6.2/6.5 rebuild for marine use

[5akman]

I"m looking at a 38' boat with twin run out SBC 350 gassers. If I purchase it, it would only be if I can afford to repower with some diesels. I've owned and do now own a 6.5 in a pickup but what about marine use on these units? How many Hp on these engines in NA form? How about adding the turbo? Are there marine parts availble for the conversion and especially a water cooled exhaust manifold with turbo houseing if I wanted to turbo the engines? Compression ratio recommendations for NA and turbo? Block casting number to look for? Stock crank or Scat? Approx what does a rebuild cost if I do the build vs purchasing a long block? Lots of questions before I write a check............

 

[THEFERMANATOR]

First what hull is it? A 38' with 350's sounds awfully underpowered to me. As far as teh 6.5 in marine use, it is doable and has been done. Look up PENINSULAR for more info, as well as HAMMERHEAD and a few others. Warning though, the 6.5's in marine use do not have a good reputation for reliability and longevity.

 

[WarWagon]

B.O.A.T. Bring On Another Thousand. :hihi:

Used military surplus 6.2 engines with 30K miles on them at $900.00 each plus shipping. 120-150 HP each.
ARP head studs (~$300)and gaskets.
Turbo precups
short body injectors. ~$550.
Gapless rings (~$300) or at least an ebay ring set (~60.00).
ATT turbo's - you will never run a boat engine where the GMx turbo's work. ~$799 each
Exhaust manifolds...
Figure over 200 HP with the ATT turbo. 1995 gas TBI 350's were rated at 200 HP.
New props with higher pitch for the lower RPM diesels. 5000 RPM gas vs. 3600 - 4000 RPM for the 6.5. IMO 4000 RPM is extreme for a 6.5 it would be more like 3600 RPM. Around a grand a prop.
Extreme water separators and fuel filters. Water and injection pumps and injectors do not mix. Water in fuel is the main reason the 5.7 Olds diesel got a bad rep as it would muck up the injection pump timing and take out the weak parts. (Head bolts or shatter cylinder liners with timing advance from water rust.)

Weight and balance of boat as the diesels will weigh more than the 350.

Boats run engine at full load and high RPM for extended time. As you see boats eat 350's for lunch and will blow a 454 with ease.

I would recommend getting Optimizer 6.5's military surplus, $2500 each or more if you can find them. Otherwise the 6.2/6.5 blocks are known to crack at the mains. This makes anything but Optimizer engines almost unrebuildable due to block cracks. So a low mile military 6.2 is a cheap option that you can blow up and get home on the other engine. A 6.5 is merely a bored out 6.2.

Water in fuel and algae/bugs/etc. is a worse problem in diesel than a gas engine. More expensive to fix.

The 6.5 is a LIGHT DUTY diesel. Marine is the only use harder that I put mine through towing, except, cooling in a boat is better.

Fuel economy is the only advantage with the ATT turbo. Translate how you like from my towing MPG; the above marine shop has better answers. Flat out 6 MPG modern computerized gas 350, 7MPG with GM3 turbo 6.5, 10.4MPG ATT turbo 6.5. I wouldn't even think about NA...

 

[THEFERMANATOR]

B.O.A.T. Bring On Another Thousand. :hihi:

Used military surplus 6.2 engines with 30K miles on them at $900.00 each plus shipping. 120-150 HP each.
ARP head studs (~$300)and gaskets.
Turbo precups
short body injectors. ~$550.
Gapless rings (~$300) or at least an ebay ring set (~60.00).
ATT turbo's - you will never run a boat engine where the GMx turbo's work. ~$799 each
Exhaust manifolds...
Figure over 200 HP with the ATT turbo. 1995 gas TBI 350's were rated at 200 HP.
New props with higher pitch for the lower RPM diesels. 5000 RPM gas vs. 3600 - 4000 RPM for the 6.5. IMO 4000 RPM is extreme for a 6.5 it would be more like 3600 RPM. Around a grand a prop.
Extreme water separators and fuel filters. Water and injection pumps and injectors do not mix. Water in fuel is the main reason the 5.7 Olds diesel got a bad rep as it would muck up the injection pump timing and take out the weak parts. (Head bolts or shatter cylinder liners with timing advance from water rust.)

Weight and balance of boat as the diesels will weigh more than the 350.

Boats run engine at full load and high RPM for extended time. As you see boats eat 350's for lunch and will blow a 454 with ease.

I would recommend getting Optimizer 6.5's military surplus, $2500 each or more if you can find them. Otherwise the 6.2/6.5 blocks are known to crack at the mains. This makes anything but Optimizer engines almost unrebuildable due to block cracks. So a low mile military 6.2 is a cheap option that you can blow up and get home on the other engine. A 6.5 is merely a bored out 6.2.

Water in fuel and algae/bugs/etc. is a worse problem in diesel than a gas engine. More expensive to fix.

The 6.5 is a LIGHT DUTY diesel. Marine is the only use harder that I put mine through towing, except, cooling in a boat is better.

Fuel economy is the only advantage with the ATT turbo. Translate how you like from my towing MPG; the above marine shop has better answers. Flat out 6 MPG modern computerized gas 350, 7MPG with GM3 turbo 6.5, 10.4MPG ATT turbo 6.5. I wouldn't even think about NA...

If the boat needs to be coast guard inspected, or is a registered vessel with the coast guard forget the ATT. You will HAVE to run a water cooled turbo, water cooled manifolds, and water cooled up pipes. Also don't forget you will need water cooled exhaust outlet risers for the turbo and wet exhaust. Add in a heat exchanger, seperate raw water pump, the maze of hoses for the cooling system, redoing the pulleys to work at the sustained higher RPM's, and completely marinizing the entire engine with spark arrestors and marine quality electrical and you will have a SMALL fortune tied up in them. Since you say it's a 38' vessel, I'm guessing this is going to be a cabin cruiser or some other type of cruiser. By the time you get the 6.5's marinized, you would probably end up being cheaper buying a PENINSULAR marinized engine at 300HP for about $18K(last I priced one, this is about what they cost). Also don't forget you will need new transmissions to hold up to the diesel torque(about $2K a piece), larger prop shafts to swing the larger diameter props you will need to get any benefit out of the diesel, and with these mods you will need new prop struts and rudders to match(these can easily cost you $10K). All of the sudden a pair of rebuilt 260HP 350's sound pretty good. Or better yet get a pair of 383 4 bolt main blocks with VORTEC heads and call it a day for ALOT less money. Alot of people want to go with a diesel repower, but they either change there mind when they find out what it costs to do it right, or do it half a$$ed and end up broken down and stranded all the time(or even worse on fire at sea because of a stray spark or electrical fire because you cut some corners and didn't fully marinize everything).

 

[5akman]

The boat is a 38' Owens fiberglass gillnetter with BorgWarner transmissions and Vee drives. Use is a salmon gillnetter in Cook Inlet where I commercial fish each summer. It comes with some 8.2L diesels of unknown history sitting on some pallets. I was hoping that I could sell them off and use the proceeds towards a bit of the 6.5 repower. I'll check into Pennisular and see what they have. The gassers would be a cheap R&R but looking at both safety of gas vs diesel and then the big difference in fuel consumption, I'm still leaning towards the diesels.

 

[WarWagon]

Is the Thousands adding up yet?

ATT can be heat shielded with water cooled shields.
http://www.performanceboats.com/dyno/80825-does-anyone-have-watercooled-turbo-heatshield-howto.html

Manifolds can be heat shielded so that nothing catches fire if spilled on them.
http://seaskills.com/DieselMarinization.html

6.2/6.5 marine diesels mentioned above and a source of some cheap take off parts for automotive use like our 6.2/6.5 trucks and SUV's.
http://www.peninsulardiesel.com

And a 6.6 option although I don't like Banks in general:

http://www.banksmarine.com/

 

[5akman]

Is the Thousands adding up yet?

ATT can be heat shielded with water cooled shields.
http://www.performanceboats.com/dyno/80825-does-anyone-have-watercooled-turbo-heatshield-howto.html

Manifolds can be heat shielded so that nothing catches fire if spilled on them.
http://seaskills.com/DieselMarinization.html

6.2/6.5 marine diesels mentioned above and a source of some cheap take off parts for automotive use like our 6.2/6.5 trucks and SUV's.
http://www.peninsulardiesel.com

And a 6.6 option although I don't like Banks in general:

http://www.banksmarine.com/

Yes, the $$$$ are adding up! It'd have to be a real cheap initial purchase to make it happen. As a business purchase however, at least I can write it off!

 

[THEFERMANATOR]

The boat is a 38' Owens fiberglass gillnetter with BorgWarner transmissions and Vee drives. Use is a salmon gillnetter in Cook Inlet where I commercial fish each summer. It comes with some 8.2L diesels of unknown history sitting on some pallets. I was hoping that I could sell them off and use the proceeds towards a bit of the 6.5 repower. I'll check into Pennisular and see what they have. The gassers would be a cheap R&R but looking at both safety of gas vs diesel and then the big difference in fuel consumption, I'm still leaning towards the diesels.

Those 8.2 DETROIT's are gonna be HARD to get rid of unless you can find somebody needing them. They have a reputation for reliability that makes the stock 6.5's with all of there PMD and block cracking hay day problems look like a 7.3L powerstroke. And V drives are some power hogging SOB's. I'm surprised a commercial type vessel would have V drives in it as most commercial vessels are straight inboards due to less power loss and reliability. Personally I would look at a set of rebuilt 383 small blocks if your trying to plane this vessel out, or a set of N/A 6.5's woulkd work if your just trying to troll around. Without knowing what the running gear set-up is though, it is hard to say what it will cost to convert it over properly to diesel. Since you say it will be a gill netting boat though, I would guess you will have to meet ALL coast guard safety regulations for a commercial vessel as you never know when that surprise inspection may occur. So you will HAVE to go all out on the marinization process to fully comply. Turbo shields and other such things just will not cut it for a commercial vessel requiring inspections. Call up Pen as they may still offer there marinization kits for them. Personally though for a true diesel repower, I would ditch teh Vee-drives as your going to be losing a good 15-25% of your top end power to the gear boxes and change of direction of power with a diesel. And I would go up to a CUMMINS 4BT or 6BT for a commercial vessel as I just don't think you wopuld be happy with a 6.2/6.5 for reliability in a hard worked application.

 

[WarWagon]

Those 8.2 DETROIT's are gonna be HARD to get rid of unless you can find somebody needing them. They have a reputation for reliability that makes the stock 6.5's with all of there PMD and block cracking hay day problems look like a 7.3L powerstroke. And V drives are some power hogging SOB's. I'm surprised a commercial type vessel would have V drives in it as most commercial vessels are straight inboards due to less power loss and reliability. Personally I would look at a set of rebuilt 383 small blocks if your trying to plane this vessel out, or a set of N/A 6.5's woulkd work if your just trying to troll around. Without knowing what the running gear set-up is though, it is hard to say what it will cost to convert it over properly to diesel. Since you say it will be a gill netting boat though, I would guess you will have to meet ALL coast guard safety regulations for a commercial vessel as you never know when that surprise inspection may occur. So you will HAVE to go all out on the marinization process to fully comply. Turbo shields and other such things just will not cut it for a commercial vessel requiring inspections. Call up Pen as they may still offer there marinization kits for them. Personally though for a true diesel repower, I would ditch teh Vee-drives as your going to be losing a good 15-25% of your top end power to the gear boxes and change of direction of power with a diesel. And I would go up to a CUMMINS 4BT or 6BT for a commercial vessel as I just don't think you wopuld be happy with a 6.2/6.5 for reliability in a hard worked application.

I got to agree with the above, not a good "commercial" engine choice. Pleasure craft maybe.

With the $$ pain I have gone through with my 6.5/6.2's... My truck isn't nickel and dimeing me to death it is hundred and fiftying me to death! I sent three 6.5 engines to the scrap metal pile in a single year. The economy working hard with a small turbo quite frankly sucked. The reliability cost me more in parts than a payment on a new truck each month. After fishing all day I am sure you don't want to be working on the engines. Only reason I know so much about the 6.5 is I have had to tear them out and replace them often...

For commercial use get a commercial use, heavy duty, diesel. Many Dodge trucks with the Cummings have 1 million miles on them. 6.5's are lucky to live to 200K without severe cracks. The improved blocks solve this but are expensive to get new. Injectors are only good for 100K, 6.5's boats would have an hour rating I am sure.

Maybe even something with a CAT engine in it.

 

[THEFERMANATOR]

I got to agree with the above, not a good "commercial" engine choice. Pleasure craft maybe.

With the $$ pain I have gone through with my 6.5/6.2's... My truck isn't nickel and dimeing me to death it is hundred and fiftying me to death! I sent three 6.5 engines to the scrap metal pile in a single year. The economy working hard with a small turbo quite frankly sucked. The reliability cost me more in parts than a payment on a new truck each month. After fishing all day I am sure you don't want to be working on the engines. Only reason I know so much about the 6.5 is I have had to tear them out and replace them often...

For commercial use get a commercial use, heavy duty, diesel. Many Dodge trucks with the Cummings have 1 million miles on them. 6.5's are lucky to live to 200K without severe cracks. The improved blocks solve this but are expensive to get new. Injectors are only good for 100K, 6.5's boats would have an hour rating I am sure.

Maybe even something with a CAT engine in it.

There are marinization kits out there for the 6BT CUMMINS 5.9L all over Ebay and many other places for not alot of coin. The 6.5's in marine use for pleasure boats in real world applications are only known to go maybe 1,000 hours before a major breakdown. Not to mention you are basically held hostage as tehre isn't many places that carry marine parts, so your basically limited to just a few suppliers. The CAT option could be done, but the smallest CAT out ther is going to be a 3208, and they don't fair well in commercial use either. Personally with the cost of boats right now, I would think you could find one with a disel in it for less than the cost of a repower.

 

[5akman]

Personally with the cost of boats right now, I would think you could find one with a disel in it for less than the cost of a repower.

Agreed, I was just liking the idea of twins for both reliablity and power. Would not be unheard of to have 10000lbs+ of salmon on board bucking the inlets 6-7 knot current. Plenty of cheap 32' alum boats up for grabs right now and most are single screw big engined diesel inboards. 3208's, 6-71's etc. Lots of cheap parts and perhaps easier upgrades with a cummins/volvo/yanmar etc.