Changing 3lt for 4.2 V6 can it be done?

[Mark RSA2AU]

Has any one swapped a 3lt 135 hp for a 4.2lt V6? I have access to a good second hand 220hp V6 mercruiser complete with leg for a great price AU$2500. My 3lt is ok but I realy need more power.

I know my boat has this as an option from new so it is capable of handeling the power. I just dont know the technical aspects. I will have a boat shop do the work, but before I do it I want to know if it can be done, and what the possable pitfalls are.

Does anyone have any ideas?

Thanks
Mark

 

[nben]

I have often thought the same thing about my 180. I have even gone as far as to compare the mount points etc. with a friends Crownline with the 4.3. When comparing, it looks as though our hulls have the mount points already molded into the fiberglass to accept the mercruiser 4.3 engine mounts. I have no idea if they have any structure underneath the fiberglass, but it wouldn't make sense to me to go through the trouble of moulding them into the bilge without a stringer or some sort of support underneath. The 4.3 mounts are on either side of the engine underneath the manifolds while the 3.0 mounts to the front of the block. Perhaps a call to sea ray would clear this up?? If I had a deal like yours on a 4.3 I also would be all over it myself.

 

[springer3]

Sorry, no help, but I suspect there is more to it than bolting-in the new mechanicals. Wiring harness? Structure? Weight distribution/ballast? Sea Ray engineering would know what pre-requisites a hull needs for each engine. It might be easier to trade for the correct boat.

Good luck if you try, and be sure to report.

 

[Lazy Daze]

Can't offer much help either. But, Mark, the 180 never had a V-6 as an option. I suspect you might actually have a 175? I can't quite tell from your picture and I don't see a model year listed. Unless the designations are different down there?

I would think the biggest challenge would be mounting it... aren't the motor mounting points totally different? But, again, just guessing.

But, I'd love to see someone do it!

I agree with Springer... how much is this going to cost? Wouldn't it just be easier (and less costly) to sell your boat and buy a boat that already has a V-6?

If you're just after more power for watersports, you could just run a low-pitch prop. When I had a 180, I used an 18" 4-blade and it ripped!

 

[Alex D]

The cheapest and best way to do this swap is to sell this boat and buy one with a V6 in it!

 

[nben]

As I posted above, the mounting points for the 4.3 seem to be moulded into the bilge. He has a 180 that is the same era as mine. The 4.3 came in the 182 which is the same hull. My dad has a late 90's 175 and it is a smaller hull than the 180 that I have.

As far as wiring, it should not be a big deal as long as the donor is a carb model. Anyone with any mechanical savey should be able to figure it out pretty quickly. The 4.3 is about 230 lbs. heavier than the 3.0 (about the same as one adult......I sit on my sunpad all the time and the boat rides fine). Gearing will need to be changed but he said he had a donor lined up on the cheap including the leg. I see the biggest problem being getting everything lined up for the two engine mounts (measurements are available from Mercruiser) and checking with Sea Ray to make sure there is structure underneath the mounting pads on either side of the engine (they seem to be moulded in). The other hurdle would be to determine the correct riser height so that water would not backflow when the boat was at rest in the water with the engine off.

If this were a job that was hired out and the donor engine/outdrive were not available for cheap, then I agree that trading up is the right move. Maybe I am more adventurous than most but I feel this is do-able on a reasonable budget......then again I do do all of my automotive work including engine rebuilds and swaps in my own shop.

 

[Lazy Daze]

Ben, the 182 is a completely different hull/boat than your model year 180. The hull that you have had a run from 1998 to 2001 and never had a V-6 as an option. I'm not saying the 180 hull will/won't support a V-6 with modifications - just that it was never an option.

 

[brad56]

Hey just throw a spanner in the works, you may want to talk to CAPA or Castlemaine rod shop about fitting a low boost supercharger to your 3L it may just give that little bit more HP and be a cheaper option!

 

[Mark RSA2AU]

Thanks Guys

I will be measuring the dimentions this week end, but no decision untill winter. I am off to Africa for a Game Safari. I will do more home work on weights and hull strength then.

I thought that any manufacturer who produces a range of hulls and motors would have standard mounting points for the motor, electrical, fuel and other controlls so as to make assembly faster and easier. I assumed the swap would be relatively simple, besides I am not sure of the condition of the motor and drive. One man's exellent is anothers rubbish.

I would love to upgrade! oh for a V8.... but it is not practicle at the moment.

I wanted to know if it was possable before I went any further, but it sounds like I need to do more homework.

Thanks a Ton

 

[springer3]

.....I thought that any manufacturer who produces a range of hulls and motors would have standard mounting points for the motor, electrical, fuel and other controlls so as to make assembly faster and easier. ....

The problem is the engines were designed for cars - these are "auto-derivative" marine engines. The hull is forced to fit the engine. Fours and sixes are different.