Page 2
By Daniel Coe
Images By Tom Riles

Valves of any size will not work without the proper camshafts. The heart of the Testastretta is a newly designed camshaft, which allows for greater lift of each valve. Intake valves have an additional .55mm of higher lift, while the exhausts gained .36mm. Shorter opening duration, higher lift and earlier valve closing resulted in reduced overlap period. According to Ducati engineers, the redesign of the camshafts provided several advantages. One result noted with a shorter duration was an increase of low rpm torque. A significant reduction in the valve/valve-seat impact was also achieved, as well as providing greater reliability of the camshafts themselves. Cam pulleys are now slotted instead of keyed for greater accuracy in timing, also allowing for faster more precise installation and service. The pulley's diameter and belt widths have grown to accommodate a wider more durable belt with less acute bends. This change was done at the request of the belt's manufacturer. To further reduce friction and improve belt life, the lower pulley has been repositioned closer to the base of the cylinder. The new belt has an increased width of four millimeters. Removable valve covers cap the top ends, allowing for easier access and inspection.

The expected advantages of the newly designed engine are greater output and efficiency, increased reliability and easier servicing.

Larger (30 gram), lighter pistons with narrower skirts have been combined with a shorter stroke crankshaft, increasing displacement to 998cc. Gone are the previous "L" style piston rings, replaced by a new rectangular sealer that allows for a ring torsionally stronger and more resistant to flutter than the previous design. Special consideration was given to the face of the ring. The upper sealers are newly shaped to accommodate the constant thrust loads and rocking movement of the redesigned slipper-type pistons. This may be particularly necessary because shorter pistons have a greater tendency to rock. New three-piece scraper rings complete the sealing tasks. To further complement the improvements in the rings and ring life, the pistons ring-lands have been anodized to prevent galling and minimize wear. The goal of reducing friction in the area of moving parts has been accomplished by the narrowing of the piston skirts and ring changes.

Shorter, more compact heads allow space for the larger volume air-box atop the Testastrettas accommodating power plant. Totally new, single spray "shower type" fuel injectors have been relocated above the throttle valves. Fuel-air mixture now exits the injectors at a tighter spray pattern of fifteen degrees. Actual mixture output has increased from 3.52 to 5.5 grams per second. The change of injector location, spray angle and intake length creates a more desired mixture turbulent into the combustion chamber. The previous dual injector units were side-fed, emptying virtually into the opposing walls of the 50-millimeter throttle bodies. New 54-millimeter throttle bodies are now used due to the changes and improved efficiency below. The overall length of the intake venture between velocity stack and valve has been shortened a whopping forty millimeters. Cugnetto explained the goals in the areas of fuel supply were to maximize intake-wave efficiency, keeping both speed and turbulence into the redesigned combustion chambers as high as possible. This is an impressive achievement given the substantial increase in throttle-body diameter. To capitalize on everything, engine compression was raised from 11.2 to 11.4:1.

The transmission has been changed, with the 998 inheriting the exact ratios from its high performance predecessor, the 996SPS. The older SPS benefited from a close ratio option that now suits the higher revving Testastretta. Claimed horsepower is now 123 @ 9,750 rpm, up from 112 hp @ 8,500 rpm. Torque figures also are reflected in the changes, with an increase of 4.3 ft lbs at the same rpm as the 996 (8,000). The final update to the business end of the 998 has the transmission output main shaft gaining an additional bearing to accommodate the higher performance of the redesigned "V."