What exactly is VVT-i?

I am somewhat familiar with Honda's VTEC as I currently own a S2000 and Civic Si. I am curious is the 2.7 VVT-I similar to VTEC or is it something completely different?

 

VVT-I = Variable Valve Timing + (Toyota's anonymous "i" designation that they add to some engine titles, such as the iForce V8 in the Tundra).

Both VTEC and VVT-i are examples of variable valve timing, they're just the different trademark names of their associated brands. Variable valve timing allows for better fuel efficiency by controlling amount of time the intake valve is open (retarded timing=less fuel used) depending on what the demand is on the throttle.

 

On our four cylinders it's about the simplest variable valve timing there is - the computer can advance or retard the intake camshaft depending on load and conditions. The exhaust cam is fixed gear and there's only one chain. I think the 4.0L V6 is a little different, in that it has a variable cam gear just on the intake cam like ours, but (I assume) that because the exhaust cams are driven by slave chains from the intake cams that they may alter exhaust cam timing in step with the intake cams, but I'm not 100% sure on that. Never had one of those apart.

(OP probably knows all the following, I'll throw it in here for the diehard 'yota guys who may not)

The Honda S2000's VTEC system is totally different. On both the intake and exhaust cams, there are three cam lobes (and rockers) for each pair of valves per cylinder. The rockers on the outer two push the valves, and the middle rocker doesn't contact a valve. Since the middle lobe on the cam is much bigger with much longer duration, as soon as the computer activates the VTEC solenoid to reroute oil pressure to lock each set of three rockers together, the middle rocker lifts the outer rockers completely off their lobes when the valves open. With valves open farther and longer, you get much better high rpm flow, and that's how a Honda can make torque to 8000 rpm and beyond without having a rough idle typical of a huge cam. I don't like calling it variable valve timing because yes, the valves open earlier and longer on the secondary lobes, but there are literally only two settings. On or off. The word "variable" makes people think there's more than that.

There's a difference with Si's engines. The S2000's F20C or F22C1 are much like the B16A2 or B18C1/5 engines of yesteryear; all the extra lobe magic, but NO variable cam gear. When they switched from the B-series to the K-series engines in 2002, the ones that said i-VTEC on the engine cover, they began including the variable cam gear as well to smooth out the torque curve better. That's when they really became VVT engines. Of course, that first K-series Si hatchback had the awesome VTEC system swapped out for the kind they put in the CR-V, where it only shuts off half the intake valves for better mpg... no extra lift anywhere, boo hiss!

You can usually which system a Honda got pretty easy. If it has a belt, guaranteed no variable cam gear; the current J35 V6 is probably one of the last ones left like this. Most Hondas with chain-driven cams have a variable cam gear or two, but there are exceptions, like my 2008 Fit that said i-VTEC on the cover but is really just the same type of fixed gear VTEC-E system you'd get in an old Civic HX.

 

Good explanation,

I worked for Honda/Acura for many years as a Service Writer, I learned a lot and loved my DC5, aka RSX-S
It was a joy to drive.

 

Actually the "I" means intake. Pretty sure. The intake cam timing can be varied but the exhaust cam is fixed.
My Dad's 2006 Highlander has "dual-VVT," which is variable cam timing on the intake and exhaust cams. His engine is noticeably peppier than my 2006 Tacoma... not sure why they didn't do dual-VVT on the Tacoma.

 

It's actually variable valve timing w/ intelligence

 

That's what I had heard the "I" stands for.

 

Much of the Newer vehicles are equipped with Dual VVTi's, my 2010 Tundra 4.6L V8 had dual VVTi and oh my it was peppier like hell compared to the tacos, was giving better MPGs as well.

 

Well it's a v8 so...

 

I see a lot of VVT engines in GM cars. I did some research on it and VVT is a patented design by Toyota so GM is quietly buying Toyota engines and sticking them into several models on their fleet. Most people don't know that and I didn't either until recently, but it kinda cracked me up. GM is so ashamed of their ability to build reliable engines they buy from other, more reputable manufacturers! Haha