Ducati DVT Valve Technology

Ducati surprised everyone this week when it announced its new Desmodromic Variable Timing (DVT) system, offering a solution to a problem that’s as old as the internal combustion engine itself. The problem is this: static valve timing is always a compromise. Figures that produce good power at lower engine speeds aren’t ideal for higher rpm operation, and vise versa. With DVT, the intake cams and exhaust cams are independently variable, allowing for optimum valve events from idle on up to redline. The system works via valve-timing adjusters built into the cam pulleys—oil pressure, controlled by valves operated by the ECU, determine how much each cam is advanced or retarded.

One of the main factors that influence an engine’s power characteristics is valve overlap. Valve overlap refers to the amount of crank rotation, measured in degrees, during which both the intake and exhaust valves are open at the same time. Overlap occurs at the end of the exhaust stroke and the beginning of the intake stroke, and the amount of overlap has a huge impact on an engine’s performance and character. (It’s significant enough that Ducati incorporated the figure into the name of the engine that powers the current Multistrada and Monster 1200, the Testastretta 11° DS.) More overlap produces more power at higher engine speeds by taking advantage of the inertia of fast-moving intake and exhaust gases. A large overlap figure is good for high-rpm operation, but inhibits midrange power and fuel economy at lower engine speeds. For low- and midrange power, less overlap is desired. DVT allows the valve overlap to be altered based on engine speed, eliminating the compromise that’s plagued engine designers for decades. It’s a beautifully simply system that should increase power and efficiency at all engine speeds.

The new Testrastretta DVT engine is an evolution of the Testastretta 11° DS (dual spark) engine that Ducati introduced in the Multistrada 1200 in 2010. That motor was in turn a street-oriented variation of the 1198 superbike engine, the main difference being that valve overlap was reduced from 41 degrees to 11 degrees. This new DVT engine likely runs the more economic, torque-centric 11 degrees of overlap (or less) at lower rpm and then phases to the 41 degrees of overlap (or more) previously used on the 1198 superbike engine.

The previous Testastretta 11° DS was said to make 150 hp at 9,250 rpm and 91.8 lb.-ft. of torque at 7,500. This new engine, which appears unchanged save for the addition of DVT, is said to produce 160 hp at 9,500 rpm and 100 lb.-ft. of torque at 7,500 rpm, with 59 lb.-ft. available from just 3,500 rpm. Additionally, Ducati says the new DVT engine 8 percent more efficient than the 11° engine.

Just about every automotive manufacturer has an engine with some form of variable valve timing, but the technology hasn’t migrated to motorcycles due to packaging restraints. Honda’s V-TEC—first employed on the 2002 VFR800—activates an additional intake and exhaust valve above each cylinder at a certain rpm, but those valves still operate based on fixed cam timing. Kawasaki's VVT system (employed on the Concours 14) varies valve timing in a similar fashion to DVT, but only for the intake cam.

It remains to be seen how Ducati's system works in practice, but in theory it seems to be a competent and compact adaptation of technology long proven effective in the automotive world. And it makes sense that Ducati has applied it to the Testastretta 1200 motor, which is used in the company's most prevalent street models, including the Multistrada 1200, Diavel, and Monster 1200.

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