Diesel Engines What to buy?

[48Sedan]

Hello,
I recently aquired a 38' 1948 Stephens Sedan weighing >20,000, it currently has 2 chrysler 318 motors 1 of which is bad. I have figured that I will just replace them w/ 2 low rpm diesels so I can afford to use the boat. My question is what should I buy? I would like to get good fuel efficency, reliability and cost effective engines. I am looking to buy 2 at once w/ transmissions. What horsepower #'s and rpm #'s am I looking for speed is not a concern I am looking to cruise this boat. If you have any suggestions on brands makes years please let me know I am no epert in these fields.
Thanks, Taylor

[woodboat]

The old naturally aspirated 671s are very reliable. Would love to have a pair.

[FAST FRED]

IF you know the fuel consumption at the cruise speeds you prefer on the gas engines , you can get a ballpark estimate of the diesels you will need.

Say the boat cruised at 12 gph , total , that would be 6 gph per engine.

You will get about 10hp from every gal of gas so your cruising on about 60 hp per engine.
A diesel LOVES to be run at a higher % of its rated power than gas does.

Those 318 may have been "rated at 200hp at WOT , so using 60 or 100 hp each is a 50% reduction , great in keeping a long service life.

Diesels of 75Hp to 90Hp would do fine at the same 60hp speed as the old gassers.

BE very wary of WHICH "HP" rating the diesle salesman gives you.

You ONLY want the M-1 rating , (24/7/360 ),
not the M4 or M5 that is pleasure boat only with VERY restrictive use at large power settings.

You may find the "advertised" power is 150 (M-5), but only 75 is allowed at the more restrictive M-1. Caviat Emptor!

Yanmar has a good reputation and to keep the boat performance , you will NOT want to install engines that are 3 or 4 times heavier.

The old 318 were light weight car engines , or if the 318-C are sleaved down 440's that weigh more but are GREAT for longevity.

The 6-71N is a grand old lady and will produce 15 to 20 hp per cylinder 90hp to 120hp for 20,000 -30,000 hours , but the bare block is 2300lbs and with reducrion /reverse may weigh 2800 .

Stick with somthing light!!

FAST FRED

[48Sedan]

FRED,
Sounds like I really need to do my homework before I buy I am unsure of the model 318 engines in my boat but they are HUGE. What engines would be sutable to replace the 318's. I would really appricate it if you could give me a model # or link so I know what I am looking for.

Thanks For the help!

[FAST FRED]

Without knowing the old fuel consumption , its not possable to guess how hard the boat is to push at the speeds you envison.

IS there a club or website that could help you?

FAST FRED

[48Sedan]

I dont know of any stephens websites all I have found is Sparkman's and Stephens Sites another old boat builder? I will try and Find one.

Thanks for the help Fred

[Nomad]

1st question is what do you want to spend

[mackid068]

How about replacing both with some smaller modern engines or even just one more modern engine. Just a thought.

[48Sedan]

The boat is designged to be used w/ 2 motors so I am going to use 2. What age and make I have yet to determine. It will propbably be decided by price.

[FAST FRED]

For price and slow speeds the Leman Ford conversions are hard to beat , although a bit heavy for a straight gas / doiesel swop.

What are the fuel tanks made of , will they need replacement $$$$ too?

A Quick guesstimate would be about $30,000 if you can do the swop yourself.

Far Far more if a boat yard does the work.

With a fine gas engine in the $4000 each range and far easier to install , do some math , and see if there would be ANY savings during your ownership of the boat.

Modern gassers , esp if fuel injected are much better at low loading fuel consumption than the old ones.

FAST FRED

[mackid068]

Fred, so true. The modern engines seem quite a bit better, whether diesel or gas.

[PowerTech]

Are you guys nuts it is 2005 you don't repower with a obsolete motor like a 671 or a lehman stick with gas before even considering a old style diesel .You will love a john Deere 4045T it is a 150 H.P. at 2500 rpm it is a exilent trawler motor.I would recomend 1 1/4 propelor shafts .These motors will out perform a 318 in every way.the hight of your engine room can limmit your repower options so take some mesurements and get some specs on a few motors but I would try for a deere first they are the cheapest very reliable feul eficient and do not smoke.If you have a borg warner reduction gear there will be no problem using it on the new deere.If the gear boxes need some freshening up it will only cost 600-800 bucks to go through them each.

[48Sedan]

powerTec,
Can you give me a link the Deer motors?
Thanks

[PowerTech]

http://www.deere.com/en_US/rg/produc...ctcatalog/mar/

[48Sedan]

PowerTech,
What are the prices on the motors it does not say on the site?