What is vtec exactly?

What does vtec actually do? i mean yeah i know i need a DOHC VTEC but what exactly is it? please tell me 'cause i wana learn.

you know how when you get a car without vtec if you want to get a really aggressive cam it starves at low rpm and sucks? when you have vtec it's like having 2 stages of cams. one that is optimal for low rpm and then one that is optimal for high rpm. so at a certain point the rocker arm switches to the higher rpm lobe, hence vtec. sohc vtec only has vtec on the intake part of the camshaft and the dohc's have it on both intake and vtec. that's y their better. they have more tunability.

DOHC vtec (http://web.ask.com/redir?bpg=http%3a%2f%2fweb.ask.com%2fweb%3fq%3dwha t%2bis%2bvtec%26o%3d8088%26page%3d1&q=what+is+vtec&u=http%3a%2f%2ftm.wc.ask.com%2fr%3ft%3dan%26s%3da% 26uid%3d056C625953C14AFF3%26sid%3d1854D6DB1FFA1950 4%26qid%3dB66AFF88BF04924BB4612EBDDD1B1AB8%26io%3d 7%26sv%3dza5cb0dc6%26o%3d8088%26ask%3dwhat%2bis%2b vtec%26uip%3d43274a0a%26en%3dte%26eo%3d-100%26pt%3dHowstuffworks%2b%2526quot%253bWhat%2bdo es%2bthe%2bVTEC%2bsystem%2bin%2ba%2bHonda%2bengine %2bdo%253f%2526quot%253b%26ac%3d24%26qs%3d1%26pg%3 d1%26ep%3d1%26te_par%3d108%26te_id%3d%26u%3dhttp%3 a%2f%2fwww.howstuffworks.com%2fquestion229.htm&s=a&bu=http%3a%2f%2fwww.howstuffworks.com%2fquestion22 9.htm&qte=0&o=8088)
SOHC vtec (http://web.ask.com/redir?bpg=http%3a%2f%2fweb.ask.com%2fweb%3fq%3dwha t%2bis%2bvtec%26o%3d8088%26page%3d1&q=what+is+vtec&u=http%3a%2f%2ftm.wc.ask.com%2fr%3ft%3dan%26s%3da% 26uid%3d056C625953C14AFF3%26sid%3d1854D6DB1FFA1950 4%26qid%3dB66AFF88BF04924BB4612EBDDD1B1AB8%26io%3d 7%26sv%3dza5cb0dc6%26o%3d8088%26ask%3dwhat%2bis%2b vtec%26uip%3d43274a0a%26en%3dte%26eo%3d-100%26pt%3dHowstuffworks%2b%2526quot%253bWhat%2bdo es%2bthe%2bVTEC%2bsystem%2bin%2ba%2bHonda%2bengine %2bdo%253f%2526quot%253b%26ac%3d24%26qs%3d1%26pg%3 d1%26ep%3d1%26te_par%3d108%26te_id%3d%26u%3dhttp%3 a%2f%2fwww.howstuffworks.com%2fquestion229.htm&s=a&bu=http%3a%2f%2fwww.howstuffworks.com%2fquestion22 9.htm&qte=0&o=8088)

Click either of those and you'll learn more than you ever wanted to know. In a nutshell, when vtec engages on a dohc engine the valves lift higher letting in/expelling more air and the computer sends more fuel, for a bigger bang. In real life (on my engine) the engine gets really loud and it goes faster.

What does vtec actually do? i mean yeah i know i need a DOHC VTEC but what exactly is it? please tell me 'cause i wana learn.
i think ricochet sums it up check out the pages he left for you... cool beans!

Vtec does'nt add all that much power, but when you want to pass some asshole on the feeway/highway, and want to do it fast, it helps to drop your car in thrird, and just slam on the gas... you'll be doing 90-100 mph before you know it.

ok killah for one thing i noticed that you have a 4 door honda accord lx and it's obviously a 4 cylinder. do you even know anything about cars? you obviously have an automatic beacuse that v-tec isn't just the droppping of the gear that's your car downshifting. my lord. . . .

Vtec does'nt add all that much power
come take a ride in my car son

Vtec does'nt add all that much power

the VTEC isn't as noticeable in a SOHC compared to a DOHC, where you have both exhaust and intake valves using a new set of cams.

Vtec does'nt add all that much power.

Don't make statements on topics that you know nothing about. if you look at the Honda Tuning Magazine, from the month that i don't know, they have an article about the ls/vtec. They dynoed a normal ls block, then the same ls block with a b16 head on there. It definately added more horses. Then they showed a turbocharged ls on the dyno, after that they showed that same turboed ls with a b16 head on there, and they got HUGE gains. i will post all the numbers later once i find the magazine.

and to answer the first question, go to this site, they got good info.

http://www.leecao.com/honda/vtec/whatsvtec.html

make sure you click around on all the other links on the left side to learn more.

the VTEC isn't as noticeable in a SOHC compared to a DOHC, where you have both exhaust and intake valves using a new set of cams.

VTEC is only on the exhaust cam in the B series and H seriers motors.

VTEC is only on the exhaust cam in the B series and H seriers motors.
Are you sure man? that doesn't sound right and if you have a true link showing that then by all means prove me wrong

VTEC is only on the exhaust cam in the B series and H seriers motors.

here's what I found for DOHC VTEC having both intake and exhaust valves changing cam profile during VTEC engagement

http://www.leecao.com/honda/vtec/

"The lack of cam profile changing for exhaust valves is the primary difference between DOHC VTEC and SOHC VTEC engines. Since the exhaust valves in a SOHC VTEC engine behaves just like a non VTEC engine, only the intake valves will be discussed below. "

-- reference can be found here
--> http://www.leecao.com/honda/vtec/sohcvtec.html

for h series motors, here's some skunk2 cams for the h22a
You can see the VTEC lobes on both intake and exhaust camshafts.
http://www.coximport.com/store/sk-305-05-0200


http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33614&item=2468177333
this one is for non-VTEC prelude
notice there are no VTEC lobes, just the standard lobes.

ok guys, so i found the magazine. it was actually the Febraury issue of Power Pages, not honda tuning mag, sorry. i tried to find the exact same dynos online, but i couldn't find those.

The first graph shows the power of the conventional Ls engine and then the VTEC frankenstein engine. Both engines were outfitted with an intake, exhaust, header, and cam gears. The plain ls engine put out about 147 at the wheels. the frankenstein engine put out about 177 at the wheels.

Then they showed turbocharged variants of the same combination. At 10 psi of boost the VTED-headed integra ls engine generated 58 horsepower more than that the same block running an LS head.

just so you guys know, the turboed lsvtec was making like 270 at the wheels.

hope this helped killah_xft who is obviously retarded and shouldn't be able to post here anymore for saying such stupid comments when he doesn't even have vtec.

VTEC is only on the exhaust cam in the B series and H seriers motors.
You on crack homie?

You on crack homie?

Uhh



Well



Ahhh



errrr

:banghead:

That should explain it:icon16:

i thought both the intake and exhaust manifolds had two differnet cam prolfiles... oh well, i like my ls integra just fine. www.cardomain.com/id/eric_n

intake and exhause manifold CAM profiles ??? HUH

In a basic long story short VERY SIMPLE explenation...VTEC is the name for a process where your computer actuates a little device that uses a pin to line a certain part of your cams up...this process makes your top end power alot more aggresive beacause it makes your cams work harder

and guys i know the full process i was tryin to make it sound simple for the guy..so dont jump on me lol

oh it just hit me what you meant eric, nevermind lol the manifold part threw me off

It doesn't make your cams work harder at all.. wtf you talking about?

its hard putting things in supersimple terms sometimes, im talking about when the hydrolic pin alligns the wild and mild rockerarms

At XXXX rpms, temp, speed, your ECU opens the vtec solenoid, which allows oil to fill a galley and lock the rocker arms effectivley engaging the vtec cam lobe, when you go below XXXX rpm the oil pressure is dropped, and the rocker arms are unlocked, which then switchs back to the normal lobes.

4 door yes, automatic NO WAY IN HELL!! (love my stickshift) and yes I have an F23 4cyl Vtec in with intake, and header, exhaust coming soon as APEXI' can get off their ass and send me a PS revolution.. anyways, Vtec is'nt all that much of a deal, sure it adds a good 10-15 hp on a STOCK motor, that's when you are hitting over 4400rpms. I have a manual, and when you downshift from 5th to 4th gear at around 50mph, and drop into 3rd, or 4th, you can hear the difference from when you are, or are not in Vtec range.. the sound is very noticeable. Especially with an intake, and exhaust system installed. Whether Sohc or Dohc.. Unless you have done a hack on your ECU, or have a piggyback system that is switching your Vtec on at other ranges..

saying I don't know shit about cars is not a good way to go about things... I may not know some things, but cars I am fairly profiecient at... not trying to start a flame war or anything, but STFU!