connection Glen Smale discusses racing engine con rod technology with specialist manufacturers from around the world

Transcription

1 Making he connecion Glen Smale discusses racing engine con rod echnology wih specialis manufacurers from around he world Making he connecion necessary beween he op end and he boom end of he racing engine solid ye as ligh and efficien as possible has never been more crucial han i is oday. Increased pressure on performance and durabiliy has forced connecing rod manufacurers o consider exoic maerials and fuurisic designs in he pursui of oal performance. Maerials Wheher produced from aluminium, seel or ianium, forged or bille, con rod maerials and manufacuring processes differ from one supplier o he nex. Brian Crower, Managing Direcor of Brian Crower, Inc in San Diego, California says: Aerospace grade 4340 seel is our preferred maerial for mos connecing rod applicaions. Some manufacurers use forged blanks and hen machine o a bille finish while some machine from fla bar. Crower noes ha 4340 seel rods are cos effecive, reliable and deliver a ime esed soluion for high horsepower applicaions. Aluminium rods are used for cerain disciplines like drag racing, where high boos and/or nirous are commonplace. While seel and ianium are sronger in erms of overall ensile srengh, he aluminium alloy delivers he required give during violen operaion. However, he aluminium rod is essenially a disposable par, requiring frequen replacemen. Compared o seel, ianium is a grea choice if you re spending oher people s money, noed Crower. A nearly $600 per rod, he lighweigh properies of he maerial are normally far ouweighed by he drasic increase in he price of aerospace qualiy 6AL4V ianium alloy bu i is a very nice rod for he price. Sefan Asplund is Managing Direcor of MX Composies AB in Linköping, Sweden a company ha makes con rods in aluminium based Meal Marix Composie (MMC). The increased specific siffness in hese maerials compared o convenional maerials such as seel, aluminium and ianium makes i possible o achieve significan weigh savings. We can make savings of 50%, or of 25% when compared o ianium due o he high specific srengh of our maerials, Asplund explained. This weigh saving on reciprocaing and roaing mass has a grea impac on engine performance, as power is increased hroughou he rev range wih reduced fricion and vibraion. Asplund noes ha he combined effec is a compleely ransformed engine characer ha runs more smoohly wih a sofer and quicker hrole response. Bushing crower 50

2 Arrow Wih inpu maerial comprising forged plaes, he MX Composies MMC con rods are machined by a paened High Speed Machining mehod. According o Asplund his resuls in cos effecive manufacuring and ousanding finish. The fine surfaces creaed by he machining mehods make i possible o run hese con rods wihou bearings and bushings. According o Cindy Verkooij, Markeing and Promoions Manager of Carrillo Indusries in San Clemene, California: Carrillo has been and remains primarily a seel connecing rod manufacurer. We do employ oher maerial ypes when he operaing parameers sugges an improvemen or necessiae he properies ha can be obained from MX One-piece nonferrous maerials. Tianium is someimes used by Carrillo in applicaions where weigh is he primary driver in he design. Mos of he Ti found in connecing rods is from he 6AL-4V family, alhough Carrillo has made rods using varians of 6-4. However, Ti has never been he low cos alernaive and is generally less durable han seel. The design requiremens of aluminium con rods primarily cenre around weigh and dampening issues. The dampening effec is driven from he relaively low Young s Modulus ( siffness ) of aluminium as compared o seel or Ti. The lower siffness can also creae difficulies in conrolling he cener-o-cener (pison-crank) disance of he rod in ension as well as bore inegriy, Verkooij explained. However aluminium also requires a comparaively large cross-secional area o achieve he necessary srengh, puing space (clearance) a a premium. Carrillo s Gen IV high-srengh seel is an excellen maerial for con-rods and would be used in applicaions ha require high srengh, low weigh and durabiliy (faigue life), and given space limiaions. Verkooij oulined ha he yield srengh of his ype of maerial would sugges a possible reducion in cross-secional area hroughou he rod, as long as aenion is paid o he modulus. A properly designed and manufacured forging can opimise he properies of he maerial o he con-rod design and reduce manufacuring ime. By opimising he grain flow of he maerial around he crank-side (big end) of he con-rod, his increases performance. Verkooij summarises: Seel is probably he bes choice for connecing rods as many race series prohibi he use of oher maerials anyway. There are insances where oher maerials should be employed, bu his generally leads o higher coss. Roslyn Arnold, Sales Manager a Arrow Precision Engineering Ld in Hinckley, Leicesershire, says: Arrow uses EN24V for he vas majoriy of our seel rods. This is double air re-mel seel ha we have drop forged, ensuring a beer grain srucure and lower sulphur conen (0.25%), which means fewer inclusions and fauls. When forged, imperfecions are reduced o an absolue minimum, ensuring consisency and i is suiable for mos race applicaions. Arrow uses 6AL-4V ianium forgings in exreme performance siuaions such as World Superbikes, where a ligh drive rain and low reciprocaing weighs gives insan hrole response and much lower gyroscopic forces, allowing he bike o urn in quicker. A 30% weigh saving over seel makes a huge difference o he reciprocaing mass of he rod and cap assembly, however hey 51

3 THE ARROW PRECISION FILE THE BRIAN CROWER, INC. FILE Connecing Rods, Crankshafs, Flywheels, Cam followers, Shims and Valve guides. Also disribuor for ARP Faseners World Rally Cars, Le Mans Series, Formula Three, Touring Cars, World and Briish Ian Arnold Superbikes, Speedway, Hillclimb, Classic and Vinage and many many more Hinckley, Leicesershire, England Managing Direcor: Ian Arnold Producion Direcor: Jeff Kiron Design Engineers: David Whibread, David Currie Technical Sales: Russell Towlson Toal workforce of 65; racing is 80% of business Founded by engineer David Arnold in His son Ian ook over as Managing Direcor in 1997 and he company has gone on o global success. In July 2006 Arrow Precision bough he business and asses of D. Kiddie Engineering Ld in and hereby successfully added crankshafs o he produc range. Sill privaely owned UK and Europe, USA, Ausralia and Asia High performance, inernal engine componens including connecing rods, camshafs, crankshafs and assored valve rain pars Circui, rally, drag, drif, ime aack and sree Brian Crower performance San Diego, California, USA Managing Direcor: Brian Crower Technical Direcor: Dusin Spencer Chief Tes Engineer: Arhur Yang Dusin Spencer Toal workforce of 15; racing is 75% of business Founded by Brian Crower, formerly of Crower Cams, o produce high performance producs for lae model engine plaforms. Dusin Spencer has spen 10 years a Crower in an Arhur Yang R&D capaciy Covering all inernaional markes including Europe, Asia, Ausralia and he USA need a lo of care and regular checking for ovaliy. Arnold again: We have made grea srides in he area of fasener reenion, which is he Achilles Heel of ianium rods. Where mos ianium rods use a bol o reain he end cap, we use a sud and nu assembly, hus allows he correc srech o be achieved wihou worrying abou hread galling. Based in Long Beach, CA, Venolia Pisons and Rods produce rods for Chevrole, Ford and Chrysler engines and forgings vary in srucure due o he applicaion. According o Venolia: In drag racing, he choice of maerial for connecing rods comes down o seel and aluminium. Seel rods have become very popular in midlevel sporsman racing. They do have heir limiaions, heir bigges problem is weigh. Typically, a seel rod for a large cubic inch engine could weigh as much as 1200 grams and as he rod becomes longer and heavier he sress on he bols and cap increase. As a resul, seel rods are ough on pisons he make he pison more suscepible o cracking where he pin boss joins he skir. Aluminium con rods on he oher hand weigh abou onehird of seel counerpars, and because of his weigh advanage, manufacurers can use a hick cross-secion wihou a big weigh penaly. According o Venolia anoher advanage of aluminium rods becomes apparen in he condiion of he bearing and he wris pin when he engine is disassembled. Venolia repors ha all of heir aluminium rods are made from Alcoa bar sock (7075-T6). In heir manufacuring process, each bille is heaed and mechanically forged wih a 3000 on press o obain he ighes grain paern in he maerial, which is hen CNC machined o provide a precision finish. Alernaively, seel connecing rods provide longeviy a an affordable price bu as he horsepower and engine speed increases aluminium rods become a more pracical choice. According o Glenn Salpaka, Presiden of Falicon Crankshaf Componens in Clearwaer, Florida: The curren engine design rend ha we are seeing is for small, compac, and lighweigh engines. These shor sroke/high RPM engine designs use bore/sroke raios ypically :1 and spin a very high engine speeds - 14,000 o 18,000 rpm. This has necessiaed he use of lighweigh reciprocaing componens (rods and pisons) and has inroduced aerodynamics in crank and rod design. Through experimenaion wih lighweigh composie maerials, Falicon has developed low ineria crank and pison designs conneced o lighweigh composie rods allowing speed increases of 500-1,000rpm wihou risk of componen failure. The Falicon Knife oval beam rod design is he ideal shape o forge difficul o machine, exoic maerials like TI 6246 ianium or AMC 225 XE. We are using his ulra-ligh composie aluminium alloy maerial in an engine design which uses roller bearing mains and rods wihou any inser or bearing. The maerial iself is an excellen bearing maerial and allows an exra margin of design possibiliy and we can increase he cross secion for srengh or produce a ligher weigh, more compac design o fi our need, Salpaka explained. Howards Cams in Oshkosh, Wisconsin, manufacures wo ypes 52

4 THE CARILLO INDUSTRIES, INC. FILE THE FALICON CRANKSHAFT COMPONENTS, INC. FILE High performance cusom and prooype connecing rod manufacurer o virually every major auomoive and moorcycle venue Carrillo has supplied componens o he winners of virually all global moorspor Vince Cipresso venues including Formula One, Two and Three, NASCAR, Champ Car, IRL, World Rally, Superbike, Trans Am, Can Am, GTP, SCCA, Sprin Cars, Modified, Land Speed Record and so on San Clemene, California, USA Dieuanh Phan Managing Direcor: Vince Cipresso Operaions Direcor: Dieuanh Phan Chief Engineer: Gerhard Oerel Sales Direcor: San Bigney Markeing and Promoions Manager: Cindy Verkooij Cusomer Service Manager: San Bigney Richard Bachelor Toal workforce of more han 50; racing is over 75% of business Founded by noed aerospace engineer Fred Carrillo in his rue passion was he mechanics of moorspors. The Dover Corporaion, under he organisaional Cindy Verkooij umbrella of Performance Moorspors, Inc (PMI) acquired Carrillo in 2001 Covering he global marke, concenraing on he USA, Europe and Ausralian coninens of seel connecing rods 4340AQ maerial formed in a closed die forging process wih 100% CNC machining and 4340AQ powder maerial formed in a closed die powder forging process o produce a powder forged connecing rod. The laer is no 100% CNC machined because his process enables close olerances o be held, and Fracure Cap Technology enables his cap-rod o reassemble ogeher perfecly wih no need for alignmen sleeves. Conrary o popular belief, hese rods are compleely rebuildable by using readily available oversize bearings from all he popular bearing manufacurers. Rober Lou says: Proper hea reamen is criical o he life of a seel connecing rod. Sress Proof Seel Sleeves for cap-rod bol alignmen and reliable faseners such as hose from ARP are very imporan. Surface Preparaion and Coaing Surface preparaion and coaings can be imporan in he durabiliy of con rods, bu no everybody agrees wih his echnology. Brian Crower expands on his: Surface prep would include hea reaing, Manufacurer of con rods, small engine (Power Spors indusry) crankshafs, adjusable cam chain sprockes and bille cluch componens. Also boom end componens for wo and four sroke engines up o four cylinders plus engine design and Glenn Salpaka prooype developmen and OEM crankshaf repair and modificaion Producs for all forms of moorcycle, ATV, waercraf and snowmobile racing; half of he company s marke is he professional engine builder or race eams Clearwaer, Florida, USA Raphael Paula Presiden and Owner: Glenn Salpaka Markeing: Raphael Paula 20,000 square fee lean manufacuring faciliy. Toal workforce of 20; racing is majoriy of business Founded in 1976 by Tom Falicon; privaely owned by Glenn Salpaka since 2000 Sales a all levels: reail, dealer and disribuor, worldwide. Falicon does business wih almos every moorcycle dealership in he USA. Expanding coverage in he European and Medierranean marke plus disribuors in Ausralia, New Zealand and Japan finishing, and coaings really are only required for he big end sides of he connecing rod on ianium. Crower uses a Teflon based coaing ha prevens he ianium from galling iself. All oher coaings are for peace of mind, i doesn necessarily hur bu he verdic is sill ou as o wheher here are any benefis aside from helping you sleep beer a nigh, Crower added. Tolerances and rueness are major concerns and he big end housing bore needs o be sized o provide adequae bearing crush on he crank pin wih clearances ranging from 0.045mm o 0.063mm while following proper fasener orque procedures. Added value feaures ha we include in our BC rods are an exclusive oiling groove in he bushing ha delivers more oil o he criical pin area as well as he choice of ARP Cusom Age 625+ bols or ARP2000 faseners depending on usage and horsepower requiremens, Crower explained. Carrillo agrees ha surface finishing is an imporan parameer wih respec o he faigue life of a con rod, and he higher srengh maerial used, he more criical he surface finish. Verkooij explains: In mos cases, a faigue crack iniiaes from he surface and propagaes due o local ension sress. Wih sho peening he ouer surfaces of he connecing rod, a compressive sress is induced ino he surface, which acs as an inhibior for faigue cracking. 54

5 The sho peening parameers need also o be adjused for differen maerials in order o gain maximum benefi. The ypical deph for he compressive sress zone in seel achieved hrough sho peening is ~0.006in. Wih he process of laser peening, he compressive sress reaches abou four imes as deep ino he maerial however i can only be applied on specific areas on he rod. This echnology is expensive and is only suiable for applicaions operaing on heir absolue limi wih igh conrol of all boundary condiions. The surface roughness on he pin end inner diameer should be low o reduce fricion beween wris pin and small end wihou sacrificing he abiliy of oil reenion. Typical values in he range of Ra 4-10µin are achieved hrough honing. However, ribological sysems like he Pin End are very complex, and heir funcion no only depends upon he fricion parner (wris pin), bu also on he engine lubricaion sysem, he oil, he siffness of he componens and many more facors. The use of DLC coaed wris pins allows running he PE wihou bushing. Assuming sufficien oil supply o he small end, no special coaing is required in he PE ID. A bushed PE sill allows beer serviceabiliy han a seel-on-seel rod, Carrillo repors. Anoher frequen poin of discussion is he surface finish of he flanges. Carrillo rods used o offer a sho peened flange as sandard, bu changes in he producion process have allowed hem o respond o increasing requess for a machined flange finish. However wo schools of hough prevail: higher fricion due o higher roughness of he sho peened surface versus lower fricion due o beer oil reenion on he sho peened surface. These heories are fighing each oher and no engine performance daa on a direc comparison basis is available o prove eiher one of hem. According o Carrillo, ianium is an excellen rod maerial due o he good Youngs Modulus o srengh raio, bu when i comes o fricion, i performs relaively weakly. The reason for his is he meal s endency owards galling, bu several coaings are available o help overcome his weakness such as DLC, Tungsen Carbide and Tianium Niride. For hrus faces, Carrillo has had good success wih DLC coaings, however he pin end ID is a more criical area and he company is currenly invesigaing differen coaing opions for bushingless Ti rods. Hardening of he bore ID s (mosly achieved hrough Case hardening) is applied for connecing rods running on roller bearings. The high local sress in he conac area beween he rollers and inner diameer of he bore requires high hardness levels for wear and galling resisance. Hardening he enire rod is o be avoided since he higher hardness also causes embrilemen making he rod less forgiving for any ype of surface imperfecions. According o Arrow hree facors deermine he performance of a compeiion seel rod: weigh, srengh and balance. Over he pas couple of years many small bu significan advances have been made in he design and manufacuring process, making is rods ligher and sronger. Ros Arnold explains: One of he mos imporan of hese seps has been he inroducion of fully auomaed peening. I is vial o harden he surface o an exacing sandard, removing sress raisers and aaining an even surface hardness righ across he rod. We have run sauraion ess o deermine he opimum exposure o he process THE GIANNONE PERFORMANCE S, INC. FILE Specialis in Cusom Aluminum Connecing Rods NHRA, IHRA Colorado Springs, Colorado, USA Managing, Technical, Chief Tes Engineer and Sales Direcor: Michael Giannone Toal workforce of five; Drag Racing is 100% of business Founded by Mechanical Engineering/Machinis Specialis Michael Giannone and his wife, a Business Managemen Graduae, in January of 1990; sill privaely owned Covering he Unied Saes, Ausralia, Canada and Europe and are now saisfied ha our rods have he ulimae consisen surfaces in he indusry oday. On ianium rods Arrow uses a hermal molybdenum coaing, which sops he ianium picking up or galling. Rober Lou of Howards Cams says: Cryogenic Treamen appears o have some value bu he cos has o be aken ino consideraion. Design Due o he differen performance demands and race caegory regulaions, engine builders need o work wihin cerain parameers placing pressure on maerials and componen design. As regards on he advanages of I- or H-secion, wo-bol or four, Brian Crower says: This quesion comes up on a daily basis and he rue answer is ha if i is a high qualiy rod, made o exacing olerances, using proven faseners, he acual design of he rod is irrelevan. The H-beam is ofen he preferred design in he inernaional marke, so Crower has oped o incorporae he H-beam wih is new radial beam design, which ensures weigh removal in a manner ha acually makes he rod sronger. Finie Elemen Analysis and on-rack esing have shown ha jus building a heavy weigh rod is no he answer o high horsepower, severe-duy use. The added weigh of he rod produces undue sress on he crank, whereas a ligher weigh rod, designed wih he radial beam echnology, produces a sronger beam configuraion, capable of more horsepower, wihou puing added weigh on he roaing mass. Verkooij of Carrillo offers his view: When considering any connecing rod, he configuraion of he beam does no dicae he srengh of he connecing rod. Differen applicaions place differen requiremens on a rod design, hence also suggesing differen beam configuraions. Deciding facors on which beam ype o use include weigh, clearance and acual load condiions in he engine. Considering he dynamics of a connecing rod, he axial compression-ension load, combined wih wis and bending forces 55

6 exered, he H-beam is mos suiable o wihsand he remendous abuse endured by he connecing rod, according o Carrillo, which was he firs o develop he H-beam connecing rod. Simply saed, when considering he mos criical srengh and durabiliy requiremens of a high performance connecing rod, Carrillo has found ha a well-developed H-beam configuraion is he bes soluion o mee mos cusomer s specific needs and requiremens. The Carrillo A-beam is made from he same high-qualiy proprieary seel as used in he H-beam rod, and is well-suied for less demanding, high-performance, afermarke applicaions. Carrillo s Pro-A design is much ligher han is sandard Pro-H and is used in moderae horsepower applicaions such sree urbo, drag, sree and srip applicaions and has been credied wih reducing windage inside he engine hrough is sreamlined design. Carrillo also offer he Pro-A Limied and Pro-Super A versions for specific applicaions. Frequenly raised is he issue of ring dowel versus dowel pin for he posiioning of he cap. The ring dowel is more common in he Norh American marke, whereas he dowel pin is more ofen a European preference. The ring dowel arguably gives a superior posiioning due o a large conac area, which is also more forgiving in he assembly process. Dowel pins wear ou more easily, bu allow decreased bol spacing. This can give advanages in he sabiliy of he big end, meaning less ovalisaion under ension load. Arrow ofen ges asked abou H and I-secion rod choice and while many engine designers have heir own personal preference, he company reckons ha in mos engines boh ypes would be suiable. For urbocharged and supercharged engines wih high gas loading Arrow recommends an H-beam as his is sronger as a compressive sru. Arnold commens: We generally recommend he H-beam alhough in some high revving engines an opimised I-beam may have a small advanage as hey can be slighly ligher. Bu I-beams are only really suiable for normally aspiraed engines. I-beam rods are also a more auhenic opion for many resoraion projecs and Arrow has found ha on fully machined rods he I-secion is a lile more expensive as i akes longer o machine, anoher facor o consider when choosing which opion. Specialis I-beam rods wih roller bearings are normally used in moorcycle and kar applicaions. Salpaka of Falicon alks abou is recenly inroduced Knife rod: Our rod design is a unique soluion o he problem of windage and aerodynamics in he engine crankcase. The oval beam of he Knife rod cus hrough he air and oil much like an airplane wing. Falicon manufacures bol-ogeher plain bearing designs and also low Falicon knife fricion roller bearing designs like hose used in he THE MX COMPOSITES AB FILE High performance componens in Meal Marix Composies (MMC) wih MMC connecing rods a specialiy Moorcycle racing Sefan Asplund Linköping, Sweden Managing Direcor: Sefan Asplund Technical Direcor: Jonas Råsbäck Sales Direcor: Lennar Nilsson Toal workforce of six working wih design, Jonas Råsbäck esing, producion developmen and sales; manufacuring is ousourced in a nework of sub-suppliers manufacuring o MX Composies specificaion. Racing is majoriy of business Founded as a spin off from Saab Aerospace in 2002 and sill par of he Saab group Lennar Nilsson Covering he European marke, concenraing on he Ialian marke beside he Swedish home marke; exploring possibiliies in he USA NHRA Pro Sock moorcycle class. These 1.6 lire moorcycle engines use ulra-low viscosiy oil for he ulimae in low drag performance enhancemen. Roller bearing connecing rod designs are also much more durable in siuaions like off road and sand racing or where vehicle urn over is possible. The oval beam shape is also very srong and resiss he endency of oher beam designs o flex and wis under heavy loads such as is experienced in he high combusion pressure of urbocharged engines. Many of our cusomers have commened ha he oval beam rod design gives a margin of durabiliy when an engine begins o fail as he rod is oleran o adverse loading and will no fold like an H-beam design when hings go wrong, adds Salpaka. Mos of Howards Cams connecing rods are of I-Beam design. Lou says: Boh I-Beam and H-Beam designs are proven in srengh and elasiciy areas. We feel he I-Beam is a sronger design. The Fuure Looking oward he fuure, Brian Crower says: We feel he radial beam echnology incorporaed ino he proven H-beam design, using premium ARP Cusom Age 625+ faseners and added pin oiling feaures is he fuure of connecing rods. Sefan Asplund of MX Composies sees i his way: MMC con rods offer grea benefis and ouperform Tianium con rods boh in performance and oal cos of usage. From a more long erm perspecive, MMC con rods even rival seel con rods in he OEM segmen when considering he benefis. 56

7 Verkooij offers an in-deph view: The fuure in developmen of high end connecing rod designs will be driven by simulaing real world load condiions hrough Finie Elemen Analysis (FEA). The more precise he acual load condiions are defined, he beer he design can be adjused o have uniform sress disribuion in he rod assembly. This of course involves more deailed measuremen sudies on he engine and new design evoluions will mos likely show more uniform changes in cross secion beween he bores and he beam, however he maerial properies do influence he design of he rod significanly. In addiion, he indusry keeps looking for he magic rod maerial. The decision on wha maerial o use is mosly conrolled hrough producion coss and limiaions in moorspor regulaions, she adds. Carrillo expecs ha alloy sysems (seel, ianium or aluminium) will be refined and opimised in he fuure, bu will lead only o sligh evoluionary, no revoluionary improvemens. The main focus on hese maerials in combinaion wih heir surface reamens is o achieve maximum faigue properies, which does no always relae direcly o he saic srengh properies of an alloy (Ulimae Tensile Srengh). Coaing echnology is advancing apace and his will allow fricion opimisaion, especially in he pin end ID which increases he durabiliy of he rod and reduces fricion losses in he engine. Arrow Falicon s producion Knife connecing rod is 100% machined from Timken Var300M Seel forging and i uses ARP 625+ alloy bols in all of is producs. The H-beam design has remained virually unchanged for over hiry years, and Salpaka predics, The oval beam design is in our opinion he nex level of echnology especially when used in modern engine designs where high RPM engines are common. However, Salpaka poins ou, some of hese exoic maerials are no allowed in cerain race disciplines due o moorspor regulaions. One soluion is a hollow beam seel rod, which is sronger han an H- or I-beam rod when subjec o load or ension in more han one direcion; an oval beam hollow rod may be he ulimae design, he adds. Falicon has produced rod designs wih he knife edge coaed o increase laminar flow, dimpled like a golf ball or apered like a sileo. Through heir advanced designs, hey can por oil hrough he rod o he pison or use he rod as a hea pipe o effecively conduc hea away from he combusion area. We can fill he void wihin he oval wih a gas, liquid or solid; here are many new possibiliies if you ake our oval beam design o he nex level, Salpaka adds exciedly. Howards Cams has developed a Parabolic X Beam Design ha combines he I-Beam and H-Beam designs. Lou adds confidenly: This is sill in he experimenaion process a his ime, bu so far seems o have an exraordinary increase in srengh and load capabiliies. Carrillo n 58