400 db what horsepower do you have

O

Ozzie-iv

New Member
Mar 27, 2007
289
Bilgola, NSW, Australia
Boat Info
Riviera 4700 sy
Riviera 37
Sea ray 400db
Engines
CAT C9 575hp
Diesel 6bta
Mercruisers 8.1s
Hi All,

was wondering what diesel engines you have and what HP. Also if you can remember what props diameter/ pitch

I was heading down the road of repowering my 8.1 Gassers but ment I had to punch larger exhausts through the boat using the Cummins qsb. I have found that a pair of Yanmars can use the existing exhaust size and also the Mercruiser 4.2el diesel models.

your info much appreciated as I don't want to underpower to much..
Mercruiser Diesel engine 320hp Yanmar 370hp

thanks

Ozzie
 
You really have 2 variables to consider in your plan.

Sea Ray put 300hp 3116 Caterpillar engines in early 400DB's and that is about as small a diesel engine as I remember, and most owners feel the 350hp Caterpillars in the 40DB are about right.........I believe they swing 22"dia X 25" pitch props. But, you cannot just relate gross hp to an engine change. If you select a light weight high rpm diesel like the Yanmar, you will not have the torque that the same hp Caterpillar engine produces. I am afraid you will have a significantly under powered boat as a result because bigger torque means larger diameter props with more pitch than you could run with lower toque diesels.

I would contact Mastry Engine Center in St. Petersburg FL (800-545-4574) with questions about Yanmar diesels.......they are a huge marine dealer and do lots of repowers. If anyone can guide you on this process, it would be them.

Other observations are 1.)the 440hp 6LY3A-STP requires a 5" exhaust tube. Changing the exhaust outlet requires a little fiberglass work, but it isn't hard or expensive. 2.) have you considered that you existing transmissions are not likely up to the torque that a diesel will produce, so you need to shop for marine gears, not just a bobtail engine. 3.)Almost all engines are electronically controlled now.....you will potentially have some additional cost involved in sending units, wiring, panel replacements, etc. 4.) don't forget the additional plumbing you will have to build a return fuel system for your new diesels 5.) Your generator is gasoline........you need to be shopping for a diesel generator too since storing gasoline in a different tank for the generator defeats one of the prime reasons for going to diesel engines --- safety. 6. Get firm quotes on everything....repower projects tend to grow by weeks and months once the boat gets disassembled in the boat yard and, 7.) Lastly, consider the after repower investment in your older gas boat and see which makes more sense...... re-powering or trading.

Good luck with whatever you decide...........
 
Even though Frank likes the Cats, go for a real world ride, Cummins wins in this boat EVERYTIME "most owners feel the 350hp Caterpillars in the 40DB are about right", this is not true from the 400db owners I know, some with cats and some with cummins. I have yet to run into a cat powered 400db owner that rides on the cummins and thinks the cats win. At least in the Pacific Ocean. (check out the NOAA bouy website and look at the conditions, quite different than S. Florida) While I am not as "smart" as Frank, I actually own this boat and do the work on this boat and not another model.
 
SR400DB said:
Even though Frank likes the Cats, go for a real world ride, Cummins wins in this boat EVERYTIME "most owners feel the 350hp Caterpillars in the 40DB are about right", this is not true from the 400db owners I know, some with cats and some with cummins. I have yet to run into a cat powered 400db owner that rides on the cummins and thinks the cats win. At least in the Pacific Ocean. (check out the NOAA bouy website and look at the conditions, quite different than S. Florida) While I am not as "smart" as Frank, I actually own this boat and do the work on this boat and not another model.
Click to expand...

Well, that settles it, Ozzie-IV. Since you're definitely in the Pacific Ocean, Cummins is the only choice. Can't argue with that loigic....
 
Ozzie is talking about putting even smaller diesels in his boat than the 350hp Cats. He asked for what other 400DB's with diesels had so he could judge power, props, etc. I'm just answering his question and not advocating anything here other than he consider more than rated hp in his decision making process.

Even though the 8.3L 6cta is probably the more desirable engine in such a stern heavy boat, it doesn't really matter since he is considering the 5.9L QSB series Cummins or a 5.2L Yanmar. The 300 hp and 350 hp Cats are the closest thing to what he is contemplating that Sea Ray ever installed in the 400DB from the factory, and neither deliver nearly as much torque as the Caterpillar engines, so that was the basis for my answer. Anthing smaller with less torque would yield an underpowered boat, I'm afraid.

Yeah........and the Gulf of Mexico is just a mill pond too.
 
You guys make me laugh..yep we have mother f..big seas here..I look over the ocean at a place called Bilgola Plateau NSW Australia (you can google it) Big seas here today..

From Pittwater to Sydney harbour 24 nautical miles (tab over an hour on a smooth day) We have boating all year round so when are you coming over to have a look around..You might never go back..LOL

thanks for the advice..

Ozzie
 
fwebster said:
You really have 2 variables to consider in your plan.

Sea Ray put 300hp 3116 Caterpillar engines in early 400DB's and that is about as small a diesel engine as I remember, and most owners feel the 350hp Caterpillars in the 40DB are about right.........I believe they swing 22"dia X 25" pitch props. But, you cannot just relate gross hp to an engine change. If you select a light weight high rpm diesel like the Yanmar, you will not have the torque that the same hp Caterpillar engine produces. I am afraid you will have a significantly under powered boat as a result because bigger torque means larger diameter props with more pitch than you could run with lower toque diesels.

I would contact Mastry Engine Center in St. Petersburg FL (800-545-4574) with questions about Yanmar diesels.......they are a huge marine dealer and do lots of repowers. If anyone can guide you on this process, it would be them.

Other observations are 1.)the 440hp 6LY3A-STP requires a 5" exhaust tube. Changing the exhaust outlet requires a little fiberglass work, but it isn't hard or expensive. 2.) have you considered that you existing transmissions are not likely up to the torque that a diesel will produce, so you need to shop for marine gears, not just a bobtail engine. 3.)Almost all engines are electronically controlled now.....you will potentially have some additional cost involved in sending units, wiring, panel replacements, etc. 4.) don't forget the additional plumbing you will have to build a return fuel system for your new diesels 5.) Your generator is gasoline........you need to be shopping for a diesel generator too since storing gasoline in a different tank for the generator defeats one of the prime reasons for going to diesel engines --- safety. 6. Get firm quotes on everything....repower projects tend to grow by weeks and months once the boat gets disassembled in the boat yard and, 7.) Lastly, consider the after repower investment in your older gas boat and see which makes more sense...... re-powering or trading.

Good luck with whatever you decide...........
Click to expand...

Actually you do advocate the Cats, as you always do, read the post. And yeah the Gulf is not the Pacific, not even close, come out for a ride anytime. He asked "400 db what horsepower do you have", I gave hime my answer. Here is the first question "was wondering what diesel engines you have and what HP", I answered that question. You actually don't have a 400db with diesels do you? If you did it would have cats, because they are the best are they not? Frank, most of your advice is pretty good, but when it comes to the engines you are biased, so be it. And I do have experience with cats in big sportfishers, both operating and maintenance, but in this boat, cummins wins hands down period. Run one for 650 ++++ hours and you will see what I mean. (in big water, with no ICW or harbor/inlet to run in if conditions deteriorate for 200 miles at a time).
 
Pissing contest aside, it depends on how fast Ozzie wants to reliably cruise. The Cummins 480CE's that '400DB' has will likely run that boat in the 22-24 knot range. I know because we run all the time with his sister ship with the same engines. And that boat is about 2 knots slower than mine (as it should be:thumbsup:).

I doubt that the 350HP Cat, despite the additional torque, will move the 40DB at that kind of speed. I would think that you'd get an honest 20 knot cruise from that setup.

Also, ignore the Cat/Cummins Gulf of Mexico/Pacific Ocean spat and listen to Frank's other excellent points about fuel plumbing, tankage, generator, transmissions etc. and ask your self if it is worth it for the value and performance you will get from such an investment. Only you know the answer to that, regardless of how big the waves are where you boat.
 
Last edited:
now 200hrs...

we are thinking of cruising to our great barrier reef..1000 nautical miles away. Since our country is nearly the same as USA and we only have 20 million people we will be moving over huge distances without refueling. Some ports don't even sell petrol.. from here to Queensland is all open ocean but enough ports within 4 hrs of each other for a quick cruise. (20kts)

Mind you Coffs harbour doesn't sell petrol at the dock and they won't allow you to bring in a tanker.

My 8.1s 370hp will push our boat along at 25kts wot (NEARLY 70 GALLONS PER HOUR) I think the torque curve is around 410ftlbs Yanmar 315hp is around 600ft/lb Yanmar 370hp around 750ft/lb Yanmar 440hp around 900lb Cummins Qsb440hp around 900ft/lb

Weight Cummins Qsb440. 1450lbs Yanmar 440hp 1179lbs Yanmar 370hp 899lbs

I am considering another boat but our market is nowhere the same as you guys (population) and most are entrenched in Riviera's Because of the downturn a Riviera 40 down the road from me 2003 model Diesel sold for $440,000AUD 400hrs
Aussie dollar about 65cents to the American dollar

Ozzie
 
Last edited:
Ozzie-iv said:
Hi All,

was wondering what diesel engines you have and what HP. Also if you can remember what props diameter/ pitch

I was heading down the road of repowering my 8.1 Gassers but ment I had to punch larger exhausts through the boat using the Cummins qsb. I have found that a pair of Yanmars can use the existing exhaust size and also the Mercruiser 4.2el diesel models.

your info much appreciated as I don't want to underpower to much..
Mercruiser Diesel engine 320hp Yanmar 370hp

thanks

Ozzie
Click to expand...

SR400DB said:
I have the cummins 6cta's 8.3 with 417 hp each, love it, love it, love it.
Click to expand...

There is a huge, massive, substantial difference between the B block Cummins and the C block. Pay attention. Details matter.
 
I had a 370DB with 7.4 gassers. I explored the re-power with Cummins or Yanmar route and came to a price of $75-$80k after the engines, gears, shafts, struts, props, exhaust, instruments, fuel system, generator, etc.

It was a $100k boat. Putting $80k into it would have made it a $130k boat. I sold and bought a diesel. It is unlikely that you can convert any Sea Ray from gas to diesel and come out ahead from an investment standpoint.

Your boat no longer fits your desired mission. My advice would be to sell it and buy one that does.

Good luck.
 
ozzie...in my humble opinion...unless you are a person who is very mechanically inclined with the tools and location req'd to do a large part of this engine replacement, along with everything that goes with it, by yourself to save labor costs I think this is a major loser. granted I am not familiar with your part of the world, but what are you going to pay (aussie) for whatever engine and trans. you decide on?, and are you going to be able to sell your gassers? huge project. how many long distance trrips are you going to be able to make after this expenditure? good luck. ric
 
In regards to repower, the 400Db I think is a great boat now if I wanted another one with similar specs but with Diesel ie Riviera 40 similar year I would have to cough-up another $150k to $200k. My 400db is the only 2003 in the country ( I could be wrong) a 2005 (455)is for sale for $600kAud with a pair of 400 hr engines (trade in on mine around the $350K)

therefor my cost around the 130k for a repower might be worth it. The other issue is IF i sell her (the boat) my wife may just take the money and forget about boating..

(http://www.perfprotech.com/store/articles/torquevshp.aspx) Interesting article re: repower..


Ozzie
 
Last edited:
Once again, I did not recommend that Ozzie rush out and buy 2 Caterpillar engines.......I mentioned them because that is just the closest optional power package Sea Ray put in the 400DB to what he was considering. My thought was to make it easy for him to use the online parts list at searay.com/customer support to more and easily accurately assemble a bill of materials for his repower.

Oh silly me for never considering that the 6CTA Cummins engine are the only engines that could possible push an ass-heavy bridge boat thru rough seas.
 
Ozzie,

Greeting from a sunny but windy and cold New England. We have 3116 Cats in our 400db. We just purchased our 400DB this winter so can't provide any performance data from experience yet. Good luck on your project.

Only the very best,
MV2/JV2
 
You must log in or register to reply here.

Forum statistics

Threads
113,227
Messages
1,428,947
Members
61,119
Latest member
jingenio
Back
Top