36ft repower question

[Senor Falcon]

Hi all,

I have a 36ft Falcon Bonito. I bought it with two GM 5.7 and Alpha 1 drives. Engines were good apart from one water pump and a starter solenoid. The drives were noisey and needed complete hydraulics.

I have recently bought two 6.5 chevy diesels, set up to peninsular engines spec and with peninsular parts. They have twin turbo´s on each engine and velvet box´s. The drives are TRS 400´s.

My question is. What do you all think, about this engine / drive combination. I don´t want to cut the transom for older drives, if the benefits are not great. I might have to change the engine bay, to take the extra length (with box´s) of the engines also.

I was thinking of swapping the box´s and TRS drives, for a pair of Bravo drives, or something similar. I think this will keep the original mountin possitions and save a lot of work. There are many questions that need to be answered but I guess the most important is, What would be the best setup, for these engines?

The boat will be used for pleasure only but as the owner of a 21ft Phantom, with 200hp on the back, I do like a bit of speed.

Any information or advice would be very helpful.

Thanks in advance.

Pete

 

[txriverrat2001]

I would chat with the guys at boatdiesel.com about the Peninsular engines - They would know more about any known issues/performance etc....

My .02 worth

 

[MILD THUNDER]

If the boat is rigged with alphas, going to a bravo setup will be easier than going to TRS. You will have more room in the engine compartment with the bravos.

 

[Senor Falcon]

Hi,

Thanks for the tip, re boatdiesel.com, I´ll check them out.

Regarding the Bravos, this was my thought exactly. I do have just enough roon for the existing setup but as you say, I would have more room with the Bravos. The only problem being, the TRS drives and the Velvet box´s came with the engines ( a job lot) so would have to find a reasonable priced pair of Bravos.

Any other ideas are very welcome.

Thanks.

Pete

 

[Senor Falcon]

Photos and Video

Hi again, I have put some photos and video on here http://s751.photobucket.com/home/FalconBonito/index

If this helps with any advice.

Thanks

Pete

 

[Ratickle]

Wow, what a project that would be.

 

[mh1031]

Would a Bravo hold up to the torque of the diesels? Very interesting project though. Good luck and keep us up to date.

 

[MILD THUNDER]

Would a Bravo hold up to the torque of the diesels? Very interesting project though. Good luck and keep us up to date.

I dont think the 6.5 diesels will make that much torque. Most bravo's hold up behind 450-500FT lbs on a HP gasser motor. I dont see those diesels making more than that, but it will be at a much lower RPM. I am pretty sure merc put bravos behind some small diesels.

 

[Ratickle]

I dont think the 6.5 diesels will make that much torque. Most bravo's hold up behind 450-500FT lbs on a HP gasser motor. I dont see those diesels making more than that, but it will be at a much lower RPM. I am pretty sure merc put bravos behind some small diesels.

Specifications
Engine RPO Codes: L49, L56, L57, L65, LQM, and LQN.
Displacement: 6.5L / 397 cu in
Bore x Stroke: 4.06 x 3.82 (in.)
Block / Head: Cast iron / Cast iron
Aspiration: Turbocharged (Borg-Warner GM-X series) Also available naturally aspirated.
Valvetrain: OHV 2-V
Compression: GM Early 21.3:1, GM Late 20.3:1, AMG/GEP Marine 18:1
Injection: Indirect
Power / Torque (lowest): 180 hp (134 kW) @ 3,400 rpm / 360 lb·ft (488 N·m) @ 1,700 rpm
Power / Torque (highest): 215 hp (160 kW) @ 3,200 rpm / 440 lb·ft (597 N·m) @ 1,800 rpm
Max RPMs: 3,400

 

[Senor Falcon]

So, with the twin turbo´s raising the HP to 330, they should be pushing more than the 440 quoted? I believe the "X" Bravos are the diesel drives, just not sure if I am better with the older and proven TRS drives?

Pete

 

[MOBILEMERCMAN]

You should look into what diesel gear ratios bravos offer..

 

[Senor Falcon]

Hi again,

Well, from what I can find out, the following specs should be very similar to mine, the main difference being that mine are standard bores, at 397 and that the electronic version of the injector pump with a brain which will let you have up to 15 psi boost early in the rev range then tail off to 10 psi at higher revs, mine will boost up slower and then I will have full boost from about 2200 all the way up to max revs. So, I guess they get the extra 20HP from the bored cylinders and the boost from the electronic pump. Specs below.

Model: 400TAI-340
Engine Type: Four Cycle
Number of Cylinders: Eight
Bore and Stroke: 4.06″ x 3.82″
Displacement: 400cu.in. (6.554cc)
Fuel Pump: Stanadyne-Mechanical (DB4)
Brake Horsepower: 340BHP at 3600 rpm
Peak Torque: 495ft.lbs. at 2200 rpm

Pete

 

[Senor Falcon]

Update

Hi All. Well, it looks like I will be keeping the TRS drives. To be honest, to pay out another 10 to 20 K for drives, was not accounted for. Also, by putting the engines further back in the engine bay, I would have to modify the deck area around the front of the engines. The Turbo´s stick up a lot higher than the sides of the boat, when in the possition of a Bravo setup. So, less $$$$$ and a lot less cutting out, is the way forward, I think?

Would the weight of the engines, further forward, effect the boat in any way?

PS, In front of the engines I have 2 fuel tanks and I have just found out that they are 50 Gallon (imp) each.

Any ideas are more than welcome. Anyone with experience of this situation, and knowing the end result, please share your experiences.

Thanks to all

Pete

 

[old377guy]

Mercury made a "diesel" gearset for TRS drives back in the day.Who know that there might not be some of these still around; perhaps Riggs or Mark at BAM could give you a lead.

 

[DollerDriveGuy]

No you won't find gears for TRS diesel. But Bravo one X gears will do just fine. So use a Bravo One X.

 

[Senor Falcon]

UPDATE

At last I have found time to get back on the boat. Stripped most of the engine bay and removed the (Alpha 1) drives and gimbles.

I made a template for the TRS gimbles and checked the difference, with the Alpha holes, in the transom. They are about the same, wide, but the TRS are quite a bit longer.

Is there a recommended height, for the gimble, from the bottom of the hull, on the TRS drives? Or is the height of the gimble, decided by what height you want the prop shaft? If yes, what is the best height for the prop shaft?

Thanks in advance.

Pete

 

[rschap1]

I am a bit jaded after watching my neighbor throw over 6 figures (no kidding) at a 6.5 turbo in his 2500 Suburban...I got say, I would go with a different motor.
There are a very few select castings for blocks, cranks, and bottom ends that are worth a $hi+. Rest are prone to failure. I would not think of a 6.5 myself.

 

[Senor Falcon]

Peninsular diesel seem to make a good living out of producing these engines (government contracts and all). It´s too late now, I bought them and at the price I paid, they will go in.

What is a good drive height, for a twin setup, with TRS drives. Also, I need to fit through hull water pickups. I was thinking of putting them through the hull, close to the transom, so that I can fit the valves directly to the pickups and support them on the transom. Is there any problem with this???

Thanks guys

Pete

 

[Senor Falcon]

Help needed

Hi All.

I am preparing the engine bay, for the engines and drives. I will have to do everything from the start, as the old drives were Alpha 1´s

I have pulled out the old mounting crossmember and most of the other things. I will check where the drives were set before, as I have been told that I should stick to this drive height, as the original makers would have set it up as per it´s design. I have also been told that the TRS will move the prop further away from the transom, so I will have to consider this, when fixing the height.

What would be fantastic is; if I could find blueprints for the Alpha 1 and the TRS drives, so I can compare the positions exactly. I would also like the blueprint for the Velvet drive box and the GM 6.5 diesel (I can allow for the added turbos etc)

So, the question is, where can I find these blueprints? Any help with this would be great.

Thanks

Pete

 

[old377guy]

Hi All.

I am preparing the engine bay, for the engines and drives. I will have to do everything from the start, as the old drives were Alpha 1´s

I have pulled out the old mounting crossmember and most of the other things. I will check where the drives were set before, as I have been told that I should stick to this drive height, as the original makers would have set it up as per it´s design. I have also been told that the TRS will move the prop further away from the transom, so I will have to consider this, when fixing the height.

What would be fantastic is; if I could find blueprints for the Alpha 1 and the TRS drives, so I can compare the positions exactly. I would also like the blueprint for the Velvet drive box and the GM 6.5 diesel (I can allow for the added turbos etc)

So, the question is, where can I find these blueprints? Any help with this would be great.

Thanks

Pete

Talk to Marc at BAM in Miami