2005 VP 5.7 to 5.0 Engine Swap

[Shelby Ladner]

I know it's not the most ideal plan but I bought a 2004 5.0 complete running engine to replace a blown 2005 5.7. The 5.7 was raw water cooled and run in salt water so total junk. I am looking for assistance with the engine wiring harness difference. The 5.0 has the round harness plug (rear of engine) and the 5.7 has the large rectangular one. Is there a way to make it adapt/convert or do I need to sell the 5.0 and find a 5.7.
Thanks

 

[Shelby Ladner]

I know it's not the most ideal plan but I bought a 2004 5.0 complete running engine to replace a blown 2005 5.7. The 5.7 was raw water cooled and run in salt water so total junk. I am looking for assistance with the engine wiring harness difference. The 5.0 has the round harness plug (rear of engine) and the 5.7 has the large rectangular one. Is there a way to make it adapt/convert or do I need to sell the 5.0 and find a 5.7.
Thanks

The 5.0 is a GM block, sorry

 

[Scott Danforth]

they are both GM block. however why do you want to go from about 280hp down to about 220? how big or small is your boat? you may not be able to get the boat on plane

are they both carb or are they both fuel injected? or is one carb and one fuel injected?

now, if they are both the same fuel system..... if you think outside the box, simply unbolt the 5.7, and have on a stand on the ground. have the 5.0 on a stand on the ground.....transfer the wiring harness from one to the other.

however my guess is you have different fuel systems, etc.

 

[alldodge]

Sounds like in short you have access to a cheap 5.0 so want to go that route. The 14 pin motor has a newer PCM and the 10 pin is either a carb or older ECM

Your boat harness can be changed to a 10 pin but we would need to know what the original motor and older motor are.

Also think about, the boat was designed with more HP, and dropping it down may cause you to want to get another motor or sell it

 

[Shelby Ladner]

I believe both engines are Vortec GM VP engines with MPI. Original 5.7 is a GI-J 300hp in a 2005 Chaparral Sunesta 252 . I searched many hours for a used 5.7 complete engine to drop in because of the salt water open cooling the motor and all components, manifolds, starter ,risers, alternator were toast. I found a VP 5.0 from a 2004 Sunesta complete turn key ready for a great price and hoping to install. I realize 5.0 is little less hp but thinking maybe I could change pitch on prop to get by, not really concerned with top speed as long as rpm's not too excessive. I have the ECM and all components with the 5.0 and it is a complete running engine just seeing if it's possible to adapt.

 

[alldodge]

While the lower HP will reduce top end, where it will really be noticed is getting up and on plane. The 5.0 has less torque and that will be noticed on first throttle up.

You could get a long block and swap all your stuff over to the new motor
https://www.michiganmotorz.com/vortec-marine-engine-1996-current-p-68.html