There have been periodic rumours about Ducati releasing a V4 road super-sport before, but this time it looks like it’s for real. Claudio Domenicalli has confirmed that they are working on such a thing, and a special edition 1299 Panigale has also been announced which looks suspiciously like a going-away party. But what’s the big deal? If anyone else were coming out with a new V4 super-sport it would be news worthy, but would not garner nearly the fanfare that it has with Ducati.

Well, the reason is this: Ducati has identified itself as the maker of L-twin motorcycles. It’s essentially been the definition of Ducati for some time now. Not V-twin, L-twin. It’s been their unique stake in trade for decades. They’ve doubled down on this curious engine configuration time and time again with each subsequent release of a new bike, they re-affirm their commitment to this peculiar choice. It’s a little bit like that kid in grade school who kept getting the same bucket head haircut because he defended it strenuously against ridicule, and was not willing to concede it looked stupid in the first place, so ended up getting stuck looking like he was trying to conceal a cranial deformation. Why is the L-twin a peculiar choice?

I’m glad you asked…

In the post WWII days Ducati was making single cylinder bikes with one upright cylinder. This was the state of the art at the time and was a pretty rational choice. The exhaust side of the engine faced forward so you got the most fresh, cool air on the part of the engine that was under the most thermal stress; the exhaust side of the cylinder head. If this is the target for the bulk of your cooling, the other way to accomplish it is to lay the cylinder flat, pointed forward so the crown of the head gets the extra-virgin cooling blast. The forward facing laid down single was also popular at the same time, though more popular in Japan and more popular in very small displacements and particularly two strokes.  It seems a natural progression that if you want to add another cylinder for more power with a minimal new part count, you would just combine the two approaches. This is exactly what Ducati did; one vertical cylinder (with horizontal cooling fins), and one horizontal cylinder (with horizontal cooling fins). Voilà! Now we have a two cylinder engine using only one head design, and one intake manifold design. Much easier that doing a parallel twin; which requires new and expensive cylinder heads and  blocks, in addition to all the other bits.  Makes sense. The biggest problem is that this makes for a very long engine. As long as a single horizontal cylinder engine. This means that to fit the engine behind the front wheel yet to maintain a short and sporty wheel-base, the swing arm has to become quite short. A short swing arm will change jacking forces more dramatically in response to bumps when under power than a long swing arm would. This was not a big issue at the time, as post-war tires had about as much grip as wet shoes on glare ice, and the power outputs were tiny by modern standards. This formula worked really well for Ducati and they committed to it whole-hog.

When the Japanese started delivering their excellent 4 cylinder bikes starting with the CB750 and the Z1, Ducati remained loyal to their L-twin configuration, despite knowing full well that the math clearly showed that a multi-cylinder engine of the same displacement had a much higher potential. “Charm” and “Low end torque” became the bulwarks to hide behind as the redlines of the Japanese multi’s climbed ever skyward, carrying specific output with it. Yet Ducati stayed the course. Even when tire grip started evolving rapidly in the 1970’s, which drove the desire for longer and longer swing arms, which would suppress thrust-induced jacking variations, Ducati stayed the course. In many ways the Panigale is the ultimate expression of this commitment/stubbornness. In an effort to remain competitive against the fundamentally advantaged 4 cylinder engines, Ducati went full-on with their super twin. The new Panigale 1299 has a bore-to-stroke ratio of 1.9:1. Which is insane. A “square” bore is 1:1 and would be typical for your average car. Racing vehicles tend to move over-square (large bore, smaller stroke), as horsepower is closely tied to bore size, while work vehicles tend to move under-square (long stroke) as torque is closely tied to stroke. But 1.9:1 is so over square, it’s essentially like the piston is a dinner plate bouncing on a pea.

For some texture; the famous Cosworth DFV Formula one engine had a ratio of 1.3:1. A modern F1 engine is about the only thing out there to go over 2:1. Engines of these dimensions are high-revving monsters, which tend to struggle to run smoothly at lower RPM; this is because the flame-front of the explosion in the cylinder has a long distance to travel, but moves the same speed no matter the dimensions of the cylinder. This means that in a big bore the frame front takes longer to fill the combustion chamber, so the time to peak pressure is delayed. That long time period also gives opportunity for engine knock to emerge. With big valves and a broad, flat combustion chamber, low rpm cylinder turbulence is poor and inconsistent. This makes for lousy cylinder filling and inconsistent combustion at low revs. Not ideal for a street-ridden machine.

Ducati took extreme measures to get revs out of an engine configuration that is inherently ill suited to rev high. Why? Because a Ducati has an L-twin. They did concede the point finally, in Moto GP and made a V4 Grand Prix bike, but the road bikes remained L-twins… Until now… Maybe. Basically, this is big news because it means the kid with the numpty hairdo just buzzed it all off. Ducati is implicitly admitting that they’ve had it wrong all these years.

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