Ok wrote this long winded post about my project. But don't know what became of it. So.
1. I have no power. Cost of rebuilt Perkins diesel 165hp 256 ft lbs of torque was going for 14k with 1.9:1 gear.
2. I already owned a low hours 6.5 optimizer that needed a marine adaptation which is already well underway.
3. HP is 6.5 Optimizer is 190hp 385 ft lbs of torque , I am going with a borg warner 1:1. while built on the Detroit 6.5 platform the optimizer was recast by AM general to eliminate the overheating and head and cylinder cracking. I chose to go naturally aspirated to eliminate complications.
Where are my potential issues at?
1. Physically this will fit.
2. At765lbs it's weight to HP is great and lighter than original.
3. I already owned it. and the motors have been used in trawlers before. 28 AlbinTE.
What questions do you have. What suggestions do you have? Has anyone ever done this? Go from a straight 6 diesel to a V8 diesel. The famous words what could possibly go wrong. Izzy
Going from an inline 6 to V8 will need exhaust system modification at the least.
You will need water cooled exhaust manifolds for your V8 which I suspect will be very rare birds.
Rated RPM for the Perkins is 2800 rpm. I would expect that the 6.5 is higher and will need either different trans or different prop.
Is your goal to have a boat to go cruising or just move about the marina?
If cruising, you are going to have to do an all out, top notch conversion.
That means rare motor mounts, bell housing, sea water pump, oil cooler, transmission cooler, heat exchanger, exhaust risers, mufflers, gaskets, and on and on.
Don't take offense, but the least costly move (and fastest) would be to either fix your Perkins, or replace it with a running take-out of the same HP. They are easy to find on the internet for <$10K. A good place to start is Trans Atlantic Diesel.
Sell to 6.5 to help pay the bills.