VTEC

[SmelltheRubber]

I dont know if this has been asked before....
I just dont get all the fuss about VTEC. Maybe, I'm missing something...

Please correct me if im wrong-
1. VTEC kicks in on the higher rpms (i.e. usually after 5500 or 6000)
2. Even when VTEC kicks in, the actual "hp gain" is something like 3hp to 5hp.
3. After VTEC has engaged, you have about 1000-2000 rpms left (depending on car, i know) before you have to shift to next gear.

So what is all the fuss about VTEC engines?? :dunno:
I hope someone can give me some good points about a VTEC engine, cause I dont understand why everyone prefers them so much over a regular honda engine. Thx in advance for clearing this up.

[importadrenelin]

SmelltheRubber-
VTEC is variable valve timing, it just has to do with open up more airflow on the intake cam side so the engine can make more HP, someone correct me if I am wrong.
But if you want to see a difference, drive a Integra RS then drive a Integra Type R.

[2000impreza]

some of the higher end variable timing systems work on both intake and exhaust cams.

[SmelltheRubber]

But the ITR engine has several completely different internals than the stock GSR engine. Thats why it puts out 190hp compared to the GSR's 170hp.
I know what VTEC stands for, and that it alters the air flow at high rpms, but I was confused as to it's actual real-world value. I dont think it makes that much of a difference, i was just looking for anyone's experience or comments who would justify paying extra for a VTEC-equipped car.

[boi-alien]

Originally posted by SmelltheRubber
But the ITR engine has several completely different internals than the stock GSR engine. Thats why it puts out 190hp compared to the GSR's 170hp.
I know what VTEC stands for, and that it alters the air flow at high rpms, but I was confused as to it's actual real-world value. I dont think it makes that much of a difference, i was just looking for anyone's experience or comments who would justify paying extra for a VTEC-equipped car.

ok go drive a civic DX and then go drive a civic Si, you'll notice a difference

[szw]

Well I think you just have to drive them to know..opinions differer from person to person.

Between 2000 Civic SI and Civic SIR, I'm sure there are other change besides just having VTEC, but the difference is like 127HP to 160HP.

I drove an SIR once and it seemed like a fun, fairly fast car. I don't really like the soundof the VTEC engines, but whatever! I have never driven an Si to know the difference. Only a DX automatic. The SIR and DX are completely different driving machines.

[buh_buh]

VTEC is overrated. There are car manufacturers that have much more advanced variable valve timing systems, but they just don't hype it up as much.

[CRXguy]

Originally posted by buh_buh
VTEC is overrated.

:werd:

[boi-alien]

Originally posted by szw
Well I think you just have to drive them to know..opinions differer from person to person.

Between 2000 Civic SI and Civic SIR, I'm sure there are other change besides just having VTEC, but the difference is like 127HP to 160HP.

I drove an SIR once and it seemed like a fun, fairly fast car. I don't really like the soundof the VTEC engines, but whatever! I have never driven an Si to know the difference. Only a DX automatic. The SIR and DX are completely different driving machines.

the civic Si, has vtec, it's just a sohc vtec, while the SiR is dohc vtec.

that's why i suggested that that he compare a civic DX with a civic Si, they're both sohc, one has vtec the other doesn't

[GingeRRRBeef]

From what I hear, (I might be wrong) VTEC is a stage 2 variable valve timing and kicks in when an engine is in a certain RPM range.

I know my Spec V has continuous variable valve timing, they call in Continuously Variable Timing Control.

I agree that other companies have more advanced variable valve timing technology and I think honda and ppl who own hondas hype it up too much.

[max_boost]

Originally posted by CRXguy


:werd:

You don't even have VTEC fag!:rofl: But you'll have boost......:D

[D'z Nutz]

Originally posted by buh_buh
VTEC is overrated. There are car manufacturers that have much more advanced variable valve timing systems, but they just don't hype it up as much.

I totally agree, except I don't think it's the companies that hype them up, just the teenage ricers. If you think about it, just about every company has their own version of variable valve timing.

[B18C]

Originally posted by buh_buh
VTEC is overrated. There are car manufacturers that have much more advanced variable valve timing systems, but they just don't hype it up as much.

I disagree man. Sure v-tec isn't what it used to be compared to some of the new stuff out now but it is still good. It is reliable and does as advertised - which is providing good, ECONOMICAL performance on a street car.

And SmelltheRubber here are a few answers for you:
1. yes.

2. I don't know where you get this 3-5hp gain from but it is a little more complicated than that. What v-tec does is give you another (more aggressive) cam profile so you can rev high efficiently. Remember that hp= (RPM*tq)/5252 or something like that and the more aggressive cam profile lets you keep your tq up at higher rpms where your less agressive cam will start falling off earlier. Therefore this 3-5hp gain is :bullshit:

3. it kicks in at higher rpms (usually between 5000-5600 rpm), but these cars usually have 8000rpm redlines and an extra 2000 rpm is usually where you are when you are racing anyways so it IS very useful.

[ancient]

Granted when your racing, your WOT....


The RPM Range your in is almost always in VTEC so your using your more aggressive cams.... Basically there is no real point of VTEC other than economy, because they could just put in a straight vtec lobed cam, and it would just idle rough and take more fuel, but still perform as well..... You just get the best of both worlds....

On certain vtecs.... like h22a... You can feel the car pull harder in vtec... I've been in my buddies civic si, and when vtec kicks in its hardly any different.

[GT2NV]

Originally posted by D'z Nutz


I totally agree, except I don't think it's the companies that hype them up, just the teenage ricers. If you think about it, just about every company has their own version of variable valve timing.
:werd: :werd:

[SmelltheRubber]

Originally posted by B18C


I disagree man. Sure v-tec isn't what it used to be compared to some of the new stuff out now but it is still good. It is reliable and does as advertised - which is providing good, ECONOMICAL performance on a street car.

And SmelltheRubber here are a few answers for you:
1. yes.

2. I don't know where you get this 3-5hp gain from but it is a little more complicated than that. What v-tec does is give you another (more aggressive) cam profile so you can rev high efficiently. Remember that hp= (RPM*tq)/5252 or something like that and the more aggressive cam profile lets you keep your tq up at higher rpms where your less agressive cam will start falling off earlier. Therefore this 3-5hp gain is :bullshit:

3. it kicks in at higher rpms (usually between 5000-5600 rpm), but these cars usually have 8000rpm redlines and an extra 2000 rpm is usually where you are when you are racing anyways so it IS very useful.


Thx for the info man! Somebody was telling me that the 3-5hp comes from the valve timing change (i.e. more efficient timing).
But hey, thats the kind of reply i was looking for to clear up this VTEC business! Thx again!

[ancient]

The HP gains are quite large actually, let me grab a dyno sheet comparing the h23 to the h22a... non vtec and vtec engines...

[B18C]

Originally posted by ancient
... Basically there is no real point of VTEC other than economy, because they could just put in a straight vtec lobed cam, and it would just idle rough and take more fuel, but still perform as well..... You just get the best of both worlds....



Well, not exactly. The non-vtec lobe has a profile that makes it better in the lower rpm range. Think of it this way, cam profiles don't really make power they just shift your power band (this is not totally true, but is a convenient simplification). Basically, you have to give something to gain something. What vtec does is allow you the best of both worlds. The non-vtec cam has good low end power at the expense of high-end power where the vtec cam is exactly the opposite. The vtec actuation point is generally where the tq curves of the 2 cams meet (where the vtec cam starts making more power than the non-vtec cam). This is also why it is stupid for people with mildly modified hondas to lower their vtec actuation point thinking it will make more power. Unless you have a dyno, you cannot possibly plot where this cross-over point it and thus will be losing power - but that is for another discussion.

[ancient]

Pay attention to the Brown and blue lines, that would be the h22a...

http://24.174.137.232:90/h23overh22.jpg


They compaired a h23 with i/h/e
To a h22a with just a filter

Not exactly fair, but thast why it looks close.....

Notice the jump in HP where the vtec kicks in... It is substantially larger.... this is all at the wheel hp.

[Ben]

Originally posted by crxboi


ok go drive a civic DX and then go drive a civic Si, you'll notice a difference


More like you will "Hear" a difference which fools you into thinking you are accelerating faster than you really are...its not that great...

[ancient]

I forgot to mention that fact b18c, that is true...

[boi-alien]

Originally posted by Benny



More like you will "Hear" a difference which fools you into thinking you are accelerating faster than you really are...its not that great...

i'm not saying you'll feel a kick in the pants cause you can't get that unless you have DOHC vtec... and a bigger motor :D... but u will notice that an si will pull harder than a dx.

[civic_rida]

How many manufactors produce engines that redline over 8000rpm.

[ancient]

I can't think of any lol

[GTS Jeff]

oh my god this thread hurts. there are about 8 different forms of vtec in honda for one thing, and in all cases, it is gooood shit. i cant believe so many of u are so uninformed about vtec...i will write a big huge post sometime later about all this...

[T5_X]

http://www.imagestation.com/picture/sraid31/p39ceac8171fdf734ac451cc842f4b99d/fd45a17b.jpg