VTEC

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  • VTEC

    bey.... ce forum de Honda e asta unde nu discutam despre VTEC?!!!

    iata niste linkuri:

    http://www.leecao.com/honda/vtec/index.html

    http://en.wikipedia.org/wiki/VTEC
    ex Civic mk.7 EX sedan 2002, 1.7VTEC
    ex Acura TL 2006, 3.2 V6 SOHC VTEC
    Civic Si sedan 2007, 2.0 DOHC iVTEC
    Acura MDX 2011, 3.7 V6 SOHC VTEC

  • #2
    cum asa?
    in fiecare zi pomenim acronimul asta.
    honda x 5
    "W" stands for Wrong
    Amerika ist Wunderbar

    Comment


    • #3
      Re: VTEC

      Originally posted by Marius -Iulian
      bey.... ce forum de Honda e asta unde nu discutam despre VTEC?!!!
      Discutii ca discutii, dar daca noi nu ürezentam ceva in romaneste despre asta,atunci pe cine sa lasam?
      HONDA. The finest from Japan. Since 1963.

      Comment


      • #4
        Tadaaam! http://www.mr2sc.com/websites/articles/vvt.htm

        Honda broke the ice when the NSX debuted in 1991 as the first production car with a variable valve timing system. Honda's VTEC (which sort of stands for Variable valve Timing and lift Electronic Control) system, which has basically remained unchanged since then, is still one of the most effective systems for making ultra high specific output.

        Eu stiam de CRX 1.6 160cp din '88 a fost primul cu VTEC.


        i-VTEC
        As successful as the VTEC system has been, one of the key arguments against it in comparison to competing systems is that it had only two profiles for timing and lift. i-VTEC answers the critics by introducing continuously variable timing. The valve lift is still a 2-stage setup as before, but the camshaft is now rotated via hydraulic control to advance or retard valve timing. The effect is further optimization of torque output, especially at low RPMs.

        Hehe, the shit I got on my car. :twisted:

        Comment


        • #5
          yep, you got the real deal man. si are iVTEC si pe admisie si pe evacuare. am inteles ca iVTEC-ul de 160CP are chestia numai pe arborele cu came de admisie.

          acu' cred ca stiti ca Toyota au inceput cu VVT si cu VVTi au realizat ca le trebuie si VTEC si si-au pus ceva asemanator. Honda ainceput cu VTEC si au pus si VVT. asa ca la momentul asta motoarele de varf ale celor 2 companii sunt similare tehnic.

          Honda insa face inca motoare mai bune si e, cu 14mil. de motoare produse anual, cel mai mare producator de motoare din lume.
          ex Civic mk.7 EX sedan 2002, 1.7VTEC
          ex Acura TL 2006, 3.2 V6 SOHC VTEC
          Civic Si sedan 2007, 2.0 DOHC iVTEC
          Acura MDX 2011, 3.7 V6 SOHC VTEC

          Comment


          • #6
            si eu care eram ferm convins ca citroen e pe primul loc.
            honda x 5
            "W" stands for Wrong
            Amerika ist Wunderbar

            Comment


            • #7
              Originally posted by Bogdan_16v

              Eu stiam de CRX 1.6 160cp din '88 a fost primul cu VTEC.:
              Asa stiu si eu si asa o spune si Honda, dar stii cum e, altii stiu mereu mai bine lucrurile altora.
              HONDA. The finest from Japan. Since 1963.

              Comment


              • #8
                VTEC e una si VVT (Honda ii zice VTC=variable timing control) e alta...

                NSX-ul are un V6 DOHC iVTEC. e posibil ca mesajul sa fie ca NSX a fost primul model cu VTEc si VVT=VTC

                iVTEC=VTEC+VTC

                iata un link despre VVTL-i al Toyota:

                http://www.billzilla.org/vvtvtec3.htm
                ex Civic mk.7 EX sedan 2002, 1.7VTEC
                ex Acura TL 2006, 3.2 V6 SOHC VTEC
                Civic Si sedan 2007, 2.0 DOHC iVTEC
                Acura MDX 2011, 3.7 V6 SOHC VTEC

                Comment


                • #9
                  Corect, asa e. E o diferenta de nuanta. NSX a fost prima cu i-VTEC.

                  Comment


                  • #10
                    Originally posted by Marius -Iulian
                    NSX-ul are un V6 DOHC iVTEC.
                    :roll: Marius, NSXul nu are i-VTEC, ci simplu DOHC VTEC!
                    HONDA. The finest from Japan. Since 1963.

                    Comment


                    • #11
                      Din arhiva, deci prafuit si de demult, dar interesant:

                      http://www.autoshow.ro/autoshow/arti...article_id=310

                      Semper Fi - Honda i-VTEC
                      Florin Oprea
                      7 Mai 2002

                      Prezenta la monovolumul Stream, dar si la modelul Civic Type-R generatia de motoare i-VTEC (intelligent Variable Timing and lift Electronic Control) are calitati ce demonstreaza ca tehnologia Honda este intotdeauna pe val.
                      Doua dispozitive noi fac parte din sistemul i-VTEC. Deschiderea variabila a supapei este facuta de doi culbutori si prin folosirea unui arbore cu came cu profil schimbat. Al doilea dispozitiv controlat de computer variaza pozitia arborelui cu came al admisiei cu peste 50¡ relativ la unghiul arborelui cotit. Un element important al motorului ce completeaza i-VTEC este colectorul de admisie cu lungime variabila controlat de un distribuitor rotativ. La sarcina joasa lungimea se mareste atingand 540 mm cu scopul cresterii vitezei de curgere a aerului creand turbulente ce asigura un amestec omogen si o buna umplere a cilindrilor. La sarcini mari lungimea colectorului scade atingand 270 mm ce asigura un volum sporit de aer aspirat cu rezultat in cresterea puterii motorului.

                      Schimbarea pozitiei arborelui cu came fata de arborele cotit se face hidraulic cu ajutorul unei mici pompe rotative situata la capatul arborelui cu came al admisiei. Computerul variaza presiunea uleiului modificand rotatia arborelui si implicit a lantului de distributie. Astfel se modifica suprapunerea timpilor supapelor. Acest timp este momentul in care supapa de admisie si cea de evacuare sunt deschise. Intarziind rotatia arborelui cu came scade timpul de suprapunere in timp ce accelerand rotatia timpul creste. Fenomenul de suprapunere al deschiderii supapelor joaca un rol important in functionarea motorului. Un timp scurt da motorului un relanti uniform si un cuplu bun la sarcini mici, dar penalizeaza performantele acestuia la sarcini mari. Un timp de suprapunere mare permite o respiratie excelenta la sarcini mari insa obtinem rezultate slabe la sarcini mici. Prin varierea rotatiei arborelui cu came si a timpului de suprapunere, Honda a obtinut performante excelente atat la regimuri joase cat si la cele mari.

                      Inaltimea variabila de deschidere a supapei este realizata de doi culbutori diferiti si de camele de pe arbore. In trecut, Honda opera pe motoarele VTEC cu trei culbutori: doi pentru deschiderea a doua supape de admisie, iar celalalt pentru blocarea celorlalti doi si fortarea acestora sa urmeze un profil al camei separat de cel initial. Cu noul dispozitiv de doi culbutori, numai o singura supapa este deschisa la sarcini joase. Acest fapt asigura o buna turbionare a amestecului carburant in cilindru optimizand arderea la regimul de mai sus. La o valoare a turatiei programata in computerul motorului presiune uleiului este folosita pentru blocarea celor doi culbutori. La aceasta turatie se vor deschide ambele supape de admisie, iar culbutorii vor urma profilul camei mai inalte urmarit pana atunci doar de culbutorul secund. Beneficile maxime ale puterii si cuplului se obtin cand sistemul i-VTEC opreaza atat pe supapele de admisie cat si pe cele de evacuare. Imbunatatirea performantelor este doar unul dintre avantajele sistemului i-VTEC. Eficacitatea sistemului este reliefata de curba de cuplu aproape aplatizata. Astfel pentru motorul de 2.0 litri al Hondei Stream, daca valoarea momentului maxim este de 192 Nm la o turatie de 4000 rot/min, cuplul de 184 Nm (96% din valoarea maxima) este disponibil inca de la 3000 de rot/min. Ajutat de o cutie performanta acest motor face minuni.

                      Tehnologia i-VTEC asigura o mare flexibilitate pentru ca ea permite motorului sa se "exprime" la plina sa valoare in toate cazurile. In plus ea gestioneaza in asa fel motorul obtinandu-se o crestere a puterii acestuia cu 20% si a cuplului, la regimuri joase si medii, cu 10% in timp ce reduce consumul de combustibil cu aproape 20%. Multumita constructiei compacte a rezultat si o scadere a greutatii propulsorului cu 10%.
                      HONDA. The finest from Japan. Since 1963.

                      Comment


                      • #12
                        Originally posted by hondatu
                        :roll: Marius, NSXul nu are i-VTEC, ci simplu DOHC VTEC!
                        mea culpa... nu m-am uitat sa verific... inseamna ca tipul cu articolul respectiv nu stia ce vorbea... da' si voi amestecarati VTEC-ul cu VTC-ul (VVT)...

                        asadar care a fost primul iVTEC?
                        ex Civic mk.7 EX sedan 2002, 1.7VTEC
                        ex Acura TL 2006, 3.2 V6 SOHC VTEC
                        Civic Si sedan 2007, 2.0 DOHC iVTEC
                        Acura MDX 2011, 3.7 V6 SOHC VTEC

                        Comment


                        • #13
                          Primul i-VTEC a fost asta:

                          http://www.hondafan.ro/modele.php?id=209

                          Vezi mai atent spre al 2lea paragraf!
                          HONDA. The finest from Japan. Since 1963.

                          Comment


                          • #14
                            asa de tarziu? iVTEC-ul de 2,0l de 160CP nu are VTEC si/sau VTC decat pe admisie...
                            ex Civic mk.7 EX sedan 2002, 1.7VTEC
                            ex Acura TL 2006, 3.2 V6 SOHC VTEC
                            Civic Si sedan 2007, 2.0 DOHC iVTEC
                            Acura MDX 2011, 3.7 V6 SOHC VTEC

                            Comment


                            • #15
                              Vin cu niste mici articole interesante despre VTEC:

                              VTEC - Variable valve Timing and lift Electronic Control. At low RPM, a VTEC engine uses a normal cam profile to retain a smooth idle, good fuel economy, and good low-end power delivery. The VTEC mechanism engages a high-lift, long-duration “race” cam profile at a set RPM value (i.e., ~5500RPM on the B16A) to increase high-end power delivery.

                              VTEC-E - Variable valve Timing and lift Electronic Control for Efficiency. This system isn’t really VTEC as we know it. At low RPM, the VTEC-E mechanism effectively forces the engine to operate as a 12-valve engine - one of the intake valves does not open fully, thus decreasing fuel consumption. At a set RPM value (i.e., ~2500RPM in the D16Y5), the VTEC-E mechanism engages the 2nd intake valve, effectively resuming operation as a normal 16-valve engine. Note: in a VTEC-E engine, there are no high-RPM performance cam profiles; this engine is supposed to be tuned for fuel economy, right?

                              VTC - Variable Timing Control. This is a mechanism attached to the end of the intake camshaft only which acts as a continuously variable cam gear - it automatically adjusts the overlap between the intake and exhaust cams, effectively allowing the engine to have the most ideal amount of valve overlap in all RPM ranges. VTC is active at all RPMs.

                              i-VTEC - intelligent Variable valve Timing and lift Electronic Control. This is a combination of both the VTEC and the VTC technologies - in other words, i-VTEC = VTEC + VTC. Currently, the only engines that use the i-VTEC system are the DOHC K-series engines.

                              Now this is where things get tricky - Honda uses the term “DOHC i-VTEC” for two different systems: The first system is used in the K20A2 engine of the RSX Type-S. The second system is used in the K20A3 engine of the Civic Si.

                              The First System (K20A2):

                              This system is pretty close to the older DOHC VTEC engines. At low RPM, the K20A2 uses a normal cam profile to retain a smooth idle, good fuel economy, and good low-end power delivery. At 5800RPM, its VTEC mechanism engages a high-lift, long-duration “race” cam profile to increase high-end power delivery. The only difference between this i-VTEC engine and the older VTEC engines is the addition of the VTC system. The intake camshaft has the automatic self-adjusting cam gear which continuously optimizes valve overlap for all RPM ranges.

                              Here we see an image of the intake cam lobes of the K20A2. Notice there are 3 lobes; the two side lobes are the low-RPM profiles, and the center lobe is the high-lift, long-duration profile which engages at 5800RPM. Basically the same setup as the old VTEC engines we are familiar with.

                              Now here we see the VTC mechanism - the gear on the end of the intake cam that adjusts valve timing (overlap) automatically on the fly.

                              This system is used in engines powering the JDM Honda Integra Type-R, Civic Type-R, Accord Euro-R, and the USDM Acura RSX Type-S and TSX.

                              The Second System (K20A3):

                              This system does not really conform to the “DOHC i-VTEC” nomenclature, as Honda would like us to believe. As I mentioned in my previous post, it actually should be called “i-VTEC-E,” because it uses a VTEC-E mechanism rather than a standard VTEC mechanism. At low RPM, the VTEC-E system effectively forces the engine to operate as a 12-valve engine - one of the intake valves does not open fully, thus decreasing fuel consumption. At 2200RPM, the VTEC-E system engages the 2nd intake valve, effectively resuming operation as a normal 16-valve engine. There are no high-RPM performance cam profiles; this engine is tuned to balance fuel economy and power, rather than provide pure performance. On the intake cam, there is the VTC mechanism which basically is an automatic self-adjusting cam gear used to continuously optimize the valve overlap for all RPM ranges. This being a VTEC-E system - and not a true DOHC VTEC system - is the reason the K20A3 redlines at a measly 6800RPM, while the K20A2 is able to rev all the way to 7900RPM.

                              Here we see an image of the intake cam lobes of the K20A3. Notice there are only 2 lobes - there is a nearly round one used only for the low-RPM disabled intake valve, and then there is the regular lobe used by the other valve at low-RPM and by both valves at high-RPM:

                              This system is used in engines powering the USDM Acura RSX base, Honda Civic Si, Accord 4-cylinder, CRV, and Element.

                              Special note: The K20A3 engine used in the Acura RSX base has a slightly different intake manifold design from the K20A3 engine used in the Civic Si. The RSX engine uses a dual-stage manifold, similar in concept to the manifold of the B18C1 in the old Integra GSR. It uses long intake runners at low-RPM to retain low end power, and switches at 4700RPM to a set of shorter intake runners to enhance high-end torque. This accounts for the extra 9 ft-lb of torque in the RSX (141 ft-lb, vs. 132 ft-lb in the Civic Si).

                              Myths:

                              1. The i-VTEC engine engages VTEC gradually, and not suddenly like in the old VTEC engines.

                              Wrong. The i-VTEC engine “engages VTEC” at a single set RPM, like always. Read the definitions above.

                              2. VTC engages at a set RPM.

                              Wrong. VTC is always activated. Read under “VTC” above.

                              3. The K20A3 engages VTEC at 5000+ RPM.

                              Wrong. Technically, there is no “VTEC” (as we think of it) in the K20A3 engine - it uses a VTEC-E technology, which engages at 2200RPM. Read under “The Second Sytem” above.

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