Iħjut Twincharging Huwa Sostituzzjoni Volvos għall-ispostament

It-tnaqqis fil-magna huwa r-rabja kollha. Li l-magna ssir iżgħar iżżid l-effiċjenza tal-fjuwil, tnaqqas l-emissjonijiet u tnaqqas il-piż tal-vettura. Bil-leġiżlazzjoni dejjem aktar stretta dwar l-ekonomija tal-fjuwil fl-Istati Uniti u r-regolamentazzjoni dwar l-emissjonijiet tas-CO2 fl-Unjoni Ewropea, il-manifatturi ewlenin qed jirrikorru għal turbochargers bħal qatt qabel. Fl-2009 5 % biss tal-karozzi mibjugħa fl-Amerika sported turbos, u li 5 % kienu jikkonsistu fil-biċċa l-kbira minn marki Ewropej bħal Volvo U BMW bi storja twila ta 'induzzjoni sfurzata. Sal-2013 dan in-numru kien aktar milli rdoppja għal 13 %. Honeywell jistenna li n-numru jitla' għal 25% fl-erba' snin li ġejjin u l-EPA tgħidli li sal-2025 jistennew 90% tal-karozzi mibjugħa fl-Amerika biex jipprattikaw magna turbo. Bit-turbos isiru daqshekk ordinarji, x'inhu pijunier turbo bħal Volvo biex iżomm vantaġġ kompetittiv? Żid supercharger ovvjament.
Riċentement kelli l-opportunità li nieħu kampjun tal-Volvo V60 il-ġdid (nistenna reviżjoni tal-ewwel sewqan dalwaqt) iżda l-istilla tal-ispettaklu kienet il-karozza nnifisha, x'inhu taħt il-barnuża. Disinji ġodda tal-magni huma tassew rarità fid-dinja tal-karozzi bil-magni jiġu tweaked maż-żmien biex iżommuhom friski. Volvos stess magna modulari misjuba taħt il-barnuża tal-biċċa l-kbira tal-karozzi Svediżi (u l-Focus RS okkażjonali) għalqet 24 sena din is-sena, iżda t-tiġieġ tar-rebbiegħa tagħha meta mqabbel mar-Rolls Royce L serje 6. Magna 75L li tmur lura għall-1952. Peress li jien il-magna nerd jien, qattajt sigħat ġodda mal-inġinier tal-powertrain Volvos jiddiskuti l-familja l-ġdida tal-magna Drive E tagħhom.
Volvos familja ġdida tal-magna hija primarjament disinn tal-folja nadifa, għalkemm ħafna komponenti tad-disinn huma dixxendenti tal-familja tal-magna modulari l-qadima. Il-linja tikkonsisti f'erba' varjanti differenti msejħa T3, T4, T5 u T6. Bħal qabel, T tindika turbocharged iżda issa n-numru jirrappreżenta output tal-enerġija aktar milli n-numru ta 'ċilindri involuti. Iva, din hija l-pum tal-mewt għal Volvos funky 5-cylinder minħabba li din hija formazzjoni stretta ta 'erba' ċilindri. Volvo qal li l-149 horsepower T3 u l-188 horsepower T4 mirbuħa se jmorru lejn l-Amerika bħalissa, għalhekk tistenna li tara kompetitur dirett għall-BMWs naqas 320i mill-Iżvezja din is-sena. Minflok ikollna l-241 horsepower T5 u t-302 horsepower T6 taħt il-barnuża ta 'kollox ħlief l-XC90.

Il-magni kollha jaqsmu disinn ta 'blokka komuni, iżda liema bidliet huwa l-ispinta. Il-magni T3, T4 u T5 jużaw turbo wieħed filwaqt li T6 iżid supercharger tat-tip Roots minbarra t-turbocharger. VW u oħrajn dabbled bi twincharging fil-passat, bi VWs 1. Magna tewmin 4L li ssib dar taħt il-hoods tal-mudelli Euro u tniżżel 140-180 horsepower. Volvo qed jieħu l-affarijiet għall-pass li jmiss billi jċempel it-2 tagħhom. Magna 0L is-sostituzzjoni għal mhux biss it-3. 0L turbo twin-scroll iżda wkoll l-4 li telqu reċentement. 4L V8.
Filwaqt li l-ħsejjes tas-supercharging u tat-turbocharging eċċessivi, hemm loġika għall-ġenn. Filwaqt li l-ogħla torque fuq it-turbo-biss T5 15 lb-ft inqas mit-T6 (meta jkun f'overboost), is-supercharger jippermetti lit-T6 jagħti madwar 140 lb-ft aktar torque ftit 'il barra mill-idle. Il-kurvi tat-torque jikkonverġu madwar 1,500-1,600 RPM meta t-T6 jaqleb għat-turbocharger. Minn madwar 2,000 RPM sa 3,500 RPM torque jibqa 'ċatt fuq iż-żewġ magni iżda t-turbo akbar fuq it-T6 jippermettilha żżomm l-ogħla torque fit-triq kollha wara 4,500 RPM. Meta t-torque jibda jonqos jagħmel dan b'mod aktar gradwali mill-magni turbo-biss.

Għaliex ma żżommx ma 'supercharger waħdu bħal Jaguar u auto makers oħra? Ir-raġuni hija darbtejn. It-turbochargers joperaw mill-enerġija tal-iskart mill-egżost. Il-gassijiet tal-egżost iduru t-turbina li min-naħa tagħha ddawwar il-kompressur li jisforza aktar arja fil-magna. Fil-verità l-enerġija tal-iskart hija misnomer minħabba li hemm pedaġġ tal-horsepower talli t-turbo jinterferixxi mal-fluss tal-egżost, iżda b'mod ġenerali dan il-pedaġġ huwa iżgħar mill-enerġija meħtieġa biex tħaddem supercharger. L-iżvantaġġ għal turbo huwa magħruf sew: turbo lag. Turbo lag huwa l-ħin li tieħu t-turbo biex tibda tagħti spinta. Għalkemm it-turbo qed idur bil-wieqfa, il-ħolqien ta 'ftit pressjoni pożittiva. Pass fuq il-gass u tieħu ftit żmien biex l-affarijiet jibdew jgħannqu u tingħata spinta biex tinħoloq. Huwa għalhekk li t-T5 għandu klassifikazzjoni tat-torque aktar baxxa mhux ingranata.
Is-superchargers huma tipikament imkeċċija miċ-ċinturin aċċessorju. Minħabba l-konnessjoni diretta mal-magna, huma dejjem qed joħolqu spinta. Minħabba li din l-ispinta sseħħ f'sinkronizzazzjoni mal-RPMs tal-magna, ir-rispons huwa immedjat. Fuq in-naħa l-isfel superchargers jistgħu jikkunsmaw sa 20% ta 'output ta' enerġija totali tal-magni skond Honeywell. Dan huwa meqjus bħala kummerċ tajjeb peress li jistgħu jibbutjaw l-enerġija sa 50%. Minħabba l-kompromessi tad-disinn, il-magni supercharged tal-fabbrika għandhom it-tendenza li jispiċċaw mingħajr nifs f'RPMs ogħla li jispjega għaliex Jaguars 5. 0L magna supercharged lags l-4. 4L u 4. 7L magni Ġermaniżi twin-turbo b'marġni wiesa 'fl-ogħla torque.
Ir-risposta ta 'Volvos għaż-żewġ problemi kienet li tuża supercharger għal rispons immedjat fil-baxx. Mill-arja wieqfa tgħaddi fis-supercharger imbagħad mit-turbo fil-magna. Dan mhux biss itejjeb ir-rispons baxx iżda jgħin ukoll biex it-turbo jilħaq il-veloċità aktar malajr. F'xi punt iddeterminat mill-kompjuter tal-karozzi (madwar 3,500 RPM) il-magna tiftaħ valv tal-farfett biex tevita s-supercharger u mbagħad tneħħi l-klaċċijiet tas-supercharger biex telimina t-telf inerenti. Dan il-proċess jippermetti supercharger sintonizzat għal rispons low-end u turbo sintonizzat għal RPM ogħla li jaħdem biex jingħaqad mal-istess magna. Ir-riżultat huwa kurva horsepower u torque superjuri għal Volvo jew BMWs 3. 0L turbos twin-scroll f'kull mod, mit-torque inattiv, it-tul tal-plateau tat-torque, għal torque RPM għoli. Biex tkompli tiżdied l-effiċjenza Volvo jiddependi fuq pompa tal-ilma elettrika b'veloċità varjabbli għat-tkessiħ, injezzjoni diretta għall-effiċjenza tal-kombustjoni u berings u ċrieki ta 'frizzjoni baxxa. Il-letteratura tal-kummerċjalizzazzjoni volvos tfaħħar dan bħala t-tweġiba għall-V8.
Imma huwa verament? Iva u le. Il-magna ta 'daqs pint tippermetti lill-XC60 iwassal 29 MPG fuq l-awtostrada fi 304 horsepower T6 trim li hija żieda ta' 50% fuq Volvos 2009 XC90 V8. Skorja wieħed għal Drive-E. Barra fit-triq, it-2. Il-magna 0L tagħti torque tat-tarf aktar baxx minn kwalunkwe 2 oħra. 0L erba 'banger mibjugħa fl-Amerika li jagħtu lill-XC60 aktar punch off idle milli stennejt. Il-kurva tat-torque T6 's tista' tkun aktar ċatta mit-tip Volvos għex 4. 4L V8, iżda mhux daqshekk robust fin-naħa ta 'fuq jew fil-wieqfa. Il-faxxa tat-torque wiesgħa u l-auto Aisin ta '8 veloċitajiet ippermettew lill-XC60 T6 jorbot XC90 V8 sa 60 MPH. Aurally, Volvos burbly V8 huwa r-rebbieħ ċar. Il-magna Drive-E għandha whine supercharger distint (iżda mmut) taħt 3,500, nota definittiva tal-egżost b'erba 'ċilindri u silenzju eerie fil-wieqfa. Volvo kien gaġġa dwar kwalunkwe melodija Polestar għall-magna l-ġdida tagħhom, iżda nissuspetta li jeħtieġ li jsir xogħol konsiderevoli biex l-aħjar Volvos stess Polestar I6.
L-inġinier ta 'ġewwa tiegħi huwa eċċitat mill-possibbiltajiet ta' teknoloġiji moderni ta 'induzzjoni furzata u magni ta' spostament żgħir. Nissuspetta li l-maġġoranza l-kbira tax-xerrejja Amerikani jkunu diffiċli biex jinnutaw id-differenza bejn Volvos iċċarġjat doppju 2. Magna 0L u V8 fil-medda 4L f'termini ta 'kunsinna ta' enerġija u kapaċità ta 'sewqan. Il-mixja kostanti lejn l-ekonomija tal-fjuwil timlini wkoll bid-dwejjaq. Ma jimpurtax kif tolqtu, V8 aspirat b'mod naturali għandu ħoss li aħna kibru jassoċjaw mal-prestazzjoni u l-lussu. Din l-assoċjazzjoni hija tant qawwija li l-pajpijiet BMW V8 jinstemgħu fil-kabini tat-turbo V8s tagħhom minħabba li t-turbos jinterferixxu man-noti tal-egżost. Hekk kif il-pocketbooks tagħna jifirħu, ingħaqad miegħi hekk kif xeħtet tiċrita għall-inline-6 u V8 aspirati b'mod naturali.

Engine downsizing is all the rage. Making the engine smaller increases fuel efficiency, reduces emissions and cuts vehicle weight. With ever tightening fuel economy legislation in the United States and CO2 emissions regulation in the European Union, mainline manufacturers are turning to turbochargers like never before. In 2009 just 5% of cars sold in America sported turbos, and that 5% consisted largely of European brands like Volvo and BMW with a long history of forced induction. By 2013 that number had more than doubled to 13%. Honeywell expects the number to rise to 25% in the next four years and the EPA tells me that by 2025 they expect 90% of cars sold in America to sport a turbo engine. With turbos becoming so ordinary, whats a turbo pioneer like Volvo do to keep a competitive edge? Add a supercharger of course.
I recently had the opportunity to sample the new Volvo V60 (expect a first drive review shortly) but the star of the show wasnt the car itself, its whats under the hood. New engine designs are truly a rarity in the automotive world with engines being tweaked over time to keep them fresh. Volvos own modular engine found under the hood of most Swedish cars (and the occasional Focus RS) turned 24 years old this year, but its a spring chicken compared to the Rolls Royce L series 6. 75L engine that dates back to 1952. Being the engine nerd I am, I spent a new hours with Volvos powertrain engineer discussing their new Drive E engine family.
Volvos new engine family is primarily a clean sheet design, although many design components are descendants of the old modular engine family. The line consists of four different variants dubbed T3, T4, T5 and T6. As before, T indicates turbocharged but now the number represents power output rather than the number of cylinders involved. Yes, this is the death knell for Volvos funky 5-cylinder because this is a strict four-cylinder lineup. Volvo has said the 149 horsepower T3 and the 188 horsepower T4 wont be headed to America at the moment, so dont expect to see a direct competitor for BMWs downsized 320i from Sweden this year. Instead we get the 241 horsepower T5 and the 302 horsepower T6 under the hood of everything except the XC90.

All engines share a common block design, but what changes is the boost. T3, T4 and T5 engines use a single turbo while T6 adds a Roots-type supercharger in addition to the turbocharger. VW and others have dabbled with twincharging in the past, with VWs 1. 4L twincharged engine finding a home under the hoods of Euro models and putting down 140-180 horsepower. Volvo is taking things to the next step by calling their 2. 0L engine the replacement for not just the 3. 0L twin-scroll turbo but also the recently departed 4. 4L V8.
While supercharging and turbocharging sounds excessive, there is a logic to the madness. While peak torque on the turbo-only T5 just 15 lb-ft lower than the T6 (when in overboost), the supercharger allows the T6 to deliver approximately 140 lb-ft more torque just off idle. The torque curves converge around 1,500-1,600 RPM when the T6 switches over to the turbocharger. From approximately 2,000 RPM to 3,500 RPM torque remains flat on both engines but the larger turbo on the T6 allows it to maintain peak torque all the way past 4,500 RPM. When torque does start to wane it does so more gradually than turbo-only engines.

Why not stick with a supercharger alone like Jaguar and other auto makers? The reason is two-fold. Turbochargers operate off of waste energy from the exhaust. Exhaust gases spin the turbine which in turn spins the compressor forcing more air into the engine. In truth waste energy is a misnomer because there is a horsepower toll for having the turbo interfering with the exhaust stream, but in general this toll is smaller than the power required to operate a supercharger. The downside to a turbo is well known: turbo lag. Turbo lag is the time it takes the turbo to start boosting. Although the turbo is spinning at idle, its creating little positive pressure. Step on the gas and it takes a while for things to start humming along and boost to be created. Thats why the T5 has a lower torque rating off idle.
Superchargers are typically driven off the accessory belt. Because of the direct connection to the engine, they are always creating boost. Because this boost happens in sync with engine RPMs, the response is immediate. On the down side superchargers can consume up to 20% of an engines total power output according to Honeywell. This is considered a good trade since they can boot power up to 50%. Because of design trade offs, factory supercharged engines tend to run out of breath at higher RPMs which explains why Jaguars 5. 0L supercharged engine lags the 4. 4L and 4. 7L twin-turbo German engines by a wide margin in peak torque.
Volvos answer to both problems was to use a supercharger for immediate response at the low end. From idle air flows into the supercharger then through the turbo into the engine. This not only improves low end response but it also helps get the turbo up to speed faster. At some point determined by the cars computer (around 3,500 RPM) the engine opens a butterfly valve to bypass the supercharger and then de-clutches the supercharger to eliminate the inherent loss. This process allows a supercharger tuned for low end response and a turbo tuned for higher RPM running to be joined to the same engine. The result is a horsepower and torque curve superior to Volvo or BMWs 3. 0L twin-scroll turbos in every way, from torque at idle, length of the torque plateau, to high-RPM torque. To further increase efficiency Volvo relies on a variable speed electric water pump for cooling, direct-injection for combustion efficiency and low friction bearings and rings. Volvos marketing literature hails this as the answer to the V8.
But is it really? Yes and no. The pint-sized engine allows the XC60 to deliver 29 MPG on the highway in 304 horsepower T6 trim which is a 50% increase over Volvos 2009 XC90 V8. Score one for Drive-E. Out on the road, the 2. 0L engine delivers more low end torque than any other 2. 0L four-banger sold in America giving the XC60 more punch off idle than I expected. The T6′s torque curve may be flatter than Volvos sort lived 4. 4L V8, but its not quite as robust at the top end or at idle. The broad torque band and the Aisin 8-speed auto allowed the XC60 T6 to tie an XC90 V8 to 60 MPH. Aurally, Volvos burbly V8 is the clear winner. The Drive-E engine has a distinct (but muted) supercharger whine under 3,500, a definite four-cylinder exhaust note and an eerie silence at idle. Volvo was cagey about any Polestar tunes for their new engine, but I suspect considerable work will need to be done to best Volvos own Polestar I6.
My inner engineer is excited by the possibilities of modern forced induction technologies and small displacement engines. I suspect that the vast majority of American shoppers would be hard pressed to notice the difference between Volvos twin-charged 2. 0L engine and a V8 in the 4L range in terms of power delivery and drive-ability. The constant march towards fuel economy also fills me with sadness. No matter how you slice it, a naturally aspirated V8 has a sound that weve grown up associating with performance and luxury. This association is so strong that BMW pipes V8 sounds into the cabins of their turbo V8s because the turbos interfere with the exhaust notes. As our pocketbooks rejoice, join me as I shed a tear for the naturally aspirated inline-6 and V8.