VTECH????

[marcello]

i know that the spec is not a vtech but is it the same consept or something?

[nametakennow]

No. It has a variable valve timing setup (CVTC), but not different cam lobes like VTECH.

[marcello]

so what does that mean? i watched a video of a spec and it sounded different once it hit 5000 rpm. and i also read people saying stuff about once it hits 5 that it is gone. could you get something like the honda mat or what ever it is called to make it kick in earlier?

[nametakennow]

Yes, the QR has more power in the lower and midrange. It tends to die off past 5k.

The CVTC controller is continuous, so it doesn't "kick in" a-la VTECH, it just responds to throttle position, RPM, etc.

[marcello]

so then it wouldnt be good do bring your spec up to higher rpms if you want to go faster? what is the peek hp and peek tq?

[nametakennow]

No, going past peak power is why it dies off, I think it's around 5k.

Higher rpm does not equate to more power in every engine.

[marcello]

so where would you want to switch at when you are racing in a spec?

[nametakennow]

Wherever it starts losing power. You'd have to play with it and see. I'm sure you could look up when its peak power and torque are and just seek to keep the revs in between those ranges as much as possible.

[marcello]

o so just switch about 5500-6000 im guessing?

[Sentientbydesign]

CVTC differs from VTECH in that it doesn't have a higher intake lobe.

VTECH has a second cam profile once it kicks in which allows higher air intake through the intake valves.

CVTC on the other hand adjusts the intake timing and possibly durration if I'm not mistaken.

So there is no changing of the CVTC to improve things.

[marcello]

o well i guess that makes sense. i was thinking about a gsr but i really want a spec v now!

[Buzzman]

CVTC differs from VTECH in that it doesn't have a higher intake lobe.VTECH has a second cam profile once it kicks in which allows higher air intake through the intake valves.CVTC on the other hand adjusts the intake timing and possibly durration if I'm not mistaken.So there is no changing of the CVTC to improve things.

Check out the post from SupreamS14, about two thirds of the way down: A Tuner's Guide to the QR25DE.There is a link to a very good, detailed article about this engine. Very good information. It makes mention of the CVTC system. As an aside, I read somewhere else that the low red line for this engine is due to the long stroke (vs. a small bore). According to this article, it has a low red line due to weak valve springs, and not the lengthy stroke. I'm of the opinion it's probably both. The long stroke in this engine greatly increases piston speed at higher RPM's, but then again, I'm no engineer.

[nismo4life11]

if you want a vtec nissan thats what the old sr20ve engines are. my dream is to do a sr20ve+t in my 01 sentra

[nametakennow]

NEO VVL is the Nissan equivalent of VTECH, yes.

The low redline on QR-powered cars is because of the weak valve springs, but the long stroke is the reason for power dropping off at higher rpm (and, therein, the reason for the high low and midrange torque).

[marcello]

okay. im still not to sure what it means but does anything kick in like a vtech?

[nametakennow]

No, like I said earlier. It's ALWAYS on.

[Sentientbydesign]

okay. im still not to sure what it means but does anything kick in like a vtech?

Go do a google for "How Vtech works" and then do one for "How Continuously Variable Valve Timing works" then you'll see the difference and you'll stop asking if there's a way to make CVTC kick in.

[gregfarz78]

optimal shift I've found is around 4500-5000 rpm, if you have a CAI it sounds awesome when the secondary intake runners open up around 5k RPM other than that you don't feel anything "kick in"

[marcello]

im not asking how to make it kick in. i am asking because in most of the videos they sound different once they hit 5000 rpm as if something kicked in.

[nametakennow]

Secondary intake runners open.

[marcello]

okay. and the only reaon i compared them to a vtech is because a vtech sounds different once it hits 5500 rpm. not like they are the complete same thing. what engine do you like better?

[gregfarz78]

yep its the intake runners opening up...most people hate the QR25 but I'd take it any day over a torqueless honda engine. Honda engines are great for reliability and long life but not torquey enough for me.

[marcello]

o for sure no torque. my friends gsr is really fast but doesnt feel that fast if that makes sense, because there is no torque. but in my brother inlaws vr6 jetta with tons of mods.....that has a ridiculous amount of torque and makes it feel super fast. by the way they raced and the gsr got his children eaten on the highway by the vr6. then he raced my buddie with a spec and got beat.

[marcello]

thats why i am going to probably go with with spec cause of torque and the lsd. and i like them better.

[Nismo_lude]

o for sure no torque. my friends gsr is really fast but doesnt feel that fast if that makes sense, because there is no torque. but in my brother inlaws vr6 jetta with tons of mods.....that has a ridiculous amount of torque and makes it feel super fast. by the way they raced and the gsr got his children eaten on the highway by the vr6. then he raced my buddie with a spec and got beat.

I know hondas don't have any torque stock, but a modded H22 or K20 would change your mind.

And it's VTEC by they way. Variable Valve Timing and Lift Electronic Control, almost every make has there own. Like some one said before Nissan has VVL, now the G37 has VVEL.

[marcello]

yeah i know i am actually think about a prelude sh because o the 2.2 vtec. but i want a spec for now