

New to the forum and looking for some insight...Recently purchased a 1993 Four Winns 180 Freedom project boat. The floor is rotten (stringers and all), which i knew ahead of time would have to be replaced. Since I basically have the floor cut out to the point i need to make a decision whether to keep or swap motors, i have a few questions. The boat came with a Volvo Penta Cobra 4.3 L and was missing the outdrive. I am considering upgrading to a 5.0 or 5.7 L volvo, and am curious as to how much fabrication would be involved. I assume the motor mounts will have to be moved but am not 100% sure if they do or how much they would need to be moved. I am already facing purchasing an outdrive for the motor i have now if i was to keep it so i am leaning toward an upgrade. Also have heard that the OMC Cobras around this year had their fair share of problems. any insight/advice is greatly appreciated, thanks!

 

[Dave-R]

There are a couple things to consider. First an 18 foot boat has a hp. limit that can not be exceeded. Second a good running 4.3 is close to 200hp and is a very powerful engine that will surprise you with what it can do. My son-inlaw has a 19' cobalt with a 4.3 that I think runs about 45 mph. My 226 Cobalt with a 5.7 fuel injected engine will maybe hit 50mph. When you drop in a heavy V-8 in that boat, the stern will be effected by the extra weight. Just my thoughts, others may feel different. Dave-R

 

[Kyle3590]

Dave-R, those are my concernes also. The info that I'm getting is that the Volvo 4.3 pinta Cobra OMC is hard to get parts for. I was looking for something fuel injected and a little newer. Thanks for you response.

 

[funk6294]

Looking up some of the dimensions the 4.3 should be the same width as the v8, the v8 mounts are about 3-4 inches forward of the v6 mounts. That likely isn't a deal breaker and if your boat has the mounts lag bolted into the engine bed would just be a matter of moving them forward and drilling new holes. As for the 5.0 or 5.7, if your going to do it go all in. The 5.0 and 5.7 weigh the same, and are about 150lbs heavier than the 4.3. The 5.7 bonus is that it produces a good bit more power than the 5.0. If you are leaning to the 5.0 I would just stick with the 4.3.

 

[Scott Danforth]

HP limit does not apply to I/O's however for that boat, I would stick with a 4.3.

 

[Kyle3590]

funk6294 thanks for the response, do you think the extra 150lb in the stern would effect the handling of the boat?

 

[Scott Danforth]

funk6294 thanks for the response, do you think the extra 150lb in the stern would effect the handling of the boat?

yes

 

[funk6294]

It will for sure change how the boat handles, how much is hard to say. From a static stand point it will be like having your 150 buddy always sitting back there, So the boat will sit a little lower in the water. The bigger factor surrounding handling would be the added power and speed.

 

[HorizonblueDK]

No way I would take a standard 5.7 V8 and drop it into an 18 footer. So damn heavy, to much cast iron. I have an 18 footer myself and I often think about a light weight V8. 5,7 with aluminium heads and intake manifold, stainless steel exhaust manifolds. But it's gonna cost.....