Diesel versus Petrol: What’s the advantages and disadvantages?

We occasionally get asked by our customers whether or not they should put a diesel engine in their vessel, or a petrol engine. As with everything else in life, there is no single “right or wrong” answer. We manufacture both types of engines, so we are truly non-biased in our opinion. The answer is, “It depends.”

Ask yourself these questions:

What is the purpose of the vessel?

How will the vessel be used?

What are the emissions regulations in my area?

What is my budget?

These all have an impact. So, to make things easier to break down, we will use diesel as a starting point, listing advantages and disadvantages versus petrol.


  1. More efficient combustion versus petrol. Diesel engines have a much higher output of torque than petrol engines. Given the same horsepower on two engines (see below), the diesel will provide more work for the fuel spent.
  2. Much longer life cycle that petrol engines. As much as three or four times longer. Petrol engines work “harder” to produce the same power, and are more complex, thus needing more frequent maintenance.
  3. Diesel is cheaper than petrol (At least in most of the world).
  4. Much lower fuel consumption.
  5. Petrol has a greater risk of explosion and fire. Requires greater ventilation.
  6. Diesel engines produce much less heat, and are cooled more efficiently. Petrol engines can require substantial cooling systems at greater cost.



  1. Diesel engines are usually more expensive than petrol engines, often up to twice the price.
  2. Diesel engines produce more smoke with dirty fuel (Though ULSDF required in Europe and the USA is actually cleaner than petrol).
  3. Diesel fuel breaks down rapidly. If engines will sit for long periods of time, the fuel will need to be stabilized or drained.

The pictures below illustrate two MD engines’ power and torque curves, showing a big difference in torque, but producing the same horsepower.

petrol 6-2

MD VGT 400 diesel power and torque curves.

MD VGT 400 diesel power and torque curves.

Engines so tough, you can drop them from aircraft





MarineDiesel engines are often sold for highly specialized military applications. One frequent use is to equip small vessels used by commandos, like RHIBS or other small high speed craft.

These vessels experience operating environments and conditions that few other vessels will ever experience. This type of stress will easily destroy engines made by our competitors that were designed for recreational or pleasure use (Yet are often installed on these types of vessels anyway). Recreational engines are simply not designed to withstand the heavy use, extreme vertical acceleration and harsh climates that military or police boats experience even during “routine” missions.

All MarineDiesel engines are designed to be in compliance with both MILSPEC and NATO requirements. A quick glance at our engines will prove it. Notice small visual differences like better shielded wiring,  and metal, rather than plastic, connectors, along with more robust seals and gaskets.

MILSPEC and NATO require extensive testing and verification. Of course, certification can get expensive (Unlike type approval, certificates are issued on a project by project basis.), but an engine that is in compliance is crucial to even obtaining these certificates. It is also critical that engine manufacturers are familiar with the process and know the steps to certification.

This brings us to the title of this short article. Yes, our engines can be (and HAVE BEEN) dropped successfully from aircraft, as the photos above show. One critical part of NATO and MILSPEC testing that often demolishes our competitors’  products is the ability to withstand the 30 g vertical acceleration experienced by an engine after being dropped by parachute. The boat pictured above is essentially useless if the engine will not start when it lands or, if the engines is started before dropping and it stalls. Both scenarios can easily spell mission failure if proven engines are not installed.

Of course, there are many other aspects to MILSPEC and NATO compliance besides vertical acceleration: You can read some of the NATO rules HERE.

However, since MarineDiesel has been engineered for this type of use, all MD customers benefit from this R&D, whether a water taxi, military boat, fishing boat, or ski boat.


Operating Angles



MarineDiesel engines are designed to provide high power in a compact size. Indeed, a major selling point of our engines is that they often fit in tight and narrow engine compartments that are simply too small for engines made by our competitors.

When building a vessel, all of the design elements must come together in order for the boat to achieve its’ stated performance. Engine, Hull, and Propulsion must be aligned properly. Often, this does not happen, for instance with an odd shaft alignment.

We can usually address these types of problems through custom engineering. However, we are limited by the Laws of Physics in what is, and is not, possible. Our engines were designed to operate and perform at specific mounting angles. You cannot simply say, oh, this space is too small and mount the engine at a 47 degree angle to make it fit.

Engines contain oil and other fluids, and pumps and seals were designed to operate at specific pressures and levels. Tilting the engine alters these levels and the engine may not function properly. Mounts are designed to hold the engine at a specific level and altering this level increases stress and vibration.

However, as the picture above shows, a certain amount of tilt will still allow the engine to operate properly. Close consultation between owner, yard, naval architect, and engine manufacturer can usually solve this kind of problem or alternative solutions can be devised.

MarineDiesel Distributor Profile – Bangladesh



This week, we feature our Bangladeshi distributor, Alam Enterprises, MarineDiesel distributor since 2012:

Brief History:     M/S Alam Enterprise is a proprietorship firm formed in 22nd July 1998 involved in various supply trade
at the initial stage. With the background of family business involved in boat and ship building industry
the proprietor Mr. S. Y. Alam moved to set-up his own entrepreneurship practice house named after Alam
Enterprise incepted with the vision of providing logistic support of hi-tech solutions to upcoming and established local and multinational companies in Bangladesh keeping in faith the intention of moving with the millennium waves. The company is one of the few and first in Bangladesh to have initiated the concept
of on-line corporate management system, integrated security solutions, specialized aviation and communications systems for upgrading and modernizing the business environment.
Main Business Activities:       Importer, Distributor, Service Provider and Local Agent of various technical and specialized products involved in consultancy, planning and designing as a one stop integrated security solutions (in various KPI). Registered contractor in Civil Aviation of Bangladesh (CAAB) since 2000, Directorate General of Defence Purchase (DGDP) under MoD since 2001 and also enlisted supplier in various Govt., Non-Government and other private agencies.
Equipment & Products:    To name some of the specialized equipments and products –
–                      Various Security Equipments i.e. X-Ray Scanner Systems, etc;
–                      Explosive Detectors, Narcotic & Chemical Detectors, etc;
–                      Archway / Walkthrough Metal & Weapon Detectors, HHMD, etc;  
–                      Aviation Refuelling Systems and various components;
–                      Airport Ramp & Ground Service Equipments (GSE);
–                      Dispenser Trucks, Fire Trucks, Mechanical Runway Sweepers, etc;
–                      Jet – A1 Hydrant Line Systems and various components & Spares;
–                      Integrated Access Control Systems, Various Security Seal Locks, etc;
–                      Security Surveillance Systems, Specialized CCTV, etc;
–                      EOD, IEDD products ranges for defence and para-military forces, etc;
Various Principals & Products:     #. Garrett Metal Detectors, TX, USA  –               AWMD & HHMD;
                                                                #. L-3 Communications Security & DS, USA  –               X–Ray Scanners, etc;
                                                                #. NOVATECH Co. Ltd., Bangkok, Thailand   –               Refuellers ;
                                                                #. FAUDI Aviation GmbH, Germany  –               Aviation Filter, etc;
                                                                #. AB Precision (Poole) Ltd., U.K.  –               EOD, etc;
                                                                #. Fluid Transfer Ltd., U.K.  –               Aviation Refuelling Eqpt.;
                                                                #. Elaflex GmbH, Germany  –               Aviation Hose pipe, etc;
                                                                #. Haneflex Singapore Pte. Ltd., Singapore –               Aviation Jet-A1 Eqpt., etc;
                                                                #. O’Connoer Singapore Pte. Ltd, Singapore  –               CCTV, PA Systems;
                                                                #. Jante, Taiwan –                Access Control, etc;
                                                                #. Mercury Out Boat Engines, US & Singapore  –               Out Boat Engines;
                                                                #. NABCO, USA –               EOD Chamber;
                                                                #. BiaZone Int. Pte. Ltd., Singapore   –               Various Office Eqpt., etc;
Major Customers:              CAAB, DGDP (Air Force, Army & Navy), Bangladesh Police HQ., DHL, WHO, UNICEF, Sea Port Authority, Border Control – Customs House, Rapid Action Battalion (RAB) Forces, Dhaka Stock Exchange, Dhaka USA Embassy, E. U. – Dhaka, Pan Pacific Sonargoan Hotel, Sheraton Hotel, WESTIN, G-4 Securities Ltd., HSBC Bank, Standard Chartered Bank, Padma Oil Co., Ltd., Private TV Channels (i.e. NTV, RTV), Various Airlines, Special Branch – Ministry of Homes, Prime Minister’s Office, Bangladesh Ordinance Factory etc.

Alam Enterprises

Suite #65, “Akash Plaza”
House #21, Road #7/D
Sector #9, Uttara Model Town
Phone: +886-895-7684
Mail: alamenter@gmail.com


ECU, Dongle, and NIRA



nira screen

As we have written on this blog before, our VGT Series of engines uses a NIRA ECU to both report faults and control the engine functions.

A primary reason we use NIRA is that it is easily accessed by MarineDiesel technicians in addition to being programmable.

So, you buy a VGT engine from us. How do you access the engine data?

It is really simple. You need:

  • MD diagnostic software
  • A laptop
  • A connecting cable
  • A dongle



Training on how to use the software.

We don’t charge anything for the software. Nearly every shop nowadays has laptops available for technicians. Cables are cheap.

What we charge for is the dongles, and there are many reasons we do so:

Most importantly, we need to restrict who has access to your engine’s functions. The NIRA software is not very difficult to learn, but it can be unforgiving. Untrained people making changes can easily ruin your engine. The average user or boat owner will not be able to learn this software without training (It is NOT intuitive). Therefore, in order to forestall problems, we charge for the dongles.

Our engines are often used on boats, surrounded by water. Ever drop your keys, or sunglasses, in the drink?

The dongle grants access to licensed software. The software is freely available, and uses international standards, but it is the intellectual property of NIRA nonetheless.

All of our dealers carry multiple dongles for their technicians to use. They usually purchase these when they undergo our training program. Some large customers undergo extensive training, and they, too, carry these in inventory. However, though an ECU is software, it was not necessarily ever intended to be modified by the average Joe.


Maintenance Tip of the Week – Fuel Consumption 08/25/2014

Maintenance Tip of the Week – 08/25/2014

Engine makers use g/kWh to measure fuel consumption because it gives a more accurate indication of fuel consumption in terms of power produced than simply the burn rate. This can give you a clearer picture of real fuel consumption between two engines, one producing, for example, 315 hp and another producing 340 hp.

On a 350 hp engine consuming 215 g/kWh

To convert to L/hr

Multiply the kWh (216) by consumption (215)

Divide by the fuel density. Diesel is 840 g/l

(216 * 215) / 840 = 55.28 L/hr


To convert to gallons per hour, multiply by .264:

(55.28 * 0.264) = 14.59 gallons per hour



Special Tools – Are they necessary?



Virtually every engine manufacturer in the world offers special tools for sale with the engines they make, and MarineDiesel is no exception. In fact, on large projects and government tenders, there is usually a requirement specified to add in to any quotes all special tools that may be required to perform service.

What is the purpose of these tools?

Are they really necessary?

Sometimes, they can get fairly expensive. Why?

The answers to these questions may not seem so obvious at first glance.

When engines need service, it is oftentimes not easy to access, or install, or remove, various components. Indeed, the MarineDiesel manuals for our VGT Series of engines run to over 500 pages if combined. Add in the various manuals for accessories, options, etc., and you have quite a large binder of information.

First off, there are maintenance and repair procedures that only factory trained service technicians should perform. These are often complicated, or require specialized facilities or heavy equipment to perform. When most of our dealers undergo their factory training, they usually purchase one or more sets of special tools. The purpose of these tools is related to many factors:

  • The specialized requirements of the engine. (Say, a special bolt needs to be manufactured for torque resistance.)
  • Design requirements. (For instance, a cover or plate needs a specific shape.)
  • Access to components. (Parts are located inside other parts, or are located in places that are difficult to reach with standard mechanics’ tools.)

On MarineDiesel engines, none of the special tools is an absolute necessity: All maintenance can be performed in a well-equipped shop. The special tools can, however, allow maintenance and service jobs to be completed more quickly and in an easier manner.

Are they expensive? Not really. However, they are specialized to a specific function, and they are more expensive than a standard, similar-sized tool. This is because the market is very limited. A manufacturer of wrenches may make a million of a standard wrench. Design the tool, and tool the machinery once, and get millions of finished products. Special tools may only be manufactured in the hundreds. We are cognizant of this fact, and strive to eliminate all necessary special tools (How often have you bought something that requires some weird wrench to assemble? Talking to you, Chinese bicycle maker!) The special tools we sell are merely designed to make service easier: Nothing more.

Here’s the complete, short list for our VGT Series of engines:

  1. Injector pullerMD44639 – Injector puller – Ensures damage free injector removal on VGT diesel engines.
  2. oil seal installerMD41221A – Oil seal installer – Consists of six tools designed to install the front and rear crankshaft seals.
  3. flywheel holderMD44643 – Flywheel holder – Used to hold the flywheel/engine stationary during removal of hub bolts
  4. rear crankshaft seal removerMD44641 – Rear crankshaft seal remover – The rear seal is press fitted to both the engine block and crankshaft, this is a special puller with three jaws to grab the inner lip of the seal. The forcing screw attached to the center plate is used to react against the crankshaft end to pull the seal out.
  5. HD Compression Test KitMD23223 – HD compression test kit
  6. specialty tool storage caseMD44648 – Specialty tools storage case

Control Panels: Analogue or Digital?



Recently, we have had a number of inquiries asking for photos of our standard control panel. All MarineDiesel engines come with the panel shown above as standard. Though it has analogue gauges, the alarms and fault codes are still electronic on electronic engines. These panels are designed to provide simple, “at a glance” information to the vessel operator, without distraction.

Since most of the vessels using our engines are small, with limited helm space, it is challenging to provide instrumentation that can adequately convey a lot of information in a small amount of real estate.

We also offer an LCD digital display, pictured below, that provides the same information as the other panel.

Finally, on projects where heavily specialized, or customized, displays are required, usually on military projects, we partner with Seacross to provide customized displays. Seacross are, quite simply, the experts in vessel display and navigation, and their products are outstanding.




Working with Naval Architects



For marine projects on new builds, MarineDiesel is normally asked to become involved in a project by the shipyard, after a vessel design has already been chosen. The naval architect has already submitted his design for approval, specifying a specific horsepower required in order to achieve the vessel’s required performance, regardless of whatever that performance metric may be (speed, weight, fuel economy, reliability / life cycle, etc.). In these situations, we are often constrained by price, first and foremost, since shipyards are usually bidding on a tender against other shipyards, and many, if not most, public tenders are “lowest price wins”.

Occasionally, we are approached by the naval architect themselves. In these situations, we often have far more flexibility in the products we offer to the end user. The reason why is that since the naval architect is designing the vessel, modifications on either the design or propulsion system can easily be made in order to better fit the end user’s needs and requirements. We always work closely with the naval architect in these situations, and we have the technical ability and knowledge to make very specific power recommendations on a new design.

Typical items looked at by a naval architect include:

  • Engine and propulsion system weight, especially critical on small, fast vessels.
  • Power curves
  • Torque curves
  • Fuel consumption curves (for range, efficiency, and operating cost)
  • Size of engine, especially in the case of small engine rooms or engine compartments
  • Engine life cycle
  • Engine service intervals
  • Emissions limits (Area of operation)
  • Mission requirements in terms of performance (eg: Commando boats used in boarding or dropped from aircraft)
  • Parts availability
  • Training capability of the manufacturer
  • Service network of the manufacturer
  • Country of origin of the engines
  • And finally, price of the engines

No single engine type or brand excels in every single aspect examined. An engine may have an exceedingly long life cycle, but the power curve may be completely wrong in helping a boat get on plane. Likewise, a particular engine may provide rapid acceleration and power, but may have a drastically shortened life cycle when compared to a different engine. This is where the engine manufacturer or dealer’s expertise becomes extremely important. It is not a simple question of price alone or of raw horsepower. Real world projects are complex, dependent on dozens of different criteria in determining success or failure in terms of performance.

Additionally, since MarineDiesel has extensive industry partnership in areas ranging from propulsion to electronics to training, we often are asked to package various components together under a single solution package. We have seen that this is the direction in which the industry is moving as projects have gotten more complex, budgets have shrunk, and mission requirements have become more complicated.

An engine manufacturer in this market must have capabilities greater than merely providing CAD drawings to a naval architect. They must have the industry knowledge to truly understand the constraints faced by naval design and to be able to offer complete solutions to complex design problems, rather than merely providing a piece of equipment.

MarineDiesel User Poll – New Engine Types



We want to hear from our readers and customers…

This week’s poll

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