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Engine Components

INFINITI’s VC-Turbo variable compression engine is the world’s first production-ready variable compression ratio engine and one of the most advanced internal combustion engines ever created.

The engine was named by the Automobile, Motor and Bicycle Association of Austria (ARBÖ) with the Grand Austrian Automobile Award in the category “Environment”. During the awards ceremony that took place in November, VC-Turbo was honoured for setting a new benchmark in terms of efficiency of next-generation combustion engines.

The experts of the automobile club acknowledged INFINITI for introducing the world’s first production-ready engine with variable compression. While in previous years, ARBÖ tended to award alternative propulsion systems, this year the organisation recognised the potential of the VC-Turbo engine which represents the next step in optimising fuel efficiency of the internal combustion engine.

Roland Krueger, President of INFINITI Motor Company said: “INFINITI would like to thank the ARBÖ members for recognising the VC-Turbo engine and the benefits it offers customers. The beauty of variable compression is that the engine makes an intelligent choice between performance and efficiency, giving drivers the performance they want combined with the efficiency they need. Not only that, it is quieter and smoother. We are excited to bring this ground-breaking technology to the road and, on behalf of the entire INFINITI team, we are grateful for the recognition.”

INFINITI engineers have worked for 20 years on the technology to make VC-Turbo production-ready. More than 100 prototypes were tested so as to deliver a truly innovative gas engine. Thanks to a multi-link system, which is able to adapt the travel of the pistons’ stroke, the all-new engine can seamlessly offer any compression ratio between 8:1 and 14:1. Lower compression ratios secure greater power and torque, whereas a higher compression improves fuel efficiency.

The result is an engine delivering the power output of a V6 and the fuel economy of a diesel powertrain without the emissions associated with a diesel engine. The development objectives of the 2.0-litre four-cylinder engine with single-scroll turbocharger are: 268hp and 390Nm torque while offering at the same time 27% lower fuel consumption than similarly-powered V6 gasoline engines.

The first INFINITI cars equipped with the VC-Turbo engine will be on sale in 2018.

Scots Auto Scene had an exclusive interview with INFINTI to find out more about this ground-breaking engine.



In simple terms, how does the new variable compression engine work? 

INFINITI’s VC-Turbo technology uses an advanced multi-link system to seamlessly raise or lower the stroke of the pistons, detecting the car’s driving condition and driver inputs, and instantly selecting the most suitable compression ratio.

The engine is able to offer any compression ratio between 8:1 (typical for high performance engines) and 14:1 (used by many manufacturers for high efficiency).

The result is an engine that combines the power of a high-performance 2.0-litre turbo petrol engine with the torque and efficiency of an advanced diesel powertrain – without the equivalent emissions – offering a compelling alternative to similarly-powered four-cylinder diesel engines. The VC-Turbo engine will be comparable to certain six-cylinder gasoline powertrains for performance, while significantly outperforming them in efficiency.


What were the main challenges in its inception?

A truly historic challenge, INFINITI has worked on this technology for more than 20 years. The first major breakthrough was the invention by INFINITI of a new multi-link technology in 1998, which held the key to a true variable compression ratio.

INFINITI has tested and developed more than 100 engine prototypes in perfecting the technology, covering over three million kilometres of equivalent road testing and spending over 30,000 hours on the test bed (equal to five million kilometres of on-road testing). The engine is now in its final stages of development on real roads.


Why is this new engine one of the biggest milestones for INFINITI?

“INFINITI has created an engine that adapts to conditions, and empowers drivers with the engine they want, when they want it. This is the world’s first truly driver-focused powertrain.”

Shinichi Kiga, Chief Powertrain Engineer, Gasoline Engine Project Group.


What are typical service intervals for this engine (UK spec)?

This information will be available closer to the time of the engine being available in the markets.


Will this engine eventually be available in all INFINITI models worldwide?

Currently this is equivalent to a 2.0ltr turbo petrol engine which will not suit every different model size or market. This is the one we are currently working on bringing to market as soon as possible.

“In future, new INFINITI products will benefit from the application of downsized, high-efficiency engines, such as VC-Turbo, which do not compromise performance. INFINITI’s progressive customer base is receptive to new technology, and the VC-Turbo engine is designed to meet this desire to buy innovative products.”

Roland Krueger, President INFINITI.


What will this engine mean for the future of INFINITI?

“Vehicle engineers believe that a breakthrough in internal combustion technology would come from mastering the variable compression ratio. INFINITI will be the first to bring this technology to the market in 2018. This new generation of powertrains will help our global growth and expansion of the INFINITI product portfolio.”

Roland Krueger, President INFINITI.


What will this engine mean for the future of engine technology in general?

“The VC-Turbo engine represents a new breed of engine which can transform continuously, and will establish new benchmarks for future internal combustion engines.”

Shinichi Kiga, Chief Powertrain Engineer, Gasoline Engine Project Group.


Anything else to add?

INFINITI’s partnership with the Renault Sport Formula 1 team has proved instrumental in accelerating the VC-Turbo’s prototype testing in the latter stages of its development program.

As part of the natural development process for the engine, testing of earlier prototypes saw INFINITI addressing the challenge of component material development and durability.

One such instance revolved around the engine’s bearings. Thanks to its advanced multi-link system, the VC-Turbo engine features around three times as many bearings as a conventional internal combustion engine. VC-Turbo engineers identified a small bearing vibration which manifested at the highest engine speeds under certain conditions.

INFINITI’s VC-Turbo project engineers worked with the Renault Sport Formula 1 team to identify and isolate the vibration, using the team’s expertise in dynamic motion analysis in conditions of up to 20,000 rpm – far higher than any production engine. The team’s experience in movement behaviour, and the use of bearing technology in a Formula 1 application, provided valuable insight into developing the engine. This stage of testing has confirmed the durability of the VC-Turbo engine under particularly challenging conditions.


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To educate buyers on the availability of new products and provide technical information to professional mechanics, Dayco, a leading engine products and drive systems supplier for the automotive, industrial and aftermarket industries, today announced it will exhibit at Auto Trade Expo 2016, October 22 – 23, 2016 at the Citywest Exhibition Centre in Dublin, Ireland. The Expo, now in its third year, caters to all aftermarket sectors including passenger cars, light commercial vehicles, heavy commercial vehicles, trailers and buses.

Timing kit with water pump.
Timing kit with water pump.

“Our business in Ireland continues to grow and we welcome the opportunity to speak directly with mechanics, aftersales managers, parts managers, owners and managers of garages, motor factors, and anyone else working in the automotive aftermarket in Ireland,” said Steve Carolan, National Sales Manager Dayco in the U.K. and Ireland.

In addition to its renowned High Tenacity timing belt kits, Dayco will showcase its combined water pump and timing belt kits, chain kits, and its latest range addition, stand-alone water pumps.

“In order for workshops to supply their customers with OE quality products, we have expanded our traditional belt-related product offering with the addition of replacement timing chains, chain kits, and stand-alone water pumps,” added Carolan. “As a result, Dayco can truly supply the repair solution for every power transmission requirement.”

Dayco offers a range of more than 200 water pump kits that provide workshops and technicians with the opportunity to carry out a full and thorough repair.

“As the amount of water pumps driven by the primary drive system increases, it’s important we continue to focus on our kit range in order to provide our customers with a full system solution,” said Franca Pierobon, Marketing and Communications Manager of Europe, the Middle East, Africa and India for Dayco. “Our strategy is to provide our customers with kits that bundle multiple engine components that work together with the timing belt and have similar lifecycles so all parts can be replaced concurrently.”

In addition to the exhibition portion of the Auto Trade Expo, expo organizers and manufacturers will conduct workshop and business seminars as well as training and demonstration sessions during the event.


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ROSS Racing Pistons designs and manufactures high-end aluminum pistons. The company handles 40 to 50 orders each week, and nearly every job is custom. The company fabricates approximately 1000 pistons in a week, using a process that involves four to five different machining operations performed on high-end computer numerical control (CNC) equipment. With CNC programming being a critical step in the production process, ROSS’ programmers must work quickly and their programs must be right the first time to avoid delays caused by rework and reprogramming. In the past, using a traditional programming process, the task required about 200 hours per week.rsz_124413_wg

Using macros created with DP Technology’s ESPRIT® CAM software, that time has been reduced to only 30 hours per week. And when a programmer wants to make a minor change to an existing macro, which is common, it takes only minutes using ESPRIT instead of the cumbersome C++ programming process required previously. In addition, ESPRIT’s simulation functionality helps avoid errors that lead to rework. “We can’t afford a lot of programming time,” explained Nicholas Plantus, Chief Engineer at ROSS Racing Pistons. “With ESPRIT, it takes about 20 minutes total to program the five operations needed to get a part ready to run.”


Power and precision

ROSS Racing Pistons began production of high-end forged aluminum racing pistons in 1979 and the company is still run by one of its founders, Ken Roble. The company offers pistons for so many cars that its catalog runs to 45 pages. While most of the company’s pistons go into drag racers, some are made for other uses, such as in antique and vintage cars for which pistons are no longer made.

The breadth of the company’s product line means that the design team must deal with 900 possible combinations of applications, cylinder heads and compression ratios – the three factors that determine the shape of a piston. “There are so many different possibilities out there that almost every job that we do is different,” said Plantus. To design a new piston, designers work from samples that customers send, as well as drawings or actual cylinder heads. Some customers even send plastic models of their engines’ combustion chambers.

The company’s production equipment includes vertical machining centers, horizontal machining centers, lathes, a turning center, and a 5-axis machining center from vendors such as Okuma, Mori Seiki, Takisawa, and Fadal.

The first step of the production process involves the selection of the appropriate aluminum forging from one of the 95 different forgings the company uses. Forgings range in size from 1.5 to 6.8 inches in diameter. Actual production begins on a pin-boring machine where pin holes are made. The part then goes to the lathe for OD turning, facing, and creating ring grooves. The next stop is the horizontal machining center, where dome shapes or dish shapes on top of the piston are made, along with the pockets for the valve. This machine also trims the sides of the forging for weight removal and to make it easier to install the lock rings. When there are valves with compound angles, the part goes next to the 5-axis machine. After that, the vertical machining center is used to remove additional material to further lighten the piston. The last step is the turning center, which is used to make the piston elliptical to compensate for thermal expansion.


Addressing programming challenges

Even though nearly every job is unique, many of the new pistons vary only slightly from those that ROSS has already made. Using a traditional approach, however, CNC programming still required 20 hours per order. With that approach, the programmer imported a CAD model into the programming software. He added a model of the workpiece and positioned the part inside. He selected and organized the features in the part. The next step was to define the machining operations. For each toolpath, he selected a tool and defined its diameter, length, tool holder and speeds and feeds.

Macros greatly simplified the creation of the CNC programs by prompting the programmer to enter dimensions and other basic information for each type of part. However, the company’s previous CAM system generated macros using C++. “The guy who was writing the macros for us was pretty good, but when he left, we had nobody who knew C++,” said Plantus.

This meant the company could no longer maintain its existing macros or develop new ones for new piston geometries. Another drawback of the previous CAM system was that it did not let end users generate post processors. The only way to get them was to buy them from the software developer, and that was expensive.

One of the main reasons ROSS chose ESPRIT was because its macro programming language is based on the industry-standard programming language Microsoft® Visual Basic for Applications, which many programmers know and is much easier to use than C++. ESPRIT enables programmers to use VBA to access virtually all of its capabilities.

For example, a programmer can create a new dialog box that asks for parameters to define a hole (diameter, depth, XYZ location, hole type). Then the VBA macro automatically creates circles representing the holes, selects the cutting tools, automatically creates the drilling operations, and produces the G-code program all in one step. All of ESPRIT’s menus and tool bars are also accessible from within a macro or add-in program via the ESPRIT API. This allows the macros and programs to adapt the ESPRIT interface to suit the individual needs of a particular application or business. “So far we have created 60,000 lines of code and we are adding to it,” Plantus noted. DP Technology also allows users to develop their own post-processors.


Streamlined process

Using macros created in ESPRIT, ROSS has created a fast 5-step process for CNC programming in which programmers simply fill in parameters and make some menu picks. The first step involves importing an IGES file for the dome and a Pro/ENGINEER CAD file for the piston. Using that geometry, he defines the features on the part. There are normally between 10 and 12 features and this step takes between one and five minutes. Next, he identifies which machining operations will be required and assigns them to the various machines, which are selected from a menu. Finally, he selects the tool for each operation. At that point, ESPRIT generates the code for each machining operation. This step takes less than one minute – for a total of 20 minutes or less for the entire process.

The programmer then uses the ESPRIT simulation functionality to visualize the cutting process. ESPRIT makes it possible to view each individual cut in the entire machining process as dynamic 3D solids. The programmer can also view a presentation of the part that will be produced by the program and compare the as-machined workpiece to the original design. By zooming in on the simulated mold, the programmer can determine whether or not it matches the customer’s requirements. The simulation process provides the ideal opportunity to take a close look at the program that has been created up to that point. At times, the simulation will show a problem with a program, which can then be corrected before any time or aluminum is wasted.

ESPRIT’s simulation functionality is more user-friendly, according to Plantus, than what was available in the company’s previous CAM system. For example, ESPRIT allows the user to place the cursor over a geometric feature and read its dimensions. “Simulation using ESPRIT is very accurate, and it’s easier, compared to our old software, to check the geometry and catch mistakes,” he explained.

The ease of creating macros with ESPRIT means that the company’s two CNC programmers have time to do other things, such as setting up jobs on the machines. It is also allowing ROSS to keep up with demand, even as its product line has expanded. “In the past, it could take half a day to program one operation,” Plantus said. “Now that it goes so quickly, we are better able to handle the complexity of our product line.”



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