THERUSH

Dean,

Gotta love the coal burners!

Payton,

From what I understand the transom was set-up out of the box for the ASD's with the modified transom. If you like I have some shots from inside the engine bay with the engines removed.

Rich

HabanaJoe

The piston mods will help you alot with heat problems and almost totally eliminate any overheat issues due the cylinder temperatures.

FYI - please run antifreeze at -20 deg F and add DCA to the cooling to prevent cavitation. The more Hp the more heat the more shock and it will make more bubbles on the cylinders -20 & DCA stops that.

I'm guessing your aftercoolers were changed because we did not like the fact that Cummins used smaller dia piping coming out of the aftercooler than going in. We used to take the tin box coolers and cut the 2.5" elbows off and weld on 3" and then on the manifold plate do the same thing - 3" all the way in.

We applied many concepts proven by Jim Fueling - who I consider to have been the most prolific cylinder head designer ever. His studies in airflow and head passage design are used everywhere, he could make more Hp per cui than anyone! His work was what I quoted in my last reply - don't raise pressure to gain flow, lower restriction to lower pressure and flow increases inversely - a brillant man!

That transom has had lots of work done to it. The bussels were different on the 34 & 40 if I recall? But, his 40 I think is a real early one?

Njawb

HabanaJoe, could you give us another shot at explaining why you are so down on the Duramax? Frankly, I've read what you have posted in this and other threads, and I'm just not getting why you think a marinized Duramax would be so inferior to a Cummins or Yanmar.

I get the fewer V8 main bearings vs. I6 main bearings argument, but I'm not convinced that the difference can't largely be compensated for with good engineering and materials. Other than the mains difference, I don't understand why you claim that the Duramax is lightly built. It has less than 12% more displacement than the 5.9l Cummins B, and the 1300 lbs. weight that MarineTech lists is very comparable to the 1350 lbs. of the Cummins. Just by weight, that doesn't sound like the Duramax is significantly more lightly built, especially when we consider the more compact V8 layout and aluminum heads of the Duramax.

In terms of hp/ci, I don't understand why MarineTech's 600 hp Duramax should be considered to be dangerously hopped-up when the hp/ci figure is less than 12% more than that of the Cummins. I can see cause for concern when people talk about getting 1000+ hp out of the Duramax, but power levels close to 600 hp seem quite reasonable in hp/ci terms. I'd also be interested in how you think tuners that allow for selectable power levels play into the engine stress consideration. It would seem on its face that having six selectable power levels from an economy mode to a high-boost mode would allow one to get better engine longevity while still being able to make occasional high-speed runs.

Even if we were to step up to Banks' claim to be able to offer a 750 hp/1000 lb-ft Duramax to the general enthusiast, those numbers just don't seem to be grotesquely greater than the Cummins' 480 hp/940 lb-ft. Both engines are making comparable torque, and both are making max horsepower at about 3400 rpm, so it looks like the Banks Duramax is doing a much better job of efficiently holding onto torque rather than producing horsepower through brute force and massive torque.

Perhaps I'm missing something that you can explain to me, but I just don't see why the Duramax is an inherently bad or inferior choice for an offshore marine engine.

HabanaJoe

Njawb,

You make some good points, so before I render more of my opinions on this subject, I will revisit it. Can you tell me where I can find any spec docs on the Marine Tech 600 Hp Duramax diesel so I can look them over?

One note, I don't think the weights your using have any bearing on the engine itself. Those numbers are with accessories etc. The basic B engine is a 950 lb unit, after all the add on it's about 1,300 lbs. So, let's look at engine mass to engine mass.

I don't know this, but what does a base Duramax weigh?

I think this will be fun, maybe you'll change my mind?

Joe

Njawb

The MarineTech weight is from the same link you provided previously: http://www.marinetechn.com/6.html

No, I don't know the weight of a bare Duramax. I have seen references to 850 lbs., which seems reasonable; but that's not an official GM number as far as I know. I am assuming that the 1300 lbs. that MarineTech lists is for the complete marinized engine with accessories.

Njawb

Hmmmm... looks like MarineTech actually starts at 500 hp, which would make the Duramax hp/ci slightly less than the Cummins. Not sure where I'm remembering the 600 hp figure from, but I think it was one of the other Duramax marinization projects.

Jassman

I think this will be fun, maybe you'll change my mind?

Joe[/QUOTE]



we sure the hell R gona try

HabanaJoe

I was hoping you had something more than what I found!!!

All joking aside, I'm not against the tuner chips or anything like those, BUT all those are in a truck running down the highway. They are not set on max and the truck running at near full load 100% of the time. Take any of those tuner kits/chips turn it to max and strap in on the dyno and run it at 80% of the max load and the engine will blow very shortly.

That is proven, there is not a chip/device in the world that allows an engine to make 50% more hp and use it hour after hour and the engine last as long as stock - impossible.

Make it last longer with the turn of a dial???? The less you put your foot to the floor, the easier you accelerate the longer the engine lasts. Less Hp used means it lasts longer. On our road trucks years ago, we had drivers that got 300,000 on a set of brakes and drivers that went 150,000 on brakes - I bet if we kept the trucks long enough we would have seen which engines ate bearings quicker?

That does not mean it does not work good in a truck, the road is not flat, you slow down, coast, etc, etc and you are never in the throttle 100% of the time. The old story is a boat is going up a 6% grade 100% of the time, no matter what you did your going to stress the engine more for every hp you put out above stock. Even in stock trim, pleasure craft diesel ratings for engine hp are generally something like 2hr out of every 10 hrs @ full load.

Your boat question, it's not so much Cummins or Yanmar it's V-8 vs In-line six. The crank throw separations on an in-line engine work better with a diesel because your firing the fuel much closed to TDC than on a gas engine. It was explained to me that you are using the combustion for a longer time period to push the piston down rather than another clyinder firing closer in degrees which helps drives that piston down quicker and you loose the effect of the combustion. This based on the fact that the diesel takes longer to burn than gas.

The only logic I can offer about that is every 4 stroke V diesel whether it was a Cummins 903, 1710, CAT 3408, 3208 or any other can not make as much power per cui as it's inline counterpart and last as longer. In fact in trucks where you have some stresses (gear shifting) similar to an offshore boat being on and off the throttle the higher Hp V diesels fall apart. Anyone that has had experince with V diesels in big trucks will tell you they don't last and mostly it's be cause of the cranks.

Now look at a CAT 3408 closer, it has offset rod journals for just that reason to allow the downward piston to be in a better position because of the deg of the V. That engine in a truck was a disaster, but in a yacht, generator or something with a hydrualic transmission it's a good engine.

So, I read that Banks had to design an oil pan that acts as a girdle to support the bottom web of the Duramax engine and they had to re-engineer the entire oil delivery system, I have to say they are doing it more as a PR stun than as a viable product.

The other thing you don't know here is how are they getting their horsepower numbers? I've asked this question before on here about this subject with no answers. I've seen many people dyno drag race engines with their SuperFlow dynos and they do acceleration runs to see what the engine puts out. Those dyno numbers are always higher than say putting an engine on an electric dyno and letting it run like you normally do with a diesel.

I think what I really want to say is this:

If you have to re-engineer the entire engine to make it work then cost of that engine is so great and the durability so compromised that you are better off buying a gas engine for a small go fast boat. No longer have what you brought a diesel for in the first place.

If you have a larger boat that you want thousnads of hours of use from, then buy big diesels and through the gearing/trans to get the speed your looking for.

Now, why would you want a diesel in a 38 Cigarette if you lived in the US?

Jassman

Now, why would you want a diesel in a 38 Cigarette if you lived in the US?[/QUOTE]



I had the twin 480 Yanmars in my 07 43 Nortech. The boat was cool...except for one thing, top end 75, fell short of goal. The engine compartment is only good for a pair of those long 6r's vs the 50 Nortech which can handle 3. The 43 can handle 3 bb or 3 diesels like the Duramax. BUT.. I would be happy if someone like Yanmar or Cummins could come out with a slightly more powerful offering than the 480hp, more like 550-575. That would get me in the 80's, problem solved. The Duramax's at the 550 hp along with the lighter weight would also do the trick. Thats why Im interested in them.

There is a company in MI who has been working on these Duramaxs for some time. The gentlemen is very knowledgable, has a great history as an engineer, worked for one the best know Cat builders for years, and Im hoping when released they will be as reliable or close to as the big 6's, but for now..we will have to see. Jeff

HabanaJoe

Jassman,

I have my answers as to why, I want yours, but I'm not looking for "cool".

I think as far as sound, eye candy, pure sex appeal the diesel can't come close to a gas engine - gas engine wins hands down.

What were the reasons you opted for the diesel? I don't want to be argumentive but you sold the boat because it went a few miles per hour slower than you wanted or was there other reasons?

I would think if all you wanted from the diesel was top end you should have gotten a gas boat from day one.

So, what were all the things you thought a diesel boat could or did do better than the gas boat?

Joe