If you read Japanese, This site explains well:
http://www.honda.co.jp/tech/auto/engine/vtec/index.html
Otherwise.... Animations are still good.

 

Cool link! Thanks for sharing. Wish I could read Japanese.

Drive Safe,
Steve R.

 

That is cool and if I read Japanese I am sure I would be pretty savvy about the hole VETEC thing

 

click this link for all VTEC questions answered

 

I didn't realize pins were inserted into the rockers. That is simple, but impressive. So if VTEC kicks in at 6000 RPM, and the valves actuate every 4th cycle, they are turning 1500 RPM when the engine is turning 6000 RPM. That means each cam lobe completes 25 turns/seconds, so one turn in 40mS. Since the cam profile is oval in shape and the follower rocker and the main rockers must be perfectly aligned when the pins are inserted, there is less than a 40mS window when the pins must be inserted. Probably considerably less than 40mS, maybe like 20mS. And it takes a finite amount of time for the pins to travel from the non-VTEC position to the VTEC position, so the time window gets even smaller. And this is all done by oil pressure? Seems to me it would be hard to get that kind of precision using oil pressure alone. Maybe the mechanism that actually moves the pins is driven by oil pressure, but the CPU controls the timing? That seems more likely to me, but what do I know. At least I do know more about it now.

 

Nice link too!

Good info all around though. I've learned about a couple of VTEC implementations that I didn't know about. That 3-stage VTEC looks particularly cool!

Thanks everyone, for the input!

Drive Safe,
Steve R.