1971 F-26 Repower Diesel or Gas?

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wolfnnj
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1971 F-26 Repower Diesel or Gas?

Post by wolfnnj »

Well I guess my Chrysler RM318 is cooked. I have a 1971 Trojan F-26 with two 65 Gallon Aluminum saddle gas tanks.

So I got the boat last year in pieces and had to put it all back together. Not knowing anything about boats was challenging but with the help of some of you and Trojan Bob coming out to my home several times to help me we got it done.

Start of the season; Engine overheating problems (head gasket) I lived with it and used about 4 gallons of water every trip. The bigger gas tanks in the boat were a huge issue the 318 didn't have the power to get on plane until both tanks were at less than half full. The boat looked like it had a load in its pants LOL.

Trojan Bob came out to my boat and installed the Mallory electronic ignition system mid way through the season nice improvement in power but too little to late. I have bad compression (45 psi) in 3 of my eight cylinders. i.e. engine Kaput.

My Paragon V-drive has 40 hours on it from rebuild and is running great.

The way I see it I have 3 options.

Option #1 ;
I can get a rebuilt Reverse rotation Chrysler 318 ($1850.00)
Pro: economical, Engine comes with a 2 year unlimited hour guarantee.
Con: Not enough power to offset extra fuel weight.

Option 2 ;
I can buy a rebuilt reverse rotation 360 ($1980.00) (what my understanding is that the 360 and 318 tin is all interchangeable)
Pro: more speed, more horse power, more torque, Engine comes with a 2 year unlimited hour guarantee.
Con: more fuel usage


Option 3 ; I own an Isuzu 4BD1T 3.9 liter 4 Cylinder Turbo Diesel engine with 130k miles on it taken out of a box truck.
There is a company on the internet that sells the bolt on kit for this engine to fit up to a Chrysler marine trans. My problem with this is the investment would likely kill my wallet. I would need to buy a forward rotation v drive transmission and custom exhaust manifold could run a few pennies as well. Also will this 3.9 liter four cylinder turbo get me up and out on plane ? Will it have the same or better top speed as my 318 The motor redlines at 3500 rpm at a whopping 135 HP. I would probably need to change props as well.
Pros: VERY economical, Much longer range,
Cons; Cost of custom installation, no guarantee that it will work right even after install. no idea of top end.

If anyone of you have knowledge or input in this matter let me know. I am lost as to what I should do. Is there a 4th option I am missing?


:?
hmc
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Post by hmc »

90 LESS hp how could it have eveen close to same speed ?
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wolfnnj
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apples to apples

Post by wolfnnj »

...diesel HP does not equal gas HP...diesel fuel produces more energy...rule of thumb is diesel HP X 35% equals gas HP.
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Re: apples to apples

Post by hmc »

wolfnnj wrote:...diesel HP does not equal gas HP...diesel fuel produces more energy...rule of thumb is diesel HP X 35% equals gas HP.

?
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prowlersfish
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Re: apples to apples

Post by prowlersfish »

That 130 HP diesel won't cut it ( more on diesel HP in a bit) its still a lot less power then the 318 ( in good shape) . Pro lowest fuel use if your in no hurry .

Con the cost of making it marine and lack of performance .


a new 318 will do better then the old as it should have the full 225 HP , That should be plenty of power , depending how far back you have the fuel tanks . Do you have trim tabs ?

Pro lowest cost and it will fit without a major redo


The 360 choice yes MOST of the parts will fit from the 318 , But you will have to get a 360 fly wheel as the 360 is externally balanced and I believe a different harmonic balancer also . Also make sure all cooling system parts are in tip top shape as the 360 will put more demand on them ( more power = more heat )
as far burning more fuel , you only burn more if using the extra power . at cruse speed ( say 20 knots ) both engines will burn about the same amount as it will take XX hp to run at 20 knots whether its a 318 or 360 and both will take the same amount of fuel to make that HP .

Pro more power and it will fit like the 318 , Con some more costs ( base engine cost + balancer & flywheel

now on the diesel hp
wolfnnj wrote:...diesel HP does not equal gas HP...diesel fuel produces more energy...rule of thumb is diesel HP X 35% equals gas HP.
That statement is both correct and incorrect . Yes diesel fuel will produce more energy , However a 100 hp Diesel makes 100 hp not 100 HP + 35% . A gas 100HP engine makes 100 hp . But the diesel burns less fuel doing it . That rule of thumb is incorrect , ( from a Isuzu site ? )

I am running twin 300hp diesels and the same boat with 330 gassers can easily out run me at top end . I can cruse faster as I can run the diesels closer to the top end then a gas engine can . It has more to do with the engine design the fuel type . And I burn a lot less fuel doing it :wink: .

If money was no object I would say find a 200-240 HP marine diesel , But in the real world I belive the 360 is the best coice most bang for the buck .
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The Dog House
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Post by The Dog House »

I agree with prowlersfish. The 360 is your best option. The cost to marinize the diesel plus installation will be way too much, and you'll also likely be limited to displacement cruising with only 130 hp. With full tanks, you're carrying an extra 420 lbs. compared to the standard tanks. If you only have 2 or 3 people on board, a 318 (producing the full 225 hp) should be able to push the extra weight just fine. The extra fuel is basically equal to an extra 2 to 3 people onboard. The 360 would be nice because it should allow you take more than 3 people out and still get up on plane without too much trouble.
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carlywolf
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Post by carlywolf »

Hey wolfnnj, I just went thru the repower on my F26 and it sounds exactly what i went thru. I had the 360 for 1900.00 with a 2 year warranty. The engine was very strong and ran like a champ, a bit more fuel i was burning but had no problem getting up on plane with a full boat , fuel , water 4 passengers etc etc. It was a rebuilt so i figured they did top and bottom on the engine, but i guess when they had it apart to them the bottom looked good so they didnt replace main bearing or any other lower parts. Top of engine was all replaced and looked like it came out of the factory. When you mix new parts with old parts sometimes they dont syncronize just right, so as a precaution i would ask that question up front, Unfortunatly for me after 50 hours with the rebuilt my main bearing spun. The engine was bought from a company in California called World Generators. Still had 6 m onths left on warranty. I called and called and no reply. Found out they went belly up. Oh well, live and learn. After buzzing around in my head for 3 weeks about my options ( and of course concerned about costs) I went with option number 4 that dreaded number 4 . After a few weeks on this site and asking questions and getting great feedback i decided to go with a new engine . I plan on keeping this boat for a long time so that weighed on my decision. Good luck!!
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Post by The Dog House »

When Bob from Beacon Marine was shrink wrapping my boat, we were chatting and he mentioned that he can put a brand new Chevy 350 (5.7L) in for less than $6,000. I believe the engine is carburated, and I'm not sure what the horsepower would be but I'm sure it would be equal to or more than what the 360 has. You would need a new bell housing, and the clearance between the top of the engine and the hatch cover would be tight. Make sure you measure the dimensions precisely. If $6,000 is in your budget, you might want to give Bob a call and get the details.
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Post by rossjo »

360 for $2k is the way to go. Least work and will run better for about same cost as putting in another 318.

The Isuzu diesel you mentioned won't work well unless you just want to putt around slow with great gas mileage. Converting truck diesel to boat is an open wallet project ...

Good luck with the project ...
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Post by DAVIDLOFLAND »

$6K for an engine ASSEMBLY sounds great. Start swapping long blocks and 'hidden costs' in peripheral parts mount up fast.
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Post by TBone »

I would locate and install a 360 as stated above.

the the Gm 360 would be nice, but as Dave stated, alot of hidded costs associated with a change like that

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Post by wolfnnj »

Dog House what do you cruise at with the 318?

I couldn't get the f-26 on plane for the first half of the summer till Trojan bob came out and put the Mallory dist in. then I was maxed out at maybe 15mph I am sure it was because the head gasket leak bad compression and exhaust manifold leaks but I wanted to know what a healthy 318 should be doing on a 71 f-26 with paragon v . I know these aren't fast boats but it should still go 25-30 ish right?
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Post by vabeach1234 »

My 72 with the 318 and 1:1 paragon v-drive cruises at about 16-17 mph at 3000-3100 rpms. At wot she does about 22. I'm sure I could get more out of her if I had a better prop and lightened up the load. I'm swinging a 14"x10 pitch bronze prop. Next haul out I might switch to a 13.5"x 11 pitch ni-bral with a cup to try to get a little more speed. Currently when the bottoms clean I can get a little over 4000 rpms at wot. From what I've seen on this forum, the 71-72 year v-drive f26's seem to be slower than the straight inboard later year f26's. Not sure why.
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Post by The Dog House »

At 3000 rpm I cruise at 21 mph (18 knots). My 318 was rebuilt six years ago and has around 300 hours on it. I've never had it above 3200 rpm, so I don't know what it will do at WOT. It gets on plane easily at 3200 rpm, and being an older boat/engine I don't want to stress it too much. I'm guessing at 4000 rpm it would be somewhere between 25 and 30 mph, but it's just a guess.
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Post by vabeach1234 »

Dog House, I wish mine could do those kind of numbers. I see your paragon isn't a 1:1 being labeled as a 32, maybe that makes a difference. Do you know what diameter and pitch prop you're running?
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