“If it sounds too good to be true, it probably is…”

Recently, it was brought to our attention by a customer that he “found a VGT engine for sale in the USA, at about half the price we were charging”. This got our attention for a number of reasons. We are long term licensees for General Motors, and all of the licensees pretty much know each other, and what they are doing. So, what gives?

The answer is re-manufactured, or “Reman”, engines.

Re-manufactured engines are a step up from rebuilt engines. When engines are rebuilt during their overhaul, the parts used may be the same, replaced, or repaired. A re-manufactured engine, on the other hand, is an engine that is stripped down to its’ bare components, and built up to a “like new” condition, with parts and components replaced, modified, or even upgraded. In general, there is nothing wrong with purchasing a re-manufactured engine. Many reman companies perform excellent work, and it is possible to buy a reman engine that will give you many years of service, usually at a much cheaper cost.


Re-manufactured is not the same thing as new…

On OEM new engines:

  • All parts and components on the engine are new. They have never been used.
  • Most manufacturers (including Marinediesel) have extensive testing and quality control procedures in place.
  • When buying a new engine, the full warranty is in effect.
  • Engines are ensured to meet quality and emissions regulations.
  • Engine manufacturers typically have robust dealer networks for spares and service.
  • Some components, like ECUs, are difficult to replicate, necessitating replacement with a different unit.
  • Though manufacturers may use the same engine blocks, many parts are customized by each manufacturer, some of which, like pistons or cylinder heads, are not easily modified or duplicated.

If a re-manufactured engines is sold as a new engine, then the practice is deceptive. Most reman companies are not doing the actual research and development work. Most re-manufactured engines have greatly reduced or highly limited warranties. Components on the engine could come from a variety of different sources that may, or may not, have been properly tested. Most vessels cannot be classed with re-manufactured engines, because the engines themselves cannot be classed.

So, the competing engine at half price? It was a re-manufactured engine. Though the engine may very well perform as the buyer expects, it also could cause problems in terms of life cycle, and depending on location, service (In this case, the buyer will be in for a rude awakening when the engine needs service). Additionally, though the customer claimed it was a “VGT” engine, the engine most certainly was very different in terms of performance. Though it may resemble the Marinediesel VGT, and share the vsame engine block, the engine itself was a completely different engine. So, yes, the engine was cheaper. But it was, certainly, not the same.

What is important to consider is the old cliche: “If it sounds too good to be true, it probably is…”

Choosing the Right Engine



As an engine manufacturer, MarineDiesel would love to be able to answer the question, “Which engine should I choose for my project?” with a resounding “MarineDiesel, of course!” every single time. However, that is not the correct answer to give. Different engines have different strengths and weaknesses, and ours are no different. We often get requests to quote where our engines are simply not an appropriate match for a project. Sometimes, people are just price shopping, matching horsepower to horsepower, and sometimes a new project pops up where the shipyard does not have a lot of experience.

When determining the engine to choose, price should be among the last crieria that should be considered. There are far more important questions to ask:

  1. How will the vessel be used? Our engines tend to focus on fast boat applications. They are normally not a good match on tug boats, for instance (Though sometimes, occasionally, they are suitable).
  2. How much space is available for the engine? Smaller spaces require smaller engines.
  3. Is noise a problem? Engines are tested for noise when manufactured. Noise can be controlled through both silencing and insulation, in addition, yet those items also have costs in space and money associated with them.
  4. Is vibration a problem? Some engines, such as our VGT Series, produce much less vibration than inline models, due to their physical characteristics. Additionally, there are aftermarket ways to control vibration, like the use of different mounts or couplings.
  5. How capable is your maintenance team? Some engines are more complex than others. Some require a higher level of skill to maintain.
  6. Price. Price is important, and does play a role. However, consideration also needs to be given to the cost of spares, service, and training.
  7. Life Cycle / Rating. An engine used 2,000 hours per year needs a longer life cycle than an engine used for recreational purposes.
  8. Service network. Some engines may fit all criteria, but there is no service in your country available. Engine maintenance gets expensive very quickly when performed across continents.
  9. Warranty. How good is your engine’s warranty? Some manufacturers have better warranties than others.
  10. Fuel consumption. Fuel costs, on average, exceed 60% of any engine’s operating cost. Cost savings are significant over time.
  11. Performance expectations. You need to have proper calculations made with bona fide data: Not just guesses. Horsepower and torque requirements can vary drastically with small differences in hull design.
  12. Emissions requirements. This can be important. Laws and regulations vary widely between regions / nations.

We realize that choosing an engine is complicated. Contact your local MarineDiesel dealer for personalized assistance on your project.





VGT Series Break-in Procedures

When engines are new, they require certain break-in, or run-in, procedures before they are subjected to heavy use. The reason is that, though the engines are tested at the factory, seals and gaskets need both heat and time to form a good seal, and the engine needs time to properly lubricate. If proper break-in procedures are not followed, severe engine damage can result.

Below is the procedures for our VGT Series of engines.

The Marinediesel VGT series engines need break-in time before being operating to its full potential. This is due to the design characteristics of the base engine.

Follow the recommendations below:

0-5hrs: Use varied load and rpm but do not load the engine above 50% throttle and keep maximum rpm below 2500. Do not stay at one load and rpm configuration for more than 30 minutes at a time.

5-10hrs: Use varied load and rpm but do not load the engine above 60% throttle and keep maximum rpm below 2800. Do not stay at one load and rpm configuration for more than 30 minutes at a time. A few short WOT trials up to 3600 rpm is allowed for performance trials

Do an oil and filter change after the engine has run a total of 10hrs.

10-30hrs: Use varied load and rpm, the engine can be used up to 100% throttle and full rpm for shorter periods. Do not stay at one load and rpm configuration for more than 30 minutes at a time.

Do an oil and filter change after the engine has run a total of 50hrs.
Use oil and filter as specified in the engine technical manual.

If you have any questions regarding this break-in procedure please consult the technical department at Marinediesel in Sweden.



What is DMAX?



With the MarineDiesel VGT Series of engines, we oftem mention that we use a DMAX engine block as the basis for our engines. However, what exactly is DMAX?

DMAX is a joint venture between General Motors and Isuzu Motors that started in 1998. Since MarineDiesel uses GM engine blocks for the majority of the engines we produce, DMAX is, therefore, the brand name of the engine block itself. This marriage between Isuzu and GM reflects the close relationship both companies have had since the early 1970’s, when they joined forces to produce small pickup trucks. Indeed, there is sometimes some confusion related to the DMAX brand, since a number of Isuzu pickup trucks also use the name as a truck model brand.

So, throughout all of this explanation, what does it mean for the MarineDiesel customer?

It means that our engines, produced by a small company, benefit from the research and development performed by two much larger companies, with many more resources. It also means that our engines are reliable: GM has produced millions of these engine blocks. It also means that the marine industry has another option for vessel power. Both large companies have very small marine divisions and departments. Yet, the marine industry is a tiny market, when compared to the market for small trucks. It is economically feasible for large companies to let companies such as MarineDiesel serve niche markets that, though they may be profitable, are too small for large corporations to devote many resources to serving.




Genset Engines



Here at MarineDiesel, we often receive inquiries as to whether or not we manufacture generators. The answer is “no”, though we do manufacture engines that can be used to power gensets. Why would someone who needs a generator just purchase an engine?

Quite simply: We can customize the engine for the application.

Most (though not all) generator manufacturers do not manufacture the engines used in the generator. The reason is because providing electrical power is a different specialization than providing mechanical power. There are dozens of different variables in power generation, and the production of standalone models requires many different options and a different manufacturing process.

So, when asked to provide an engine for a generator, we nearly always receive this type of inquiry from either a generator manufacturer or from someone who needs a very specialized generator with needs that “off the shelf” models cannot meet. For instance, we can manufacture engines with customized levels of continuous power or multiple engine maps for different uses of the same genset.

MarineDiesel has, over the years, provided both marine and industrial engines for gensets and applications as widely varied as for electricity on large mining equipment to small fishing boats. We also can often refer people to our customers who are generator manufacturers and specialize in electrical power.



MarineDiesel User Poll: Engine Performance



Today’s article is the latest MarineDiesel user poll (no registration required and no cookies kept), related to aspects of engine performance that make your decision as to engine choice.

We hope you find it interesting.

[socialpoll id=”2241265″]



Multi-engine Installations



The picture above is an example of a triple engine installation MarineDiesel completed. Though the vast majority of our marine projects involve single or twin engine installations, we occasionally receive requests to power triple or even quadruple engine projects.

Indeed, as is evident in the photo above, engine compartments are often very limited in the amount of available space, and the compact size of the MarineDiesel V-8 engines means that our engines are often the only engine that will fit in some engine compartments.

Triple installations are usually more expensive than twin installations of higher horsepower engines, and there are other challenges as well, particularly on vessels that use propellers for propulsion. On these vessels, the nature of propellers means that vessels will have a tendency to “pull” in one direction of the other, due to the torsion of the propellers themselves.

However, a triple installation also offers additional redundancy, and normally lower weight than twin installations with larger engines.

So, which is preferable?

Normally the decision comes down to cost, though weight and space constraints also have an impact.

Nonetheless, the compact power of MarineDiesel engines means that multi-engine installations are far less uncertain regarding performance and are a cost effective alternative to providing high power in a limited space.

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Some MarineDiesel Projects – Commercial Vessels



Today’s post is some more reference photos of projects that use MarineDiesel engines. These photos are of high performance commercial vessels.

MarineDiesel engines are rated to take the heavy use and harsh conditions that commercial operations experience, and are the only engine in the market specifically developed for these types of applications.

We hope you find these photos interesting. Contact us or your local MarineDiesel distributor today for a quote on your project.














A Dictionary of Diesel Engine Terminology



Here at MarineDiesel, we recognize that engines are complex devices. We also know that the jargon and terminology can often be a bit confusing. Please see the dictionary below as our effort to help clarify some of the terms used on this site and in the industry. This post links to a permanent page on the blog. We hope you find it useful.





Vessel Performance Problems – Who’s to Blame?



Designing high performance vessels is both an art and a science. Performance is one of those terms that can be defined in many different ways. However, when dealing with vessel design, performance is measured in terms of a customer’s expectations when a boat is designed. On recreational boats, built by large yards as a production run or as a specific model, performance means a standard that can be advertised to potential buyers. On military, commercial, or government service boats, performance is strictly defined in terms of expected speed, vessel load, and vessel use.

So, what happens when a boat is built and it does not perform up to expectations?

Enter the blame game.

  • The yard will blame the engine manufacturer.
  • The engine manufacturer will blame the propeller manufacturer.
  • The propeller manufacturer will blame the yard.
  • The yard will blame the naval architect.
  • The naval architect will then say that the customer’s demands were not realistic.

A cycle that is common, and usually is completely unproductive when solving the problem: WHY is the boat not performing?

Vessel design is a question of balance and the laws of physics. Numbers do not lie, and the laws of physics apply to everyone. What happened?

In our experience, the vast majority of performance issues are related to lack of communication between all of the different manufacturers of the vessel systems. In general, the following items are performance critical:

Vessel Weight / Displacement. This is the most common problem. It is either calculated incorrectly, or different materials were used than specified in the design (usually for cost reasons). Sometimes, it is not the yard’s fault. The vessel owner will often make changes after construction was started, sometimes ignoring the advice of the yard. This will put the builder in a delicate position of keeping the customer happy or achieving performance. It is not just with recreational vessels, either. MarineDiesel has seen many projects fail when a military commander decides to change the weaponry or vessel mission without any understanding of the physics involved, sometimes to comical results.

Bad Propeller / Propulsion Design. This is also not always the fault of the manufacturer. Propeller makers (or drive makers, or jet makers) can only make calculations based on the information that they are given. If they are given incorrect information, then the vessel performance will not be correct.

Bad Engine Selection. Engines cost money. Power costs money. As an engine manufacturer, the guarantees we make are based on the power of the engine we provide. So, if you buy 500 horsepower, we guarantee that the engine you buy will produce 500 horsepower. We do not make guarantees based on a project’s performance. Why not? How can we guarantee a performance level when we did not design or manufacture the hull, propeller, or drive? In some cases, a customer will try and save money by buying an engine that is under-powered for an application in order to save money. This returns us back to the laws of physics. There is no such thing as a free lunch.

Bad Hull Design. This is also quite common, especially on new, or prototype, hulls. On high speed or high performance vessels, design mistakes are often magnified, due to the increased forces on the hull at high speeds. We have seen such mistakes in water intakes, spray rails, steps (especially), foils, and simply bad designs. This is also why many yards insist on having designs that are proven, with other customers using the vessel.

It has been our experience that when vessels do not reach their required performance levels, it is usually a case of “all of the above” to varying degrees. It is important for vessel buyers to understand what they are buying and for everyone to be upfront and honest with all information. Unfortunately, in the competitive marketplace, costs are often the driving criterion on projects, and the ever present desire to reduce costs oftem is the real culprit, leading to bad decisions and poor engineering.