15 March 2013 | Eindhoven

PACCAR MX-11 engine offers maximum performance and efficiency


A brand new development for Euro 6 with outputs of 290 to 440 hp

DAF Trucks is announcing a brand new generation of engines with a displacement volume of 10.8 litres and outputs ranging from 290 to 440 hp. The new state-of-the-art PACCAR MX-11 engine is compact and offers optimum fuel efficiency and a low weight and noise level, in combination with excellent performance and maximum reliability. The new PACCAR MX-11 engine, developed and built by DAF Trucks in Eindhoven, is scheduled to go into production in the autumn of 2013 and will be available in the new DAF Euro 6 CF and XF series.

PACCAR MX-11 Euro 6
  • State-of-the-art 10.8-litre six-cylinder in-line engine for Euro 6
  • Newly designed engine block for optimum stiffness and integration
  • Cylinder head with double overhead camshafts
  • High-pressure common rail fuel injection system, for injection pressures of up to 2,500 bar
  • Turbo charger with variable geometry
  • Innovative technologies for maximum efficiency: integration of functions, encapsulated wiring harnesses and advanced management systems

"The new PACCAR MX-11 engine fits completely in the trend towards achieving high efficiency at lower displacement volumes", explains Ron Borsboom, member of the Board of Management of DAF Trucks with responsibility for Product Development. "11 litres is the ideal displacement volume for achieving outputs of 290 hp to 440 hp within the requirements of the Euro 6 legislation and using reliable single-stage turbo technology. When developing the PACCAR MX-11 engine, we started with a clean sheet of paper. Our main development criteria were high performance, low weight and fuel consumption, as well as maximum reliability and durability and excellent vehicle availability. The new PACCAR MX-11 engine has service intervals of up to 125,000 km".

Double overhead camshafts

The PACCAR MX-11 engine block is a completely new design. It is made of strong compact graphite iron, with vertical ribs to maximize strength and achieve low noise levels. As with the 12.9 litre PACCAR MX-13 engine, as many functions as possible have been integrated to maximize reliability and durability. Pipes, for example, have been cast into the cylinder block and the two pump units that generate pressure for the common rail system have been worked into the block. The timing gear case and the pre-separator of the crankcase ventilation system have also been nicely integrated into the engine block.

The double overhead camshafts are a key feature of the new cylinder head, which has four valves per cylinder and an integrated inlet manifold. "This configuration offers significant advantages", explains Ron Borsboom. "Firstly, the valve train can be configured in a smart and more robust manner, which optimizes durability. The cylinder head is also extremely robust, which enables us to use higher top pressures combined with larger reserves; these factors are key to improving durability and reliability as well as efficiency. Direct valve control also has a positive effect on fuel consumption, as it minimizes losses. The double overhead camshafts ensure that the integrated MX Engine Brake delivers an outstanding brake performance: it releases more than 70% of its exceptional 320 kW of power at low speeds (1,500 rpm). The overhead camshafts also help to reduce weight. The camshafts can be hollow as the injection system is driven by a separate FIE (Fuel Injection Equipment) camshaft, saving 15 kilos in weight".

Common rail injection and turbo with variable geometry

The new MX-11 engine shares its advanced common rail system with the PACCAR MX-13 engine, although each has its own engine software calibration. The common rail allows high injection pressures of up to 2,500 bar, and provides the opportunity to use pre- and post-injection, or a combination of both. This results in finer fuel atomisation and many more opportunities to optimise combustion to ensure the lowest possible emission and noise levels, and the best possible fuel efficiency. The fact that the temperature of the exhaust gases can be controlled so effectively also means that the engine can be optimally integrated with the exhaust gas after treatment system. We use a turbo charger with variable geometry (VTG), which ensures that the engine can call on the best turbo settings at all times and across its entire speed range in order to deliver maximum performance. The EGR system is highly compact and designed for a perfect mixture of exhaust gases and fresh air. All this technology is controlled optimally and accurately by three actuators: the Back Pressure Valve, the VTG turbo and the EGR valve. The compact design of the PACCAR MX-11 is also a key feature of the engine, making it ideal for use in the DAF CF series.

Exhaust gas after-treatment for Euro 6

In order to meet the stringent Euro 6 emission requirements, DAF is using various exhaust gas after-treatment technologies such as an SCR catalytic converter and an active soot filter. "Just as with the 12.9 litre PACCAR MX-13 engine, the aim is not only to achieve the right exhaust gas composition, but also the right temperature in the soot filter", explains Borsboom. "The basic principle is to have as much passive regeneration of the soot filter as possible by getting the engine to create the ideal circumstances for this to happen. That is why the exhaust manifold, as well as the key parts of the exhaust system, have been encapsulated. If despite of this, the temperature of the exhaust gases drops too low due to a specific vehicle application, the engine will switch to active regeneration. A seventh injector, placed behind the turbo and in front of the soot filter, has been added to the engine for this purpose. It can inject fuel into an oxidation catalytic converter in the exhaust in order to generate exactly the right amount of heat. The SCR catalytic converter has also been designed to maintain optimum temperatures. Thanks to its smart coating, it is able to achieve maximum performance across a wider range of temperatures, which means that the engine can function optimally and in the most efficient way.”

In addition to maximising efficiency, excellent vehicle availability was an important criterion when developing the exhaust gas after treatment system. Thanks to the low and stable oil consumption of the PACCAR MX-11 engine, soot filter cleaning intervals of up to 500,000 kilometres are achievable, depending on the truck operation. Another unique feature is the option of fitting the SCR catalytic converter and the soot filter separately from one another on opposite sides of the chassis, which is important when the truck is fitted with crane supports or twist-locks.

Many innovations

The new PACCAR MX-11 engine features numerous innovations, such as a single poly V-belt and a fan that is mounted directly onto the crankshaft without an intermediate drive — saving on maintenance costs, improving reliability and reducing weight and fuel consumption. To achieve optimum fuel efficiency, minimising parasitic losses was a primary focus during the development process. For example, the engine features a new water pump with a 2-speed electromagnetic coupling for optimum efficiency. During deceleration of the vehicle, the intelligent air compressor brings the air system up to maximum pressure, which means that it can often remain switched off on level roads. To maximise reliability and durability, the wiring harnesses are encapsulated. The alternator and compressor pump for the air conditioning are mounted on the engine as a single unit, and the fuel module with integrated heating and automatic moisture separator are located directly on the engine for maximum protection. The oil module has an integrated oil filter and oil cooler of which the last is made of stainless steel for even greater robustness.

Greater choice of PTOs

A wide range of PTOs will be available for the PACCAR MX-11 engine. On the rear, in addition to the familiar one o'clock engine PTO, an 11 o'clock version will be made available with a torque of 250 Nm. Another new option is a generator that is fitted directly on the engine, specifically for refrigerator bodies. A single poly V-belt in combination with automatic tensioners ensures reliable operation of this water or air-cooled Frigoblock generator, which, in turn, has a positive effect on repair and maintenance costs. As the generator is mounted directly on the engine, the excellent ground clearance is maintained. In addition, there is an option at the front of the engine for driving a hydraulic pump.

Distribution and heavy applications

The new 10.8 litre Euro 6 PACCAR MX-11 engine will enter series production after the summer of 2013, with no less than five different ratings available for two main application areas. The 210 kW/290 hp, 240 kW/330 hp and 271 kW/370 hp versions with maximum torques of 1,200, 1,400 and 1,600 Nm respectively (at 1,000–1,650 rpm) are perfect for urban, regional and national distribution applications. For heavy use, 291 kW/400 hp and 320 kW/440 hp ratings are available with maximum torques of 1,900 and 2,100 Nm respectively (at 1,000–1,450 rpm).

With high torques at low speeds, outstanding fuel efficiency, market-leading reliability and even more PTO options, the new PACCAR MX-11 engine will be one of the key engines for the versatile CF series, of which the new Euro 6 model will be launched in April. The PACCAR MX-11 engine is also a valuable addition to the DAF Euro 6 XF range. Fuel consumption of the 10.8-litre PACCAR MX-11 engine is on average even another up to 3% lower than that of the already very fuel efficient 12.9-litre PACCAR MX-13 engine, and the weight reduction of over 180 kilograms presents another opportunity to further increase efficiency, particularly in bulk and tank transport.