VTEC vs CVTC

[chris0276]

Hey Guys, which is better? Honda's VTEC or Nissan's CVTC? After using both, the CVTC feels more powerfull, but those Preludes and Integras are keeping up with the Spec V. I don't know much about engines. I hope you guys do. Thanks.

[sr20de4evr]

They are completely different technologies that do completely different things, I don't know how you can begin to compare them. I mean that's like comparing a civic's shifter to a sentra's driver's side window.

[chris0276]

Now I'm even more confused....LOL!!!!

[sr20de4evr]

VTEC - the car essentially has 2 cam profiles. The lower profile is tuned for gas mileage and driveability, when the rpm gets high enough, the engine switches over to a more aggressive cam for extra power

CVTC - stands for continuously variable timing control. The ECU adjusts the engine's timing continuously to prevent detonation/pinging and optimize gas mileage. There is no crossover point, there is no 2nd cam profile, there is no extra power generated (actually there might be, depending on the specifics, but that's not what CVTC is there for, and it's only 1-2hp at most)

[j scam]

Originally Posted by chris0276

Now I'm even more confused....LOL!!!!

cvtc wins at 5000 rpm the secondary lobes open up on the qr25de motor and it sounds like a vtec and boost a lil more. but you have to have a cai to hear it. vtec hits at 5300rpm and there's no comparison. the 2.5 with the right tuning and a turbo can spank almost any car on the street. i just sold my 00 civic si even with all the mods it still couldn't keep up with an ser spec v honda's don't have torque case closed

[sr20de4evr]

Originally Posted by j scam

cvtc wins at 5000 rpm the secondary lobes open up on the qr25de motor and it sounds like a vtec and boost a lil more. but you have to have a cai to hear it. vtec hits at 5300rpm and there's no comparison. the 2.5 with the right tuning and a turbo can spank almost any car on the street. i just sold my 00 civic si even with all the mods it still couldn't keep up with an ser spec v honda's don't have torque case closed

what is it with you? do some research, you don't know what cvtc is, you don't know what the intake runners are, you don't know what happens at 5k, you don't know anything about how these engines work, and you don't know anything about the potential of the qr25 vs the potential of any other car out there.

[TeggyLS]

Yep its the intake runners, that smooth out the power band, it switches in high and low rpm to give better low/top end power. but thats not CVTC

[j scam]

Originally Posted by sr20de4evr

what is it with you? do some research, you don't know what cvtc is, you don't know what the intake runners are, you don't know what happens at 5k, you don't know anything about how these engines work, and you don't know anything about the potential of the qr25 vs the potential of any other car out there.

i'm just learning about the cvtc so if i have the wrong info. why don't you say hey buddy look here it doesn't work that way it works this way and here's why etc. i don't get that i get guy's like you that suck d**k for a living. And try to flame ppl that are here to learn i am here to learn more about the qr25de. But guys like you suck so i can't expect respect from a d**k sucker. if you were a respectful person and you have knowledge to share. if you have the know how or knowledge then turn ppl on with quailty info when they have the wrong info about something. But once again since i had the facts about the secondary lobes wrong. Instead of geting set str8 with the 411. i get you some two bit sucker. had you responded respectfully you would have my att: and i might had even looked up to you and asked for more knowledge that you my have. But now i know that your a punk and don't treat ppl with respect. so f**k you

[94tegRS]

because you come off as some kid that knows everything and just throws out facts like hey, this is how it is, I know all...

and you really have no clue.

[j scam]

Originally Posted by 94tegRS

because you come off as some kid that knows everything and just throws out facts like hey, this is how it is, I know all...

and you really have no clue.

look i learned a lesson don't repeat what someone else tells you unless you can prove it. so qouted what i heard on another board and the info was incorrect. so i get flemed by some disrecpectful punk f that.

[TeggyLS]

For someone who goes around calling helpful and respected members d**k suckers, id say your the little punk.

Now with a little searchin i have found this.

Variable-Valve Timing: "Nissan's Continuously Variable Timing Control (CVTC) electronically measures throttle position, vehicle speed and engine rpm, then adjusts the moment each valve breathes in. And it does this throughout the power band - from that first boost off the line to when you approach redline. Response time and efficiency are optimized. Power and torque, too." - Nissanusa.com

What does it mean?: Variable valve timing allows the SE-R's engine to get as much air as it can when you want it to. This adaptability enables the QR25DE to breathe very well no matter what engine speed it happens to be at. This technology gives the engine the most possible torque and horsepower from 1,000 to 6,200 RPM without the use of a turbocharger.

Variable Intake Timing: "More advanced breathing techniques, courtesy of Nissan. This one boosts torque in the low- and mid-rpm ranges, while tapping into the engine's full potential when it revs higher. At those higher rpm, it opens a secondary (and shorter) airflow path in the manifold, putting instant 'go' at your command." - Nissanusa.com

What does it mean?: When the engine reaches 5,000 RPM a second air route is opened up. This gives the engine more air. More air means more power. More power means more fun!

Last paragraphs from http://www.specplace.com/Performance.html

Now the ctvc smooths out the power band and does add some power, but there is no kick. the slight kick u might mean is from the intake.

Basically there is a short and a long intake runner. In low Rpms, air comes through the long runner only, at about 4.5k Rpm, a valve opens and air comes through both the long and short runners. Giving more air flow for your high rpm power.

[94tegRS]

I am just taking a guess here but wouldnt it only come through the short at high RPM and not bothe because wouldnt the turbulence of 2 different airflow paths cause some sort of problem. I thought on the GSR at least it switches over to the shorter runners not opens both because the shorter runners flow better at high air speeds because of less surface area or something.

also jscam- you are right, dont quote someone else, unless YOU know that information or know they are right. and if you werebnt sure, there might be a couple words you can lreave off your post sto make yourself not sound so cocky and get flamed. and they are "CASE CLOSED" that doesnt sound like the words of someone who questions if hes right or not. and then "the 2.5 with the right tuning and a turbo can spank almost any car on the street." might not wanna add those words as well without any proof as to why you think this, even though its not even close to accurate no matter how hard you would try and prove it.

[TeggyLS]

Well im not sure but this media file from nissan shows both open

http://www.specplace.com/Performance.html then go and click this Links: Learn how variable intake timing works!
under the variable intake paragraph

Really you can make almost any car spank another with enough money. But im sorry a well tuned spec will not come close to a well tunes, Supra, Skyline, WRX among others. No use bench racing, but Those play forms can make big power easily, Even the 4 cylinder wrx is AWD, which gives it a decided advantage over the Spec. Yes a turbo on a spec V will let u spank many street cars, but not all.

[j scam]

[quote=TeggyLS]For someone who goes around calling helpful and respected members d**k suckers, id say your the little punk.

if you come disrespect 1st then there's no way i'm going to swallow thats what you do. i don't even know you- don't come at me with that bullsh*t. 94tegrs just gave me a great response set me str8 but did not call me names and i get the point. he's kewl. when i 1st posted sr20det responed to my post saying you don't know anything. flaming me up instead of helping me out and being respectful about. if you look my post i had the wrong facts but i didn't know any better. i never called anybody anything untill he flamed me. instead of being informative. he came at me. so teggy "ls" "licks and sucks" you came at me calling me a punk when i never said one word to you i was talking to sr20det so fu*k you too. i will say something and i know civilians don't care about what i'm going to say. i enlisted in the marine corp and just got out not to long ago i was in iraq big deal right. but i went out there made it back. i don't know much about the qr25de yet but i'm learning. And i know that no one would know that i was in the usmc unless i told them that i was in. but to come to this site and have the wrong info you guys act like this is war. i was there so fu*k you

[TeggyLS]

im not american, and your service to your country really doesnt impress me, sorry. And im not gonna get into a little flame war, with someone as immature as you. Maybe if you would take a more respectful angle at things you would get a little more respect.