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okay i've scanned the archives for all the feuding, and I've personally debated with others on the issue, but I was driving w/o the radio and paying attention to my intake today when I heard something interesting.


The debate ... Do our civic ex's have that 3-stage vtec or regular ole' vtec?

The intake's argument: Get in your aftermarket intake equipped Civic, get in 3rd or 4th gear, radio off, and drive at 2000rpm.... Now put it in the floor and LISTEN to the intake sound. At 2500rpm it gets slightly deeper. Ive done it over and over again, in 1st-5th, and every time at 2500rpm the note gets a little deeper. I had to use an exhaust silencer to actually hear it better, but its there.

This makes it interesting, b/c a deeper note would make me think that another valve is in use, as is the case with the 3-stage vtec. I hope that I didn't screw up in my search, and miss the post that settled this. Last time I checked it was unsettled. Sorry if its old news [IMG]i/expressions/face-icon-small-smile.gif[/IMG]

av

 
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The Note gettign a little deeper as actually just midrange frequency noise cancellation.... go to HowStuffWorks and look through how a muffler works for a great example on this.

Cheers
Mohawk

 
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at exactly 2500rpm, the specified rpm per honda? I am aware of frequency noise cancellation, but this is too abrupt/different/coincedintal(sp?) imho....


edit--- its actually very abrupt, not gradual

 
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yah i know what ur talking about but i don't have an intake, try this one!

open your hood, with the engine on of course, and reach back behind the throttle body and slowly start to lift up on the throttle, the rpm will go up, do this slowly and have a friend sit inside and watch the tach, right around 4400 for me anyway it gets deeper, and vibrates just a little more, this i know for a fact is vtec engagement cuz if you've ever done similar on an si you can hear that engage like 2 miles away. hehe but yeah i dunno about the 2500 rpm thing

 
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I have noticed with my intake that in third gear, after taking 2nd too the limit, that my center console shakes cause vtec is so loud and this has happened in 4th gear to. Has anyone else experienced that.

 
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DAMN why do people keep on talkin about VTEC.................????????

To me i believe VTEC is just a little assistance and that's all. It's nothing to
be all happy about........ Just because you have VTEC....... it doesn't mean you
gonna beat sumone that doesn't have it........ so stop posting VTEC shizt.

 
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No need to get all rowled up GTekCiViC. He was just talking about the sound.

avenger: As far as I know there are only two modes on the camshaft. Less aggressive and more aggressive. You basically only have VTEC ON and OFF. It is possible to make a continuously variable VTEC. All they would have to do is make a camshaft with a less appresive profile on one side and a more aggresive one if you pushed it in a little. The VTEC selenoid would have to be changed too. Not only one position, but a changing position with rpm's. Maybe a mechanical solution is possible too without all the complicated electronics. Although with the electronics you can change modes on the fly from economy to performance. Anyway, I'm positive that it's only 2-stage VTEC.

 
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thx for the defense grey!

everything I've read suggests 2stage vtec, and in past arguments I've had the same point as you. But I just noticed this sound. I'm going to make a recording of it soon, and i'll post it. Its not a loud bang or anything anyone else has said, its a very slight change in the sound but it is abrupt and does get slightly deeper. Everything i've read states that 3-stage vtec opens the 2nd intake valve at 2500 rpm, and the sound change is at exactly 2500rpm..... its too coincidental to just dismiss, and the change is too abrupt to be freq cancellation. Someone said to check for the existence of an extra solenoid on my motor, which I'll try once I ride BART back after work.

Oh well, while all signs point to 2stage Vtec the sound makes me wonder... i'll make a recording [IMG]i/expressions/face-icon-small-smile.gif[/IMG]


Edit: Has anyone with an intake actually tried this yet? Results?

 
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I have noticed the noise also, it does make me wonder about whether its changing the timing at around 2500rpm. It is real noticable when passing 2500 in third gear. Peace

 
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I have an Lx and i hear simaler with my Intake win i hit 4000 rpm

 
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you can't engage vtec with the car in netural and parked.

I'm half-half on the fact that our engine may be 3 stage vtec. if it is the case, it should really yield more mileage than what we're getting. but it has been quoted from sources that the D17A2s are 3 stage sohc-vtec engines. *sh

certain conditions are needed for vtec to be engage, oil pressure for one, engine temperature, etc. hence u can't just sit there in the car in neutral, and rev up the engine, expecting vtec to engage.

we'll find out in due time if the engine is indeed 3 stage or not.

 
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At 2500 RPM is when the VTEC-E opens all of its valves. I have already posted on this. So I don't think the question is do we have a 3-stage VTEC but if we have VTEC-E and I know that this has been debated before but I looked on my sticker today in my glove box and it said VTEC-E but I don't think I do. Do any cars in the US have 3-stage VTECs??

 
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I didnt say to do it in neutral, I said to do it when the vehicle is driving. The civic ex was quoted as having "Vtec-E" but whether or not the USDM VTEC-E is the same as 3-stage Vtec, thats what this is about.....

 
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No its not the same. VTEC site Read it and you will find lots of stuff on VTEC.

 
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I said do it in neutral, my bad, i just kinda figured that would work! Guess not [IMG]i/expressions/face-icon-small-sad.gif[/IMG]

 
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From what I have read the VTEC on the 2K1 will kick in at two different RPM ranges depending on load conditions. I belive it is in the 2500 and 4000 + RPM ranges. It's not a three stage cam, but the electronics tell it when to kick in. So you have regular cam and VTEC cam at two differen't operating ranges.