this my first post
what is the variable valve timing and what does it do

 

Variable Valve Timing= Valve timing that is variable. :-). Easiest example is honda's VTEC, in which at high RPMs, the timing is changed to optimize power at that range.

Like with everything else, Nissan has something better :-). Continuosly Variable Timing on most of it's newer engines. Basically, instead of changing the timing at a certain RPM, it does it progressively with engine speed. This give you a much more linear powerband, whereas in a Honda VTEC you have crap power until about 5200rpm when the VTEC kicks in, and then you get into its powerband. Too bad that by that time, the Max is already gone... MUHAHAHAHAHA!

 

umm doesn't Honda have I-VTEC now which is more like continuous? not sure though.

lots of cars now have continuous VVT

 

Honda VTEC/I-VTEC engines have a VERY linear powerband. Seen an RSX-S or Integra Type R dyno chart lately? Their torque curves are flat, they just don't make much of it, but their gearing makes up for it.

There are many different versions of variable valve timing and NO, they don't all do the same thing:

Variable cam phasing only= Nissan CVTS, Honda I-VTEC (ex. base RSX, 2002+ Civic SI), BMW Double VANOS, Toyota VVT-i

Variable valve lift only= Honda VTEC (ex. NSX, Integra Type R), Nissan Neo VVL, Mitsubishi MIVEC

Variable cam phasing and variable valve lift= Honda I-VTEC (ex. RSX-S), Toyota VVTL-i (ex. 2000+ Celica GT-S), Porsche VarioCam

There are obviously more, but these are the examples that came to mind.

 

MAN! it was the guy's 1st post, I was only trying to keep it simple for him to understand what it does and get a general idea. Why do you have to come out with your PhD in "Valve-Timenologics" and confuse the noobie? lol

Besides, I never said anything about iVTEC, I was very specific on regular ol' VTEC. and y are u giving those lawnmower and motorcycles guys any credit, they're the enemy, you INFIDEL! I'd ban you if I were a Moderator, j/k lol.

I don't like the gearing for crap in Hondas, the gears are way too short for my taste, for God's sake at 20 mph that engine is already beggin for mercy. I do however like their smoothness, Honda trannies are some of the smoothest I've tested (got to give them SOME credit) lol.

 

Although the fact of the matter is that when you start to modify those motors, the transmission immediately starts to slip.