3.0l to 4.3l engine swap

[Rurru]

Hello, I have a 2008 Larson 180 with a 3.0l GLP-J Volvo Penta motor. I need to do a complete engine overhaul, and was thinking to replace the engine with a 4.3l instead of doing all the necessary repairs. I found a used Volvo Penta 4.3GS PMDA from '94, freshly rebuilt. The engine was used with a DP290 outdrive, while I have the SX drive. I have a few questions...

1. Is this conversion even possible? Both engines have side mounts 23 inches apart, but would I need to move the mounts backwards since the V6 is probably shroter?

2. Since the 4.3 had a DP290 drive, could I use the bell housing from the 3.0 and mount it onto the 4.3? Are these compatible?

3. Are they compatible electrically?

4. Any other issues I may encounter?

Thank you!

 

[Bondo]

4. Any other issues I may encounter?

Ayuh,..... Welcome Aboard,..... You'd have to regear, or replace the drive, as the gear ratio is very wrong,......
A prop change wouldn't be enough,....

 

[Scott Danforth]

I would look for a 96 or later 4.3 to swap in

as Bondo stated, you will need a different drive with the 4.3 than the 3.0

same bolt pattern on the flywheel housing

this is a case where it would be cheaper to sell what you have and buy a boat with what you want.

and what is wrong with your 3.0 that you need a complete engine overhaul?

 

[Rurru]

I would look for a 96 or later 4.3 to swap in

as Bondo stated, you will need a different drive with the 4.3 than the 3.0

same bolt pattern on the flywheel housing

this is a case where it would be cheaper to sell what you have and buy a boat with what you want.

and what is wrong with your 3.0 that you need a complete engine overhaul?

Thank you. What's the difference between pre 96 and a 96 or later? I was thinking to put a 19 pitch prop, wouldn't that tackle the gear ratio problem?

 

[Bondo]

Ayuh,.... Vortec heads came out in '96,.....

The ratio difference is bigger than can be fixed with just a prop change,....

 

[Scott Danforth]

Thank you. What's the difference between pre 96 and a 96 or later? I was thinking to put a 19 pitch prop, wouldn't that tackle the gear ratio problem?

To expand on Bondos answer. The vortec heads and other changes make the 1996 and later 4.3 the one to get

You would be over-reving with a 26p prop, the 19p would allow the motor to spin to 8000RPM or more when the pistons will want to go out the bottom of your boat

 

[Rurru]

Okay.. so the only option would be to replace the gears. I currently have a ratio of 1.97. what would be a suitable ratio?

 

[Scott Danforth]

Okay.. so the only option would be to replace the gears. I currently have a ratio of 1.97. what would be a suitable ratio?

1.6:1 for a V6, 1.5:1 for a small v8, 1.3:1 for big block

 

[QBhoy]

exhaust set up is different, need new engine mounts glassed in properly, drive ratio may be a little stretch perhaps, as said.