Fixing up my 440s

[Haymaker55]

I’ve been reading topics on diesel vs gas since I bought my f36. Port motor was bad when I bought it 2 years ago. Here’s the twist can fuel gkm be improved by upping the compression ratio to 10.5:1 and adding a Holly sniper fuel injection system with spark control. I’m at the jumping off point on the motors. I bought this boat with my first trip in mind. I’m going to take my boys from Tulsa Oklahoma to Belize. Tulsa is my closest waterway and Belize being where the boat will be kept. The trip creates at huge problem of fuel storage. (600km across the Gulf of Mexico)
At .75km I need 1100 gallons of gas on board to get 825km range before wind and current. The boat is in my machine shop waiting on me to figure out the direction we’re going. I love working on stuff and will be doing all the work myself with my 6 kids. The rebuild is for learning our ship before the trip and teaching them how to do stuff. Can an f36 with 440s be fixed up into the 1:1 fuel to mile range with gear? Do I have to go diesel? I’m not against it. I would love the challenge but the money looks pretty steep going that way. I won’t get to use my boat more that 4 weeks a year for at least another decade due to work. That said I will still own this boat on my last day. I was hoping fuel injection and a motor builder could help me out but I would like some experienced opinions?

[prowlersfish]

At 7.5 knots I would think you should be able to get over 1 mpg. Done right FI can help milage, done wrong it could hurt. I have seen a lot done wrong. Diesels a great but a very expensive job. Easy 80k plus. 10 to 1 won't make any big difference in mpg. I would look at upgrading to more modern EFLI engines. Parts are getting harder to find for the 440 anyway

I love my F36 sedan and its a great boat But its not a boat I would want to take a 600km or about 375 mile open water trip in. And I have the range as I run diesels. It's not a ocean crossing boat. Rn along the coast maybe (research on ports needed). Transport ship would be best bet


There are boats better suited for this but not cheap.

BTW what model F36

[Haymaker55]

After doing a bunch of research I’m going to switch gears and just repower with diesels. As to the trip. It is a long way on open water, but going around from where I have to go it adds 1000 miles to the trip. With extensive planning and weather predictions I think it can be done safely. The boat will have the latest electronics before it leaves. That and being careful should get us there. It’s an f36 express.

[prowlersfish]

Trojan did not build a F36 express per say,( by name) I will assume it has no fly bridge Do you know if its a model 460 or 461? Any photos? What diesels are you looking at? I have Cummins in mine.

[Haymaker55]

Yes on fly bridge don’t know on the 460? I’m going with gm 6.6s for the extra few rpm’s the v8 diesel provide.

[prowlersfish]

460 or 461 a model # on the ID plate likely on the AC elc. panel also the last 3 numbers on the ID on the transom I can also tell by a photo. The 6.6 is not real common in marine use(yet)
But there are some. Who's conversation are you thinking about?

Heres a sample of the panel plate.(302 is the model on this one)

Trojan id plate.jpg (121.94 KiB) Viewed 11976 times

[Haymaker55]

Still working out the conversion. I’ve found one real nice right up that seems very strait forward. I have not made much progress on gears. They need to handle upwards of 1000lbs torque is all I know so far. I’ve got to locate 2” 316 ss shafts and figure out propellers too. Going to be a fun project.

[prowlersfish]

2" shafts? that pretty big. What HP and @ what rpm are you looking at? What gear ratio? Thats a pretty big shaft to fit in an F36. Your limited on how much prop you can put under the hull.

You sure are talking about spending a lot of $$$, but thats what we do on boats LOl

[Haymaker55]

I work hard so I can spend time and money with my family. This boat is a great way to do that.

[prowlersfish]

I would need full info but I don't think 2" shafts would be needed . not unless you put in to much reduction gear than you have a prop issue.(too big)

[Haymaker55]

The boat has 20x21s props with 1.91:1 gears now. I could never get above 3500 with the 440s. I figured 1:1 with the same props after the new motors? I’m going from 330hp and 375lbs tq. To 500hp and 850 lbs tq.

[prowlersfish]

Lot of times the F36 does better with 20x20 props . With 1 to 1 gears, Your stock shaft size may work if aqumet 21 or go up to 1.5 shafts Remember your 440s torque at the shaft x1.91. And you won't be pulling full torque at any rpm unless your WOT. I can run it on shaft cal to be sure.

[prowlersfish]

The boat has 20x21s props with 1.91:1 gears now. I could never get above 3500 with the 440s. I figured 1:1 with the same props after the new motors? I’m going from 330hp and 375lbs tq. To 500hp and 850 lbs tq.

The max torque on the 500hp Duramax is 750, not 850 on the chart I found. so you 750 at the shaft vs 716(375x1.91)

Have you messured to see if it will fit?? Its pretty wide and deep. Yanmara has some compact engines but less HP .I honestly think 500hp would be more then you ould use in normal use.

[prowlersfish]

The boat has 20x21s props with 1.91:1 gears now. I could never get above 3500 with the 440s. I figured 1:1 with the same props after the new motors? I’m going from 330hp and 375lbs tq. To 500hp and 850 lbs tq.

The max torque on the 500hp Duramax is 750, not 850 on the chart I found. so you 750 at the shaft vs 716(375x1.91)

Have you messured to see if it will fit?? Its pretty wide and deep. Yanmara has some compact engines but less HP .I honestly think 500hp would be more then you ould use in normal use.

I will ad that my cummins has 732 flbs of torque with a 1.5 gear so its 1120 at the shaft, much higher than the DM 500 and 1 to 1 gear. I run a 1.5" shaft. Hope this helps.

[Haymaker55]

It’s got 1.5” shafts now. That would shave many things off the change list. I do agree it will be a bit over powered with this setup but where I’m headed having extra power will come in handy.