Wednesday, November 23, 2011
Wednesday, October 26, 2011
Tuesday, September 20, 2011
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.
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
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.
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...
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
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
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
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
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.
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
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
Wednesday, February 16, 2011
Sunday, January 30, 2011
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
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...
Thursday, January 20, 2011
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?