Daihatsu Diesel (Infinearth) Marine Engines

Daihatsu Diesel Mfg. Co., Ltd., renamed Daihatsu Infinearth Mfg. Co., Ltd. in 2025, is one of Japan’s principal builders of medium-speed and high-speed four-stroke marine engines, with a particular concentration in shipboard auxiliary generating sets. The company is based in Osaka, traces its corporate lineage to a 1907 Osaka engine venture, and is listed on the Tokyo Stock Exchange under ticker 6023. Most marine engineers know it for the DE and DK genset engines that sit in the engine rooms of Japanese-built bulk carriers, tankers, and container ships. For the broader population of comparable builders, see the marine engine makers index; for the underlying machine type, see medium-speed four-stroke marine engines. The companion sizing tool for this class is the medium-speed 4-stroke auxiliary engine calculator.

What Daihatsu builds and where it sits

Daihatsu is not a slow-speed two-stroke main-engine licensee. It does not build the large bore crosshead engines that drive most deep-sea ships at the propeller. Instead it occupies the four-stroke trunk-piston space: engines that run at higher rotational speed, drive a generator or a smaller propeller, and use a piston connected straight to the crankshaft through a connecting rod, with no crosshead. The architecture is covered in four-stroke marine diesel engine fundamentals and, for the structural detail, in trunk piston engine architecture.

Within that four-stroke space, the company’s center of gravity is the auxiliary genset. A deep-sea ship typically carries three to four diesel generators to supply the electrical load at sea and in port. Daihatsu is one of a small group of makers whose engines dominate that role on Japanese-built tonnage. The role itself, sizing rules, redundancy practice, and the difference between auxiliary and emergency sets, is set out in marine auxiliary engines and generators.

Japan supports several four-stroke builders in parallel, and they specialize by power band and duty. Daihatsu’s domestic peers include Yanmar in the smaller and higher-speed bands, Niigata Power Systems across propulsion and propulsion-with-thruster work, Hanshin Diesel in coastal medium-speed main engines, and Akasaka Diesel in the coastal and domestic trades. Against the global four-stroke majors the comparison is different, and we draw it out below. The short version: Daihatsu competes hardest where the order is for a fleet of standardized gensets rather than a single very large propulsion engine.

Corporate origins and the 1907 lineage

The 1907 founding date that Daihatsu cites belongs to an Osaka engine venture set up to give Japan a domestic capability in internal-combustion engines. The early enterprise grew out of work at Osaka Higher Technical School and was organized to manufacture gas and oil engines at a time when most engines in Japan were imported. The venture that the modern company traces to is usually rendered in English as Hatsudoki Seizo, literally an engine-manufacturing company.

The name “Daihatsu” is a contraction. It joins the “Dai” of Osaka (the city character read “Dai” in the older reading of the place name) with the “Hatsu” of “Hatsudoki,” the word for engine or motor. So the brand reads, roughly, as “Osaka Engine.” That contraction is the thread that ties together two companies that the public often confuses.

The relationship to the car company, stated accurately

Daihatsu Diesel and Daihatsu Motor Co., Ltd. are not the same company, and one is not a subsidiary of the other. They share the early Osaka engine lineage and the “Daihatsu” brand contraction, but they became distinct businesses. Daihatsu Motor is the small-car and kei-car maker that is now a wholly owned subsidiary of Toyota Motor Corporation. Daihatsu Diesel, now Daihatsu Infinearth, is an independent company listed on the Tokyo Stock Exchange in its own right.

It is easy to overstate the link, so it’s worth being precise about what is and isn’t true. True: the two firms descend from the same early-twentieth-century Osaka engine activity, and they carry related branding. Not true: that the diesel company is a division of the car company, or that Toyota controls the marine-engine business through its ownership of Daihatsu Motor. The marine and stationary diesel-engine business has run as a separate corporate entity, and its shares trade under ticker 6023. If you read a source that treats “Daihatsu” as a single company spanning cars and ship engines, treat that as a simplification.

From Osaka engine works to marine specialist

Across the twentieth century the diesel-engine business built relationships with the Japanese shipbuilding industry as that industry grew into the largest in the world. Japanese yards preferred Japanese auxiliary machinery for reasons of supply, service, and language, and Daihatsu became one of the standard answers when a yard specified gensets. That domestic base is the foundation of the company’s position even now, and it is the reason the auxiliary genset, rather than the propulsion engine, is the product the company is known for.

The choice to specialize was a commercial one as much as a technical one. The slow-speed two-stroke main engine is a licensed product dominated by a small number of licensors, and the largest medium-speed propulsion engines are held by the global four-stroke majors with deep reference bases. The auxiliary genset, by contrast, is a higher-volume, more standardizable item where a domestic maker close to the yards can win the specification and keep it across a ship series. Daihatsu took the volume segment where its proximity to the Japanese supply chain counted, rather than the prestige segment where it would have been a marginal entrant. That decision, made early and held, explains the shape of the catalogue today.

The 2025 rename to Infinearth

In 2025 the company changed its corporate name from Daihatsu Diesel Mfg. Co., Ltd. to Daihatsu Infinearth Mfg. Co., Ltd. The “Infinearth” coinage signals a positioning toward lower-carbon and lower-emission products, and the company groups its environmental engine work and decarbonization message under that identity. The listing, the ticker, and the engineering operations carried over unchanged; the rename is a brand and strategy statement, not a change of ownership or a spin-off. Throughout this article we use “Daihatsu” for the engine business across both names, since the product families predate the rename and the marine market still refers to the engines by their series codes.

Medium-speed four-stroke engine families

Daihatsu’s marine catalogue is organized into series, each identified by a two-letter code and a bore figure. The bore (the cylinder diameter) is the single number that anchors the rating, because for a four-stroke trunk-piston engine the power per cylinder scales with bore, stroke, mean effective pressure, and speed. The relationship is captured by the brake-mean-effective-pressure identity, which is the cleanest way to compare engines across the catalogue.

Read that card the practical way. For a fixed bore and stroke, the only levers a designer has to raise power per cylinder are the mean effective pressure and the rated speed. Auxiliary genset engines run at a fixed speed set by the grid frequency and the generator pole count, so the speed lever is effectively locked. That is why genset development concentrates on raising mean effective pressure and on holding fuel consumption flat while the pressure rises.

The DE series

The DE series is Daihatsu’s current-generation medium-speed line, developed for auxiliary genset duty and for some smaller main-propulsion work. The series spans several bore sizes, with the model code carrying the bore figure: the engineering community refers to engines such as the DE-18, DE-23, DE-28, and DE-33 by those bore-derived numbers. The DE-28 is the workhorse of the range and is the engine most often quoted when people discuss Daihatsu gensets.

The DE-28 carries a project-guide reference point used in the companion calculator: a per-cylinder rating in the order of several hundred kilowatts at a genset speed near 720 rpm, with specific fuel consumption near the high-180s to mid-190s in grams per kilowatt-hour at the rated point. Those are reference figures for estimation, not a substitute for the order-specific datasheet, and a real project guide will give the exact rating, fuel curve, and ambient-correction basis. The card below ties the per-cylinder figure to total output.

For a six-cylinder DE-28 the total continuous rating follows directly from the per-cylinder figure multiplied by cylinder count, then trimmed for the ambient correction the standard requires. You can run the same arithmetic in the DE-28 MCR-per-cylinder calculator, and you can size the resulting generating set against a ship’s electrical load with the auxiliary engine sizing calculator.

The DK series

The DK series is the long-running medium-speed family that established Daihatsu’s reputation, and many vessels in service still run DK engines as gensets and as small main engines. The series covers a bore range from roughly 200 mm at the small end to around 360 mm at the large end, with model codes again keyed to bore: the DK-20, DK-28, and DK-36 are the commonly cited members. The smaller DK engines serve genset duty; the larger DK-36-class engines reach into small main-propulsion territory for coastal and short-sea vessels.

A DK-28 genset engine runs at a genset speed, typically 720 rpm for a 60 Hz, six-pole machine or 750 rpm for a 50 Hz, eight-pole machine, with the exact speed fixed by the alternator. The DK and the DE overlap in bore but the DE carries the later combustion and emissions development, so a new genset order today is far more likely to be a DE than a DK. The DK remains important because of the installed base: spares, overhauls, and replacement parts for DK engines are a continuing part of the aftersales business.

The DL series

Daihatsu’s larger medium-speed work sits in the DL series, which reaches above the DK and DE bores toward the bottom of the band that the global four-stroke majors occupy. The DL line addresses larger gensets and propulsion duty where a single four-stroke engine must deliver several megawatts. Because the DL competes more directly with the larger four-stroke engines from the global makers, it is the part of the catalogue where Daihatsu’s positioning against medium-speed four-stroke marine engines from the majors is most direct.

Mean piston speed across the families

A useful cross-check on any of these engines is mean piston speed, which is the average speed of the piston over a stroke and a leading indicator of mechanical loading and wear rate. Medium-speed marine four-strokes run mean piston speeds in the high single digits of meters per second at the rated point; pushing higher buys power but costs ring and liner life. The mean piston speed calculator gives the figure from stroke and rated speed, and it is the right tool for comparing a DE-28 against a DK-28 at the same bore but a different combustion package. The figure follows from $c_m = 2 \cdot L \cdot n$, where $L$ is the stroke in meters and $n$ is the rated speed in revolutions per second, so a long-stroke genset engine at a fixed genset speed sits lower on the wear curve than a short-stroke engine at the same speed.

Why the bore figure anchors the rating

The two-letter code plus bore figure is the shorthand the whole market uses, and it works because bore is the dimension that scales hardest with power. For a fixed mean effective pressure and mean piston speed, the power per cylinder rises with the square of the bore, since the working area of the piston is what the gas pressure acts on. That is why a DK-36 at 360 mm bore reaches small-main-engine territory while a DE-18 at 180 mm stays firmly in the smaller-genset band. It is also why a maker can cover a wide power range with a compact set of series: change the bore, hold the combustion concept, and the rating follows.

The corollary is the warning in the Limitations section below. The bore figure tells you the family and the broad power band, but not the exact rating, because two engines at the same bore can carry different stroke, different mean effective pressure, and different speed ratings. The model code is a starting point for selection, not a substitute for the datasheet.

High-speed four-stroke and emergency sets

Below the medium-speed band, the emergency generator and some compact auxiliary sets fall into the high-speed four-stroke marine engine class, which runs at 1,000 rpm or above and trades fuel economy and overhaul life for compactness and fast starting. The emergency genset is a regulatory requirement separate from the main auxiliary sets, and it is sized to carry the safety and blackout-recovery loads rather than the full sea load. The high-speed emergency genset calculator handles that sizing case, and the distinction between emergency and auxiliary duty is one of the practical points covered in marine auxiliary engines and generators.

Why the auxiliary genset is the core business

The reason Daihatsu’s strength concentrates in gensets is partly arithmetic and partly market structure. A single slow-speed-engine ship carries one main engine and three to four diesel generators. Across a fleet of standardized ships, the genset is the higher-volume item, and a maker that wins the genset specification on a series of newbuildings books a stream of identical engines plus the spares and service that follow them for the ship’s life.

Gensets also reward standardization in a way that propulsion engines do not always. A yard building a series of bulk carriers wants the same genset on every hull so the crew training, the spare-parts holding, and the maintenance routine carry across the fleet. A maker with a tight, well-proven genset range and a deep service network is exactly what that yard wants, and that is the position Daihatsu has built. The company is among the leading suppliers of marine auxiliary diesel engines by unit volume, with that strength rooted in the Japanese newbuilding market.

Redundancy and the N-plus-one rule

The number of gensets on a ship is set by redundancy and load, not by a single power figure. A common arrangement carries enough sets that the ship can lose one and still meet its sea load, the so-called N-plus-one logic, with the sets sized so that two or three running cover the at-sea demand and the spare covers a failure or an overhaul. A reefer-heavy container ship or a ship with large cargo pumps carries more genset capacity than a plain bulk carrier of the same size, because the electrical load, not the deadweight, drives the sizing. This is the reason a genset maker books several engines per hull, and the reason the auxiliary specification is a fleet decision rather than a per-ship one.

Loading the sets correctly matters as much as sizing them. A diesel generator runs most efficiently and cleanest around three-quarters of its rated load, and running a large set lightly loaded for long periods carries a fuel and maintenance penalty. The point of sizing the set against the real electrical load profile, rather than against a single nameplate peak, is to keep the running sets in their efficient band. The auxiliary engine sizing calculator is built to match the genset count and rating to that load profile.

Fuel consumption is the headline number

For a genset that runs thousands of hours a year, fuel consumption dominates the operating cost, so specific fuel oil consumption is the figure owners scrutinize. It is reported in grams of fuel per kilowatt-hour at a defined load point and ambient condition, and small differences compound across an operating year. The relationship between specific consumption and the engine’s thermal efficiency is direct: a lower consumption figure means more of the fuel’s energy reaches the crankshaft.

A genset specified at, say, the mid-190s in grams per kilowatt-hour on a heavy fuel of known lower heating value converts to a brake thermal efficiency you can read straight off that relationship. The thermal-efficiency-from-SFOC calculator does the conversion. The point of running it is to compare quoted fuel figures on a common basis, because two makers may quote at different reference loads or ambient conditions.

Ambient correction matters when you compare quotes

Specific fuel consumption and rated power are both stated at a reference ambient condition, and both shift when the engine-room and charge-air conditions differ from that reference. Higher charge-air temperature lowers air density, reduces the trapped air mass, and pushes fuel consumption up unless the rating is derated. Comparing two quotes without aligning the ambient basis is a common error in genset selection.

That sensitivity is why a tropical-trade ship and a North-Atlantic ship can see different real-world consumption from the same engine model, and why the order datasheet, not the brochure, is the document that governs. The standard reference basis for marine diesel ratings is set out in ISO 3046, and the NOx side of the same operating point is governed by the IMO framework discussed below.

Emissions: NOx Tier III, SCR, and EGR

Marine four-stroke engines must meet the nitrogen-oxide limits in MARPOL Annex VI Regulation 13, certified against the IMO NOx Technical Code 2008. The regulation sets three tiers keyed to engine rated speed and to the ship’s construction date, with the strictest, Tier III, applying to ships built from 1 January 2016 onward when they operate inside a designated NOx Emission Control Area. The North American and US Caribbean ECAs have been in force since the start of Tier III, and the North Sea and Baltic Sea ECAs apply Tier III to ships built on or after 1 January 2021.

Tier III cuts the NOx limit to roughly a fifth to a quarter of the Tier I level for the relevant speed band, and a conventional diesel cannot reach it on combustion tuning alone. Two aftertreatment or in-cylinder routes dominate, and Daihatsu, like its peers, offers both depending on the application.

Selective catalytic reduction injects a urea solution into the exhaust upstream of a catalyst, where ammonia from the urea reduces NOx to nitrogen and water. SCR is the higher-conversion route and is the usual choice when a ship needs deep NOx reduction across a wide load range. The technology, its temperature window, and the urea-dosing control are the same in principle as the marine SCR systems covered in SCR retrofit on two-stroke engines, even though that article addresses the two-stroke case. Exhaust gas recirculation takes the other route, routing a portion of exhaust back into the cylinder to lower peak combustion temperature and suppress NOx formation at the source. The trade-offs between these compliance routes also shape the wider Tier III engine market described in Tier III compliant two-stroke engines.

The carbon side of the same engine is a separate accounting problem from NOx, governed by the fuel’s carbon content rather than by aftertreatment. Carbon dioxide per kilowatt-hour follows directly from the specific fuel consumption and the fuel’s carbon factor, which is the basis the IMO uses in its efficiency indices.

Because carbon dioxide scales with fuel burned and with the fuel’s carbon factor, the only ways to cut it are to burn less fuel per unit of work or to switch to a fuel with a lower carbon factor. The first is the efficiency story above; the second is the alternative-fuel story below. The ship-level version of the same logic underpins the existing-ship efficiency index explained in what is EEXI.

The infinearth environmental brand

The “infinearth” identity, adopted with the 2025 rename, is the umbrella under which Daihatsu groups its lower-emission and decarbonization-oriented engine work. In practice that covers the emissions-compliant medium-speed engines, the aftertreatment and EGR options that meet Tier III, and the alternative-fuel development described below. The brand is a positioning statement about where the company intends its product to go, rather than a single product line; the engines themselves still carry their DE, DK, and DL series codes in the order documents.

For a marine engineer the practical content of the brand is the menu of compliance and fuel options available against a given engine order: which Tier III route is offered, whether a dual-fuel variant exists at the required bore, and what the fuel-flexibility roadmap looks like for the ship’s intended service life. Those are the questions an owner asks when matching a genset specification to a route and a regulatory timeline.

Dual-fuel and methanol development

The pressure to cut carbon dioxide has pushed every medium-speed four-stroke maker toward fuels with a lower carbon factor, and Daihatsu’s development work follows that direction. Dual-fuel engines run on a gaseous or alternative liquid fuel for most of the work while retaining the ability to run on conventional liquid fuel, which gives an owner a hedge against fuel availability and price. The classic dual-fuel pairing is natural gas with a pilot injection of liquid fuel, but the field has broadened toward liquid alternatives.

Methanol is one of the liquid alternatives drawing the most attention, because it is liquid at ambient conditions, simpler to bunker and store than a cryogenic gas, and available as a lower-carbon fuel when produced from renewable feedstock. The engine-side considerations, the lower energy density that raises fuel-flow rates, the materials compatibility, and the pilot-fuel and safety arrangements, are set out in methanol marine engines overview. Methanol’s lower energy density relative to a distillate is the reason a methanol-capable engine must move more fuel per unit of work, which feeds back into the fuel-pump and injection sizing. Marine methanol carries roughly half the lower heating value of a distillate per kilogram, so the fuel system must deliver close to twice the mass flow for the same energy release, and the fuel pump delivery stroke calculator is the tool for sizing that delivery.

The pilot-fuel arrangement is the other engine-side change a methanol conversion brings. Methanol does not autoignite readily under the conditions a diesel cylinder provides, so a methanol four-stroke needs a small pilot injection of a conventional liquid fuel, or a comparable ignition aid, to start combustion. That pilot is a few percent of the energy at full methanol operation, and it is the reason a methanol-capable engine remains a dual-fuel engine in practice rather than a pure single-fuel machine. The dual-fuel logic also gives the owner a fallback: if methanol is unavailable at a port, the engine runs on its conventional liquid fuel.

Where exactly Daihatsu’s methanol and dual-fuel offerings stand at any given bore is a question for the current product documentation, because alternative-fuel ratings and availability move quickly and a brochure can lag the order book in either direction. The honest summary is that the company has alternative-fuel development underway across its medium-speed range, in line with the rest of the four-stroke field, and that the specific available bores and ratings should be confirmed against the live datasheet for any real order.

Test beds, type approval, and the aftersales network

A marine engine builder lives or dies on two things the brochure does not show: the test bed and the service network. Every engine series must pass a type-approval test, and every delivered engine runs a works test before it ships, with the results recorded against the order. The test bed is where the maker proves the fuel curve, the NOx compliance point, & the mechanical behavior at the rated load, and where the classification society witnesses the acceptance run.

Class involvement runs through the whole life of the engine. The classification societies, including ClassNK as the Japanese society most often involved on Japanese-built tonnage, plus DNV, Lloyd’s Register, ABS, and Bureau Veritas on internationally classed ships, approve the engine design, witness the type test, and survey the engine in service. The auxiliary generating set as a whole, engine plus alternator plus controls, is approved as a unit for the electrical and safety functions it must perform.

The aftersales network is the other half of the proposition, and for a genset maker it is arguably the larger half. An engine that runs for decades needs spares, technical support, and overhaul capability in the ports its ship calls at, and a maker without that reach loses the repeat business no matter how good the engine. Daihatsu supports its installed base through a service network reaching the major bunkering and repair ports, which is part of why Japanese owners and yards keep specifying its engines: the parts and the support are there when the engine is halfway through a thirty-year life.

The EIAPP certificate and the Technical File

Every engine that must meet the NOx rule ships with an Engine International Air Pollution Prevention certificate and a Technical File that records the certified configuration. The Technical File is the document that defines what “compliant” means for that specific engine: the components, settings, and operating ranges that hold the engine inside its certified NOx point. A surveyor checking the engine in service is checking it against that file, not against a brochure, and an engine modified outside the file’s allowances loses its certification. For a genset maker this is part of the delivered product, because the file travels with the engine for its whole life.

The carbon side has its own paperwork at the ship level rather than the engine level. The IMO efficiency indices that the carbon-per-kilowatt-hour figure feeds into are calculated for the ship, combining the main engine, the auxiliary engines, and the ship’s reference speed and capacity. That is why the genset’s specific fuel consumption is not just an operating-cost number; it is an input to the ship’s regulatory efficiency, and a heavier auxiliary load pushes the ship’s index in the wrong direction unless the sets are efficient. The ship-level mechanics are covered in what is EEXI.

Overhaul intervals and component life

The economic case for a genset rests on the time between overhauls as much as on the fuel figure. A medium-speed four-stroke runs scheduled inspections and component replacements on a running-hours schedule, with the major overhaul, piston pull, liner inspection, and bearing renewal, falling at intervals measured in tens of thousands of running hours. Holding mean piston speed and peak firing pressure within the design envelope is what protects those intervals; an engine pushed for extra power at the same bore trades overhaul life for the power. This is the practical reason the bore-anchored rating matters: the rated point is chosen to give the overhaul life the owner is paying for, and over-rating it quietly shifts cost from the purchase price to the maintenance budget.

Positioning against the competition

Daihatsu’s competitive position is clearest when you separate the domestic four-stroke field from the global four-stroke majors. Both comparisons matter, and they pull in different directions.

Against the Japanese builders

Within Japan, the four-stroke builders specialize by power band and duty rather than competing head-on across the whole range. Yanmar is strong in the smaller and higher-speed bands and in the fishing and workboat trades. Niigata Power Systems carries a propulsion-oriented medium-speed line and is known for its integrated propulsion and thruster work. Hanshin Diesel and Akasaka Diesel concentrate on coastal and domestic main-propulsion four-strokes. Daihatsu’s center is the auxiliary genset across the deep-sea fleet, which is a different niche from any of those, and that is why the Japanese makers coexist rather than cannibalize each other. The full set is laid out in marine engine makers.

Against the global four-stroke majors

The global four-stroke majors, the European makers whose engines span the largest medium-speed gensets and propulsion units, compete with Daihatsu at the top of its range, in the DL band, and on large genset orders. Daihatsu’s advantage in that contest is rarely the single largest engine; it is the fit to the Japanese newbuilding supply chain, the proven genset range, the price on a series order, and the service reach for owners running Japanese-built ships. Where the order is for a fleet of standardized gensets on Japanese-built tonnage, Daihatsu is hard to displace. Where the order is for one very large four-stroke propulsion engine at the top of the medium-speed band, the majors have the edge in installed reference base at that size.

The strategic read is that Daihatsu does not try to win every contest. It defends the genset niche where its volume, standardization, and service network compound, and it extends upward through the DL line only as far as that defense supports. That focus is the reason a relatively specialized builder holds a leading global position by unit volume in the one segment it has chosen.

What standardization buys the owner

The case for a standardized genset across a fleet is concrete, not abstract. A series of sister ships running the same engine model lets the owner hold one set of spares for the fleet rather than a different kit per hull, train one crew rotation on one engine, & negotiate one service contract across all the ships. The maker, in turn, books a run of identical engines and can plan production and parts supply against it. That mutual benefit is sticky: once a yard and an owner standardize on a genset, switching costs a retraining and a re-stocking that the next order rarely justifies. A maker that holds the standard on a fleet holds it for years.

This is the structural reason a four-stroke builder can specialize narrowly and still hold a leading global share. The genset is a recurring, standardizable item bought in multiples, and the maker who wins it early on a successful ship series rides that series through every repeat order, every spare, and every overhaul. Daihatsu’s domestic position in the Japanese newbuilding supply chain is exactly that kind of incumbency, built over decades of deliveries to the major Japanese yards.

Worked perspective: reading a Daihatsu genset spec

Put the pieces together the way an engineer reviewing a genset quote would. Start with the engine series and bore, which fixes the family and the broad rating: a DE-28 is a 280 mm bore medium-speed genset engine. Confirm the cylinder count and the rated speed, since the speed is locked to the grid frequency and pole count, and multiply the per-cylinder rating to the total continuous output using the DE-28 calculator. Apply the ambient correction for the ship’s actual engine-room and charge-air conditions, because the brochure figure is a reference-condition figure.

Then read the fuel figure on a common basis. Convert the quoted specific fuel consumption to brake thermal efficiency with the thermal-efficiency calculator so two quotes can be compared even when their reference loads differ, and check the ambient basis of each quote before drawing a conclusion. Finally, confirm the Tier III route, SCR or EGR or a dual-fuel variant, against the ship’s intended trading area and build date, because the compliance route is part of the engine cost and part of the engine-room arrangement, not an afterthought. That sequence, series and bore, output, ambient correction, fuel basis, emissions route, is the practical content behind every figure in this article.

Limitations

Treat the figures in this article as orientation, not as order data. The DE-28 per-cylinder rating and the specific-fuel-consumption band quoted here are reference points carried from a project-guide baseline for estimation; the governing numbers for any real engine are on the order-specific datasheet and project guide, which state the exact rating, the fuel curve, the ambient-correction basis, and the certified NOx point. A brochure or a third-party listing can lag the live product range in either direction.

Bore-derived model codes are a guide to the family, not a precise rating. A DE-28 and a DK-28 share a 280 mm bore but carry different combustion and emissions packages, so their power and fuel figures differ even at the same bore and speed. Do not infer a rating from the model number alone.

Alternative-fuel availability moves quickly. The dual-fuel and methanol positioning described here reflects a development direction across the medium-speed four-stroke field; whether a methanol-capable or dual-fuel variant exists at a specific bore and rating must be confirmed against the current product documentation for the order in hand. The same caution applies to ammonia and other future fuels, where the field is still maturing.

Emissions compliance depends on the certified configuration, not the engine model. An engine meets Tier III only with its aftertreatment or EGR system installed, commissioned, and operating within its design window, and only inside the ECAs and for the build dates the regulation specifies. The NOx limit, the SCR temperature window, and the urea-dosing control all have operating boundaries that a nameplate does not show. Confirm the certified configuration and the Technical File against MARPOL Annex VI Regulation 13 and the engine’s EIAPP certificate for the actual ship.

Finally, the corporate facts here describe the relationship between Daihatsu Infinearth and Daihatsu Motor as a shared early lineage and brand, not a parent-subsidiary tie. Sources that treat “Daihatsu” as one company spanning cars and ship engines are simplifying; the marine-engine business is the independently listed entity under ticker 6023.

Related calculators

• Auxiliary engine sizing: medium-speed 4-stroke
• Daihatsu DE-28: MCR per cylinder
• Brake thermal efficiency from SFOC
• Mean piston speed
• Emergency genset: high-speed diesel
• Fuel pump delivery stroke
• Generator synchronization

See also

• Marine engine makers
• Medium-speed four-stroke marine engines
• High-speed four-stroke marine engines
• Four-stroke marine diesel engine fundamentals
• Trunk piston engine architecture
• Marine auxiliary engines and generators
• Yanmar marine engines
• Niigata Power Systems marine engines
• Hanshin Diesel marine engines
• Akasaka Diesel marine engines
• Methanol marine engines overview
• Tier III compliant two-stroke engines
• SCR retrofit on two-stroke engines
• What is EEXI