Du­cati un­leashes the V-4 Pani­gale su­per­bike

Cycle World - - Contents - By KEVIN CAMERON

De­spite the ob­vi­ous rea­son for this story’s ti­tle, I chose it for the Pani­gale V-4’s par­al­lel with Fiat’s 28-liter S.76 rac­ing car of 1910—the 300 hp “Beast of Turin.” Dorna CEO Carmelo Ezpeleta said a few years ago, “Liter-bikes are fin­ished, and they’re not com­ing back,” re­fer­ring to when sport­bike sales col­lapsed dur­ing the Great Re­ces­sion of 2008–09. Are liter-bikes now mythic gi­ants from a past age, des­tined like Fiat’s S.76 to be re­placed by smaller, nim­bler ma­chines? I put this ques­tion to Clau­dio Domeni­cali, the ad­mired and re­spected CEO of Du­cati, a man whose abil­ity has car­ried him up through en­gi­neer­ing, rac­ing, and R&D to the high­est man­age­ment level.

He an­swered that Du­cati’s suc­cess is driven by the com­pany’s abil­ity to bring the lead­ing edge of mo­tor­cy­cling to its cus­tomers. Du­cati must there­fore con­tinue to sat­isfy their ex­pec­ta­tion that the com­pany will re­main the “ar­row of progress.” The fo­cus of V-4-en­gine de­vel­op­ment has been to com­bine great power with ride­abil­ity. This is in con­trast to the tra­di­tional sport­bike torque curve, which is weak at the bot­tom and even in midrange, ris­ing steeply at higher rpm.

The V-4’s max­i­mum torque is 92 pound-feet, and lies in a broad flat zone from 9,000 to 11,700 rpm. The curve is an arc of a cir­cle with a broad, flat on its top. Con­tribut­ing to this flat torque is a mo­tor-driven dual-length in­take sys­tem. When the four bell­mouth ex­ten­sions are lifted, in­take length be­comes 25mm shorter. Each oval in­take port is equiv­a­lent to a 52mm (2.05 inches) round hole. Air­box vol­ume is a large 14 liters. Each pair of throt­tles has its own con­trol mo­tor, and throttle bod­ies are barely an inch high.

Bologna’s twins have ad­vanced the state of mo­tor­cy­cling over four decades, but pressure for change has forced the desmod­romic-valve V-4 Stradale en­gine into

ex­is­tence. Du­cati’s first sea change was from sporty sin­gles to Taglioni’s V-twins, driven by the vi­bra­tion and lim­ited power of one cylin­der. In the Pani­gale 1299 twin, cylin­der bore be­came a tremen­dous 116mm (more than 4-9/16 inches), stretch­ing the lim­its of high-speed com­bus­tion. This now forces a sec­ond great change— adop­tion of four cylin­ders to re­set bore to 81mm to put Du­cati at the top of su­per­bike per­for­mance world­wide.

The new V-4 at 81 x 53.5mm bore and stroke dis­places 1,102.7cc, but a 1,000cc ver­sion for World Su­per­bike will be pro­duced. Like the twins be­fore it, the V-4’s V-an­gle is 90 de­grees, mak­ing a bal­ance shaft un­nec­es­sary. With the two crankpins of its three-main-bear­ing forged-steel crankshaft off­set at 70 de­grees and with cylin­ders fir­ing as 90-de­gree pairs, en­gine sound re­mains close to that of the twins. Du­cati calls this “twin pulse” be­cause each sound pulse is ac­tu­ally two cylin­ders fir­ing 90 de­grees apart. Com­pres­sion ra­tio is 14:1, pro­tected by det­o­na­tion sen­sor. The spring­less desmod­romic ma­chin­ery driv­ing this en­gine’s 16 valves is tightly packed in its heads, and valve-clear­ance ser­vice in­ter­vals are 15,000 miles.

Although horse­power is only one el­e­ment of per­for­mance, ev­ery­one wants the num­ber: 214 hp at 13,000 rpm or, with the closed-cir­cuit-only Akrapovic ex­haust, 226 hp and a 414-pound weight. This en­gine is not work­ing hard at peak power, if we con­sider that max­i­mum pis­ton ac­cel­er­a­tion is 6,350 G at 13,000 rpm—less than in stock 600 Su­pers­port en­gines of the past decade.

Like Du­cati’s present 81 x 48.5mm Mo­togp V-4, this en­gine ro­tates “back­ward” (op­po­site the wheels) to re­duce re­sis­tance to di­rec­tion chang­ing by caus­ing wheel and crank pre­ces­sion forces to par­tially can­cel out each other. As an added ben­e­fit, it also re­duces wheelie and rear-lift ten­den­cies. In many re­verse ro­ta­tors of the past, this has been ac­com­plished with a jack­shaft, but in this V-4, an idler gear does the job.

As in the Pani­gale V-twin be­fore it, the V-4’s re­mark­ably light 142-pound en­gine is a struc­tural chas­sis mem­ber. But as ne­ces­sity has forced upon all builders, the V-4’s chas­sis aims for an op­ti­mum mid­dle ground be­tween ex­tremes. The V-twin Pani­gale’s mono­coque air­box/steer­ing head chas­sis was ini­tially too stiff, but the long-serv­ing and ef­fec­tive steel-tube trel­lis chas­sis was no longer stiff enough for the ris­ing grip of modern tires.

As GP en­gi­neer Mike Sin­clair once put it, “Some­thing must pro­tect the grip of the tires from the in­er­tia of the en­gine.” This isn’t hard to un­der­stand: Leaned over in a cor­ner, when a tire re­ceives a bump im­pact, some­thing’s got to give—if there’s no flex in the chas­sis, then tire grip it­self must give. Then you have a con­trol prob­lem.

Pro­tec­tive flex­i­ble chas­sis ele­ments are now in place: Up front it is four struts join­ing the steer­ing-head box to four points on the en­gine. In the rear, it is blade­like ver­ti­cal ele­ments cou­pling the oth­er­wise rigid sin­gle-sided swingarm to pivot lugs on the back of the gear­box. When I asked Ste­fano Strap­pa­zon, ve­hi­cle project man­ager, about the de­sign of this new forward frame, he said it must pro­vide three ba­sics: bend­ing stiff­ness suf­fi­cient to handle brak­ing force, tor­sional stiff­ness to keep the wheels in plane (pre­vent­ing the up­set of “flex-steer”), and lat­eral flex­i­bil­ity in a de­sired range of val­ues, to pro­vide rider “feel” and sus­tain tire hookup at high lean an­gles and on rough sur­faces.

In ad­di­tion, weight must be con­trolled and man­u­fac­tura­bil­ity guar­an­teed. Com­put­ers now use al­go­rithms that cal­cu­late and adjust stiff­ness with re­la­tion to part di­men­sions at high speed, slightly chang­ing the de­sign at each step. In this way, a de­sign can be made to con­verge on an op­ti­mal so­lu­tion. The V-4’s forward-frame so­lu­tion weighs 9.2 pounds.

In the past, the length of V-twin en­gines has made modern mass-forward weight dis­tri­bu­tion hard to achieve. The 1098 S, for ex­am­ple, was an even 50/50 front to rear, while the 1299 Pani­gale went to 53/47. Now in the more-com­pact V-4 (con­sider the 1299’s stroke of 60.8mm with the V-4’s 53.5), it be­comes the sought-af­ter 54.5/45.5. Cen­tral to achiev­ing this is en­gine ori­en­ta­tion in the chas­sis: In the first V-twins of the ro­man­tic beveldrive era, the front cylin­der was raised only 15 de­grees from hor­i­zon­tal, but in the V-4, that an­gle is 42 de­grees.

The en­gine em­bod­ies the hor­i­zon­tally split crank­case orig­i­nally planned by ot­to­valv­ole cre­ator Massimo Bordi, who de­signed the orig­i­nal four-valve-per-cylin­der 851 V-twin. The four hard-plated closed-deck cylin­ders are

die-cast in unit with the up­per crank­case. This is not an adap­ta­tion from the Mo­togp en­gine but is de­signed for modern se­rial pro­duc­tion. In the Mo­togp en­gine, the four camshafts are driven by spur gears, but for pro­duc­tion, the cam drive be­comes silent chains. Steel chains have re­placed the rub­ber-toothed belts used on past Du­cati V-twins be­cause in­creased dura­bil­ity is re­quired to give both short valve tim­ings (to boost low and midrange torque) and high valve lift (to pre­serve top-end power).

A ma­jor goal of any pro­duc­tion en­gine is ride­abil­ity, so the V-4’s cams have a mod­er­ate 26 de­grees of sym­met­ri­cal over­lap. In gen­eral, the longer the over­lap is made in the in­ter­est of increasing power, the fussier the en­gine’s be­hav­ior.

Steel con­nect­ing rods are side by side on the two crankpins, com­pelling the cylin­der blocks to be off­set as well, with the rear cylin­ders to the right. The cam drive of the rear bank is on the left, and that of the front bank on the right. So that cen­trifu­gal force will help rather than hin­der oil de­liv­ery to the crankpins—oil is fed into the end of the crank rather than bled off the main bear­ings as is usual in auto en­gines. There are four oil pumps: one pressure, three scav­enge. One scav­enge pump re­turns oil from the heads while the other two pull from the two crank cham­bers, all of which re­turn to a deep un­der­engine sump.

Pis­tons are hard an­odized from the pis­ton ring belt up­ward. This not only dis­cour­ages trans­fer of alu­minum to the top ring from the bot­tom of its groove, but it also pro­tects the pis­ton crown from det­o­na­tion’s tiny teeth. These are modern nine-cav­ity forg­ings with short nar­row skirts, mak­ing them ul­tra­strong and also light.

The forward po­si­tion of the en­gine al­lows swingarm

length to in­crease to 23.6 inches (3 inches longer than the 1199 unit, in­ci­den­tally, but the same weight). Part of what makes this length pos­si­ble is tuck­ing the gear­box shafts on a slant, closely under the rear cylin­ders. Swingarm weight is 11.2 pounds. Steer­ing ge­om­e­try is 24.5 de­grees rake and 3.94 inches trail, on a wheel­base of 57.8 inches (that’s 1.25 inches longer than the 1299).

Brake calipers are Brembo Monoblock Stylema 4.30, an evo­lu­tion of the pre­vi­ously king M50 units, which are 2.5 ounces lighter but equally stiff. They fea­ture the cur­rent trend to­ward re­duced fluid vol­ume and in­creased coolin­gair ac­cess (thanks in part to their hol­low cen­tral bridge). Front-brake discs are 330mm in di­am­e­ter. Wheels on the base bike are cast alu­minum, and the start­ing bat­tery is lead acid (lo­cated just be­hind the steer­ing head).

The S ver­sion, as well as the Spe­ciale (lim­ited edi­tion of 1,500 ma­chines), in­cor­po­rates an Öh­lins NIX30 fork and TTX36 shock plus forged mag­ne­sium wheels (sav­ing 2.2 pounds of cru­cial ro­tat­ing weight) and a Lithium-ion bat­tery. The Spe­ciale gets an all-ti­ta­nium Akrapovic ti­ta­nium ex­haust, plus car­bon and bil­let spe­cial parts (bil­let fork crown, hinged clip-ons, ar­tic­u­lated levers, car­bon fend­ers, plus spe­cial at­ten­tion to de­tail).

When the 1098 pro­gram was ini­ti­ated, Domeni­cali had re­cently be­come R&D direc­tor. He an­nounced, “For ev­ery part, you must think about the weight and about the per­for­mance—no com­pro­mises.” One of the big changes in en­gines in the 21st cen­tury has been the ap­pli­ca­tion of cast­ing meth­ods that con­trib­ute to the V-4’s low en­gine weight. Also im­por­tant is the use of mag­ne­sium (only 64 per­cent of the den­sity of alu­minum) for non­struc­tural case and cam cov­ers plus the deep oil sump and forward fair­ing mount/air in­take.

This is what the Du­cati Su­per­bike has be­come: a ve­hi­cle engi­neered for pro­duc­tion (the “af­ford­able ex­otic”) yet in­cor­po­rat­ing the lat­est in­sights from Mo­togp, with style we ex­pect from Italy’s his­toric role as the cross­roads of de­sign. Mo­tor­cy­cle evo­lu­tion never ceases, so there can be no ul­ti­mate. This new V-4 shows Du­cati is de­ter­mined to lead the ad­vance.

TOP LEFT: The in­takes stack up to where the fuel tank would be, mak­ing the en­gine look tall. It’s ac­tu­ally 1.1 inches shorter top to bot­tom than the 1299 en­gine, and 1.5 inches shorter front to back.

ABOVE: The tail of the bike is light, in more ways than one—the rear sub­frame weighs 4.2 pounds. OP­PO­SITE: The en­gine is 1.7 inches wider than a 1299, but the V-4 keeps the waspy Pani­gale shape.

OP­PO­SITE: When asked which part of the Pani­gale V-4 he would hang in his house, the V-4’s de­signer, Julien Cle­ment, said: “The sec­ond panel of the fair­ing, the in­ter­nal one. I re­ally like this con­cept.”

The front sub­frame cradling the head­light and mir­rors is mag­ne­sium and weighs 1.5 pounds—ev­ery lit­tle bit helps.

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