[info] Apakah itu VTEC??

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anuarul

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Apakah itu VTEC??



VTEC adalah kependekan bagi Variable Valve Timing and lift Electronic Control (Pemasaan dan bukaan Injap Boleh Laras Kawalan Elektronik). VTEC adalah sistem pamasaan injap boleh laras yang diperkenalkan oleh Honda bagi meningkatkan kecekapan volumetrik enjin, dan sistem VTEC adalah sistem pemasaan injap boleh laras komersial pertama digunakan dalam industri automotif. Sistem VTEC dicipta oleh jurutera R&D Honda, Ikuo Kajitani.

Dalam sesebuah enjin, saiz sesondol bukan sahaja menentukan bukaan injap, malah turut menentukan pemasaan dan tempoh masukan / keluaran. Apabila kelajuan enjin semakin meningkat, tempoh masukan campuran udara-bahan api serta tempoh keluaran gas ekzos menjadi semakin terhad. Walaubagimanapun, saiz bukaan injap yang tetap menghalang lebih banyak campuran udara-bahan api untuk masuk ketika kelajuan tinggi, sekaligus mengehadkan kuasa maksimum enjin. Oleh itu, sistem pemasaan injap boleh laras dicipta bagi membolehkan lebih banyak campuran udara-bahan api masuk ke dalam kebuk pembakaran semasa kelajuan enjin tinggi, seterusnya meningkatkan kuasa enjin.

Jenis-jenis VTEC

VTEC konvensional (SOHC dan DOHC)
VTEC-E
VTEC 3 Peringkat
i-VTEC
VTEC pada motosikal
VTEC Konvensional(SOHC dan DOHC)

Sistem VTEC yang paling asas ialah DOHC VTEC. Di dalam sistem ini, sistem VTEC mengawal pemasaan dan bukaan bagi kedua-dua injap masukan dan injap ekzos. Setiap aci sesondol mempunyai 2 sesondol bagi setiap silinder - sesondol bukaan kecil dan sesondol bukaan besar. Semasa kelajuan rendah, sesondol bukaan kecil digunakan secara lalai bagi penjimatan minyak. Semasa kelajuan tinggi, solenoid elektronik membuka laluan minyak ke pin pengunci sesondol bukaan besar dan tekanan minyak mengunci pin sesondol bukaan besar. Akibatnya, sesondol bukaan besar digunakan untuk kuasa maksimum. Apabila kelajuan enjin kembali menurun, solenoid tersebut dimatikan dan pin pengunci dilepaskan, menyebabkan sesondol bukaan kecil digunakan kembali.

Bagi SOHC VTEC, mekanisme yang digunakan adalah sama tetapi aci sesondol tunggal tersebut hanya boleh mengawal pemasaan dan bukaan injap masukan sahaja.

VTEC-E berfungsi dengan cara yang berbeza; jika VTEC konvensional digunakan untuk meningkatkan kuasa enjin, VTEC-E pula direka bagi penjimatan bahan api yang maksimum. Di dalam sistem VTEC-E, hanya satu sahaja injap masukan yang dibuka secara lalai pada kelajuan rendah bagi penjimatan bahan api yang maksimum. Pada kelajuan tinggi, tekanan minyak menolak pin mengunci yang mengunci injap masukan kedua, membolehkan kedua-dua injap masukan digunakan.

VTEC 3 Peringkat menggabungkan kedua-dua teknologi VTEC-E dan VTEC konvensional. Pada kelajuan rendah, hanya 1 injap masukan sahaja dibuka secara lalai. Pin pengunci pertama mengunci injap masukan kedua semasa kelajuan enjin sederhana manakala pin pengunci kedua digerakkan untuk membolehkan sesondol bukaan besar digunakan pada kelajuan tinggi. Dengan ini, enjin yang menggunakan VTEC 3 Peringkat dapat memanfaatkan kedua-dua penjimatan minyak dan peningkatan kuasa enjin.

i-VTEC menggabungkan teknologi pemfasaan sesondol yang digunakan oleh sistem pemasaan injap boleh laras yang lain dengan teknologi VTEC sedia ada bagi mengurangkan “kejutan kuasa” semasa mekanisme VTEC berfungsi.

VTEC pada motosikal

Selain pada enjin kereta, Honda turut menggunakan teknologi VTEC pada beberapa model motosikalnya. Ia mula digunakan pada motosikal Honda CBR400F Super Four HYPER VTEC, dan seterusnya pada motosikal Honda VFR800.



info tambahan dari kawan2 CG yang lain. terima kasih. :)



source: zth


Originally Posted by carneo
Anyone know Alza engine 3SZ-VE DVVT or VVT-i ?
According to the search of the ALZA's 3SZ-VE engine is made in China Tian Jin Toyota factory and suppose to be VVT- i but Perodua claim that is only DVVT it was same engine as 4WD Nautica(in malaysia) and 2WD Rush, event Toyota Malaysia call the 3SZ-VE for Rush as VVT-i. Is that when the engine mounted in Alza the VVT-i proccesor has been taken out in order to make the price more compatative hence the variable cam shaft link it to the mechanical actuator so it call DVVT.
Is that any one know the story behind ?
Originally Posted by yeehau86
Hi carneo, The main change between Perodua Viva and it's predecessors (Perodua Kelisa and Perodua Kancil) would be their engines. Then it came the term of DVVT, and Perodua claiming their 1.3l DVVT saves fuel and provide power as same as normal 1.5l engines.

Let us get back to the basics, DVVT or it's full name Daihatsu Valve Variable Timing is based (copycat) on Daihatsu mother company Toyota engine, which is VVT-i (Variable Valve Timing - intelligence). We believe that DVVT is just VVT-i's engine brand name for Daihatsu cars.

DVVT and VVT-i is based by Yamaha's YPVS (Yamaha Power Valve System). Yamaha was bought over by Toyota for it's YPVS because Toyota afraid of losing to Mitsubishi's MIVEC and Honda's Vtec. Yamaha has been provinding Toyota and Daihatsu engines since.

DVVT and VVT-i engines are always put together to be compared with V-tec (Variable Valve Timing and Lift Electronic Control System), i-DSI (intelligent Dual and Sequential Ignition) that is developed by Honda earlier.

All of the Vs (DVVT, VVT-i, i-DSI, Vtec, CVCC, MIVEC, CVVT...) was meant to increase fuel efficiency which is to use less fuel and produce more power from the engine. The objective is the same, the only difference would be their methods.

DVVT and VVT-i

Normal engines is good in the low RPM. However, when the RPM reaches higher level, the amount of power produced per fuel is lesser. This is because the air from outside the engine couldn't get into the combustion space in a short period of time. That's what Yamaha sees, and they developed YPVS, VVT-i and DVVT.

DVVT and VVT-i valve works like a normal engine while in low RPM. However, as the RPM increases, the valve timer shifts the time of opening of the valve a little bit earlier. The higher the RPM goes, the earlier the valve opens.

By doing this, air would hav enough time to go into the ignition room, thus making the fuel burning in high RPM more efficient than conventional internal combustion engine.

Vtec

Vtec have the same idea with DVVT and VVT-i. It acts like a normal fossil combustion engine in low RPM, however when the user revs until certain limit (usuall 5000rpm). The valve timer would activate (this is what people usually calls Vtec change) and produce a noisy sound.

It sounds a little bit like a 2-stroke motorcycle engine revs high. You feel like the torque suddenly increases and you have more power to accelerate.

What actually happens is that the valve intake open longer than normal. Allowing more air to come into the combustion chamber. The more air in the chamber, the more efficient the fuel burns.

i-DSI

i-DSI is a new technology by Honda. Instead of changing the valve timing of an engine, Honda put two spark plugs on each piston. The reason is the same.. to burn the fossil more efficiently.

These spark plugs however have the main and secondary plugs. The main plugs usually sparks first, followed by the secondary plugs to burn the remaining gas in the chamber.

The interval between two sparks was calculated in such a way to its most efficient fossil burning. In the highest RPM level, those two spark plugs might sparks at the same time to produce the largest power from the engine.

Conclusion

DVVT, VVT-i, Vtec and i-DSI is a good way developed by Japanese car automaker (Toyota and Honda) to improve the burning of fossil gas. All of them have the same objective (increase efficiency) and they do achieve their goals.

For the best fuel efficiency, MyPerodua would say i-DSI would be the best choice. For power, Vtec is the best.. and DVVT and VVT-i is in between those two.

MyPerodua welcomes DVVT engines in Perodua Kelisa and Perodua Kancil replacements (Perodua Viva). We are waiting that Perodua would implement a 7-gear no gap gearbox (like Honda Jazz) in their future installments. Coz that surely would increase the fuel efficiency of a car.

:)paid:)paid:)paid:)cgrock:)cgrock:)cgrock
 
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Ok lah tu dpt belajar ilmu & makna VTEC tu....kdg2 tau sebut jer tp x tau ape ke mende nya tu, yg ak tau VTEC ni sinonim dgn jenama HONDA, pe2 pun gud info oleh TT....fanatik HONDA agaknya TT ni hehehe...

Ak suka TOYOTA dr kete bapak ak dulu KE30 sampailah skrg ak pakai TOYOTA gak tp system VVTI sama jer mcm VTEC tu
 

duzzz

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vtec memang syok..
layan b16a pn dh puas
 

mnzaim

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Abg anuarul nk jual enjin plak ke pasni??? :D:D:D
 

oxygenO2

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hehehe..sape yg nk citer psl silver/black top plak nie...heheheh
 
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