Was it a mistake from Honda to phase out the pushrod engine of the CG 125 in Brazil.

Probably the most widely copied motorcycle on a worldwide basis, the 5th-generation of the Honda CG 125 released in late-'99 was the last one to be fitted with a pushrod engine in Brazil until being phased out locally in 2009, in a time when some small competitors brought Chinese copies for CKD assembly while Honda switched to the same OHC layout carried over from the international Honda CB 125 at the time, yet the name CG is so strong in Brazil it was retained despite still being mostly used elsewhere on motorcycles fitted with OHV/pushrod valvetrain. Sure Brazil following stricter emission standards than places such as Pakistan where the pushrod engine is still available in Euro-2 trim with carburettor, or even the United States where a less stringent regulation applied to motorcycles enabled the grey import of small-displacement motorcycles from Mexico in a seemingly legal way covered by the NAFTA free trade agreement, would seem to prevent the pushrod engine to remain available in the CG, but in fact it seems like emission regulations were not a justifiable reason for the Brazilian phaseout of the pushrod engine. Just like many other engine manufacturers keep up with modern features such as electronic fuel injection which has been effectively widespread on motorcycles in the Brazilian market since 2009, and it still could be fitted by Honda itself to the pushrod engine like it's nowadays also fitted in China to the pushrod engine by its official joint-ventures for the domestic market as the emission laws there became tighter there, yet remaining less stringent in many export markets where a carburettor is still prefered, an actual demand for such a simple valvetrain design is still the driving force (no pun intended) for the Honda CG 125 having become the most copied motorcycle ever.

While small enterprises which resorted to outsourcing for local CKD assembly of Chinese copies of the pushrod Honda CG 125 eventually went away for the most diverse reasons, including lack of emissions compliance as many retained a carburettor until it was no longer viable to retain resonable performance levels, it's still fairly common to spot the original model in Brazilian streets being used for actual work, to which the reliability of the pushrod engine under the harshest conditions is a valuable asset, because the lack of a timing chain leads most riders to regard this engine as a less maintenance-intensive option to newer OHC models which have a timing chain and its tensioners to require inspection and sometimes a replacement. Of course EFI would be a desirable feature had the pushrod engine remained available in Brazil, mostly because of eventual improvements to the fuel savings it could result, and other measures such as the oil-squirt for piston cooling added for the 2004 model-year of the Honda CG 125 in Brazil enabled the engine to run leaner instead of relying on a richer air/fuel ratio simply as a cooling aid at the expenses of the higher hydrocarbons (HC) emissions which are basically unburnt fuel being wasted through the exhaust. Considering how the old pushrod Honda CG 125 and its international derivatives are still directed toward a more conservative buying pattern wherever they remain available, and also the pushrod 125 was retained from 2004 when the OHC CG 150 was released in Brazil to 2009 when EFI became standard for the 150 and a carburettor-fed 125 OHC version always fitted only with a kick starter meant to replace the pushrod 125 was also introduced, and the OHC 125 would only receive EFI from 2016 to 2019 when it was phased out in Brazil with the local models of the CG retaining only the 160 engine introduced in 2016, it can be argued the economics of scale dictated the phaseout of the pushrod engine more than emission regulations.

Sure keeping a separate engine exclusively for entry-level utilitarian motorcycles, to which the price is a more critical aspect than for a leisure-oriented model usually with a more sophisticated engine, can be harder to justify once it's remembered Honda haven't gone as far as some Chinese factories which have made larger-displacement versions ranging from 150 to 200cc, and sometimes they go as far as 250cc with liquid cooling in order to be used in cargo tricycles and other special vehicles. Definitely resorting to different displacement ranges with the same basic project, while retaining the dependability of the pushrod engine for harsher conditions to which a chain-driven OHC valvetrain would be less desirable, could still give Honda an advantage to retain so many conservative riders who are still out there, yet left behind from the new motorcycles market in Brazil. While a pushrod layout would still enable the usage of a timing chain in larger engines such as a Harley-Davidson Milwaukee Eight fitted to the current generation of the Big Twins or the Ford Godzilla fitted to full-size trucks, the simpler gear-driven layout of the valvetrain in the Honda CG 125 engine was also important to consolidate the preference in Brazil for 4-stroke engines and put an end to the former dominance of Vespa and Lambretta in the market for small-displacement motorcycles, and to a minor extent in other countries where 2-stroke motorcycles were only phased out due to carburettors remaining common, so maybe it was a mistake for Honda to simply phase the pushrod CG 125 engine in Brazil while there was still some room for improvements.

A somewhat grassroots reinterpretation of the Easy Rider motorcycles?

Just like Harley-Davidson used to be "the standard of the world" when it comes to motorcycles, maybe now this title belongs to the Suzuki GN 125, better known in Brazil as Suzuki Intruder 125 and widely appreciated due to its affordability and a better aftermarket support than so many Chinese motorcycles with random copies of the Honda CG 125 engine which were dumped into the local market for a while.

The classic appearance of the GN 125, which is no longer available new in Brazil mostly due to some emission regulations, yet still available in many other countries where small-displacement motorcycles meant to be used as a daily commuter outsell the large-displacement ones more oriented toward strictly recreational riders, naturally ends up catering to those looking for something which may even resemble the nostalgia appeal strongly tied with the Harley-Davidson brand image.

Usage of cellphone networks as an alternative to landlines: an option which may make more sense than it would be supposed to

The usage of mobile telephone networks as an alternative to provide a service analogue to landlines in rural areas is, to a limited extent, still relatively common in my homeland Brazil, and to be honest there were times it could address the needs of urban customers too. Sure it would eventually be simpler to use just a regular mobile phone for such service, yet it's relatively easy to find cellphones meant to be used the same way as a landline phone, also enabling the usage as a (usually 4G) internet router according to the data packages available from the carriers. However, excepting some rural areas where the service is subsidized and has no traffic limit, nowadays most mobile carriers only offer data packages with limited traffic requiring customers to either buy additional data packages (also usually with some monthly limit to the purchase of such additional packages) or a decrease to the connection speed which is often worse than the old dial-up connection and then basically leads to an unsuitability for most of the modern usage of the internet. Had the possibility of using the cellphone networks instead of landlines being offered to urban customers with the same benefits, it would be much easier for some users who need portability due to moving more frequently than usual such as military personell, or simply as a better choice than having to wait for a technician to come by and install telephone and broadband internet wiring at a rental apartment in an older building where the entire infrastructure would require retrofits to enable a telephone or internet company to provide the service. As a former user of what used to be known as Ruralcel, maybe I would still be using such service as it seemed so practical when the 3G internet speed was still reasonable for most of my usage at home, and even the reduced speed once I reached the limit remained suitable for a fairly normal usage.

Why was the Honda XR 200R fairly successful in Brazil during the '90s and early 2000s?

The motorcycles market in Brazil tends to revolve around low to intermediate displacement models, as they are seen both as a leisure-oriented vehicle and as a workhorse or daily commuter to which a lower cost of ownership is a critical feature. Back in the day when the 125cc displacement range was still the most usual for entry-level motorcycles, even a slight increase would be perceived as somewhat upscale in the eyes of a budget-conscious motorcyclist. An example of how such circumstances influenced the tastes of some motorcyclists up to now is the Brazilian Honda XR 200R which had a production run for the domestic market from '93 to 2001. A fairly competent motorcycle for amateur off-roaders, and even for novice cross-country/enduro riders, yet still affordable for the average Joe to ride daily to work or to use it effectively as a professional tool, it's still relatively easy to spot a XR 200 in some of the biggest cities in Brazil such as my hometown Porto Alegre as well as in the countryside. Seating is comfortable for tall riders, yet safe for median-stature riders who remain able to leave at least one foot on the ground while standing still, and the long-travel suspensions provide a relatively smooth ride either on unpaved pathways or paved streets and roads in a state of disrepair. A versatile motorcycle, which used to also be perceived as more "aspirational" than simpler models more often associated with the stereotypes about motorcycle couriers in Brazil, and so was favored by budget-oriented motorcyclists back in the day, the Honda XR 200R was successful in Brazil due to its balance of suitability to different needs, a beautiful design reminiscent of the competition-level enduro motorcycles during the timeframe of its production run, and some ease of maintenance enabling some of this model to remain in use today.

Engine options of the Brazilian Ford Super Duty: comparable to the times of the Model T?

Released in Brazil in late-'98, the first generation of the Ford Super Duty had its engine range adjusted to some regional conditions of that moment, such as a demand for turbodiesels being a top-tier priority due to fuel costs and a work-oriented profile, with the F-350 resorting until late-2011 to Cummins B3.9 mechanically-governed engines while the F-250 was available at first also with the same Cummins until mid-'99 when a 6-cylinder 4.2L MWM Sprint engine was offered initially alongside it in order to reach a more leisure-oriented buying pattern until it effectively replaced the Cummins for the F-250 in 2001. At a later stage however, the Cummins returned to the F-250 in late-2005 in an electronically-controlled version compliant to Euro-3 regulations which soldiered on until late-2011 when the Brazilian F-250 was phased out, while the competition from the imported Dodge Ram with a 6-cylinder 5.9L version of the Cummins clearly overshadowed the F-250 among private owners who were more leisure-oriented. Odd enough, while the only gasoline-powered engine fitted to the Brazilian F-250 for the local market was the 4.2L Canadian Essex V6 never available for this model outside the Mercosur region, there were export-only RHD versions mostly for Australia fitted with the gasoline-powered 5.4L Triton V8 and the 7.3L PowerStroke V8 turbodiesel, with the MWM also available for Australia in entry-level trims and in South Africa as the sole engine available.

Also noteworthy is the Brazilian F-250 having been available with a shorter wheelbase on regular-cab rear-wheel drive versions, considering the different evolution of the Brazilian full-size pick-up trucks in general, which previously tended to share bodystyles with their American 1/2-ton counterparts in order to save on retooling of the factories while the Brazilian car market was basically closed to imports from '76 to '90, and in that meantime Diesel engines became more relevant on this class and some regulatory aspects required an upgrade to 3/4-ton to become eligible to the fitment of Diesel engines on rear-wheel drive vehicles with accomodation to fewer than 9 passengers (driver not included). As there was a hurry to provide a locally-made Diesel engine to previous generations of full-size pick-ups trucks in Brazil, at a lower cost than it would be to manufacture locally the same engines available elsewhere as economics of scale dictated so, due to the smaller overall sales volume compared to the United States, it was much easier to use some random agricultural 4-cylinder engine, while a more conservative buying pattern of many buyers enabled such makeshift to remain relevant once the Ford Super Duty was released locally. Sure the fierce competition from grey-imports with beefier engines and options such as 4-wheel drive and automatic transmissions, mostly neglected by Ford through most of its manufacturing of the model for the local market had its appeal among private customers who started to draw inspiration from the American Way of Life somehow...

Even though Ford already made long-wheelbase regular-cab models for export to Australia and South Africa, and offered even the 4-wheel drive option with the MWM engine, such features were introduced to the local Brazilian market only in late-2005 alongside the electronically-controlled Cummins engine, while the F-350 retained the mechanically-governed in a slightly detuned rating to comply with Euro-3 too. Such circumstance may lead to comparisons between the engine selection for the Brazilian versions of the Ford Super Duty and what Ford did with the Model T on a worldwide basis. Sure resorting to just one engine, and manual transmission exclusively, tended to be favored in order to keep the logistics of replacement parts and servicing simpler with fewer resources and tools even deep in the countryside, yet the 4-wheel drive option also justified itself while driving through rough terrain either for working purposes or recreational off-roading. As a full-size pick-up truck was too far from being as nimble as a Ford Model T, even though it also retained a similar body-on-frame layout with longitudinal engine and rear-wheel drive, in spite of all those obvious evolutions which happened through almost one century regarding frame designs and all its subassemblies such as brakes or suspension systems and the steering gear, it would be somewhat predictable to expect some Brazilians until late-2005 to either get US-spec grey-imports (also featuring different engines to which it could be more difficult to get servicing at the official Ford dealerships) or resort to specialty 4-wheel drive conversions, relatable to some extent to a few 4-wheel drive conversions implemented at a small scale to the Ford Model T by entrepreneurs such as Jesse Livingood which were adopted even by the United States Military as the Army shifted from the usage of horses to motor vehicles during World War I.

While the F-250 finally got a factory-fitted 4-wheel drive on the local market in late-2005, even though it could have been implemented since the introduction of the Super Duty in '98, the Brazilian F-350 was never available with such option, unless the regional F-4000 could be related to dual rear wheel variants of the American F-350 to which its gross vehicle weight ratings were closer, and it's worth noticing how GVWR became too critical as most 3/4-tons such as the F-250 started to grow heavier than the limit for regular car driving license holders in Brazil which is stricter than in the United States or in Australia, so it was just a matter of time for compact and mid-size pick-ups trucks to become more relevant locally for both working purposes and recreational users. The cost and bureaucracy to get a commercial driving license in Brazil renders it undesirable for some people if their only reason to do so would be driving a Ford F-250 or F-350, leading to a phaseout of the Brazilian Super Duty in late-2011 as Ford claimed it was uneconomical to upgrade the engines in order to comply with the Euro-5 which became enforced in Brazil in 2012. Odd enough, a very specific demand for the F-350 and F-4000, which justified retaining a mechanically-governed engine until the Euro-5 regulations required an electronic engine management and full compliance to OBD-2 standards, has also led to another unusual situation when Ford was urged by dealers and a more traditional customer base to resume production of the F-350 and F-4000 which ultimately ran once again from mid-2014 to late-2019 with an electronically-governed engine.

To much surprise of the most conservative public, the B3.9 engine gave way to the downsized ISF2.8 as a budget-oriented way to decrease the cost of the exhaust aftertreatment devices required as the Euro-5 emission regulations were enforced, yet the F-350/F-4000 once again repeated the strategy of a single smaller regionally-sourced engine and manual transmission only, in contrast to what Ford does in the NAFTA region where beefier engines (both gasoline-powered and turbodiesel options) are the rule and so has been an automatic transmission in recent years, even though the earliest generation of the Super Duty still had the option for a manual transmission even in the United States where the automatics have been prevalent for a long time. As the intention was to simply offer a traditionally-designed truck to an austere and more professionally-oriented buying pattern, to whom such makeshift was perceived to be enough considering Brazilian conditions (and a limited availability on regional export markets within the Mercosur region), Ford once again did something which can be traced back to how the Ford Model T retained only one engine type from September 27, 1908 to May 26, 1927 with a very unusual built-in 2-speed semi-automatic transmission. Most likely, as the GVWR limits for car driver licensing in Brazil became unfavorable for the Ford Super Duty to retain its previous foothold among private/recreational buyers, and the lower speed limits applied to trucks on Brazilian highways might have rendered it quite unnecessary in the eyes of the management of the local branch of Ford to use a beefier engine back in the day, there is another aspect which may lead to an accurate comparison to how the Ford Model T had a maximum speed which became quickly obsolete...

While resorting to some simpler Brazilian-made engines for local variants of the Ford Super Duty could be perceived as just another makeshift suitable only to a Republic of Bananas where anything else is too costly, or where a shade-tree mechanic more familiar with an old-school mechanically-governed tractor engine is the nearest one able to provide technical assistance in a hurry, just like the Ford Model T was designed in order to address the needs of farmers back in the day, there are some obvious coincidences which are hard to neglect. Some requirements for the engines to be manufactured locally sounded like an unusual motivation for only a simpler engine always bolted to a manual transmission to be available in Brazil due to economics of scale, even though differing emission standards dictated a few changes through the local production run of the Ford Super Duty, in a similar way to how the Ford Model T was always fitted with just one powerplant through its entire production run on a worldwide basis, including CKD assembly in some export markets. In the end, while some obvious technical evolutions through the 90-year timeframe between the release of the Ford Model T and the Super Duty would seem to have set them too apart, there were ultimately some conceptual similarities, and the different engine options for the Brazilian versions of the Super Duty can be traced back to the same strategy applied by Ford back in the Model T days...

Why would I not be so tempted to replace the engine of an Opel Corsa B for a more modern one?

A car which became somewhat like a Volkswagen Beetle replacement in countries such as Mexico, and to a smaller extent my homeland Brazil, rebadged as a Chevrolet, the Opel Corsa B has a pretty reliable and no-nonsense engine, which may be more friendly to a shade-tree mechanic than it appeared when it introduced electronic fuel injection to entry-level cars in Brazil. In contrast to Mexico where both 1.4L and 1.6L variants were more common by a fair margin, both engines with either throttle-body injection or multi-port according to different model-years, the 1.4L was overshadowed in Brazil not only by the 1.6L bur also by the Brazil-specific 1.0L which was also a 4-cylinder, in contrast to some post-facelift European versions which resorted to a 3-cylinder 1.0L engine. Even though all the engines fitted to the Brazilian and Mexican Chevrolet-rebadged versions of the Opel Corsa B were more orthodox than the Volkswagen Beetle's engine, which would make other conservatively-designed engines sound easier to assimilate once swapped into a Corsa, maybe it wouldn't be great to replace it with a more modern one.

The timing belt not being of the oil-bath type, which is a plague of so many modern small engines, may be a reason to single out a replacement engine from GM itself for instance, as the easier to fit inside the engine bay of the Opel Corsa B would be the 3-cylinder 1.0L and 1.2L used in models such as the Onix and the Tracker. Had those engines been fitted with a timing chain instead, just like the Fiat GSE engine which is available as either 3-cylinder 1.0L or 4-cylinder 1.3L both naturally-aspirated or turbocharged, maybe it would be easier to assimilate such engine swap, because the wet-belt design being much more sensitive to the specifications of the engine oil makes it less "Brazilian-proof" than it should be. Other options such as engines from Japanese manufacturers with a timing chain instead of a timing belt, into a car which still seems to have been the last effective chance GM had to remain competitive against its Japanese and Korean contenders on entry-level cars, it would be quite strange to fit an engine from the "enemy" into an Opel Corsa B...

Why would a Brazilian small car be so unlikely to have an US-spec version once again?

It's well known the first generation of the Volkswagen Voyage, rebadged as Fox, was a captive import in the United States and Canada through mid-'80s to early-'90s, having received a considerable amount of modifications to comply with American regulations and address some demands of the American buyers, yet maybe the most important which was the absence of an automatic transmission had been neglected. Nowadays even in Brazil the demand for automatic transmissions skyrocketed in recent years, which at a first glance could make it sound fairly reasonable to expect sourcing econoboxes from Brazil as a safe bet to address the preferences of some conservative people who still prefer to avoid compact SUVs as a replacement for a more traditional car. However, different regulations pertaining mostly to safety and to a certain degree emissions render it much harder to make in Brazil a car which ultimately could have a comparatively lower sales volume once it reached American and Canadian dealerships...

Mexico on the other hand still gets some cars and light-duty commercial vehicles from both Brazil and Argentina because of a trade agreement with the Mercosur region, based on reciprocity which enables a Mexican car which doesn't comply to some specific Brazilian regulations such as lighting for instance being available in Brazil and vice-versa. And even though Mexican-made vehicles tend to fare better when it comes to safety, mostly based on economics of scale as exports to the United States and Canada play a pivotal role for the motor industry in Mexico, safety standards are much more lenient there, just like it is in Brazil or other countries such as China and even India which also export cars and light-duty commercial vehicles to Mexico. And since safety and fuel-efficiency regulations in the United States in recent decades favored SUVs, which have an inherently higher profit margin, the cost of picking some random Brazilian econobox and upgrading it to comply with NHTSA crash standards would be harder for both Americans and Brazilians, while making smaller batches of a nearly-customized version only for export would be simply out of question...

Why would a drop-in replacement engine suitable for a Mazda RX-7 be a good opportunity for LiquidPiston?

Comparing the projects of LiquidPiston to the Wankel engines is unavoidable, and of course Mazda is a major reference when it comes to rotary engines because of models such as the RX-7, not to mention all the aftermarket supports oriented mostly toward Mazda's 13B Wankel engine and its variations. As the Wankel fanbase goes beyond the old Mazda range, including many adaptations to which a compact size and high power-to-weight ratio of the 13B engine are a valuable asset, the opportunity for players such as LiquidPiston claiming to solve major handicaps of the Wankel design is clear, and eventually a better deal than relying solely on its contracts with the Department of Defense of the United States catering to the unmanned aerial vehicles (UAVs - a.k.a. drones) propulsion systems and portable in-field generator sets. Sure the deals with the military in the United States might be a comfortable source of funding for an engineering company, and a baptism-of-fire in a real battlefield may also be exploited for marketing purposes as a statement of reliability, yet it's pointless to forget other segments already consolidated.

As the Wankel engines are known to have the apex seals as their most critical aspect, and LiquidPiston claims its design solves most of the problem by placing the apex seals on the housings instead of on the rotors, a drop-in replacement engine suitable for the RX-7 and other models either fitted with a Mazda 13B engine from the factory or adapted with one usually for performance reasons. Most likely, as the claimed improvements on reliability and fuel-efficiency compared to both regular reciprocating engines and Wankels could be assessed in real-life conditions if LiquidPiston also decided to finally venture into a leisure-oriented application such as the worldwide Mazda rotary engine fanbase, many other segments to which the Wankel ultimately failed, there would be much better opportunities for an improved rotary engine for repowerings beyond a strictly performance-oriented market. And after some automakers tried to eliminate internal-combustion engines from their ranges due to all that political movements favoring electric vehicles, despite a massive backlash from customers who regretted buying electric cars for a tax break, there is another opportunity for LiquidPiston as many companies would ultimately outsource the engines in order to retain customers. 

Sure the market for military engines is still very promising, and ultimately LiquidPiston benefitted from partial funding by DARPA (Defense Advanced Research Projects Agency), but it would still make more sense to venture into the civilian market which provides many opportunities which remain neglected by both major automakers and independent engine manufacturers in many different segments to which the compactness and higher power-to-weight ratio are much desirable. Placing all the eggs in a same basket is quite risky, and that's exactly what LiquidPiston does once it keeps far away from the Mazda Wankel fanbase and other applications to which its improved rotary engine projects may be more effective and commercially viable than a Wankel. And since the Mazda 13B engine which found its way into models such as the RX-7 was compact enough to be also easily adaptable into other models with an even more space-constrained engine bay, it's an obvious benchmark if LiquidPiston ever ventures into this field...

'99-'05 Argentinian Toyota Hilux with the 1KZ-TE engine still soldiering on as a work truck

Instead of the proper '97-'05 worldwide 6th generation of the Toyota Hilux, a facelifted 5th generation had an extended production run in Argentina for Mercosur countries such as Brazil, where it was the first model to feature a turbocharged engine in the Diesel range, the 3.0L 1KZ-TE which was offered only with a 5-speed manual transmission. And despite not being so much of a power and torque beast as some newer direct-injection engines, once in a while I still see some old Hilux fitted with this engine and pulling some trailer which a true-blooded redneck would think only a V8 gasser would handle with ease. Despite newer automatic transmissions being actually better suited for a modern work truck, the manual transmission in this old-school ride may get some credit for its aptitude for the job, compared to older slushboxes which charged a huge performance penalty even with a bigger engine.

 

Why could Diesel engines based on a LiquidPiston project actually be a good idea?

Diesel engines have been a mainstay of trucking for decades, and some manufacturers such as Scania used to keep traditional designs and a higher degree of modularity across different generations of their engines. Obviously many technical improvements lead to a distancing between older and newer models, including aspects pertaining to the engine itself and other features of a vehicle as a whole. Considering how long-nose cabins gave way for flat-nose ones in most markets, which eventually makes it harder to overhaul a wet-sleeve engine without removing it from the frame, going quite radical such as resorting to a rotary engine might sound more tempting, yet the Wankel rotaries usually have a poor compression ratio only suitable for spark-ignition and volatile or gaseous fuels. So, maybe a Diesel engine developed following some principles of the LiquidPiston projects may be a better option, even though any chance to succeed commercially would need to go beyond the single-rotor proof-of-concepts to venture into the dual-rotor layout at least, yet a triple-rotor might also be desirable to keep up with current standards for modularity seen on reciprocating engines, even though for heavy-duty trucks they tend to be straight-6.

Just like Ford resorted to Cummins engines of the B series in 4-cylinder versions ranging from 3.9L to 4.5L and 6-cylinders around 5.9L and 6.7L in most Brazilian versions of the Ford Cargo, so modularity was already a key factor, also considering how some degree of parts interchangeability between engines with different amount of cylinders makes it easier pertaining to maintenance, inherently simpler designs devouted to rotary engines may take one step further. Even though engine blocks and cylinder heads for inline engines can be made basically with the same tooling, yet it may not be so easy to simply chop the block and cylinder head of an engine with more cylinder barrels to fit to the crankcase of a similar one with fewer cylinders or adding more cylinders to a larger crankcase, an increased modularity inherent to rotary engines by simply adding or removing one more rotor housing and intermediate plate according to the need like Mazda did to the 2-rotor 13B and 3-rotor 20B engines on road-legal models, and even a 4-rotor Le Mans racing engine, may render it somewhat easy to apply LiquidPiston designs on a Diesel engines range. Of course some parts will still be specific according to the amount of cylinders or rotors in an engine, such as intake and exhaust manifolds, and the crankshaft for a conventional engine or the eccentric shaft for a rotary, while rotaries not featuring a valvetrain may still have a lower total amount of parts and noticeably getting rid of a camshaft.

While the amount of cylinders used to vary more often according to the gross vehicle weight rating of a vehicle, and so a 4-cylinder would be seen as inherently better suited to a minibus and articulated buses would be supposed to always have to resort to a 6-cylinder, nowadays some power ratings above 200hp are also covered by 4-cylinder engines in regions where stricter emission rules favored the downsizing, even though modularity continues to play a pivotal role for commercial vehicle engines and sometimes greater power rating are achieved with the smaller versions within the range of the predecessor engine. Improved efficiency of turbocharging technologies to overcome turbo-lag and a more accurate control of the electronic fuel injections (usually common-rail, yet unit-injector setups still hold their fair market share too) made a difference, even in a conservative market such as Brazil where a 4-cylinder engine is favored because the cost of replacement injectors for electronically-controlled ones is proportionately higher than for their mechanically-governed counterparts. Considering a LiquidPiston engine will have 3 injectors per rotor housing, maybe at a first glance the cost-effectiveness can be brought into question, since a 2-rotor engine would overcome the perceived economy once downsizing took place.

When it comes to long-distance buses/coaches, eventually the promised compactness of a LiquidPiston engine design proportionate to power ratings might be a good option for the double-deckers which are fairly common in the South and Southeast regions of Brazil and also in neighboring countries such as Argentina and Paraguay, which are usually fitted with 6-cylinder engines around a 12-litre displacement range. Sure a difference between such engines with a larger displacement and others with the very same amount of cylinders, which may be capable of reaching similar power ratings at a higher RPM requiring a shorter differential ratio to provide a similar performance, would still be favorable to the perception of an increased durability under such operating conditions, yet it may already lead to a comparison with the LiquidPiston engines being pointed out to achieve performance levels suitable to replace engines up to 5 times their displacement, considering the 2-stroke LiquidPiston XTS-210 design compared to some conventional 4-stroke Diesel engine. Well, as long as the rotors and the eccentric shaft don't reach sonic speed, and how Wankel engines such as the Mazda 13B are pointed out to be much more rev-happy in order to prevent carbon deposits which could harm the apex seals, despite LiquidPiston engines having substantial differences and the inherently lower compression of the Wankel designs being unsuitable to a Diesel engine, the space constraints caused by the location of the air conditioning and the engine too close to the main luggage compartment would be very compelling to a LiquidPiston-designed engine in order to improve luggage capacity, among other advantages pertaining to overall fuel-efficiency.

A more compact engine layout may be specially relevant in South America where front-engined buses are still fairly common, for both urban transit buses and long-distance coaches, and the stricter emission regulations such as the recently-enforced Euro-6 increase the complexity and physical volume taken by aftertreatment devices, which also tend to be installed remotely from the engine and causing clearance issues with other parts of the vehicle. It may not be much of an issue for urban transit buses, despite the requirement for a lift to comply with the Brazilian accessibility regulations for wheelchair users as most front-engined buses have no provision for a stepless entry, while the underfloor space tends to be taken little to no advantage of, in contrast to coaches on which some valuable underfloor space is already too compromised by the frame rails preventing the fitment of pass-through luggage compartments, and the accessibility regulations also charge their toll on newer models. Having to manage one more clearance issue due to the fitment of a more complex aftertreatment module might be another aspect to consideer in favor of a LiquidPiston engine, because the inherently smaller packaging could free up some space to bring the aftertreatment module closer to the engine bay, which may also be advantageous considering a more direct exposure to the exhaust heat which could lead to an improved efficiency and durability of the particulate filter (DPF) and oxidation catalyst (DOC).

Even though some folks may consider Diesel engines somewhat "superfluous" for private vehicles due to the high complexity of modern aftertreatment devices, they may still retain a foothold on commercial vehicles for a long time because factors such as a much better fuel-efficiency and reliability under the most demanding conditions. While professional operators may have a conservative profile and prefer to invest on solutions already tried and tested, with some drivers and fleet managers still taking 4-cylinder engines on medium-duty trucks with a grain of salt after some 20 years for instance, the ever-increasing strictness of emission regulations may open the doors for some technical solutions which may take one step further, such as resorting to a definitely unorthodox LiquidPiston-based design for instance. In the end, as fully-electric vehicles are proving themselves troublesome time and time again despite all those political attempts to ban internal-combustion engines in general, the suitability of LiquidPiston designs to the operating principles of a Diesel engine may become a reason to give them a chance...