Wednesday, November 23, 2011

Motorcycles: a cost-effective option for police pursuits, and even some tactical duties

Due to their lower cost of purchase and maintenance, motorcycles are often pointed as a good option for affordable personal transport. Also, their enhanced maneuverability in tight urban spaces is a feature highly desired in the crowded urban centers worldwide.

It's also worth to notice the cost advantage in comparison with an automobile in a close performance level. In certain markets a motorcycle such as a Yamaha YZF-R1 can be about 4 times cheaper than a Chevrolet Camaro SS and more than 15 times less expensive than a Ferrari F458 Italia, for example.

Not everytime the budget of a law enforcement agency allows it to mantain an adequate pursuit vehicle powerful enought to hunt down either a high-end sports car or an average street-racing machine with its loud fart cans, and those "police-packages" well known in the United States are not offered in every country. Then, motorcycles, such as a Honda Hornet, can be considered as a viable alternative due to their cost/performance ratio and the mechanical setup tuned to stand under higher speeds...
I would, however, strongly recommend to fit an automatic clutch, such as a Rekluse, to enhance the safety for the officer, still allowing the handle of a gun while riding. And anti-skid brakes are also a desirable feature...

Models such as the classic Harley-Davidson Electra Glide have been used for highway patrol since its introduction, altough they have some handling limitations due to their weight and the position of the foot stands. Also, the top speed is not so impressive. No wonder why the Philippine National Police (PNP) has some Ducati Multistrada as police interceptors, since they have a good balance between speed and handling.

However, it's not only on paved roads that motorcycles have advantages. For off-road operations, beyond their maneuverability in tight spaces, they can deal with higher approach and departure angles and side inclination than a 4WD vehicle usually found on rural patrol, and often get into some routes where a 4-wheeled vehicle wouldn't be able to go due to its size. So, sometimes even an old Yamaha DT180 can be more suitable for an environmentally-extreme operation than an acclaimed Land Rover...

Due to some artificial obstacles in urbanized areas, a dual-purpose (a.k.a. on/off-road) can also be suitable due to the ease to deal with this operational condition.

However, I'm usually not so favorable to carry a passenger on a motorcycle, but for police operations often a well-trained "co-pilot" can help, shooting while the pilot is more concentrated for a safe ride. This is widely done by the Philippine National Police, as shown in the video below. Audio is in Tagalog but it does still worth to watch, but due to the graphic content I strongly recommend "sensible" people and those who dislike bloody images to avoid it.
video

Wednesday, October 26, 2011

Diesels and ambulances, a good match

Ambulances are highly demanded for dependability and throttle response, usually even more than top speed.
Also, heavy urban traffic where some health issues usually occur is not the easiest stage for racing tricks...
Then, engines that provide a better low-end torque and have less electric features prone to fail and also lead to some performance issues while using some high energy-demanding devices such as a defibrilator are desirable. And the best answer for these requirements is a Diesel engine.
Tougher than a gasser with a similar performance, Diesels are a great option to use in off-road-capable rescue vehicles due to their increased reliability due to the absence of an electric ignition setup, without spark plugs, ignition cables, coils and specially the distributor that is widely sensible to harsh environmental conditions. But even a simple coil can be a source of trouble, I still remember an occasion when I had some problems with the coil of a 1.0L Opel Corsa after getting the engine washed...
For some operators such as military corps, the dependability of a Diesel is a #1 priority, for example...
Also, another advantage is the adaptability to the use of alternative fuels, going from biodiesel (which biggest consumer in the world is currently U.S. Navy) and ethanol to waste cooking oil or some lube oils from different grades. Due to the compression-ignition setup relying on the injection timing, there are no pre-ignition issues like an Otto (average spark-ignited 4-stroke) running on low-octane gasoline, so no sensible power/torque losses.
 Not just for military tactical use, the possibilities of biofuels are a good alternative for regular civilian ambulances due to their lighter environmental impact...

While they're often quoted as "agricultural tools" due to the noise, vibration and harshness (NVH) from some older developments, in the last 2 decades their evolution has been noticeable, and the ride on a recent Diesel-powered vehicle can be as comfortable as in a gasser. Improvements on electronic injection management systems apart, the evolution in the turbocharging has benefitted the Diesel in the performance field, and also due to its already stronger-than-gasser construction these engines don't sacrifice too much reliability under some heavy boost. Nowadays, some smaller-displacement Diesels are spotting some performance levels that once were restricted to larger gasoline-powered engines.
As far as vibration goes, counterbalancing shafts and hydraulic motor mount cushions have been a successful way to deal with this issue. Noise is attenuated with the use of some sound-deadening materials in the linings, and also considering the sirens are usually louder than a Diesel engine...
Another usual report against Diesels is related to cold-start capability. Newer engines fitted with direct injection have quicker start-ups in cold weather than some earlier indirect-injection ones, but some features like glow-plugs and grid-heaters have been still widely used to ease the cold-start...
So, even with some misconceptions around, Diesel engines are a good feature for ambulances...

Tuesday, September 20, 2011

Atkinson cycle: a nice marketing strategy to fool the hybrid car buyers

Back in 1882, British inventor James Atkinson was intending to overcome some patents of Otto's 4-stroke engine. Then, he developed an articulated crankshaft that allowed his engine to have all the 4 strokes in a single flywheel spin, instead of the 2 spins required in the Otto cycle. It also had a power stroke longer than the compression stroke, and then a higher efficiency was achieved.

But the articulated crankshaft is more expensive to produce, and demands a more accurate lube system to avoid failures, then it ended up becoming not so popular. It's also usually heavier and larger.

Nowadays, with the hybrid cars trend, the Atkinson label has been applied to some Otto engines, because of a different setup of the intake valve timing, that are held open for a longer time, allowing a portion of the intake air to return, leading to a reduction of the so-called pumping losses, and a smaller amount of fuel is required. However, its side-effect is a decresement on power and torque, even followed by the raised compression ratio due to the lower cylinder heads also employed.

This cheap workaround has been presented as a really advanced feature, but actually it's more about marketing to make the same engines be perceived as "greener" in a low-cost way. But, alongside the auxiliary electric drive system, the so-called Atkinson engines end up as another excuse to get a higher price tag at the dealership...

Monday, August 08, 2011

Some considerations about the Nissan LEAF

Starting to have some cult-follow as the first pure-electric vehicle released to the regular market by a major player in the industry, the Nissan LEAF actually doesn't look so revolutionary. As some friends of mine said, at a first sight it doesn't seem to be nothing more than "a regular car body relying on the drivelines of a golf-cart" just like all those tiny electric vehicles from smaller manufacturers.
OK, sometimes a so-called "revolution" is not a complete solution in terms of real-world conditions. For example, cab heating is an essential feature in some places. As far as the Brazilian market goes, even in some southern regions with a cold winter, no-frills versions of the 1-litre cars are often available without cab heating provision to reduce the cost. The elimination of the heater core and secondary cooling fluid lines represents some savings for the automakers, and lower price tags for the customer who doesn't care about all those amenities and just wants something safer and more comfortable than a motorcycle.


As far as electric cars go, it's not so easy to have this feature in a way that wouldn't sacrifice the overall efficiency with an electric heater, then some vehicles have supplementary heating units such as those gasoline-powered or diesel-powered ones used in Europe. However, while a lot of electric vehicles, either dedicated or converted ones, don't have a water-cooling circuit for the motor, the LEAF has it, so can use the waste motor heat to make the cab more comfortable in the winter, just like a regular internal-combustion vehicle. OK, it ends up adding weight and some mechanical complexity when compared to its opponents in the electric cars scene, but was an effective way to deal with the comfort issue.
Its engine bay actually doesn't look so different of an average gasoline-powered hatchback. But it has noticeable differences on the transmission due to the absence of a gearbox. Some electric motors allow the reversibility by their own, so there is no need to have a reverse gear, and since there is no idling they can even be coupled permanently, without the need of a clutch or any torque converter.
Even with a joystick featuring the usual P, R, N and D, with an "eco" mode, its motor is directly bolted to the differential, reducing the friction losses. Except for the "eco" and the P, the same setup as a golf-cart or some pure-electric or series-hybrid transit buses. However, some people who test-drove it in Porto Alegre, my hometown, thought it had either a CVT or a regular "hydramatic" with sequential 2-speed mode...

Only problem with the LEAF, actually, is its range, limited to 160 kilometers/100 miles. Considering its more compact design than the serial-hybrid Chevrolet Volt, one of its opponents in the American market, it would be hard to fit an on-board genset to act as a range-extender. However, if hub-motors were used, bolted to the rear wheels to avoid higher efforts for the steering system due to the increasement on the non-suspended mass, the space currently occupied by the differential and the single motor could leave room either to supplementary batteries or a "range-extender". However, instead of the 4-stroke gasoline-powered setup found on the Volt, a smaller and lighter 2-stroke would have noticeable advantages on packaging. Another good option could be diesel power, allowing the biodiesel as a clean option. But since it was developed to be purely electric, the front compartment could be used for more batteries and maybe even a spare tyre...
Some customers still prefer to have a spare tyre than just these lighter, space-saving quick-sealing setups.

There is already a gap in the automotive market that can be filled by the LEAF, but some reviews on its current concept could make it wider...

Friday, July 29, 2011

Diesel engines: some taboos still around it

Since the 80's, there is no diesel-powered sedan from any American automaker in the domestic market. Often, the experience with Oldsmobile Diesel engines used by GM is blamed for the bad reputation diesels still hold there, due to the absence of a water separator filter on the fuel lines and some head gasket issues, but actually the biggest problem were the mechanics more used to service regular gasoline-powered vehicles. However, this is going to change. The world-acclaimed Chevrolet Cruze is scheduled to be offered with a 2.0L turbodiesel in the U.S. domestic market. Already offered in other countries, it's even the only engine option for the model in India. Actually, since it has a better low-end torque, would even be more pleasurable to the average American driver than its gasoline-powered counterparts.

One of the taboos about diesels is related to the maintenance: it's actually not so harder as most people think. Due to the absence of an electric ignition system, they're even simpler to work on. And currently with all that electronic engine management systems all-around, their fuel injection hardwares are getting closer to the a gasoline/E85/CNG/LPG setup, easing the first contacts for mechanics unexperienced on the diesel field.

Another taboo is about their noise, vibration and harshness. OK, they're quite louder than a gasser, and it's perfectly normal due to their compression-ignition. The same phenomenon can happen in a gasser in an unintentional way when a lower quality fuel is used, leading to the pre-ignition. As far as vibration goes, counterbalancing shafts and different designs on the engine mounting brackets and cushions are reducing this issue and its effects over the riding comfort.

Other incorrect image about diesels is related to pollution: they're reported to pollute more than its gasoline-powered counterparts, but it's actually not true. While there is a dark, thick smoke, out of the exhaust pipe on some diesel-powered vehicles, due to the so-called particulate matter, it's related to incorrect tuning, with a higher amount of fuel being injected and then released unburnt or incorrectly burnt. Nowadays with all that electronic management, injection setups can self-correct the injected fuel amount nearly instantly, leading to a higher reduction on the particulate matter formation, and the evolutions on the exhaust aftertreatment have been helping considerably too. Diesel-cycle combustion proccess is more efficient, then cleaner, and they have the capability to handle a wide range of alternative fuels such as biodiesel, waste vegetable cooking oil or even the nowadays acclaimed ethanol. Dr. Rudolf Diesel himself used peanut oil in his initial trials with a reliable, safe and economically viable compression-ignition engine, and suggested it could even help to improve the economy in agricultural regions, allowing farmers to be self-sufficient on fuel to run their agricultural machinery.

Safety is another thing to consider when opting for a diesel-powered vehicle. Diesel fuel is less volatile than gasoline and ethanol, then reduces the risk of an explosion or a fire. No wonder they're so widely used by military forces worldwide as a NATO standard.

There is also the energy safety: since diesels can use a wider range of alternative fuels, it would lead to a reduction on the dependance on imported oil. And some of the money sent overseas for oil is even used to sponsor terrorist acts in the Uncle Sam's lands...

So, even being still a taboo, light-duty diesels are a great option for the American market.

Saturday, June 18, 2011

Turbo: from the discrediting to the hope

Turbo has been known by diesel motorheads and credited for the revolution in those formerly regarded essentially as an agricultural tool and currently dominate some of the main automotive markets such as Germany. But still divides opinions about its application in engines powered by other fuels, usually operating in the Otto cycle.

Worshiped by motorsport enthusiasts, despised by automotive industry experts for decades, nowadays depicted as the salvation in these times of downsizing, the turbocharger (often just called “turbo”) is having as a prestige feature even in segments where it was seen as a mere improvisation or 
workaround. Taking the kinetic energy expelled alongside the exhaust gases to push more air into the intake ends up pointed a way to have a more complete and efficient combustion process, leading to better performance and lower emissions of carbon monoxide, a lethal gas (also used as a poison by the Nazis) and more polluting than carbon dioxide. Gone are the days when an executive sedan, for example, would need at least a 2.0L engine to be considered a "respectable car", while after all the development of an "environmental consciousness" a 1.4L engine turbo often getting a wider market share in this segment. It's still a bit away from the Brazilian reality, where only the Fiat Linea has such an option (and still offered as “sporty”, quite far from being taken seriously in a more formal market - lacks the Dualogic automated transmission optional for the non-turbo 1.8L), but in more developed markets finds space in larger models such as the Opel Insignia (which shares the platform with the Chevrolet Malibu) are equipped with this kind of powerplant. It is worth noting that, for example, the Insignia in the Portuguese market is not being offered with naturally-aspirated engines for the wagon (Sports Tourer) versions.

Some consumers, however, still associate the turbo to the street races underground illegal culture, as well as a slow at low revs, a phenomenon known as turbo-lag that was harder to get around in the days when the carburetor was 
majesty. Today, however, with various electronic management systems for injection and ignition, turbo-lag effects can be reduced at the engine start-up, to get the turbo "full" sooner. Yet it must be remembered that a proportionally-dimensioned for the engine’s displacement and speed range makes the turbo lag less sensible, especially now when there are variable geometry turbochargers, in which the position of the blades is changed according to engine speed and pressure of the exhaust gas flowing inside the hot turbo housing to "fill up" faster.

Perhaps the average Brazilian customer concerns with the turbo because of the way the local market was limited both due to the circumstances of an economy more closed during the military regime and by the poor quality of the locally available gasoline leaded the engines to have lower compression ratios 
to avoid "knocks", making it impossible, for example, the use of more compact powerplants in some domestic cars of the 70s and 80s. A case in point is "Dodginho" 1800/Polara, based on the British Hillman Avenger.While in the land of afternoon tea used 1.2L and 1.5L engines, this one ended with the 1.8L. And with the advent of alcohol another myth gained strenght: that such fuel was the only one that properly supports the use of turbo, so that even today is not difficult to find mechanics who fiercely defend it because of the greater ease to tune a turbo engine due to the higher octane in the sugarcane-based fuel making it less prone to knocks when it reaches its optimal operating temperature, and that "culture" makes many good professionals to be considered "amateurish" and "relaxed" due to their work with turbos. It is worth noting that in Argentina the "Dodginho" even used the 1.5 engine, actually with a compression ratio different from similar European but not as low as the Brazilian counterpart.

Another case that can be analyzed under this perspective is the Ford Sierra, similar to the Maverick in sine and that in some markets such as Argentina came to use the 2.3L OHC so-called Georgia engine manufactured in Taubaté, shared with the Maverick and that was even 
exported to the United States in turbo version with Holley fuel injection, which use was not allowed in the Brazilian market due to the Informatic Technology Law, reserving the market for locally manufactured products - such option could have given a good survival for the Galaxie-based Landau on the market, for example. But the engines range for the Sierra in other markets included even some engines that here would be restricted to models like the Escort and the Renault-based Corcel, such as the 1.3L that for years was benefited from a more favorable taxation in Sweden, leading to the local Stockmann dealership to offer a plug-and-play turbo kit, so the 1.3L reached a performance comparable to the aspirated 2.0L offered in higher-end versions. Interestingly, some Brazilian companies such as Larus manufactured turbo kits for Argentinian cars like the Sierra, the Renault Fuego and classic Peugeot 504 and 505.

A similar situation occurred between 2001 and 2004 in Brazil when Volkswagen was selling the Gol and Parati spotting a 16-valve 1.0L turbo engine rated at a similar power to the 8-valve non-turbo 2.0 (albeit with slightly less torque), which ended up leading the gasoline-powered 1.6L going out of offer for a brief moment. 
And Ford itself came to use the supercharger (popularly known as "blower") in the RoCam 1.0L Zetec engine for the Brazilian, Venezuelan and Colombian versions of the Fiesta and EcoSport (this one had the supercharged 1.0L only in Brazil due to a favorable tax class, using in Colombia and Venezuela an argument attributing a "sporty" character to the mechanically-driven compressor, even when the aspirated 1.6 engine had a slightly better performance (and the use of the turbo could bring more benefits to 1.0 to take advantage of an energy wasted instead of taking engine’s own power to be driven as the blower does).

And now the turbo again is having a very favorable moment like never before. 
With all the impact of issues relating to ecology, has been appointed as the easiest solution in the short term to reduce pollutant emissions in cars with Otto cycle engine, powered either by gasoline, alcohol or gaseous fuels like CNG widely used in Brazil (although there are myths about its use in turbocharged engines, mainly due to an even greater penetration of the so-called "faucet kit" in the Brazilian market for conversion to CNG) or liquefied petroleum gas that is forbidden to automotive purposes in Brazil, but widely used in countries such as Japan (where the turbo engines range goes from the Kei-Jidosha with their 660cc engines sometimes with a better performance than an average Brazilian non-turbo 1.0L to prestige supercars like the Nissan GT-R), Hong Kong, Italy, Australia and even the United States. Not only for more efficient combustion, as well as the possibility of a smaller engine to perform the same service that often would require an engine nearly twice bigger. A case that seems particularly interesting to analyze is the traditional American pickup Chevrolet Silverado / GMC Sierra, which has the basic versions fitted with a 4.3L V6 engine rated at 195hp/4600RPM and 260lb.ft/2800rpm, while Chevrolet even offered on some models as the HHR and Cobalt a 2.0L 4-cylinder engine with turbo, direct injection, 260hp/5300RPM and the same 260lb.ft already at low 2000rpm - is that there comes a certain aspect of "culture" of Uncle Sam's land, home to large motor enthusiasts, and the agency responsible for establishing emission limits for vehicles, EPA is infested with bureaucrats who are not so committed to environmental protection. What interests me in this case is that the Chevrolet engine plant in São José dos Campos currently produces 2.0 turbo engines for export, and this would fit like a glove in the Blazer, still widely used by police forces, where the V6 engine is still worshiped by the enviable performance and that after being removed from the Blazer Brazilian versions got without a suitable replacement. But despite initial resistance from some consumers to use a significantly smaller engine, the arch-rival Ford is having some success up with the EcoBoost turbo engines range, then could provide a pretext for giant GM counter-attack. It is worth noting that GM has considerable experience with the turbo, from the time they controlled the automotive division of Saab and also the use of the system in models from Opel and Isuzu, now a partner in the design of medium-sized pickups, and that in some markets use the sales and technical assistance network from the traditional American company to sell trucks.

Although some mistrust still surround the turbo, it’s appearing as a very suitable solution to meet a broad and diverse consumer market worldwide, contributing to a reduction in operating cost of the car manufacturers, enabling the 
development of a more compact design to some vehicles (creating a lower barrier to air resistance and further improving the performance and consumption) that could have been fitted with smaller engines and still provides a gain in production scale, turning possible with different stages of tune the same engine become adequate to meet the consumers in various vehicles’ classes, from a pocket-rocket or a midsize executive-class sedan, through a sport-utility vehicle or a work truck.

Saturday, June 11, 2011

Hub-motors: how a hybrid can make sense.

Electric drive is often reported as better because, despite the use of heavy batteries, can be applied as a weight-saving feature eliminating the components associated to a mechanical transmission when hub-motors are used, and also allowing a smaller (then lighter) internal-combustion engine to provide all the kinetic energy needed to move a generator to provide electric power to the drivelines, like the Audi A1 e-tron that uses a 250cc 20HP Wankel engine to move the generator and 4 hub-motors delivering 61hp to the wheels like a 1.0L average Otto engine would do, but the 145Nm torque range is closer to a 1.6L.
Another benefit is the flexibility to the floorpan arrangement due to the absence of a gearbox (this is due to their reversibility, not requiring a reverse gear) and a driveshaft tunnel in the middle of the vehicle, allowing a lower boarding platform, extremely useful when handling heavy loads or there is an elder or a wheelchair user getting inside the vehicle. These advantages are well-known by the hybrid/electric vehicles enthusiasts but we don't see it so widespread as it's supposed to be. For example, would be the best setup for a serial-hybrid such as the Chevrolet Volt. Even the acclaimed parallel-hybrid Toyota Prius, cult-followed by a lot of tree-huggers just for being the first mass-produced hybrid car, could have some benefits from a quite simple change in its current driveline, replacing the electric motor bolted to the front transaxle for a pair of hub-motors in the rear wheels. We must also consider that usually a parallel-hybrid relies on the electric drive only in low speed, such as city traffic, while in highway the electric driveline means just a dead weight. The hub-motors setup, by the other side, while providing traction would even allow the internal combustion engine to have a lighter work, then needing less fuel.
When a front-wheel drive vehicle accelerates, there is always a weight transference to the rear axle due to gravitational acceleration, then, plus the advantage of the friction losses reduction, the rear electric drive would compensate for the weight distribution unfavorable to the traction, improving the drag and then reducing the energy amount needed for the vehicle to start moving. Driving uphill the traction enhancement from this system is far more sensible. Also, with all-wheel drive the stability in higher speeds is enhanced...

In partnership with Protean Electric, GM Europe is developing a hybrid version of the Opel/Vauxhall Vivaro van, a major developer of the hub-motors technology.

While the current non-hybrid versions are fitted with an average FWD driveline, some of the prototypes when fitted with a parallel-hybrid setup have hub-motors added to the rear axle. This system can even be retrofitted into existing vehicles. Considering again the benefits of the auxiliary rear-wheel drive, would also be helpful either in snow days or unpaved roads.

Friday, June 03, 2011

Corvette and the downsizing: time for a change?

This post is dedicated to some of the Truck Mod Central guys.

Well-known worldwide as an American institution, the Corvette is portrayed as a legend, comparable to famous European high-end sports cars such as some Ferrari and Porsche models, among others.
It's also known to spot another America's #1, the Chevrolet small-block V8, currently in its 4th generation but still relying on a traditional OHV layout while its opponents from Europe and Japan usually have DOHC cylinder heads. However, some hoaxes about a possible engine downsizing are getting some space in the media and already generating some discussion. OK, it's a possibility in these days of EPA and CAFE witch-hunting, but would it be really a change so enormous in the Corvette's basic concept? Maybe not...

Currently powered by either a 6.2L (430HP @ 5900RPM/424lb.ft. @ 4600RPM - also available with a supercharger for 638HP @ 6500RPM/604lb.ft. @ 3800RPM in the ZR-1 version that is "cheaper", has a close performance and is not so gas-guzzler as a Ferrari 599 GTB Fiorano with its hi-revving normally-aspirated DOHC 6.0L V12) or a 7.0L V8 engine (505HP @ 6300RPM/470lb.ft. @ 4800RPM). But, instead of its European counterparts with specially developed engines, the Corvette relies essentially in the same engines used by the large pickups and body-on-frame SUV's from Chevrolet and GMC, with a smoothier throttle response, preferred by a lot of American customers.

Rumors about a smaller engine have gained force since the GT2-class C6-R Corvette appeared with a 5.5L version of the V8, with 500HP. For a street-legal version, reported to be released in a 440HP rating, a feature that would be expected is direct injection, already found on some of its opponents such as Ferrari 458 Italia. But either hi-revving or a DOHC head still find some resistance from the most traditional Corvette customers and enthusiasts. Then forced induction comes as a reasonable option to manage the lower displacement issue without sacrifice the power but, again, different concepts have been shown as the way to go: turbo or supercharger?

While some people are still worried about the turbo-lag, and then considering the engine-driven supercharger as the most cost-effective option, there are those who would prefer to enjoy the kinetic energy thrown away by the exhaust pipes to drive a turbo. Nowadays, with the advances on engine management achieved with the electronics, a turbo setup seems to be the most reasonable. Advancing the ignition point at the engine startup has been reported to "wake up" the turbo earlier, for example, and also more modern turbo designs such as VGT have become helpful to manage this issue. And obviously, a properly-sized turbo is essential to have the most suitable boost ratio according to the engine revving.

As far as a lower displacement goes, considering FIA's current standards considering each liter in a forced-induction (most notably turbocharged) engine equal to 1.7L in a normally-aspirated, I wouldn't expect anything above 3.6L to replace the 6.2L in the entry-level Corvettes, retaining its current power/torque ratio or improving it. Maybe now that Ford, GM's archi-rival, is having some success with its Ecoboost range even in the F150 pickup, could be an incentive for a downsizing attempt. And it's perfectly viable for GM, since a 3.6L DOHC V6 engine is already available in its range and some aftermarket turbo setups have been successful, specially in Australia. However, a loyal Corvette enthusiast would still desire the V8 layout. Then, even the DOHC Northstar engine in its supercharged 4.4L version, rated at 469HP @ 6400RPM/439lb.ft. @ 3900RPM from the STS-V is often pointed as a reasonable option for an entry-level model to meet both EPA newer regulations and the enthusiasts.

Anyway, one thing is certain: even with some changes, the Corvette must retain its essentially American soul, and this is a hard challenge for the engineering team...

Saturday, April 30, 2011

Lowered Jeep Wrangler: an insult to off-road enthusiasts


This '97 TJ Jeep Wrangler had its 4WD setup and its stock automatic transmission removed, and was retrofitted with the driveline of a RWD Chevrolet Opala, an Opel-based Brazilian sedan similar to the South-African Chevrolet Ranger and fitted with some engines offered in the Chevy Nova, including the 151cu.in. "Iron Duke", also offered in the Wrangler as a factory option for a while.






Its wider wheel arches actually would look good in a race car oriented to the Pikes Peak, but the owner of this Jeep said it's an "asphalt cruiser". So, wouldn't make more sense to get another vehicle for this purpose?

Thursday, March 10, 2011

Two-stroke engines: still a viable technology?

Well-known for their simple design and ease to servicing, two-stroke engines had been almost left to die at their own, mainly because of some misconceptions about its pollutant emissions. However, if the same efforts taken by the major automobile and motorcycle industries to turn the 4-stroke the rule were employed to improve the 2-stroke combustion process all those arguments wouldn't be so true.






Some companies such as Orbital Engines and Two-Stroke Shop, both from Australia, still concentrate efforts to develop real solutions to show the 2-stroke cycle as a viable option. Orbital's engine management systems had been commercially successful either in the motorcycle industry or marine engines for jet-skis or small boats. Important companies like Bombardier, Aprilia and Bajaj adopt Orbital systems in 2-stroke engines. Two-Stroke Shop is more focused on high performance but its engines range is more old-school, with carburettors instead of Orbital's advanced direct injection, that wouldn't work with TSS's very interesting toroidal cylinder head inserts.


Considering the biggest trends on the motor industry nowadays, that are the downsizing and the search for a renewable energy matrix, the 2-stroke layout seems to be even easier to face them. Its own design is not just simpler, but delivers an increased power-to-weight ratio, sometimes allowing an engine with less than a half of the size of a comparable 4-stroke to get about the same performance. And since the ethanol had been shown as one of the responses to the demand for "greener" fuels, a 2-stroke would be even easier to turn into the most efficient flexfuel. SAAB had been working on a variable-compression version of the GM 2.0L Ecotec turbocharged, but since it's a 4-stroke there are some issues with the camshaft timing setup, absent in an average 2-stroke.

Another advantage to be seen more carefully by the automakers is their production cost, since less raw materials and manufacturing processes are required. Back in the 80's, Chrysler had an experimental fleet of compact vehicles fitted with 2-stroke engines, and one of the cost-cutting features was the cylinder head integrated to the block, eliminating the need for head gaskets and bolts.



Chrysler actually wasn't a strange in the 2-stroke scenario, since it had offered a great variety of stationary and marine engines with this layout. Other manufacturers such as Ford, Fiat and BMW had some R&D partnerships with Orbital from the 80's to the 90's. Ford had been one of the most involved with the 2-strokes but even with favourable results after some endurance tests in Australia and the United States there was never a regular Ford offered with such engine layout.

However, 2-stroke innovations are proposed not just in the developed world. Brazilian engineer Luciano Gama has been working with a different lube system, similar to the average 4-stroke system. I must confess I'm actually not against the currently predominant lube method because it can avoid some waste motor oil to be disposed incorrectly and then generating soil and underground water contamination risk, but since the average Joe would prefer not to burn the oil alongside the fuel it seems to be a great deal.

2-stroke engines are perceived as more pollutant because of their distinctive smoke due to the burnt oil, but either with Orbital management system or some newer, higher technology synthetic oils this problem is significantly attenuated. Another option could be the use of vegetable-based oils, such as castorbean oil widely used in kart racing.

Another advantage on the 2-stroke layout is to work on gaseous fuels such as CNG and LPG, or even hydrogen. It's not so hard to find people who complain about premature valve seats wear on 4-stroke engines converted to CNG or LPG, but since there is no valvetrain in a 2-stroke there is no problem.

As we can see, despite the media promoting more the 4-stroke, 2-stroke layout is still a great option to face the demands of the market...

Wednesday, February 16, 2011

Tricycles: a good option for commuting and light hauling

 Maybe a vehicles class currently too underestimated are the tricycles. These vehicles are still useful, but with all the "car culture" promoted by the media they're shown as a simple curiosity or as a comic feature.
If someday models like the Piaggio Ape were considered an affordable option for light transport, either commercial or private, in a ruined Europe after World War II, nowadays the market has been more restricted. Almost nobody considers the possibilities of a 3-wheel vehicle as a personal commuter to face the narrow streets in some European cities with their very ancient urban scenario, or crowded Manhattan with its traffic jams. However, these curious vehicles can meet the needs of a wide range of customers, from the European teenager that is not allowed to drive a regular automobile legally (and doesn't like those "qualified quadricycles") but want more comfort and safety than an average moped to the small businessman intending to have a vehicle that arranges the capacity of an average car-based commercial vehicle with the running cost of a motorcycle.
Is not hard to find models closer in size to a Smart offering a cargo room similar to an average economy car-based van. In some cases, the ease to find engine tuning components for some 50cc tricycles is perceived by some young customers as an advantage over some "quadricycles" with their small stationary engines with limited performance parts avaliability. And it's easier to find space to accomodate a snowboard or a skate...




When there is almost no tricycles serving as taxi in the so-called "developed" world anymore, except for a few touristic places, these vehicles could actually be a good option to meet the even-more restrictive environmental laws getting enforced. Due to the lower weight, smaller engines can work properly, increasing even more the efficiency, and the pavement suffers a lesser damage than would happen with a regular-sized taxi. Also, there is one tyre less to be discarded. Another advantage to be considered by some drivers is the cockpit placed in a way that can ease the adaptation of a physical barrier to protect from eventually aggressive passengers, currently mandatory in some cities like London or New York.


For light cargo transport, by the other side, tricycles are still seen as a reasonable option, either in "developed" or "underdeveloped" countries. Even in some countries where a "tricycle culture" doesn't exist, such as Brazil, converted motorcycles have becoming more usual to see, from small towns to main cities.
At last, but not at least, tricycles can be fun to ride...

Sunday, January 30, 2011

Turning a gasser to dedicated-ethanol?

Now with all that environmental concernments, ethanol has been considered a good option by some people. I prefer biodiesel or straight vegetable oils, but there are those who prefer something that can be easier to burn in their regular gassers. But to have better results with this alternative fuel a few mods are recommended.

Ignition: since ethanol resists more to the detonation, it requires some advance and a higher-capacity ignition coil is also a good option. Ignition wiring must be in good conditions to avoid electric runaways, so those high-performance silicone-coated copper cables are strongly recommended. Spark plugs with a lower thermal grade usually have better results in ethanol-powered engines.

Compression: it's usual to have higher compressions in engines to work with ethanol. Compression ratios above 12:1 can lead to not need too much variations in the ignition advance. Either a different piston design or a lowered cylinder head can be used. Ethanol has a lesser energy density than gasoline, but higher compressions help to take it more efficiently.

Cold start ability: this is a sensible point to ethanol. In Brazil it's very common to see an auxiliary gasoline tank to be used in cold starts, while in other countries such as Sweden, France and the United States it's more usual to find the ethanol blended with regular gasoline from 15% (E85) to 30% (E70). A few years ago, Robert Bosch Gmbh. released a start system special to the so-called "flexfuel" vehicles, the FlexStart, spotting injector tips with a heater element incorporated to them, allowing the fuel to be heated until 120°C, easing the startup and also stabilizing the idle speed in the first 2 minutes after the start. The device had been used commercially only in a special edition of the Volkswagen Polo for the brazilian market in 2009, but should still be considered a serious option to a dedicated-ethanol engine.

Air intake and fuel injection: in some older dedicated-ethanol engines the intake manifold was made out of metal and could be heated by the water from the cooling system to avoid it to freeze due to the ethanol flowing alongside the intake air, but currently plastic manifolds are found almost in every car. With regular indirect injection or with a carburettor the heating is extremely helpful, but currently there are some engines featuring a direct injection setup, so it would be not so easy to have this problem. Maybe direct injection could also ease the cold starts. By the way, since ethanol has a lower energy density, its consumption is about 30 to 43% higher than gasoline, so more flow would still be required even with some mods intended to increase the efficiency with ethanol.

Cooling system: ethanol usually works better when the engine is allowed to operate in a higher temperature, for this reason a more restrictive thermostatic valve can do miracles in a water-cooled engine. For an air-cooled one it's harder to control the temperature, so idling and startups won't be so smooth, but it's not impossible to overcome this difficulty. In some older Volkswagen boxer engines from the 80s there was an automatic fold-away thermostatically-controlled airflow restrictor to leave the engine reach a temperature more suitable to operate with ethanol. However, currently only Honda motorcycles are offered with air-cooled engines able to run on ethanol and there is no airflow restrictors, mainly because of the current electronic fuel injection system that adjusts itself to operate smoothier.

Another thing that I would recommend is about valve seats lubricity requirements: it's not a bad idea to blend from 2% to 5% 2-stroke engine oil in the ethanol, even when using it in a 4-stroke engine. The oil would reduce the fatigue on valve seats, and also protect fuel lines from the more corrosive effects of the ethanol.

Thursday, January 27, 2011

why ru sucha diesel douche

i like diesel engines because of their advantages for heavy duties and for mudding, and the range of a diesel vehicle compared with a simillar with an otto-cycle engine, either a gasser, ethanol-burner or cng/lpg, and due to diesels usually last longer than other engines... i have driven some cars with cng setups and it takes a cargo space that is preserved in a diesel-powered one...

when there is no guidance the people fall, but in abundance of counselors there is victory

Thursday, January 20, 2011

Is GM ready to play the downsizing game?

Even facing some resistence from the (stereo)typical GM's most loyal customers, the downsizing is a reality that can't be denied. However, even famous for its bigger engines, as a global car manufacturing group, General Motors is ready to face competition in the newer trend in engine development.
 

A clear example is the 4.3L Vortec V-6 engine still offered in basic versions of the Silverado. Some versions of the 2.0L straight-4 Ecotec fitted with turbo and intercooler can deliver the same 260lb.ft. torque rating in a lower engine speed, as well as more than its current 195hp rating. Then, not just due to the smaller weight and displacement of the engine, also since a lower speed is required to do the same jobs it turns the 4cyl turbocharged more efficient.
Some american customers can still see the downsizing as an european trend, and possibly hard to overcome EPA regulations, but the use of improved smaller engines has been a way to cut greenhouse gas emissions, among other pollutants. The combustion proccess is more efficient due to the higher air flow, then less carbon monoxide is generated, for example. And an old phenomenon widely reported in early turbo setups, the turbo-lag, had its effects reduced with newer engine management systems. GM has been dominating the technology of turbochargers, and ready to face some opponents well-known for their advanced technology, such as BMW. Recently, BMW released a 2.0L twin-turbo straight-4 engine, developing 245hp and 260lb.ft, to replace its 3.0L straight-6 (258hp/230lb.ft.) in some models such as the X1. Considering the manufacturing cost, GM still has an advantage since their engine uses only one turbocharger. Even with the benefits of the smaller engine, a traditional customer would not want to pay too much more for it.
Some people possibly would never wonder something more than 50% smaller in displacement performing the same job of a 4.3L V6, often considered even "too small". For example, it's too hard to see a Chevy ambulance with a 6-cyl engine, or a police vehicle, traditionally powered by large V8's , often even restricted to the so-called "police packages".
Drawing above is only for artistic purposes, Chevrolet Astro was never used by any police department in Brazil

 
However, a smaller engine is not necessarily a worse engine. Recently, General Motors of Brazil limited the offer of the Blazer to a 2.4L flexfuel 141/148hp engine, but until 6 years ago there was the option for the iconic 4.3L V6 that was imported from the United States, that still have some cult status in police departments due to its performance, and some older versions fitted with this engine remain on duty, including some very specific police departments such as Tobias de Aguiar batallion, better known as ROTA and famous for its former all-Chevy fleet. What is hard to understand is why an option for this very specific application was never offered, while the 2.0L turbocharged engine is still made in GM's São José dos Campos engine plant for export markets. Could be a bolt-in replacement...

In other markets, most notably european countries, GM has been successful with the downsizing. Some of its models are currently offered only with turbocharged engines in Portugal, such as the Opel Insignia, currently offered in the american market as Buick Regal, featuring a 2.4L Ecotec non-turbo (182hp/172lb.ft.) not avaliable in its european counterpart and the turbocharged 2.0L in a 220hp/258lb.ft. version (this setup would already be enought to replace the 193hp/250lb.ft. 4.3L V6 in the Blazer). Surprisingly, in a segment where 4-cyl engines are perceived as "less luxury", GM is not offering the 2.8L turbocharged V6, that with its 325hp/320lb.ft. could beat the 3.6L currently used from the Chevy Camaro to the Cadillac SRX (without any V8 option in the current generation) delivering 300hp/273lb.ft., again, at higher engine speeds. Even the Vortec 4800 V8 with its 295hp/305lb.ft. could be replaced by the 2.8L without any prejudice in the performance. All of that with systems already avaliable in GM's portfolio.

So, seems like GM is ready to play the downsizing game. What about you?