i kno it stands for variable valve timing
but how excactly does that work? like do all the valves kick in around a certain rpm
as it does in the hondas v-tec??? i kno that stands for variable valve timin lift and control or some **** like that.

 

VVT doesn't make the valves "kick in" on either Hondas or any other car. The way VVT works is that the computer has essentially CAM "profiles" which it can select between depending on engine speed. The "profiles" modify the timing of the cam so the valves open and close at optimal times depending on engine speed. It allows you to make the CAM more efficient at all RPM ranges instead of only one range.

 

I think Honda's new VTEC varies continuously, so "VTEC JUST KICKED IN YO" might not be accurate anymore. Like VVT, iVTEC can continously change profiles.

 

The valve timing is automatically adjusted (retard / advance the timing) for the difference in octane, air temp, and altitude.
This will keep it from knocking or pinging and to maximize performance and efficiency.

 

chekc on youtube, there's a video that explains it all

 

most of what is posted is basically true. The cams in the 2.4 are controlled by oil pressure -- each cam has an adjuster and a solenoid that controls how much the cams advance or retard. There is also a spring loaded piston/pin that locks the cams in place when you shut the engine off so they are in the right position for starting the engine. Depending on preset conditions based on engine load, vehicle speed, engine RPM, TB blade position, etc the cams are independently advanced or retarded for optimum power and emissions. If you read up on intake and exhaust valve-overlap this is what the VVT is controlling. For example a race engine without VVT generally uses a cam (or cams) with a lot of overlap which causes the idle to be very poor (Loping) but efficient on the top end (106-110 degrees of overlap -- opening of the intake and closing of the exhaust -- the separation of the cam lobes is closer so there is more overlap), A responsive street engine without VVT generally has a cam (or cams) with less overlap so the idle is smooth but the top RPM suffers (114-118 degrees of overlap -- the separation of the cam lobes is wider for less overlap). With VVT we get the low overlap for good idle and the higher overlap for higher upper RPM power. This is a very simplified example since the cams move all through the RPM range. The valve lift is not affected -- only the timing of the opening and closing of the valves relative to the crankshaft.

 

Thats right ^^ what this man said... That is one hell of a answer, Im not sure that many on here will understand it..but I tip my hat to you sir for the great detail..

For those who do not understand his post:

It works because it just does!!..
How does a posi-trac rearend work in a Plymouth??? It just does!!
How come ham with the little specs of cheese in it taste so good?? It just does!!

 

yea man one hell of an explanation

 

VTACK!!!

 

Very well put Hard enough to explain the concept of cam timing to someone, let alone variable cam timing

Now if they could give us variable lift as well.........