Ducati Introduces Desmodromic Variable Valve Timing

[SDRider]

http://www.sportrider.com/sportbike-news/ducati-introduces-desmodromic-variable-timing?src=SOC&dom=fb

A new generation of Testastretta engines will use new variable valve timing, Multistrada 1200 likely to be the first.

Ducati has announced a new Testastretta DVT engine, which utilizes variable valve timing on both the intake and exhaust camshafts. The system continuously adjusts intake and exhaust valve timing independently of each other, optimizing engine power through the rev range while at the same time improving fuel efficiency. Ducati's press release does not mention a specific motorcycle that the new DVT engine will be fitted in, but the Multistrada 1200 is likely the prime candidate; bore and stroke measurements are identical to the 1200's at 106 x 67.9mm. Peak power is listed as 160 hp at 9500 rpm, up from 150 hp on the current Multistrada; the DVT engine makes 100 foot-pounds of torque compared to 92 foot-pounds for the Multistrada.

DVT retains Ducati's trademark Desmodromic actuation of the valves, with two spark plugs per cylinder. Each camshaft has a hydraulic actuator as part of the cam belt pulley; the actuator can rotate inside the pulley housing, advancing or retarding that camshaft's timing as needed. The amount of advance or retard is controlled by varying oil pressure inside the actuator, which in turn is controlled by dedicated valves and the ECU.

The full text of Ducati's press material follows:

Ducati presents the first motorcycle engine with variable timing of both the intake and exhaust camshafts. Named Ducati Testastretta DVT, Desmodromic Variable Timing, Ducati's new Desmodromic engine is the first in the world with variable timing on both inlet and exhaust camshafts, leading the way for a whole new generation of such engines. The innovative, new design overcomes an engineering gap in current production motorcycle engines and underlines Ducati's strength in developing ground-breaking engine and motorcycle technologies.

The variable timing system is able to continuously adjust valve timing, by acting independently on both the intake and exhaust camshafts. The system optimises engine performance throughout the rev range and in any operating condition, to guarantee the highest power, smooth delivery, muscular torque at low rpm and reduced fuel consumption. With full Euro 4 compliance, DVT sets a new standard in the combination of power, delivery and usability of motorcycle engines. Scroll through the image gallery above to see more detail images of the system.

Ducati Testastretta DVT engine characteristics
•Brand-new DVT (Desmodromic Variable Timing) system
•Bore 106 mm, stroke 67.9 mm
•Capacity 1,198 cm³
•Max power 160 HP at 9,500 rpm
•Max torque 136 Nm at 7,500 rpm
•Desmodromic distribution
•Dual Spark (DS) ignition
•Anti-knock sensor
•Euro 4 compliant

New generation
By independently adjusting both the timing of the camshaft controlling intake valves and the timing of the camshaft controlling exhaust valves, the Ducati Testastretta DVT engine optimises high rpm performance for maximum power, while at medium and low rpm, it ensures smooth operation, fluid power delivery and high torque. This means that the vehicle's engine will adapt its characteristics according to rpm values, while always ensuring compliance with exhaust emission standards and keeping fuel consumption low.

When a new engine is designed, one of the most critical parameters to determine its 'character' is the amount of intake and exhaust valve overlap. The overlap angle is defined as the interval of crankshaft rotation, expressed in degrees, during which both the intake and exhaust valves are open at the same time. This overlap occurs between the end of the exhaust stroke and the start of the intake stroke and is normally a single value that does not change. However, the Testastretta DVT is not limited by a fixed valve overlap angle.

Instead, the Ducati Testastretta DVT's overlap angles can change, thanks to the introduction of the DVT (Desmodromic Variable Timing) system: a valve timing adjuster fitted to the end of each of the two camshafts per cylinder head. The DVT system consists of an external housing, rigidly connected to the cam belt pulley, and an internal mechanism which is connected to the camshaft and can independently rotate inside the housing. This rotation of the internal mechanism, either in advance or in delay with respect to the housing, is precisely controlled by varying the oil pressure in special chambers of the mechanism. The oil pressure is adjusted by dedicated valves and the timing of each cam is dynamically controlled by a sensor located in the cam covers.

Desmo attraction
The Ducati Testastretta DVT engine uses the unique valvetrain that made the Bologna-based Italian manufacturer a world-famous name. Thanks to this unique system, the intake and exhaust valves are closed mechanically and with the same level of accuracy as they are opened. The term Desmodromic derives from the Greek words “desmos=link” and “dromos=stroke, travel”; in mechanical engineering terms, it refers to mechanisms designed to actuate valves both in the opening direction and in the closing direction.

This system, used in all Ducati models, has also been extremely successful in Ducati Corse World Superbike and Desmosedici MotoGP motorcycles. In the development of the DVT, the Desmodromic valvetrain represents a major advantage over a traditional spring based timing system; the actuation of the valves at low engine speed requires less force, not having to compress the valve springs, this allowed Ducati to limit the size of each cam phaser with obvious benefits in terms of lightweight construction and compactness for a perfect engine integration.

Ever-present strong torque
With its 106 mm bore and 67.9 mm stroke for a total capacity of 1,198 cm³, the newborn Ducati Testastretta DVT engine produces a maximum power of 160 HP at 9,500 rpm, and a torque up to 136 Nm at 7,500 rpm with a perfectly linear delivery curve. The torque is already 80 Nm at a low-range value of 3,500 rpm, and it remains consistently over 100 Nm between 5,750 and 9,500 rpm.

Despite an increase in power, however, the DVT system has a positive impact on fuel efficiency, with an average 8% reduction in fuel consumption compared to the previous non-variable configuration.

Ducati's permanent research and development efforts applied to injection systems have repositioned the fuel injectors to target their spray directly onto the rear of the hot intake valve, instead of the colder surface of the intake port wall. The resulting enhanced fuel vapourisation improves combustion efficiency and ensures a smoother delivery.

The Testastretta DVT is equipped with a Dual Spark (DS) system that uses two spark plugs per cylinder head, providing a twin flame-front that ensures complete combustion across a very short period of time. Each spark plug is managed independently, to optimise efficiency throughout the rev range and in all conditions of use. An anti-knock sensor ensures safe engine operation even while using lower octane fuel or in situations potentially detrimental to combustion efficiency, e.g. at high altitude.

In order to achieve a smoother cycle-to-cycle engine operation, Ducati has used a secondary air system similar to that developed for extremely high-performance engines. This optimizes combustion without increasing emissions, by completing the oxidisation of unburned hydrocarbons to reduce HC and CO levels.

Suitable for any condition
Thanks to all these characteristics, the Ducati Testastretta DVT sets new standards for Ducati twin-cylinder power units and introduces new, revolutionary parameters to achieve the best possible balance among maximum power, smooth delivery, low-rpm torque, low fuel consumption and reduced emissions, thus standing out as the most technologically advanced Desmodromic twin-cylinder engine on the planet. The Ducati Testastretta DVT system does not affect the valve clearance adjustment schedule, and in fact requires major services only at ownership-friendly 30,000 km intervals. This engine can be used in a wide variety of conditions and locations, while always delivering top performance and exceptional user-friendliness, safety and sheer excitement

[thorn14]

Old vs new graphs...





Closest comparisons I found as far as graphs, the scales are different and proportions weird, but it's illustrative of these gains for the visually inclined.

[DarkMonster620]

first bike to get it will be MTS1200 . . .

[HotIce]

Very interesting ... 

[Düb Lüv]

That didn't take long for the volkswagen group to put their junky vvt system on a ducati

[xcaptainxbloodx]

That didn't take long for the volkswagen group to put their junky vvt system on a ducati

except that this has really nothing in common with that system...

DVT=/=VVT

[Düb Lüv]

It's the same system vw uses no matter what ducati calls it. Started on the 24 valve vr6 engine in the states.  Camshaft adjusters controlled by oil pressure advancing and retarding the camshafts from the engine computer.

[Speeddog]

It's the same system vw uses no matter what ducati calls it. Started on the 24 valve vr6 engine in the states.  Camshaft adjusters controlled by oil pressure advancing and retarding the camshafts from the engine computer.

Is it a full range control, or just two position?

[Düb Lüv]

Is it a full range control, or just two position?

Full range. It's constantly adjusting the camshafts throughout the rpm range while the vehicle/bike is in motion.

[ducpainter]

Why don't you like it?

[Düb Lüv]

Why don't you like it?

Well this maybe different with motorcycles than cars. At work, majority of people reglect oil changes/service. Since this system is oil pressure controlled, there are tiny oil passages and screens that become clogged and cause running problems and CELs. The gears are very expensive and possibly won't have a performance camshaft option.

[Düb Lüv]

Sorry for being a copy and paste person but here's an explaination of the vw system.

[Howie]

My experience (including my own car) is these problems are rare if oil oil changes are not ignored and VW spec oil is used.  The problem is also not unique to VW.

[xcaptainxbloodx]

Well this maybe different with motorcycles than cars. At work, majority of people reglect oil changes/service. Since this system is oil pressure controlled, there are tiny oil passages and screens that become clogged and cause running problems and CELs. The gears are very expensive and possibly won't have a performance camshaft option.

you cant really say the system is bad if the reason its bad is that people don't take care of it.  any machine will fail if the recommended services are ignored.


There is enough difference in the engines (besides the DVT/VVT) that you cant really compare the two yet. obviously they are going to share R&D and as a result have a similar method, but the systems are still very different.  service, use,ELECTRONICS and construction are very different between a  1998 VR6 and a 2015/16 multistrada.

no cam options would be a bummer but Ducati hasn't offered a performance cam option since, what? 2009? if you want a more aggressive profile you already have to go custom.

[Rob Hilding]