Mazda skyactiv technology

SKYACTIV® TECHNOLOGY

1. At-A-Glance: Defy convention

Engines, transmissions, body and chassis: Mazda’s all-new range of SKYACTIV® technologies are designed to improve the efficiency and sustainability of the company’s new generation of vehicles while at the same time further enhancing safety and driving dynamics.

Innovation is at the heart of SKYACTIV TECHNOLOGY, which is focused on optimized internal combustion and lightweight engineering. These technologies will be implemented into all future models — not just expensive ―green‖ variants — in order to benefit all Mazda customers.
SKYACTIV-G 2.0-liter gasoline engine: The quest for the ideal combustion engine
A range of entirely new technologies has gone into the highly-efficient direct injection SKYACTIV-G gasoline engine. Exceptionally strong yet remarkably efficient, it takes compression to an all-new level, solving all the issues that until now have prevented this approach from being feasible. Such unconventional methodology is typical of Mazda’s unique way of engineering.

Highlights:

• Exceptionally high 13:1 compression ratio in North America (14:1 in other markets due to a higher fuel octane)
• Extraordinary compression ratio made possible thanks to a 4-2-1 exhaust system, redesigned piston cavity, new multi-port injectors as well as other innovations to avoid abnormal combustion (―knocking‖)
• Continuously variable sequential valve timing (dual S-VT) on the intake and exhaust minimizes pumping losses
• Internal engine friction reduced by 30 percent
• Overall weight reduced by 10 percent
• Approximately 15 percent lower fuel consumption and CO2 emissions than the current Mazda 2.0-liter MZR gasoline engine
• Approximately 15 percent more torque at lower and mid-range rpms

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SKYACTIV-D 2.2-liter diesel engine: More torque, cleaner combustion
Clean, high-revving, responsive and more fun than ever, Mazda has raised the bar for diesel power with SKYACTIV-D. The engine’s low compression ratio plays a central role here, too, as internal processes were again completely re-examined. The result: efficient power engineered to achieve the highest environmental standards without the need for special and expensive aftertreatment systems.

Highlights:
• Approx. 20 percent less fuel consumption (compared to the current 2.2-liter MZR-CD diesel) thanks to an extraordinarily low 14:1 compression ratio and subsequently greater expansion phase after combustion
• Variable valve lift for exhaust valves enables internal exhaust recirculation, immediately stabilizing combustion after a cold start
• New two-stage turbocharging delivers strong and steady responsiveness across the engine range (max. 5,200 rpms)
• Highly efficient active ceramic diesel particle filter (DPF)
• Fulfills Euro 6, Tier II BIN 5 (North America) and Japan’s Post New Long-Term Emission Regulations without expensive NOx aftertreatment
• Weight reduced by 10 percent
• Internal engine friction reduced by 20 percent


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SKYACTIV-Drive six-speed automatic transmission
A smooth, responsive and fun yet fuel-saving automatic transmission, Mazda’s SKYACTIV-Drive is engineered to deliver the best of all worlds in automatic performance and efficiency – even for a high-torque diesel engine.

Highlights:
• Unique technology combines the advantages of continuously variable (CVT), dual clutch and conventional automatic transmissions
• Full range direct drive (torque converter with a full range lock-up clutch) delivers a direct manual gearbox-like feel
• Improved fuel economy by up to 7 percent
• Fast and smooth shift response thanks to new mechatronics module
• Powerful, steady acceleration from a standstill
• Available for both SKYACTIV-G and SKYACTIV-D engines


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SKYACTIV-MT six-speed manual transmission
Lighter, smaller, more efficient, Mazda built the innovative new SKYACTIV-MT six-speed manual transmission to improve fuel economy, but without compromising on enjoyment. The benchmark was the swift and precise shifting feel of Mazda’s legendary MX-5 Miata roadster.

Highlights:
• Optimized for front-engine, front-wheel-drive vehicles with easy and tight shifting
• Re-engineered with a considerably smaller and lighter design
• Compactness enables efficient packaging
• Better fuel economy thanks to reduced internal friction


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SKYACTIV-Body
Lighter, stronger and safer, Mazda’s developers went back to the drawing board to design SKYACTIV-Body, which integrates lightweight engineering, increased material strength and more efficient structures.

Highlights:
• Weight reduced by 8 percent using a newly-developed body structure, new production processes (bonding methods) and a larger proportion of high-tensile steels
• Enhanced driving dynamics owing to 30 percent more rigidity with the ―straight structure‖ and ―continuous framework‖ (ring structure) concepts for frame components
• Enhanced passive safety performance by re-engineering crash zones using multi-load paths


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SKYACTIV-Chassis
Mazda has developed a chassis that combines nimble handling with ride comfort and stability when pushing the vehicle to its limits. The SKYACTIV-Chassis also achieves superior rigidity from a lightweight design. The driver will feel at one with the car.

Highlights:
• A ―Jinba Ittai‖-like feeling of oneness between car and driver inspired by the MX-5’s exceptional handling and ride comfort
• Improved driving quality at all speeds (low- and mid-range agility as well as high-speed stability) following a complete re-engineering of rear suspension mountings, trailing arm position, steering components and set-ups (among other things)
• Superior rigidity along with a 14 percent reduction in chassis weight thanks to newly developed suspension with front struts and a multi-link rear axle


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2. Introduction
“The sky’s the limit”: This phrase stands for an all-new generation of Mazda technologies and symbolizes a new era for the company. Distinct among manufacturers, Mazda’s unique way of engineering has always included one key element: the joy of driving. The principal goal of Mazda’s engineers when developing its SKYACTIV technologies was to dramatically increase vehicle efficiency for all next-generation vehicles by improving fuel economy and reducing CO2 emissions while, at the same time, further enhancing safety and driving fun. And, they have managed to successfully reconcile these, at times, conflicting objectives with the completely new SKYACTIV range of engines, transmissions, body architecture and chassis that will go into Mazda’s next generation of models beginning in 2012.

Internal combustion engines will still power more than 80 percent of vehicles in 2020. Today’s versions operate at only 30 percent efficiency, however, so there is much room for improvement. Defying conventional wisdom, Mazda’s engineers focused on one objective: achieving ideal combustion. Therein lays the basis for Mazda’s SKYACTIV-G gasoline and SKYACTIV-D diesel engines in all next-generation models – and not just pricey ―green‖ models. This underscores the company’s uncompromising commitment to improving environmental sustainability, vehicle safety and driving dynamics.

One of Mazda’s core business objectives is to make personal mobility environmentally friendly and affordable for a broad section of the population. This is why Mazda has made it a priority to increase the efficiency of its internal combustion engines. The company’s R&D staff in Hiroshima sought the best means of achieving a significant optimization of processes within this basic engine architecture, steadily and broadly reducing fossil fuel consumption.


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Internal combustion: Still the basis for mobility in 2020
Many carmakers plan to concentrate on hybrid propulsion over the medium term and fully electric drives in the long term. Mazda is no different in this respect, having already spent more than 20 years working on hybrid and fully-electric vehicles. In fact, an electric version of the Mazda2 will be offered in very limited numbers in 2012 in Japan as part of a leasing program. This electric vehicle project should deliver valuable new insight into electric drive technology as well as how electric vehicles are used. But even if optimistic assumptions prove accurate – that around 12 percent of all passenger cars in North America and 23 percent in Europe will be powered by electricity by 2020 – the vast majority of people will be driving vehicles with internal combustion engines.


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According to TrueCar Inc., an automotive solutions provider and publisher of new car transaction data, by 2020, hybrid vehicles will have an 8 percent market share in North America with purely electric cars garnering 4 percent of the market. Estimates are slightly higher in Europe. According to a 2010 EUROTAX study, electric only-powered vehicles will comprise 10 percent of the market. Sales of hybrid vehicles are also estimated at an additional 10 percent.
Whether low or high on the sales estimates spectrum, 10 years from now, vehicles powered exclusively by gasoline and diesel engines will still make up for 80 to 88 percent of the market. And the CO2 footprint of internal combustion engines will remain lower than electric drives as long as their electricity comes from non-renewable sources.


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3. “Sustainable Zoom-Zoom”: A Building Block Strategy
In 2007, Mazda devised its “Sustainable Zoom-Zoom” strategy, which calls for a staggering 30 percent increase in fuel efficiency (compared to 2008 levels) for all Mazda vehicles offered worldwide by 2015. This corresponds to a 23 percent reduction in fuel consumption and, therefore, CO2 output.
This ambitious objective will be implemented using Mazda’s building block strategy, meaning the step-by-step introduction of auxiliary electrical systems to SKYACTIV internal combustion engines.


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Mazda’s own ―i-stop‖ (stop-start system) technology, introduced in 2009 in some markets, represents one step on the path to the comprehensive optimization of this underlying technology. Additional electrical components will follow. One example currently under development at Mazda is a regenerative braking system designed to recover energy during deceleration. As far as hybrids are concerned, Mazda has formed a partnership with Toyota to combine its hybrid technology with SKYACTIV engines (see box). The reductions to fuel consumption and CO2 anticipated by 2015 would only be otherwise possible if half of all new Mazda passenger cars were hybrids or almost one quarter purely electric.

“Monotsukuri Innovation”: Innovative processes, innovative manufacturing
In 2007, even before SKYACTIV TECHNOLOGY was previewed, Mazda began reforming all the processes involved in making cars, from R&D to manufacturing. This company-wide approach, called Monotsukuri Innovation, is organized around a common architecture concept and a flexible manufacturing concept based on Bundled Product Planning. Monotsukuri has led to breakthroughs in diversification (to meet varying customer needs) as well as standardization of architectures and systems for increased efficiency, thus enabling Mazda to deploy high-grade, high-performance technologies over a wider range of vehicle models as well as respond more quickly to changes in customer demands. Monotsukuri Innovation enables a high level of cost-efficiency that ultimately benefits the customer.

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Mazda hybrid system technology in cooperation with Toyota
Toyota Motor Corporation and Mazda Motor Corporation reached an agreement in 2010 on the supply of the hybrid technology components, upon which the Toyota Prius is based. Mazda plans to combine this hybrid system with its next-generation SKYACTIV technologies to develop and introduce a hybrid vehicle in Japan, starting in 2013.
Advanced internal combustion for an efficient Zoom-Zoom hybrid
Mazda plans to offer hybrid vehicles in the medium term. However, it has chosen a different development focus than its competitors. Again, enhanced SKYACTIV internal combustion engines form the basis.

The fuel efficiency of today’s engines decreases significantly from medium to low loads at low engine speeds. Why hybrid vehicles deliver such good fuel economy is because the internal combustion engine is used at its most fuel-efficient range to generate electricity, which (together with regenerated energy) powers the vehicle at lower loads. But the wider the internal combustion engine’s inefficient lower load range is, the larger a hybrid’s electric motor and battery need to be to compensate for it.
Therefore, thanks to its efficiency over a wide operating range, the combination of a SKYACTIV internal combustion power plant and an electric drive enhances overall hybrid effectiveness while achieving a Zoom-Zoom hybrid with a lighter electric motor and battery. Regenerative braking can thus serve as the predominant source of power to charge the battery.


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4. SKYACTIV TECHNOLOGY

SKYACTIV TECHNOLOGY will be launched in North America in an all-new generation of models with new engines, transmissions, bodies and chassis. Along the way, Mazda followed what is known as the “breakthrough” approach. It calls for the resolution of technical conflicts – like enhancing safety, driving dynamics and fuel economy all at the same time – to continually improve the underlying automotive technology in new product generations.
Engineering the ideal internal combustion engine
Mazda is blazing its own trail based on the long tradition of ingenuity at its in-house engine R&D center. Even after 120 years of non-stop development the internal combustion engine still fails to utilize 70 to 90 percent of the energy contained in the fuel. Since this energy loss is primarily thermal in nature and can be attributed to the exhaust, cooling system, and engine and transmission surfaces, the R&D team’s central focus was on improving the engine’s thermal efficiency. Beyond that, Mazda has also been busy working to reduce internal engine friction as well as engine weight.

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The six controllable factors at the heart of this approach are:
• compression ratio
• air-to-fuel ratio
• combustion duration
• combustion timing
• pumping loss
• mechanical friction loss
The goal was to optimize these factors, making them function as optimally as possible and taking decisive steps towards creating the ideal internal combustion engine. Ultimately, the compression ratio would end up playing a central role among these factors in both gasoline and diesel engines.

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One of Mazda’s strengths is its willingness to defy conventional wisdom and approach challenges in new and innovative ways. An example is Mazda’s unique rotary engine, which powered the legendary 787B – the only rotary to ever win the 24 Hours of Le Mans (in 1991). Yet another is the MX-5 Miata, a car that revived the market for roadsters worldwide. Innovative SKYACTIV technologies will mark Mazda’s latest milestone in automotive history. Developed using characteristic Mazda processes, they demonstrate once again how Mazda is the master of its own technological destiny.
The new SKYACTIV engines, for example, were not developed independently in separate departments. Instead, a relatively small group of highly specialized engineers first developed the best possible individual engine architectures. These then served as the basis for all new engines, regardless of the number of cylinders or type of fuel.
―Our mass production development division worked together to engineer the best possible architecture with incredible efficiency, dramatic performance and the best quality we’ve ever had,‖ said Seita Kanai, executive vice president, Mazda Motor Corporation. ―We could then, for example,


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make the cylinder larger, smaller, multiply it by three, four, six, etc. create a range of engines for any future application.‖
Extreme compression ratio rather than downsizing
Some automakers are looking to improve the average fuel economy of their internal combustion engines by reducing displacement. Called ―downsizing,‖ the loss of power and torque is offset by forcing air into the combustion chambers using turbochargers or superchargers.
Although this is an effective approach, Mazda has chosen another route. As mentioned earlier, striving for the ideal internal combustion engine is an important basis of Mazda’s building block strategy. According to Mazda’s roadmap for the ideal engine, the most effective next step was to optimize the compression ratio.


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5. SKYACTIV-G Gasoline Engine
The advantages of the unique direct-injection SKYACTIV-G gasoline engine are the result of Mazda’s unique “breakthrough” engineering approach. By thoroughly analyzing and rethinking common thermodynamic principles, engineers succeeded in building an engine with an extraordinarily high 13:1 compression ratio. This is a level only seen thus far in high-performance race car engines not intended for everyday use. Mazda has overcome these barriers.
13:1 – an extremely high compression ratio
Any discussion about the compression ratio needs to examine the advantages and challenges of high compression. Raising the compression ratio in a gasoline engine increases its thermal efficiency, thus improving fuel economy. However, high compression in conventional engines leads to unwanted abnormal combustion (known as ―knocking‖) and an associated reduction in torque. A richer mixture and delayed ignition timing are used to avoid knocking, but these also come at the expense of fuel economy and torque. So how were these issues overcome?
High compression without knocking


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Knocking takes place when the air-fuel mixture ignites prematurely because the temperature and
pressure are too high. This can be countered by reducing the quantity and pressure of hot residual
gases in the combustion chamber. Mazda, in response, developed a special 4-2-1 exhaust
manifold, which, due to its relatively long structure, prevents the exhaust gas that has just moved
out of the cylinder from being forced back into the combustion chamber. The resulting reduction in
compression temperature inhibits knocking.
The combustion duration was also reduced. Faster combustion shortens the time the unburned airfuel
mixture is exposed to high temperatures, which enables normal combustion to conclude before
knocking occurs.
The new engine also received special piston cavities, which allow the initial combustion flames to
propagate without interference, and new multi-hole injectors, which enhance fuel spray
characteristics. Together with the 4-2-1 exhaust manifold, these innovations resulted in a
substantial 15 percent increase in torque over Mazda’s current 2.0-liter MZR gasoline engine.


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Everyday drivers will love the SKYACTIV-G’s noticeably higher torque over a wide range of rpms as well as its 15 percent improved fuel economy.
Minimizing pumping loss
To improve engine efficiency, it is also necessary to reduce the ―pumping loss‖ that occurs at lower engine loads when the piston draws in air while moving downward during the intake stroke. Generally, the amount of air going inside the cylinder is controlled by the throttle located upstream of the intake pipe. At lower engine loads, only a small amount of air is necessary. The throttle is nearly closed, causing the pressure inside the intake pipe and cylinder to be lower than the atmospheric pressure. As a result, the piston has to overcome a strong vacuum. This is known as pumping loss, which negatively affects efficiency.
Mazda managed to minimize pumping loss with a continuously variable dual S-VT (sequential valve timing) on the intake and exhaust valves. This changes the opening and closing timing of the


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valves, enabling the air intake quantity to be controlled by the valves rather than the throttle. During
the intake stroke, the throttle and intake valves are kept wide open while the cylinder moves
downward. The intake stroke finishes when the piston reaches the cylinder bottom (bottom dead
center or BDC). But if the intake valves close here, there is too much air inside the cylinder when
only a small amount of air is needed at lower engine loads. In order to push out the excess air, the
intake S-VT keeps the intake valves open when the piston starts to move upward during the
compression stroke. The intake valves then close when all unnecessary air is pushed out. This is
how an S-VT minimizes pumping loss, making the overall combustion process more efficient.
A drawback to this process is destabilized combustion. Since the intake valves are kept open even
when the compression stroke starts, the pressure inside the cylinder decreases, making it difficult
for the air-fuel mixture to combust. This is not a problem for the SKYACTIV-G, however, thanks to
its 13:1 compression ratio. The high compression ratio increases combustion chamber temperature
and pressure, so the combustion process remains stable — despite reduced pumping loss — and
the engine is more fuel efficient.
Reducing weight and internal engine friction
Reduced weight Reduced friction

A vehicle’s overall responsiveness can be enhanced by decreasing the size and weight of its
components. And a complete engine redevelopment project presents the
opportunity to forge new paths when it comes to lightweight design. With
20 percent lighter pistons, 15 percent lighter connecting rods and a 30
percent reduction to internal engine friction compared to the current 2.0-
liter MZR engine, the new SKYACTIV-G power plant is gleefully freerevving,
adapts faster to load changes and thus bolsters the sporty
character of the Mazda it powers. With less energy expended in the
process, fuel economy is improved by 15 percent compared to the current
engine.


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6. SKYACTIV-D Diesel Engine
The other member of Mazda’s new generation of innovative engines is a diesel: the all-new common rail SKYACTIV-D. At 14:1 SKYACTIV-D is the lowest-compression diesel engine in the world. SKYACTIV-D is also one of the first diesels to comply with strict Tier II BIN 5 North American emission regulations without needing expensive selective catalytic reduction (SCR) aftertreatments or a lean NOx trap catalytic converter (LNT).
Diesel engines do not require spark plugs. The injected fuel mixture ignites on its own at high pressure and the resulting high compression temperature near the ―top dead center‖ (TDC), or when the top of the piston is closest to the cylinder head. To ensure reliable cold starting and stable combustion during the warm-up phase, conventional diesel engines have high compression ratios of 16:1 to 18:1. But not Mazda’s unique SKYACTIV-D.
Its low 14:1 compression ratio enables combustion timing to be optimized. When the compression ratio is lowered, compression temperature and pressure at TDC decrease. Consequently, ignition takes longer even when fuel is injected near TDC, enabling a better mixture of air and fuel. The formation of NOx and soot is alleviated since combustion becomes more uniform without localized high-temperature areas and oxygen insufficiencies. Furthermore, injection and combustion close to TDC make a diesel engine highly efficient. The expansion ratio (or amount of actual work done) is greater than in a high-compression diesel engine. Simply put, optimized combustion timing means


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the SKYACTIV-D diesel engine makes better use of the energy contained in the fuel. And that is how a 20 percent reduction in fuel consumption was achieved.
Tier II BIN 5 without NOx aftertreatment
Thanks to its low compression the SKYACTIV-D diesel engine also burns cleaner, discharging far fewer nitrous oxides while producing virtually no soot. It can thus do without NOx aftertreatments and still meet tough emissions standards the world over.

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The fact that Mazda’s SKYACTIV-D is still considered a pilot development today – no other
manufacturer has attempted to emulate it thus far – can be attributed to the system-related
drawbacks of low compression. For example, the compression-ignition temperature for cold starts
and during cold operation is normally too low in a diesel engine with a compression ratio of only
14:1. It would run rough, particularly in winter conditions, misfiring during the warm-up phase. And
at extremely low temperatures, the engine might not start at all.
Exhaust Variable Valve Lift (VVL)
To improve cold starting and cold running, SKYACTIV-D diesel engines are furnished with ceramic
glow plugs as well as exhaust variable valve lifts (VVL). The role of the latter is to allow the internal
recirculation of hot exhaust gas into the combustion chamber. How it works is a glow plug is used
to carry out the first combustion cycle, which is enough to raise the exhaust gas to a sufficient
temperature. After the engine starts, the exhaust valve does not close as usual during the intake
stroke. Instead, it remains slightly open to allow some exhaust gas to re-enter. This increases the
air temperature in the combustion chamber, which in turn facilitates the subsequent ignition of the
air-fuel mixture and prevents misfiring.
Reducing weight and internal engine friction
Reduced weight Reduced friction


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SKYACTIV-D’s lower compression ratio means lower maximum pressure and less strain on engine components than in conventional diesels. This allows room for structural modifications to further reduce weight: cylinder heads with thinner walls and an integrated exhaust manifold are 6.6 pounds (3 kilograms) lighter while the new aluminum-made cylinder block saves another 55.1 pounds (25 kilograms).
Add another 25 percent decrease in the weight of the pistons and crankshafts, and Mazda has managed to reduce overall internal engine friction by 20 percent in the SKYACTIV-D diesel engine relative to the current MZR-CD diesel. For the driver, this translates into superior responsiveness, more pulling power and better fuel economy.
Two-stage turbocharger
Turbochargers not only help diesel engines deliver more torque but also improve fuel economy while reducing harmful emissions. SKYACTIV-D utilizes two-stage turbocharging.
One small and one large turbocharger are featured, which are selectively operated according to driving conditions. The small, quick-responding turbo feeds air to the combustion chambers at low engine speeds to provide low-speed torque and eliminate ―turbo lag,‖ which is characterized by abnormally low torque and


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poor throttle response caused by a lack of exhaust pressure to rotate the turbocharger’s turbine up to a speed necessary to supply boost pressure.
A two-stage turbocharger ensures increased torque and responsiveness at low engine speeds and more power even at unusually high rpms, enabling SKYACTIV-D to easily reach its 5,200-rpm redline. There is no compromise to power, driving dynamics or driving enjoyment, despite the engine’s extraordinary efficiency. And the synergetic effect of the two-stage turbocharging and low compression ratio enables optimal timing for combustion. Since there is a sufficient supply of air (oxygen), NOx and soot emissions are kept to a minimum.

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7. SKYACTIV-Drive Automatic Transmission
Striving for the ideal automatic transmission, Mazda focused on the following:
• Improving fuel economy
• Ensuring a direct gas pedal response
• Shifting gears smoothly
• Delivering comfortable acceleration

SKYACTIV-Drive was designed to do all this and more.

The all-new SKYACTIV-Drive six-speed automatic transmission combines the benefits of conventional automatics with those offered by continuously variable (CVT) and dual clutch transmissions. It shifts quickly and smoothly, reacts dynamically to changes in the engine load right from the get-go and raises the bar when it comes to fuel economy. The heart of SKYACTIV-Drive is a newly-developed six-speed torque converter with a full range lock-up clutch for all six gears called full range direct drive. The lock-up clutch ratio has been raised from 64 percent from the current five-speed automatic to 88 percent during vehicle operation.

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The early lock-up between engine and transmission by the torque converter (which enables engine output to be sent directly to the drive wheels) inhibits the characteristic loss of power during acceleration, delivering a more direct driving feel. Preventing engine output loss also improves fuel economy. High-precision hydraulics are essential to such a design. In order to make the necessarily fast and accurate oil pressure modulation possible in the first place and improve reliability, Mazda furnished SKYACTIV-Drive with a mechatronics module.
While maximizing the lock-up range is necessary to improve the driving feel and fuel economy, a negative effect is an increase in NVH (noise, vibration and harshness) because there is nothing to absorb the difference in the rotational speeds of the engine and transmission. A new torque converter was adapted to resolve this conflict. The expanded lock-up meant the role of the torus piece was confined to very low speeds. Therefore, it became smaller and thus creating space for an improved damper as well as a multi-disk lock-up clutch and its piston, which improve clutch durability and control.

SKYACTIV-Drive is available in two versions, making the automatic transmission compatible with both SKYACTIV gasoline and diesel engines.
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8. SKYACTIV-MT Manual Transmission

Mazda came up with a redeveloped, high-precision six-speed gearbox. With a remarkably compact and lightweight design along with diminished internal friction resistance, SKYACTIV-MT represents yet another contribution to economical resource usage.
Like its automatic transmission sibling, the SKYACTIV-MT six-speed manual transmission will be launched in two versions to meet different engine torque requirements. The goal was to reduce weight by between 7 to 16 percent (depending on the model) relative to the current manual transmissions. A completely new approach was needed to generate something truly innovative since today’s manuals have a relatively simple architecture. Every single component was paid attention to in order to gauge its functionality. With a new architecture featuring a shortened countershaft and no separate shaft for reverse gear in the larger model, SKYACTIV-MT is a testimony to Mazda’s innovative power.
MX-5 Miata sets the standard

A sporty shifting feel was at the top of the specifications list, with the MX-5 Miata roadster’s extraordinarily precise and agile manual gearbox serving as the inspiration. With the shift knob having only a 1.8-inch (4.57-centimeter) stroke from neutral to the in-gear position, the SKYACTIV-MT’s tight-shifting is reminiscent of the MX-5. Gear changes feel crisp yet with minimal effort. Simply put, SKYACTIV-MT radiates its Zoom-Zoom DNA.
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Mazda used a sophisticated mechanism to realize this desired shift precision and crisp feeling. The ideal operating characteristics were carefully considered based on benchmarking the MX-5 and its competitors. SKYACTIV-MT was given a continuous and lighter shifting feel with less resistance. To add precision and crispness, the shifter was designed to feel moderately heavy at the start of a gear shift and gradually became lighter, as if simply sliding into the next gear.

# # #

S ene charge system

vn turbo

Turbocharged Direct Injection

TDI

Most of us as North American consumers associate diesel engines with trucks. Volkswagen is hoping to change that perception next year when it will introduce all-new diesel engines in virtually every model they sell. From a 100hp 1.9l engine in the Golf, Jetta and New Beetle to a 133hp 2.0l in the Passat to a full 10-cylinder TDI powerplant with over 550 lb-ft of stump pulling torque in the new Touareg sport utility vehicle, diesel technology is coming and you only need to remember three little letters: TDI.

In the spring of 1976 series production began of VW’s first diesel passenger car – the 1.5-litre, 50-bhp naturally aspirated unit for use in the Golf and Rabbit. This engine with its superior fuel economy and high levels of low-end torque created a market for itself, particularly in Europe where gasoline prices are considerably higher than they are here in America.

In the early eighties Volkswagen introduced turbocharging and bumped displacement to 1.6l bringing the horsepower to 70hp and creating the new designation of "Turbodiesel" for all its diesel models. Later in the early 90's Volkswagen introduced direct fuel injection technology calling it TDI, the initials standing for Turbocharged Direct Injection. TDI enabled engineers to make the engine quieter and more efficient which meant even better fuel economy and more power. Compared to indirect injection engines, the TDI had a fuel savings potential of up to 15 percent.

Further development lead to the adoption of a variable-geometry turbocharger which utilized variable vanes within the turbine wheel to vary the amount of air and effectively reduce turbo "lag" at low RPM's but also allow for a higher volume of air at high RPM's. Volkswagen also added charge-air cooling in the form of an air-to-air intercooler as standard equipment. This boosted the current 1.9l unit to 90hp and 110hp with impressive levels of torque and refinement.

The next major peak in TDI development was high-pressure fuel injection called "pumpe duse" in German. By utilizing upwards of 20,000 psi in certain applications, Volkswagen was able to atomized and meter fuel delivery very precisely using a unit-injector developed by Bosch. This resulted in superior economy, further increases in power and even quieter running engines. Power in the 1.9l TDI is now available in europe in 100hp, 130hp and 150hp variations.

While the 1.9l 4-cylinder TDI powerplant is the bread and butter of Volkswagen's diesel offerings, it is far from being the only unit available - Volkswagen has everything from a 3-cylinder super high-efficiency TDI unit capable of nearly 90 miles per gallon, to inline-5, V6 and V8 models and even a V10 TDI that is available in the Touareg and Phaeton luxury car in Germany with unheard of levels of refinement, power and economy.

Today diesel engines make up over 40% of the Volkswagen models sold in Europe. Here in America, TDI sales represent less than 10 percent of total sales. Volkswagen has only offered us one TDI engine choice, the 90hp 1.9l TDI with a 2-valve head and older low-pressure injection systems. Why? Well two main reasons, one, diesels don't sell well here because gasoline is cheap and two, diesel fuel in North America is far less refined than European equivalents and makes it difficult to apply strict car emission standards to the TDI engines sold here.

Currently the 90hp 1.9l TDI is available in the Golf, Jetta and New Beetle and is rated at 42 mpg city and 49 mpg highway. With a 14.5 gallon tank and a 49 mph highway rating, you could theoretically drive over 710miles on a single tank of fuel. These models are only sold in limited numbers in states that have stricter emission standards such as California, Maine, Massachusetts, Vermont and New York so they don't affect Volkswagen's CAFE fleet standards too adversely but are otherwise available in the 45 remaining states.

While Volkswagen owners tend to be an enthusiastic bunch, TDI owners have elevated themselves to near-cult like status. Owner sites like Fred's TDI Club (www.tdiclub.com) have cropped up as a means for TDI owners and fans alike to communicate, share war stories, help each other with maintenance and other issues and even seek new ways to extract even more power from the existing 90hp 1.9l TDI.

TDI fans have been clamoring for the latest TDI technology available in Europe to find its way over to our shores. So far the new generation of pumpe duse/high pressure TDI engines have not been offered here due to the sub-par diesel fuel we have available. Particulate standards are nearly impossible to meet with the fuel available here, but Volkswagen's engineers have finally devised a way to get some of the new engines to run properly and pass emissions in 45 states. We'll start to see these new TDI engines starting with model year 2004 which we will cover in depth in our fifth installment.

In anticipation of these new TDI offerings coming to North America we set out to Germany last year to drive a number of the latest and greatest TDI models available in that market. We drove everything from the phenomenally economical Lupo 3L TDI to the tire shredding 150hp 1.9l TDI Bora/Jetta (with the same torque as a 3.2l VR6!) to the foundation moving V-10 TDI in the Touareg. Over the next several installments we will be highlighting a number of these TDI equipped vehicles to give you a feel for the different TDI offerings available in Europe and a little preview of what to expect in 2004.

Radiator Pressure cap

Radiator Pressure cap

    Beating the Heat: Advantage of a High Pressure Radiator Cap
 Spoon, Mugen, TRD, and about two dozen other ‘big name’ companies all sell these “High Pressure” radiator caps. However, if you ask the average person what they actually do, you’ll be met with cricket chirps.

Most imports use 1.1 kg/cm2 radiator caps while these aftermarket pieces are typically 1.3 kg/cm2. These caps are also available for domestics and some exotics as well, but the same principle applies regardless of the make/model of car. Sometimes they are rated in the “bar” unit.  The conversion factor is 1.02, so for the purposes of this article, because kg/cm2 is more awkward to write, I will say 1.1 bar and 1.3 bar. 1.1 bar is nearly exactly equal to 1.1 kg/cm^2. So, yes, I realize import caps are rated in the metric unit, but I’m going to use bar instead to make my writing a little easier.

These caps look cool, and they’re sold by big names – but let’s look at what they actually do and why you may or may not want one.

A Little Technical Background
To understand why the higher pressure radiator caps might be useful, we first need to understand something about the fluid inside the cooling system.

In an ideal world, engines would be cooled by straight water with no antifreeze added. Water is an excellent cooling agent and is extremely efficient at carrying heat away from the engine and then exchanging that heat with the air via the radiator.

However, water has a few properties that make it imperfect as an automotive coolant. For one, it has a relatively high freezing temperature at 32 degrees Fahrenheit. Freezing would be bad enough but water also has the unique property that it expands at its freezing (which if you’ve ever left a soda in the freezer before, you know why that’s bad). It also has a relatively low boiling point at 212 degrees Fahrenheit.

Since most engines are operating at a temperature of around 185-205 degrees, that only gives us a small amount of wiggle room before boiling would occur. Boiling is bad for a number of reasons which I won’t get too into here, but, steam/bubbles in coolant actually insulate coolant from the combustion chamber and would render the coolant useless at cooling the hot engine. It can also cause water pump failures amongst other damage via a process called cavitation.

Water is corrosive and it will gradually eat away at seals and cause metal inside your engine to deteriorate. Finally, it isn’t a very good lubricant and the water pump and seals in your cooling system rely on other compounds in your coolant to provide those properties.

So, we generally add antifreeze to distilled water to create the coolant we run in the car.

Antifreeze both keeps water from freezing in the winter (by lowering the freezing point of the water) and at the same time raises the boiling point of the water. A 50/50 mixture as we typically use actually gives us a freezing point of -35 degrees Fahrenheit and a boiling point of 223.

The trade off for the extra wiggle room of course is that antifreeze is not a very efficient heat exchanging fluid. In fact, 100% antifreeze in your cooling system would be an absolutely terrible idea. When you add antifreeze to water, the ability to cool evenly and quickly drops. Besides that, up until about 60% coolant, you do gain boiling point and freezing point. However, past 60% coolant to water, you start to go the other way again, sharply.

While we’d love to run 100% distilled water in the cooling system, we can’t because of corrosion and boiling/freezing points. We also don’t want to use 100% antifreeze because it would be a poor cooling fluid. Therefore, we need a compromise, which is usually a 50/50 ratio of the two fluids mixed together.

The Role of Pressure
 But, back to the radiator cap. As the coolant gets hot it expands creating pressure in the system. The hotter things get, the more pressure created. The radiator cap allows pressure to build up in the cooling system and will eventually vent that pressure to the overflow bottle as the need arises. The cap does this by a spring loaded valve which serves as a pressure relief valve at a rated pressure. You’ll notice that there’s a plunger on the bottom of the cap. As pressure builds, it pushes up on that valve until eventually the valve is opened far enough for coolant to flow out of the tube connected at the radiator fill neck. It closes again when the pressure has dropped to the desired level.

This tank is there just to catch the coolant and store it until things cool back down, when a vacuum will be created and most of the coolant will return to the cooling system.

Pressure actually increases the boiling point of a fluid as you may know from high school physics class. The pressure literally forces the liquid to remain a liquid longer and does not allow it to transform into vapor. All modern automotive cooling systems are under pressure, completely regulated by the radiator cap. 1.1 bar is roughly 15psi, and 1.3 bar is around 18psi.

How much does the pressure raise the boiling point? Well, it’s about 2-3 degrees for every psi that we increase the pressure of the system. Therefore, by using a 1.1 bar cap we make the average boiling point of a stock cooling system somewhere closer to  around 257-260 degrees.

When we change from a a 1.1 bar to 1.3 bar cap, we gain 0.2 bar or roughly 2.9psi of pressure. So, we effectively get 8.7 degrees (or around that) on top of the 257-260 degrees  before we might experience boiling coolant in the system.

So if some extra pressure is good, why not a lot? Well, it may seem obvious, but the cooling system on your car is rated to a certain pressure. The radiator cap is designed to be the weak point in your cooling system so it can safely vent pressure, you don’t want to use a cap that is so resistant to venting pressure that it causes some other part of the system to become the weak point.

What does it DO for you?
Under normal operating conditions, with everything else untouched it gives you a small amount of extra protection against localized boiling and therefore hot spots in the cylinder walls and cylinder head. If you’re running a 50/50 ratio of antifreeze to water and aren’t overheating, there is no real measurable benefit.

However, when mixed with a slight change in coolant, these caps can actually add quite a bit of cooling efficiency to your car, especially for hot summer track days. It’s a cheap tweak that can give you some extra insurance against engine failure or detonation in extreme conditions, or, make you legal to be on certain tracks.

What these caps can be used to do, is run  less antifreeze and more distilled water in your cooling system in the summer. It can also be used to run nearly straight water and water wetter (an additive which… increases the wetting ability of water.) for the track. The benefit on the track being two-fold. Some tracks do not allow you to use antifreeze as it is literally slick as snot if it leaks or spews onto the track. The other benefit is that straight water as we discussed before is the most efficient cooling fluid. Add a product called Water Wetter and that can be a really powerful combination.

So let’s get to the point…

Remember that a 50/50 ratio of coolant has a boiling point of 223 degrees. Straight water has a boiling point of 212 degrees. Both however are boosted significantly by the pressure in the system. A standard 1.1 bar cap adds 48 degrees to the boiling point of either fluid. So the coolant in your car will not actually boil until ~260 degrees, or ~271 degrees if it has antifreeze mixed in. Adding the additional 0.2 bar of pressure gives us another 8.7 degrees in both cases.

By upping our cooling system pressure to 1.3 bar we gain about 8.7 degrees. Antifreeze only adds 11 degrees to our boiling point, so the main reason for running a 1.3 bar cap is to run straight distilled water (with water wetter to prevent corrosion) or a significantly reduced antifreeze ratio without danger of boiling over. Specifically, in the summer months.

So why not run it this way all the time? Well, let’s not forget the freezing point. While the pressure cap trick gives us a higher boiling point, it does not a thing for freezing point. If your area doesn’t get down to negative temperatures in the winter, you can run a decreased ratio of antifreeze to coolant if you like all year round. However, I’d still run 50/50 in the winter. The good news is, in the winter, there’s less need for excellent cooling as air intake temps and ambient temps help you out a lot more than in the summer.

So Should I Get One or Get Rid of Mine?

 Well, they’re generally inexpensive, around $20-30. I would never pay more than maybe $40 and really, you can get just about any old 1.3 bar cap that fits for around $10 that will do the job just fine.If an OEM tuning house sells one for your car, you may want to go with that one – the cap is simple but it’s extremely important it functions properly. OEM quality is important here.

They are a small amount of insurance against possible overheating, especially for tracked cars or for excessive idling in the hot summer months. Add another $10 for a bottle of water wetter as well. For a daily driver, the extra pressure would only be particularly helpful if running a modified coolant ratio. Installing one won’t hurt anything. If you ever do approach boiling point, they’ll give you a little more insurance against it, and they’ll keep the coolant doing its job longer before the bubbles in the fluid create problems.

For a car that sees track time, specifically road race time, it would be a good cheap upgrade to your cooling system. Especially when mixed with the straight distilled water+water wetter or reduced antifreeze ratio combo.

If you do run straight distilled water, make sure you put water wetter in with it, or you will create corrosion problems and the water wetter will make the distilled water more efficient as well.

In particularly hot areas with engines that are running high compression or boost, a 1.3 bar radiator cap, water wetter and a reasonable coolant ratio or distilled water setup would be a good “stock upgrade” to help prevent detonation. Granted, if your engine is fairly close to stock, you don’t need to worry about detonation as long as you run the right fuel as dictated in your factory service manual.

In closing, if you want to run the same setup all year round and want to be extra safe, run 50/50 antifreeze with Water Wetter (it improves coolant efficiency and especially helps evenly cool the cylinder head), add a 1.3 bar cap for good measure.

In a later article I will discuss other common ‘coolant system upgrades’ like low temperature thermostats, fan switches, as well as if/when you should upgrade your radiator.

Types of Oil Pumps

 Gear-type oil pump

Gear-type oil pumps have
a primary gear that is driven by an external member, and which drives a companion
gear.  Oil is forced into the pump cavity, around each gear, and out the other side
into the oil passages.  The pressure is derived from the action of the meshed gear
teeth, which prevents oil from passing between the gears, forcing it around the
outside of each gear instead.  The oil pump incorporates a pressure relief valve, a
spring-loaded ball that rises when the desired pressure is reached, allowing the
excess oil to be delivered to the inlet side of the pum

 
Rotor-type oil pump

A rotor-type oil pump for sucking and discharging oil to be supplied to a variety of oil-requiring parts of an automotive engine. The oil pump comprises a generally annular outer rotor which is rotatably disposed in a pump casing. A generally annular inner rotor is disposed eccentrically inside the outer rotor and has an external gear which is partly in mesh with the internal gear of the outer rotor. The outer rotor is designed such that stress at the tooth base section of the internal gear is generally equal to stress at the tooth base section of the external gear of the inner rotor in their dynamic condition, thereby reducing the thickness of the tooth base section of the outer rotor.

Crescent type oil pump 

 

Vane Type oil pump

Lubrication System

how a engine lubrication system functions and talks about the main components for lubricating an engine (oil pump, oil filter, oil store, oil splash, etc


Functions of oil
   
Oil reduces unwanted friction. It reduces wear on moving parts, and helps cool an engine. It also absorbs shock loads and acts as a cleaning agent.

 Viscosity
   
Viscosity rating indicates flow rate of oil at a given temperature. There are many grades. Thin oils tend to be for cold conditions. Oil with improver is called multi-grade or multiple-viscosity oil.

 Oil additives
   
Different additives do different jobs. They can inhibit corrosion, foaming and oxidation, and act as dispersants.

Synthetic oils
   
Synthetic oils offer better protection against engine wear and can operate at higher temperatures. They have better low temperature viscosity, are chemically more stable and allow for closer tolerances in engine components without loss of lubrication.

Lubrication systems
   
The lubrication system
   
The lubrication system is designed to keep the components in the engine lubricated and to reduce friction.

Splash system
   
In the splash lubrication system, a dipper or slinger splashes oil through the internal parts of the engine. Oil is also splashed up to the valve mechanism.

 Pressure system
   
In force-feed lubrication, pressure forces oil around the engine. In a wet-sump system, oil is kept in the sump ready for the next use. In a dry sump system, oil falls to the bottom of the engine and a scavenge pump sends it to an oil tank.

 2-stroke engine premix fuel systems
   

Most 2-stroke gasoline engines use a set gasoline-oil mixture for lubrication. As the air, fuel and oil enter the crankcase, the fuel evaporates, leaving behind enough oil to keep parts coated and lubricated.

 2-stroke engine oil injection systems
  
An oil injection system doesn't need the oil and gasoline mixed manually. An engine-driven oil pump takes oil from a tank and pumps a measured amount directly into the engine where it mixes with the fuel and lubricates the internal engine parts.

 Rotary engine lubrication system

In addition to normal internal lubrication, the rotary engine uses oil injection. A pump injects a measured amount into the intake manifold. Oil from these nozzles goes to the engine and lubricates the rotor seals.

Corrosion/noise reduction
   
Engine oil performs many other functions apart from lubricating moving components. Two other functions are corrosion protection and noise suppression.

Lubrication system components
   
Sump
   
The sump is at the base of an engine. It can be used as a storage container in a 'wet sump system'.

 Oil collection pan
   
An oil collection pan is used in 'dry sump systems' prior to being returned to an oil tank.

 Oil tank
   
The oil tank is part of the dry sump lubrication system and is used for oil storage.

Pickup tube
   
A pickup tube is used to provide a means of collecting oil for the oil pump.

 Oil pump
   
Oil pumps deliver oil under pressure to the internal engine parts. In a rotor-type oil pump, an inner rotor drives an outer one. Pressure differences force the oil to move. Geared oil pumps use a similar principle.

 Oil pressure relief valve
   

The pressure relief valve is used to prevent damage to an engine due to too much oil pressure.
 
Oil filters
   
The oil filter helps to clean the oil in the system. If the filter clogs, a valve opens and directs unfiltered oil to the engine. Most oil-filters on diesel engines are larger than those on similar gasoline engines.

Spurt holes & galleries
   
Spurt holes and galleries are used to deliver oil from the oil pump to various components and bearings in the engine.

Oil indicators
   
Oil indicators are used to check when there are safe oil levels in an engine.

Oil cooler
   
An oil cooler cools oil prior to its reuse in the engine.

Lubrication procedures
   
Checking engine oil

The objective of this procedure is to show you how to check and adjust engine oil level and condition. Make sure the vehicle is on a level surface and the engine is off before taking a reading. If you don't, you'll get inaccurate readings.

 Draining engine oil

Oil loses its clean, fresh look very quickly and yet may still be serviceable. The best guide to changing oil is knowing the vehicle's mileage and period of time since the last oil change. The objective of this procedure is to show you how to safely drain engine oil.

Replacing an oil filter

The objective of this procedure is to show you how to replace an oil filter to the manufacturer's specifications. Before removing an oil filter, first refer to the Service Manual for the vehicle and identify the type of filter required.

Refilling engine oil
   
The objective of this procedure is to show you how to safely refill engine oil. The service manual or the owner's manual will also tell you the correct grade of oil for the vehicle, and the quantity you will need to fill the engine.

cav rotary pump (epic)

Careful section of a CAV rotary pump for training purposes, showing all its operating parts. The transfer pump, the speed governor, the automatic advance regulator, the hydraulic sensor device, the fuel circuit and the pumping small piston are clearly shown. It is operated by hand through a hand wheel.

It is supplied complete with an indirect injector and mounted on an elegant laminated plastic base.

New vehicle air condition system

air condition system
 Vehicles are found to have primarily three different types of air conditioning systems. While each of the three types differ, the concept and design are very similar to one another. The most common components which make up these automotive systems are the following: COMPRESSOR, CONDENSER,EVAPORATOR, ORIFICE TUBE, THERMAL EXPANSION VALVE , RECEIVER-DRIER,ACCUMULATOR.
 Note: if your car has an Orifice tube, it will not have a Thermal Expansion Valve as these two devices serve the same purpose. Also, you will either have a Receiver-Dryer or an Accumulator, but not both.
 COMPRESSOR
 Commonly referred to as the heart of the system, the compressor is a belt driven pump that is fastened to the engine. It is responsible for compressing and transferring refrigerant gas. The A/C system is split into two sides, a high pressure side and a low pressure side; defined as discharge and suction. Since the compressor is basically a pump, it must have an intake side and a discharge side. The intake, or suction side, draws in refrigerant gas from the outlet of the evaporator. In some cases it does this via the accumulator. Once the refrigerant is drawn into the suction side, it is compressed and sent to the condenser, where it can then transfer the heat that is absorbed from the inside of the vehicle.
 CONDENSER
 This is the area in which heat dissipation occurs. The condenser, in many cases, will have much the same appearance as the radiator in you car as the two have very similar functions. The condenser is designed to radiate heat. Its location is usually in front of the radiator, but in some cases, due to aerodynamic improvements to the body of a vehicle, its location may differ. Condensers must have good air flow anytime the system is in operation. On rear wheel drive vehicles, this is usually accomplished by taking advantage of your existing engine's cooling fan. On front wheel drive vehicles, condenser air flow is supplemented with one or more electric cooling fan(s). As hot compressed gasses are introduced into the top of the condenser, they are cooled off. As the gas cools, it condenses and exits the bottom of the condenser as a high pressure liquid. . EVAPORATOR
 Located inside the vehicle, the evaporator serves as the heat absorption component. The evaporator provides several functions. Its primary duty is to remove heat from the inside of your vehicle. A secondary benefit is dehumidification. As warmer air travels through the aluminum fins of the cooler evaporator coil, the moisture contained in the air condenses on its surface. Dust and pollen passing through stick to its wet surfaces and drain off to the outside. On humid days you may have seen this as water dripping from the bottom of your vehicle. Rest assured this is perfectly normal. The ideal temperature of the evaporator is 32 Fahrenheit or 0 Celsius. Refrigerant enters the bottom of the evaporator as a low pressure liquid. The warm air passing through the evaporator fins causes the refrigerant to boil (refrigerants have very low boiling points). As the refrigerant begins to boil, it can absorb large amounts of heat. This heat is then carried off with the refrigerant to the outside of the vehicle. Several other components work in conjunction with the evaporator. As mentioned above, the ideal temperature for an evaporator coil is 32 F. Temperature and pressure regulating devices must be used to control its temperature. While there are many variations of devices used, their main functions are the same; keeping pressure in the evaporator low and keeping the evaporator from freezing; A frozen evaporator coil will not absorb as much heat.

 PRESSURE REGULATING DEVICES
 Controlling the evaporator temperature can be accomplished by controlling refrigerant pressure and flow into the evaporator. Listed below, are the most commonly found. ORIFICE TUBE The orifice tube, probably the most commonly used, can be found in most GM and Ford models. It is located in the inlet tube of the evaporator, or in the liquid line, somewhere between the outlet of the condenser and the inlet of the evaporator. This point can be found in a properly functioning system by locating the area between the outlet of the condenser and the inlet of the evaporator that suddenly makes the change from hot to cold. You should then see small dimples placed in the line that keep the orifice tube from moving. Most of the orifice tubes in use today measure approximately three inches in length and consist of a small brass tube, surrounded by plastic, and covered with a filter screen at each end. It is not uncommon for these tubes to become clogged with small debris. While inexpensive, usually between three to five dollars, the labor to replace one involves recovering the refrigerant, opening the system up, replacing the orifice tube, evacuating and then recharging. With this in mind, it might make sense to install a larger pre filter in front of the orifice tube to minimize the risk of of this problem reoccurring. Some Ford models have a permanently affixed orifice tube in the liquid line. These can be cut out and replaced with a combination filter/orifice assembly.
 THERMAL EXPANSION VALVE
 Another common refrigerant regulator is the thermal expansion valve, or TXV. Commonly used on import and aftermarket systems. This type of valve can sense both temperature and pressure, and is very efficient at regulating refrigerant flow to the evaporator. Several variations of this valve are commonly found. Another example of a thermal expansion valve is Chrysler's "H block" type. This type of valve is usually located at the firewall, between the evaporator inlet and outlet tubes and the liquid and suction lines. These types of valves, although efficient, have some disadvantages over orifice tube systems. Like orifice tubes these valves can become clogged with debris, but also have small moving parts that may stick and malfunction due to corrosion.

 RECEIVER-DRIER
 The receiver-drier is used on the high side of systems that use a thermal expansion valve. This type of metering valve requires liquid refrigerant. To ensure that the valve gets liquid refrigerant, a receiver is used. The primary function of the receiver-drier is to separate gas and liquid. The secondary purpose is to remove moisture and filter out dirt. The receiver-drier usually has a sight glass in the top. This sight glass is often used to charge the system. Under normal operating conditions, vapor bubbles should not be visible in the sight glass. The use of the sight glass to charge the system is not recommended in R-134a systems as cloudiness and oil that has separated from the refrigerant can be mistaken for bubbles. This type of mistake can lead to a dangerous overcharged condition. There are variations of receiver-driers and several different desiccant materials are in use. Some of the moisture removing desiccants found within are not compatible with R-134a. The desiccant type is usually identified on a sticker that is affixed to the receiver-drier. Newer receiver-driers use desiccant type XH-7 and are compatible with both R-12 and R-134a refrigerants.
 ACCUMULATOR
 Accumulators are used on systems that accommodate an orifice tube to meter refrigerants into the evaporator. It is connected directly to the evaporator outlet and stores excess liquid refrigerant. Introduction of liquid refrigerant into a compressor can do serious damage. Compressors are designed to compress gas not liquid. The chief role of the accumulator is to isolate the compressor from any damaging liquid refrigerant. Accumulators, like receiver-driers, also remove debris and moisture from a system. It is a good idea to replace the accumulator each time the system is opened up for major repair and anytime moisture and/or debris is of concern. Moisture is enemy number one for your A/C system. Moisture in a system mixes with refrigerant and forms a corrosive acid. When in doubt, it may be to your advantage to change the Accumulator or receiver in your system. While this may be a temporary discomfort for your wallet, it is of long term benefit to your air conditioning system

Diesel Electronic Unit Injector

The unit injector combines a high-pressure pump and nozzle with a solenoid valve to form compact assembly. As a result, high-pressure lines are no longer necessary and injection can be controlled by the integrated and extremely precise solenoid valve at pressures of up to 2000 bar. Each cylinder has a unit injector fitted between the valves in the cylinder head. The unit injector is used in both passenger cars and commercial vehicles. The Bosch Unit Injector system was first used in the VW Passat TDI in 1998, after which it rapidly found favour within the VW range. With the V10 TDI, VW recently presented what is currently the most powerful diesel engine for use in a car.

Diesel injection pump

Robert Bosch has contributed to Diesel In-Line Fuel-Injection Pumps: Bosch Technical Instruction as an author. Robert Bosch GmbH is ranked among the world's major equipment suppliers. The Bosch experts that make up the editorial team come from the relevant divisions of Bosch and are at the forefront of technical developments in their field. Bosch demonstrates its leading competence in automotive technology through the sheer number of its applications for patents and patented designs. inline pump

The diesel fuel pump is a fairly complex and sturdy mechanism. In fact, it is the most complex diesel engine part. Additionally, a diesel fuel pump must be durable enough that it can withstand the pressure of the compressed air, and the heat of the injection process. The fine mist of fuel needed for the proper ignition must be maintained by the diesel fuel pump under these extreme conditions. Diesel fuel pumps may be located just about anywhere on the engine, depending on the manufacturers design. Much experimentation has been done over the years regarding the most effective placement of the diesel fuel pump. So far it seems that so long as the pump is mounted on the engine, it will effectively deliver fuel to the cylinders. A gasoline fuel pump, on the other hand, may be mounted anywhere in the engine compartment or along the fuel distribution system. Depending on the location and design of the diesel fuel injector pump, pre-combustion chambers, customized induction valves, and other systems are often used in the injection process. These injection enhancers often aid in circulating, or swirling the air inside the cylinder for more efficient combustion. Just as with any engine fuel injection system, diesel fuel pumps are constantly being improved to be more efficient and less costly.

Common Rail System

The common rail system accumulates high-pressure fuel in the common rail and injects the fuel into the engine cylinder at timing controlled by the engine ECU, allowing high-pressure injection independent from the engine speed. As a result, the common rail system can reduce harmful materials such as nitrogen oxides (NOx) and particulate matter (PM) in emissions and generates more engine power. DENSO leads the industry in increasing fuel pressure and maximizing the precision of injection timing and quantity, achieving cleaner emissions and more powerful engines. DENSO’s common rail systems are supplied to a variety of vehicles including passenger cars and commercial vehicles. DENSO Technology – Leading the World In 1995, DENSO launched the world’s first common rail system for trucks. In 2002, DENSO launched a 1,800-bar common rail system that achieved the industry’s highest injection pressure, and five-time multiple injections at a high accuracy. This system comfortably cleared EURO4 emission regulations without a diesel particulate filter. Benefits and Features DENSO’s common rail system can inject fuel at up to 1,800 bar, significantly reducing the concentration of PM in emissions. DENSO’s new injectors can perform five injections during each combustion stroke. The five times multiple injections, including pilot injection with a predetermined small fuel quantity, reduce PM and NOx in emissions, and achieve quietness at idling equivalent to gasoline-powered engines. The high fuel injection pressure is generated by the supply pump, which is the lightest in the world for passenger car common rail systems.

diesel engine

internal combus­tion engines designed to convert the chemical energy available in fuel into mechanical energy. This mechanical energy moves pistons up and down inside cylinders. The pistons are connected to a crankshaft, and the up-and-down motion of the pistons, known as linear motion, creates the rotary motion needed to turn the wheels of a car forward. Both diesel engines and gasoline engines covert fuel into energy through a series of small explosions or combustions. The major difference between diesel and gasoline is the way these explosions happen. In a gasoline engine, fuel is mixed with air, compressed by pistons and ignited by sparks from spark plugs. In a diesel engine, however, the air is compressed first, and then the fuel is injected. Because air heats up when it's compressed, the fuel ignites. The diesel engine uses a four-stroke combustion cycle just like a gasoline engine. The four strokes are: Intake stroke -- The intake valve opens up, letting in air and moving the piston down. ­ Compression stroke -- The piston moves back up and compresses the air. Combustion stroke -- As the piston reaches the top, fuel is injected at just the right moment and ignited, forcing the piston back down. Exhaust stroke -- The piston moves back to the top, pushing out the exhaust created from the combustion out of the exhaust valve. Remember that the diesel engine has no spark plug, that it intakes air and compresses it, and that it then injects the fuel directly into the combustion chamber (direct injection). It is the heat of the compressed air that lights the fuel in a diesel engine. In the next section, we'll examine the diesel injection process.