Mi-tech Vs V-tech

[Kasuncp]

Hi Guys,

Whats the difference between V-Tech & Mi-Tech. One of my friends vehicle's engine says MI-Tech. whats that. is it a good Technology?

Regards,

Kasun

[GihanFX]

  Kasuncp said:

Hi Guys,

Whats the difference between V-Tech & Mi-Tech. One of my friends vehicle's engine says MI-Tech. whats that. is it a good Technology?

Regards,

Kasun

is it MI-Tech or MIVEC ?

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How Vtec Works

This month we are delving into the dark deepths of the incredibly popular variable cam technology commonly known as V-tec (Honda) or Mivec (Mitsubishi) in the import scene.

Honda kicked off in 1989 with an Integra running the first of its V-tec engines. Originally designed to increase fuel economy it was re-designed into an engine that was able to start & idle like any other car yet have much larger power & torque figures than any of its predecessors.

What is V-Tec

What is V-tec? (Variable valve Timing and lift Electronic Control) V-tec is a way of switching the cams to a different cam profile while the engine is running. You have most likely heard the term "boobah" thrown around the place & this refers to the throatier sound these engines make as they switch from the smaller or primary cam to the larger secondary cam. Most engines have one set cam lobe & cannot change from this where the V-tec system allows it to switch onto a much larger cam lobe giving a lot more lift & duration high in the rpm which in turn gives the engine more breathing capabilities resulting in more power.

How V-Tec Works

Every engine has oil flow up to the head to lubricate the cam journals, lobes, rockers, lifters, etc & Honda managed to use this oil pressure to their advantage. Each cam runs two lobe profiles for each set of valves, a primary & secondary. There are six rockers to each cylinder, three in & three out which control the four valves per cylinder, two in & two out. Two of the rockers are always functioning & these follow the primary lobe & operate the valves. The third rocker follows the larger cam lobe but can operate separately from the others. This is positioned in between the two primary rockers. As the engine runs at idle & the lower rpm range the rockers can only be operated by the primary lobes giving the same characteristics as any other production motor, good drivability/fuel economy etc.. When the computer knows its time to switch to the larger of the two lobes it opens a solenoid which has been blocking off oil pressure to the V-tec system. Oil pressure runs from the solenoid through its own galleries down the rocker shaft & to the rockers. Now as this oil pressure gets to its rocker (one of the low cam rockers) the pressure pushes a pin out which locks the large lobe rocker & the other low lobe rocker to each other. Now the rocker on the large lobe has taken over from the smaller cam profile & is operating the valves through the rockers on either side of it. With the larger cam profile doing the hard yards now it lets the engine suck in & spit out a lot more air/fuel. Its just like having a switchable race style cam in your car.

V-Tec Variants

As the years have passed there have been more variants of the V-tec system from Honda. There is the V-tec E system which unlike the normal power making V-tec system it uses different lobes only on the intake side of its single cam & is able to only allow one intake valve to operate normally at idle & the low rpm range instead of the two creating much better fuel economy. Also the newer i V-tec uses the two cam lobes like the original V-tec but is now capable of advancing & retarding the intake cam timing as well. This uses a computer controlled oil driven cam gear & its operation is determined by a combination of engine load & rpm.

Mitsubishi's version of the V-tec system is known as Mivec & is incredibly similar although uses a slightly different lock up pin design locking the larger cam rocker to the rocker shaft.

Slightly technical but a very simple idea that has come a long way since its conception & is sure to carry on for some time.

[Kasuncp]

The way i saw Its MI-Tech 16 Val, is it correct? Its a KIA Car (1600 CC)

Kasun

[charitha19]

well looks like the KIA's copy of V tec to me.. the new sephia's and the rio hatch back has these engines.. usally DOCH 1500 16v mi TEch which apprently stands for Millennium Innovation Technologies .

same thing different words i guess. promises to delveir more ponies than the standard KIA engines...