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Diesels for boats

Old 04-05-2008, 05:04 PM
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Originally Posted by HabanaJoe View Post

Humor me here

The Yanmar weighs 1411 lbs without gear @ 480hp

The "C" weighs 1975 lbs with a gear @ 600 hp (I think that is a standard big reduction gear???)

So, the Yanmar with a gear must weight 1,800 +/- lbs with a gear.

Use a lighter gear on the Cummins and the weight difference is probably like leaving me (220 lbs) on the dock when you go out!!!!!!

Couple that with the lighter lay up you mention and you might be able to invite me!!!!

So, I think what you want is available but I still think how the boat manufacturers are applying the diesels is what your problem is with speed not the "C" series engines.

I also think if you put the QSM11 at 715 hp in there with the right 2 speeds the boat could fly. I know they add about 1,000 lbs but the 700hp at 2,500 rpm with all the extra cubes will work much better with the 2 speeds as you have the torque to carry through the shift.

Again, I could be wrong and I would never tell anyone how to spend their money without doing it first myself but I think the "C"'s are a safe bet for what you want?

Joe Gere
I didnt realize that the Cummins was 600hp..I thought it was a turned up you have a website or more info..Ive got a two speed Im looking at and am reserching drives again..either asd-8's like my last boat or #6's like my present boat to possibly get more of the boat out of the water. Thanks Jeff
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Old 04-05-2008, 10:12 PM
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I'll convert you to the BLUE side yet!!!

On side a note, the Duramax or similar small V-8 should in theory make a great engine but they are just not designed for that mid-range market place, no matter how much you modify them, they are a "light" duty diesel. Second the marine market for performance diesel in so small that for other than promotional write-offs it makes no sense for any "engine" company to build them. You look at Mercruiser with all their resources is still not an engine company, they are a marinizer of automobile engines. Mercury choose not to build a diesel engine but instead turned to Cummins for a base engine.

Last edited by HabanaJoe; 04-05-2008 at 10:22 PM.
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Old 04-06-2008, 01:07 AM
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It's not just diesels!

It's real evident on the diesel side that I-6s out perform V-8s. But also it's evident in the gasoline world too. Nissan builds a 2.6L I-6 engine that can be built to put out over a 1000 ponies
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Old 04-06-2008, 04:13 AM
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Firefox ,I can,t follow you by saying a inline 6 will outperform a v8...

( for example Ricardo) When develop a F1 engine ,those people started with a 1 cilinder engine to measure the power output this single cilinder head /block /exhaust combo did produce .
By knewing that ,they start to make those in V10 or V 8 configuration, in the F1 they found that the V10 concept was the best configuration for them,and all teams started to use v 10,s (not only for output but size too)now they cut off 2 cilinders (FIA) and all use a v8 now 2,4L with around 800 hp naturally aspirated .

In the eighties ,they used all types of concepts ,a lot used a turbocharged 1,5 litre 4 cilinder in line with 1500 hp ,later when rules changed ,1,2 L also with 1500hp.

What I,m trying to say is ,its not that a inline engine produces more horsepower /torque than a v8 will do..

Every 720 degrees there,s a spark,Does it matter if the piston pushes on a angle or straith downward ?
With today,s ignition technology its possible to overcome the smaller angle blocks in V configuration,thats why you see 60 degree V8 engines now instead of traditional 90 degree 720:90 degree =8 cilinders .....

A 350 z that produces 1000 hp ....if one invest in a solid block,crank,rods pistons etc ,and a set garretts ,it can be done with a 4 cilinder v6 ,v8 no matter what configuration.

I agree a inline 6 has less moving parts,and therefore less change on broken parts
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Old 04-06-2008, 04:28 AM
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there getting 500-600 hp out of a duramax,and running it in a 40'+cat ,x -race boat ''tommy bahama'',i can't post pics,but look up ''diesel performance research'' and you can find out everything,there light and weigh about what a bbc does
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Old 04-06-2008, 04:43 AM
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Old 04-06-2008, 05:46 AM
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Now thats Sweet ..........
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Old 04-06-2008, 10:12 AM
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Correct me if I'm wrong here.

It looks like that Duramaxx has "dry" exhaust manifolds, cross over pipes and turbo-charger?

Think real hard about this, your buying a very expensive Nortech V-bottom like Jass wants to do. His engine room temps are going to be close to double than what they were with a gas engine with these engines. Those manifiolds are glowing red almost white hot.

That is an accident waiting to happen, is that what he wants diesels for?????? No boat manufacturer would put them in a boat without sometype of release from liability, so what does tell you?

Why does anyone wants diesels - last longer, safer, less maintenance, more dependable, less fuel consumption?

Please someone go out and buy a set of those Duramaxx's, buy engines from a company with no published certifications, no test data or standards on how they got their data and absolutely not one single shred of information about how what the TBO's are, what the gph are, what marine agenecies certified them, what the warranties are, etc, etc.

My point is - Your buying the same problems that you have already with your gas engines, your not going forward with engines like these.

They're nice to look at and I'm sure then run good to some degree but everyone that gets on here talking about diesels is not wanting them because they want race style engines. It's because they are tried of what they think are short lived, problematic gas engines.

Jass, your in touch with Nortech how are those Cummins boats doing that they built/are building?

Why do I care about this - one reason - diesels are finally coming around in a positive way. Hot Rod stuff like these Duramaxx's pushed into the recreational market will do nothing but take the good work that Yanmar, Cummins & Mercruiser have done and taint it.

Sorry, my opinion,
Joe Gere
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Old 04-06-2008, 11:40 AM
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Originally Posted by HabanaJoe View Post
Correct me if I'm wrong here.

everyone that gets on here talking about diesels is not wanting them because they want race style engines.
That's quite a presumption, Joe; and it's wrong. I know that there is at least one person talking about diesels here who would indeed consider it to be moving forward if we could get engines that were effectively the equivalent of race style gas engines except burning diesel. That is for the simple reason that diesel is the most promising biofuel (e.g. ), and simply doing the same old same old but with a renewable, domestically sourced fuel that will have potentially much better pricing than gasoline in the not too distant future would actually be significant progress. If diesel engines can do even better than race style gas engines, so much the better. Yes, engine R&D oriented toward future fuels availability and pricing is forward looking, and it's likely not a large concern for someone who wants to run their high-performance boat next week, but you needn't dismiss it as useless or even somehow tainting what Yanmar, Cummins, Mercruiser, and AMT have done in the past.
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Old 04-06-2008, 12:32 PM
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Originally Posted by 29Firefox View Post
It's real evident on the diesel side that I-6s out perform V-8s. But also it's evident in the gasoline world too. Nissan builds a 2.6L I-6 engine that can be built to put out over a 1000 ponies
This rule does not hold for gasoline engines. Specific output typically goes up with the number of cylinders for a given displacement because (1) there is less reciprocating mass, so specific engine speed and horsepower can be increased, and (2) chamber volume is smaller, reducing octane requirements and flame propagation time from spark plug to chamber wall. Diesels have a completely different form of combustion so the above issues do not apply.

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