Cycle News - Archive Issues - 2000's

Oucati 996R Testastretta cise in faster turns - I actually thought it turne~ in better than the Bayliss racer I rode on the same track three into the tarmac and delivering great drive, with no bucking or pumping thanks to the ideal setup of the rear months back. And getting on the gas for a hard drive out of the last second-gear turn leading onto the main Ohlins. Not sure the front Michelin has as much grip as its Dunlop or Pirelli rivals, though - but the 996R's straight was sportbike satisfaction overall handling sets a standard that's worthy of the benchmark performance of its Testastretta motor. supreme - it just gathers speed, and goes, with the rear Michelin digging In developing the new-generation Testastretta version of their established desmo V-twin family of engines, Ducati engineers, headed by Massimo Bordi - father of the desmoquattro concept, ever since it formed the subject of his Mech.E university thesis back in the early '70s - focused on making significant improvements to their existing design, rather than starting afresh with a clean sheet of paper. Evolution, therefore, rather than revolution - a fact which Bordi, who has since left the company in favor of a top-level executive career in charge of Italy's largest tractor manufacturer, was at pains to emphasize at Intermot last September, when he personally unveiled the latest and, for the time being at least, his own final contribution to Ducati's desmodromic dynasty_ Many 'Ducatlsli' may well consider the Testastretta to be Bordi's legacy to the company whose fortunes he's been so completely identified with over the past quarter century. "While it's in every way a completely new engine which shares scarcely a single existing part with any of its predecessors, the Testastretta has its roots firmly set in our established desmoquattro heritage," said Bordi, when he first showed the new engine some months ago, in its prototype phase. "We briefly examined reducing the cylinder angle, or a more compact installation - but apart from the technical disadvantages, such as the need for balance shafts to eliminate the consequent vibration not present in our perfectly balanced 90-degree V-twin layout, we also decided this was a mistake in terms of philosophy. Same thing with a nondesmo valvespring engine - every time Porsche tries to change its Boxer engine layout, nobody buys it and they end up returning to their roots. Well, it's the same for Ducati - and that's why we opted for evolution, not revolution, in developing the Testastretta. We set out to make our established motor still better, and to provide the basis for even greater performance, in the future." That explains, then, why various alternative formats for the new-generation Ducati Superbike engine were all discarded - such as any which didn't feature positive valve operation, or the 75-degree V-twin design that was certainly drawn up, then discarded, or revised layouts for a 90-degree format but with the cylinders rotated around on the crankcase like on the Suzuki TLl 000 or Honda RC51, in order to reduce the overall length of the engine for a more compact installation and thus more ideal weight distribution. Same thing for the Honda-type gear camshaft drive or Suzuki's modular gear/chain system, or even the pneumatics and especially electromagnetic operated valve gear that many believe must inevitably appear on high-performance four-stroke motorcycles - especially those bringing leadingedge four-stroke technology to the streetbike customer, as Ducatis do. Still, for the time being at least, this is a Ducati engine in every traditional sense - but incorporating the most modem design philosophy, especially in terms of thermodynamics. The Ducati desmoquattro engine for the 21st century is therefore a liquid-cooled 90-degree L-twin like its predecessors, with the cylinders rotated only slightly backward by 10 degrees in order to permit gravity oil scavenging from the front cylinder, and with toothed belt camshaft drive to the twin overhead camshafts located in the all-new cylinder heads. The design of these, in a departure from established Ducati tradition, was sub-contracted to an outside consultant, retired Ferrari design engineer Angiolino Marchetti, who sadly died soon after completing his work. As the former head of the Maranello drawing office, Marchetti's experience in helping design the abortive V-12 Formula One desmo engine (complete with a total of 96 opening and closing rockers!) which Ferrari built but never raced in the late-'80s, surely played a key role in the design of the Testastretta cylinder heads. 22 APRIL 4, 2001 • cue • • In fact, I'll be very surprised if this is Ducati's next-generation back-to-back tests with other pretenders to the crown of all-round engine, in what is essentially an 8year-old 916 chassis. As an interim sportbike excellence, like the Suzuki GSX-R750, Honda RC51/SP-1 and MY Agusta F4, don't reveal the 996R as setting new standards for others to halfway house to the next generation of desmo dominance, the 996R is already pretty damned fine: How much better still will the all-new 999 aim at. It really is that good - and the worrying thing for its rivals are that end up being, with this engine, when it comes on line in a couple of years? 1:11 To this extent, the link between Ducati and their Cava!lino neighbors just under 20 miles away· whose wind-tunnel facilities they've been using for the past four years - is a very real one, in terms of the Testastretta's evolution. Although the basic architecture of the wet-sump 996R motor is therefore essentially unchanged from its SPS predecessor, for the first time since the Pantah engine introduced belt-drive technology to the Ducati range back in 1977, an all-new crankcase design is employed in the Testastretta, known within the company as a 'coppa bassa', or 'bottom cup' design. That's because of the wedge-Shaped sump incorporated as an integral part (so, not bolted on) of the extemally reinforced crankcases, sandcast at present to speed up development of the first 500 limited-edition versions, and still vertically split as on all previous Ducati V-twin engines: Ducati engineers cite the difficulty of featuring a horizontal split while still retaining the Ltwin format, with a near-horizontal front cylinder, as the reason for this. The purpose of the 'coppa bassa' is to ensure constant oil flow by preventing the pump that's immersed deep within it from sucking air under the G-Ioads caused by cornering or braking - or wheelies! Yes, Ducatisti, you can 'now lift the front wheel of your desmo Vtwin with impunity - as if that ever stopped you before! Set within the crankcases which don't have any provision for a side-loading gearbox: the six-speed transmission is broadly unchanged, and access still requires splitting the engine - is a plain-bearing crankshaft essentially similar to the 996SPS's, except for one thing: it has a shorter stroke, matched to the bigger bore of the slipper-type Asso forged pistons mounted to Pankl titanium connecting rods, and running in Nikasil cylinders. This is the Testastretta's first major difference compared to its 94 x 66 mm predecessor: the new bike measures 100 x 63.5 mm, in pursuit of higher revs in Superbike guise, and the extra power that comes with them. Bordi's experience in getting his Supermono single, which also shared a 100mm bore, revving to over 12,000 rpm quite safely, helped prove the viability of this layout for a V-twin application. Yet those revs would";'t deliver that extra horsepower without the more free-breathing Marchetti-designed heads, which have a flatter 25-degree valve angle for the paired valves, rather than the 40-degree layout of the older engine. The 2mm bigger cylinder bore and flatter combustion chamber permit the use of oversized valves (inlets are now 40mm, up from 36mm - and exhausts 33mm, instead. of 30mm), and though compression is unchanged at 11.5:1 in street guise, there's now extra space for that to be increased, in pursuit of more power. The bigger pistons are actually 30 grams lighter than their 98-bore predecessors, and feature a single long relief in their flat tops, rather than the individual valve pockets of before; while still employing three Japanese-made rings, as previously, their oil ring has three separate segments, instead of a single spring-loaded device - this substantially reducing blow-by oil losses, says Ducatl. The narrower valve angles and bigger valves of the Testastretta wouldn't have been feasible while still retaining desmodromics, without a new approach to the geometry of the valve operating system - no room between the twin overhead camshafts for all those eIght rockers, otherwise. This meant Marchetti had to completely revamp Bordi's previous design, which featured the opening, finger-type rockers positioned directly above the closing, forked rockers inboard of the camshafts. He did this with a new layout which sees the opening cam followers relocated outward to the front and rear edges of each cambox, while all rockers and followers are made substantially smaller and therefore much lighter than before, and the narrower central cast-steel sparkplug tubes each now contain a single 10mm plug rather than the 12mm ones on the old desmoquattro, and employ Fl-type stick coils attached to each plug cap. Interesting that Ducati sees no need for the dual ignition featured on their rival compatriot Aprilia V-twin's Cosworthdesigned cylinder heads, either. All this makes the whole cylinder head smaller dimensionally in every way (the word 'stretta' in Italian means slimmer, as in diet, as weB as narrower in terms of width!). This is helped by the removable car-type valve covers, which reveal bolted down camshafts belt-driven as before, but now rotating directly in plain metal bearings, rather than the previous roller bearings that were both heavier and bulkier. This and all the other detail attention to saving weight and space means that the more compact Testastretta engine weighs just 156.2 pounds, almost seven pounds lighter than the current 996SPS, in turn contributing to a 14.9-pound overall weight reduction on the complete bike: the 996R weighs in at 411.4 pounds half-dry - so with oil/water/battery, without fuel. Uke the 2000 World Superbike Manufacturers title-winning 996 works Superbike, the Testastretta features a single centrally-positioned, external FI-type spray injector per cylinder (rather than the total of three, or previously two, used before, some beneath the throttle butterfly) for its Marelli EFI, fed by two 54mm throttle bodies with elliptical chokes, rather than the 50mm cylindrical-choke ones used on the SPS, and controlled by an ultra-compact, new-generation Marelli ECU which alone is responsible for 1.76 pounds in weight savings, as well as delivering much greater management efficiency. Marchetti's new, much straighter, steep downdraught cylinder head porting sees the mixture get a much cleaner hit at the valves than was the case with its curved predecessor and equally enhanced is the exhaust porting, which is an equally straight updraft design which will surely optimize getting those hot, burnt gasses out into the larger-diameter stainless-steel exhaust quickly. The ex-Ferrari designer made good use of his proven Formula One experience in penning the all-important top end of the new-generation Ducati engine, producing a pair of cylinder heads that are more compact and lighter than before, but yet, in spite of the flatter valve angle, are no taller/longer than the previous design - so don't impact on installation and weight distribution. Combined with Ducati's 15-year in-house empirical experience on desmoquattro evolution, the resuit has been to produce a power unit that has future potential for racing, as well as everyday excellence for the street, written all over its design. But - it's still very recognizably a Ducati - and it goes like one, too.

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