Vtec makes the car idle smoother. Actuate it all the time and the idle is a bit cooler.
Oh yeah. It improved the low end torque of a Honda. Yeah, that's it. Like you ever hoon a Honda below 4500 rpm...
The only car I've really noticed it(or something very much like it) was in the old VX Civic, where it was impossible to drive at 105kph, because it kicked in at 104, and would immediately send you to 110, where you backed off...and so on.
Shaun said:The 99-00 Civic S with the B16 I had the pleasure to drive quite a bit in the 2000's definitely perked right up when it hit VTeK YO! Super fun car, the drivetrain was OEM and young, sounded fabulous and loved to spin. Fast is was not- but the great gearbox, snappy turn in, fairly neutral handling, decent brakes, and relatively low mass made for a great secondary road car. 100 hp per liter NA is still uncommon- It is worth experiencing IMHO.
Frisbees had 100hp/l from the FA20... and they got a torque dip without the need for VTEC 
None of the five Hondas I've owned have had the variable valve timing tuned for performance. Vtec engagement is pretty imperceptible.
I've had 2000 and 2005 odysseys with some version of the J35. I had a 95 accord wagon with an F22 automatic and a 99 accord coupe with an F23/5 speed. Both of the accords were real slugs.
I just bought a 2008 civic coupe with the the 1.8 (I think it's an R18) and a five speed manual. It does seem to pull pretty well in upper RPM, but I sure can't tell when it engages.
In reply to pres589 (djronnebaum) :
Honda did muck around with the switchover point over the years. On the earlier years it was 6800rpm. Starting with '06 (the year I have) they changed to 6400rpm on the way up, but lowered the switchover to 6100rpm to help eliminate mid-corner on-off-on problems. Not sure what the later bikes have.
On that note, after 3 years of ownership, I love the bike and don't understand the sometimes parroted around the internet criticism/problem some riders claim to have with "sudden" mid-corner VTEC engagement. You've got 12,000rpm to play with...going fast? Work the gearbox like you're riding a little bike and keep it above 7000rpm. Cruising and relaxing? Keep it below 6000rpm until you're past corner exit onto along straight. Or if you really insist, stick to that crappy riding technique that always puts you near the changeover point mid-corner, but don't expect sympathy from me when you start with the "Hur-dur, stupid VTEC making impossible to ride when it suddenly unexpectedly kicks in mid-corner, making it hard to control...what a stupid bike!" criticisms. 
Bonus video to give you an idea of the auditory and character change; the sound is certainly part of why I love this bike!
I had an '04 so I'm familiar with the VTEC kick on that era VFR. It wasn't really an issue for me, it just seemed overly complicated. Still a great bike. I still think I'd rather pick up a 5th gen at some point soonish.
In reply to Jesse Ransom :
The experience on OEM cars varies-doesn't feel like much on an NSX but it's definitely there on the s2000, type r and some others.
Since you'll be tuning the car you'll be able to move the cross over point around or turn it off entirely depending on personal taste.
In reply to Sonic :
I've still haven't driven a NSX. They seem to be beyond me and never on the road anymore.
In reply to yupididit :
Oddly I saw one Tuesday evening.
They drive nicely–like, fast and composed without any real vices.
Maybe because my 8th gen is higher miles, but when driving it solo you can feel the changeover in 2nd and 3rd gear. In my Integra GSR you didn't really feel the changeover just more better sounds.
When my J35 hits VTEC it shuts 3cyl off. I don't recommend it.
8th gen Si has a pretty significant VTEC jump. I think the later cars Honda realized it sells better if it feels more fun, even if the result is it is slower.
Random image from the GIS, lots just like this out there:
Paul_VR6 (Forum Supporter) said:When my J35 hits VTEC it shuts 3cyl off. I don't recommend it.
That is the VCM system, not the VTEC.
The later V6s are very, very complicated under the valve covers...
yupididit said:In reply to Sonic :
I've still haven't driven a NSX. They seem to be beyond me and never on the road anymore.
I drove mine to work today, now that we are going back to the office for the first time in two years it will share DD duties with my 84 Corvette. You're up in MD now right, so if you are ever up near Reading PA let me know and we can go for a spin.
I put 100K on a d16y5/'HX' (96-00) set up which I put in my 1996 Civic Hatch YO which is the backward 'VeeTk YO' lean burn roller rocker D16 single cam engine that later became marketed as 'I vTeK YO' in the K and other Honda engines. It runs as a 4 intake valve engine until more load or RPMs dictates the actuation of then the other 4 intake valves opening. With the long HX gearbox gearing 2,800 RPM was 80mph and I would get just over 40mpg keeping it at 70-85 for hours on I5 up and down the west coast. In 4 valve mode the throttle was very spongy and long travel (I think with vacuum?- it is quite a bit of air and going through 4 wee vales at 2,500- 2,800 RPM and therefore lots of velocity) untill VteK YO!! slammed in and all of a sudden it quit being spongy. Very low overlap cam so it ran out of breath at 6k. Super not exiting, but interesting. 40mpg going 80 is not remarkable anymore.
That picture above had me rolling. I once saw a bumper sticker that said "VTEC, all of the lag, non of the turbo." I had a chuckle.
For me, I always felt annoyed how Honda dorks would be so proud of it, so I had a bit of a negative, contrarian association with it, as silly as that sounds. I've never really noticed it on the Hondas I've driven, but I've never driven any of the performance Hondas except briefly a Integra and NSX and dint take them to redline.
It's a bit like hitting a second wind.
It's like in weightlifting when you're pushing hard, you start to hit a sticking spot and slow down, and you dig just a bit deeper and things starting moving again.
Or when you're running and you get that point where you start to run out of steam, and just before you start to lose pace, you dig a bit deeper and find just a bit of extra oomph.
'03 S2000
And I do miss our B16As. We had a 2000 Civic Si plus a B16A-powered ’88 CRX HF that we prepped for track: tuned ECU, open intake/exhaust, suspension, etc. It was awesome, especially when all the way up near red line. I kept the HF cluster, so I could take the needle all the way past the numbers.
This is an interesting array of answers!
Sounds like... it can probably be tuned not to do anything unsettling or annoying, but there's definitely some variation in how it's perceived from "the sound changes a bit" to "there's a discernible spike in power delivery" (I'm going to need a spreadsheet to track who said what about which incarnation of VTEC...)
I should do some reading up on tuning VTEC engines... It sounds like if you made a number of pulls with the switchover at different revs (or just did dyno pulls at no-VTEC and all-VTEC) you could probably find a spot where the torque is the same or near and thus you don't get any weird behavior. I mean, by definition the low-RPM mode should be tapering off at some point below which it's providing more torque than the high-RPM mode... Math says that creates a crossing of graphs, right? I guess if the graphs had very different slopes where they cross that could still feel weird, but at least it wouldn't be an instant jump.
I wonder whether that RPM changes with other conditions at all... Any reason that the graph's crossover RPM might be different at, say, 70% throttle compared to WOT?
As an aside, it's really the K fours and J sixes that are of interest to me (I think, and I clearly need to do more reading on the divisions within those groups), but I didn't realize there were so many different variations under the "VTEC" label.
In reply to Jesse Ransom :
Yes- The Vteck YO and EYE Vattack YO change over points are managed by the ECU within a range depending on what sensors are telling it. Implementations vary by engine year and all sorts of stuff. Im pretty sure aftermarket tuning can dumb that down to just RPM.
I've got about 20miles under my belt in a 2004 or2005 Civic with a jdm 2.4 litre swap. When the vtec kicked in it got very noisy, I thought something had broken. Aside from the noise it was a pretty smooth transition.
Seems to depend on the car. On my 1st gen S2K it was a kick in the butt. Guess I didn't realized the Odysseys had VTEC. With the K20A2 in the Exocet, it was like hitting the afterburner - you could hear it and definitely feel it. You had to use some care about hitting that threshold while in a corner, or the rear of the car might want to catch up and maybe pass the front.
BTW, here's a S2000 dyno chart and a "torquey" Subaru 2.5RS dyno chart laid over each other.
Note that the smaller engine actually makes more torque below 2500RPM, is running much closer to the 25% larger engine than it has any right to, and then takes off over 5000.
That is the advantage of having multiple cam lobes, you can optimize for a broader area. The Subaru engine is good between 3000 and 5000 and that is about it, which is great if you like peaky engines that need to be shifted a lot.
And the S2000 didn't even have variable cam timing like a more modern engine! That helps out a lot even more.
It is a shame that Hyundai is all-in on turbos, I'd love to see what could be done with their wild continuously variable duration system. (talked about it here before, it puts the cam lobes on a camming mechanism that varies their position on the camshaft as it moves, real crazy stuff)
The blue line is my AP2 (2.2) S2000, the red is a friend's AP1 (2.0). Both are supercharged.
Where would you guess my switchover is?
You'll need to log in to post.
