VTEC's function
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From: Elkhart, IN, UA
VTEC's function
what exactly does the VTEC do when it kicks in? I heard the pistons 2 and 3 lock up and run simultaniously. This coming from a friend who does not know a whole lot about Hondas. I have driven my friend 99 Si and I think the VTEC is awsome. But how does it work
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Re: VTEC's function (r30slick)
what exactly does the VTEC do when it kicks in? I heard the pistons 2 and 3 lock up and run simultaniously. This coming from a friend who does not know a whole lot about Hondas. I have driven my friend 99 Si and I think the VTEC is awsome. But how does it work
When VTEC engages, there is a pin the runs through the head, it locks the VTEC lobe in place, and opens the valves using the VTEC lobe on the cam. Otherwise, the cam runs off the primary lobes.
Just a quick way to explain it.
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Joined: May 2000
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From: PASADENA, CA, USA
Re: VTEC's function (r30slick)
what exactly does the VTEC do when it kicks in? I heard the pistons 2 and 3 lock up and run simultaniously. This coming from a friend who does not know a whole lot about Hondas. I have driven my friend 99 Si and I think the VTEC is awsome. But how does it work
It's not exactly the engine's pistons -- but the tiny pins in the rocker arms (which can be called pistons, i guess) move/slide over due to the oil pressure and ECU control functions which then run off the bigger 'vtec' lobe - once vtec is engaged.
here's a more **** explanation of it...
on the DOHC VTEC valvetrain...
there are 6 rocker arms per cylinder
3 rockers for the intake side | 3 rockers for the exhaust side.
Your friend means to say that when you're out of vtec (before vtec crossover point), rockers 1+3 are engaged and working. Once vtec kicks on or engages, the pin (or like you say 'piston') INSIDE the rocker slides over, locking rockers 2+3 -- #2 rocker being the one which makes contact with the bigger lobe (or vtec lobe).
...does that help any?
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From: Maple Valley, WA, USA
Re: VTEC's function (B18C-EJ1)
Well actually there is a piston(pin) located in each set of rocker shafts. That is what locks up. VTEC will only engage when the engine is warm and there is adequete oil pressure. Basically when you "hit VTEC" The solenoid adds additional oil pressure causing the pistons inside the rocker shaft assemblies to move over (read lock up). Doing this causes the middle or VTEC lobe to come into use. Normally the two outer(primary lobes) are the ones that open and close the valves. But under VTEC, bigger VTEC lobe is what opens and closes the valves.
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From: Austin, Tx, USA
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From: Cumming, GA, USA
Re: VTEC's function (RedlinedVTEC)
just to add stuff, the middle lobe that locks in at 5,000 or so RPM goes at a different rate and keeps the valves open alittle longer for more fuel coming in. That's why you feel a kick and if you look at a dyno plot there's a nice little jump around 5,000 RPM. Good stuff.
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