# Sticky  Can I use a VAFC to change CVTC??



## 04SerSpecV (Aug 25, 2004)

Hi all
My question is is there anyway to have that kick in before 5000rpm. Like does anyone make a controler for that ex: the A'PEXi V-TEC AFC II. If so please let me know also if not will there ever be one in the future?

Thanks
Preston


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## chimmike (Oct 17, 2002)

before I give you an answer, I want you to tell me what you think CVTC is and then tell me what VTEC is and tell me the differences............this way you'll answer your own question.


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## chimmike (Oct 17, 2002)

hint: if you don't know what CVTC stands for...check out www.nissandriven.com and find the Spec V there and read up on it..... or search for CVTC on the board here


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## pherschel (Jun 29, 2004)

Maybe he's refering to the secondary air pathway opening. I believe you mentioned that it makes no difference to open it early.

I have an 04 and i've listened for it opening. Maybe I was expecting a clunk or something, but I didn't really notice it. I expect its because of the increased engine noise and need to shift real soon that occupy me.

I do think the CVTC technology along with the variable intake, plus a lighter aluminum block make for an excellent combination. Just not to modder friendly. 

And for those balance shafts, well my ford focus buddy (one for the wife, one for him) was impressed by how smooth the car ran.

Just my 2 cents


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## chimmike (Oct 17, 2002)

I just want him to understand exactly what CVTC is....I mean it tells you what it is on the tag on the side of the car when you buy it........that should answer his question before asking


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## Dwntyme (Dec 18, 2002)

:waving: :waving: :waving: I know, I know.....


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## chimmike (Oct 17, 2002)

well let's hear it.....please explain what CVTC is and why you could/couldn't use a VAFC!


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## 04SerSpecV (Aug 25, 2004)

Continuously Variable Valve Timing Control System (CVTCS) Spec V
Variable Valve Timing and Lift Electronic Control (VTEC) Weedwacker


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## chimmike (Oct 17, 2002)

awesome 

Do you know what VTEC does? 

VTEC is a hydraulically actuated change of cam profiles from a lesser aggressive street grind to a highly aggressive cam grind. That's what the VTEC changeover point is.

CVTC is simply continuous variation of cam timing....from idle to redline. There's no different cam profile like on VTEC cars, so there's no changeover point. That loudness at 5400rpm is the secondary intake manifold runners opening up............and opening those earlier has shown power losses.

basically, if you were to use a VTEC controller (which you couldn't) you'd be robbing power from somewhere in the band to put somewhere else (lose low end to gain high end or vice-versa) The stock CVTC setup is great just how it is


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## Dwntyme (Dec 18, 2002)

dangit he beat me to it.... see what happens when your don't pay attention


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## tryptych (Mar 14, 2004)

*say what?*

the second det of butterfly valves in the short runners open at 5000 rpm, not 5400 rpm. But you can use the Apex AFC on the SER. Keep in mind that it will not control the variable intake or CVTC, of course, but it does modify the air/fuel ratio at different rpm's. The QR25DE tends to run quite rich at moderate to full throttle, and it has been shown that lightly leaning out the mixture made power gains as common with newer engines from almost all manufacturers. With several engine modifications done, one SER owner showed a gain of 22 hp on a dyno after tuning with the AFC from Apex. It's cheap too, only about $350 to $380.


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## chimmike (Oct 17, 2002)

nobody has seen 22hp from an SAFC....and the butterfly valves have been proven to open up at 5400rpm.


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## Beardog (Mar 3, 2004)

chimmike said:


> nobody has seen 22hp from an SAFC....and the butterfly valves have been proven to open up at 5400rpm.


 :wtf: ....22hp??? NOT! 

Dont argue with the master ( aka chimmike ) :cheers:


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## chimmike (Oct 17, 2002)

12hp I can fathom. but 22? no way in hell, unless you failed to mention he was running 400cc injectors untuned, LOL


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## BlackoutSpecV (May 8, 2002)

tryptych said:


> one SER owner showed a gain of 22 hp on a dyno after tuning with the AFC from Apex.


 :bs:

with a turbo, maybe.


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## Marc Z31 (Jul 25, 2004)

With a hell of a tune, I could see that. A friend of mine took a STOCK D series honda (no intake, no hedder, no NOTHING, SOCH non v-tec) with a s-afc, and made 120 WHEEL HP, coming from <100whp

Tuning can do a lot more than most people will belive.

But that was over 6 hours of tuning.


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## chimmike (Oct 17, 2002)

Marc Z31 said:


> With a hell of a tune, I could see that. A friend of mine took a STOCK D series honda (no intake, no hedder, no NOTHING, SOCH non v-tec) with a s-afc, and made 120 WHEEL HP, coming from <100whp
> 
> Tuning can do a lot more than most people will belive.
> 
> But that was over 6 hours of tuning.


a d16 honda isnt' a spec v or SER.

these obd II 32 bit ECUs maintain optimum a/f ratio at all times except WOT.......22whp is not possible on these cars unless he was using larger injectors than stock.


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## CLOVIS (Jan 6, 2005)

The dude did say w/a few engine mods, so I'm assuming intake/headers/exhaust. Those mods w/ a SAFCII could easily put out 22hp, if not more, esp. if tuned by an exp. person.


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## Zac (Mar 10, 2004)

CLOVIS said:


> The dude did say w/a few engine mods, so I'm assuming intake/headers/exhaust. Those mods w/ a SAFCII could easily put out 22hp, if not more, esp. if tuned by an exp. person.


SAFC2 gains alone, mind you this is on the 02-03, are very impressive. I have seen a dyno sheet of an 02 which with all conventional bolt ons did 169 WHP and 167 WTQ. After the SAFC2 and tuning it was 176 WHP and 173 WTQ respectively. This was on a dynojet. That's pretty nice power.


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## chimmike (Oct 17, 2002)

ya, but that isn't any 22hp.


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## Zac (Mar 10, 2004)

chimmike said:


> ya, but that isn't any 22hp.


Ide imagine they meant 22 WHP gain between I/H/E/SAFC2
22 from just an SAFC2 on the QR is a goofy claim.


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## tryptych (Mar 14, 2004)

*lol... you have no idea*



chimmike said:


> nobody has seen 22hp from an SAFC....and the butterfly valves have been proven to open up at 5400rpm.


No. Next time you drive your car, listen, and use your head. The secondary butterflies open at 5000 rpm. If yours don't, then maybe you have a problem, but mine have since I bought the damn thing. Try doing a little more work. and the 22 hp. thing, i didn't mean to make it sound like fact, it was something that i was told, and thought i would throw that tid bit out there. Personally, i don't believe it either, i can see about 8.


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## Zac (Mar 10, 2004)

IIRC the FSM does say 5000; although that doesnt necessarily mean that they do open up there.


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## Matt Runstock (Aug 20, 2005)

chimmike said:


> nobody has seen 22hp from an SAFC....and the butterfly valves have been proven to open up at 5400rpm.


What are you hearing open up when the tach hits 5k? Unless the tach is off as far as the speedo is on these cars. LOL. I have a CAI and when it gets alot louder, the tach reads 5 on the button. Is there something else making the noise? Not trying to question you, just trying to learn.


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## PoppinJ (Jun 13, 2005)

Thats the sound of your secondary runenrs opening up. Sound bad ass huh :thumbup: :hal: :fluffy: :cheers:  . At like 5100 RPMS they open up to allow more air into your engine.


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## B13Sentra2DR (Dec 7, 2003)

VTEC operates on oil pressure. The computer tells a solenoid to open up and the oil pressure moves a pin into place activating extra rocker arms that contact the agressive cam lobes.


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## drwky (Sep 3, 2005)

B13Sentra2DR said:


> VTEC operates on oil pressure. The computer tells a solenoid to open up and the oil pressure moves a pin into place activating extra rocker arms that contact the agressive cam lobes.


Yup, you got it right. All the BS about the cam profile changing is just that, BS. It would be imposible to change the profile of a solid state cam. Thus far motor technology dictates that you can only change the way an engine runs with a specific cam and internal setup not the other way around. 

Oh, and I would have to agree that the second runners are not fully open until ~5100 RPM or so, they probably start to open at 5K. I have tried running my car to figure it out but it seems that the vavle is not letting the maximum amount of air in (and therefore is not fully open) until 5100 RPM.


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## specv_21 (Nov 16, 2005)

damn chimmike knows his stuff thats dope i wish i knew all of that , is there a way that the spec-v can be tune differently, u know how euro cars get chip and that makes a big big different cause my friend has a jetta and he did that and his car is really fast now , so is there a chip that can do that to our cars, if there is what is it? cause my friend had hear about putting a REVO chip but i dont know about that. thank


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## ScarCrow28 (May 14, 2002)

I'd like to know more about his tuning theory. On a dead stock 06 spec, would it gain anything? Heck even if all it did was increast gas mileage (safely without risking engine harm mind you) it just may be worth it to such a thing?


For example, im not about to put money or time into any kind of bolt ons at this point, but a few tricks i've heard sound tempting to take a closer look into.

Namely a voltage controller and this advanced tuning stuff. I really know nothing about either, but if i can plug and play a little box that better controls the cars voltage and results in a side effect of better mileage and a tick more power, im all for it as it will save me money in the long run and make things a tad more fun.

And tuning? Im always hearing about these computer programmer tools for trucks and American automotives that will increase power and milage without changing anything on the car itself; just push the button the on controller as its plugged into the car. Y don't i ever hear about that on here? And do manufactures really deprogram the ecus to be that restrictive? I mean adding gas mileage and hp without having to bolt on a preformance exhaust seems like kind of a no brainer to me.

Or is this SAFC thing which i haven't a clue what your talking about, is that tool


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## modenaf1 (Nov 12, 2005)

tryptych said:


> No. Next time you drive your car, listen, and use your head. The secondary butterflies open at 5000 rpm. If yours don't, then maybe you have a problem, but mine have since I bought the damn thing. Try doing a little more work. and the 22 hp. thing, i didn't mean to make it sound like fact, it was something that i was told, and thought i would throw that tid bit out there. Personally, i don't believe it either, i can see about 8.



Is there a way to see the runner control? In my '96 Taurus you can see the butterflies snap open at 3500RPM from under the hood. Just put it in neutral and yank the throttle cable until you see movement, if they work or not. That might be easier than trying to listen to it as you rev past 5K.


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## MySpecVBlows (Jul 11, 2006)

chimmike said:


> nobody has seen 22hp from an SAFC....and the butterfly valves have been proven to open up at 5400rpm.


You may see powergains if you are running a turbo system with an untuned safc, then after you tune the safc you may see power gains. On an NA car it doesnt do anything really. And yes butterfly valves do open around 5400-5500rpm ish


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## chimmike (Oct 17, 2002)

you're insane if you run an SAFC untuned while boosting.


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## blueB-15 (Aug 18, 2005)

04SerSpecV said:


> Hi all
> My question is is there anyway to have that kick in before 5000rpm. Like does anyone make a controler for that ex: the A'PEXi V-TEC AFC II. If so please let me know also if not will there ever be one in the future?
> 
> Thanks
> Preston


"Continuous Valve Timing Controller" Try the A'PEXi SAFC-II. Im petty sure that you cant change the RPM that CVTC "cracks" though.


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## Timmah603 (Feb 20, 2007)

Ok, first I havent been here long and I can tell that chimmike knows his stuff. Nice schooling on the CVTC vs.- V-Tec. However I have to ask where you got that it opens up at 5400 RPM though. I have had my 04 since it came out of the show room, and it has always engaged the secondaries at 5,000 even with a 6250 RPM fuel/rev. cut. 

FYI, I dont have a scanner so I cant prove it numbers wise, but I will post a link to a picture of my interior when I can. I had my Apexi' SAFCII tuned for max peak power while still maintaining a safe fuel ratio on the dyno, and all I saw was 8 hp. In order to see more of a power gain and really appriciate the SAFCII I had to replace a LOT of parts.


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## Timmah603 (Feb 20, 2007)

modenaf1 said:


> Is there a way to see the runner control? In my '96 Taurus you can see the butterflies snap open at 3500RPM from under the hood. Just put it in neutral and yank the throttle cable until you see movement, if they work or not. That might be easier than trying to listen to it as you rev past 5K.


Just so you know, you can only hear the difference going down the road with a spec-v. Revving it at idle only makes it bark really loud. Also, you cant rev them from under the hood. There is no throttle cable, its all electronic controlled.


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## cornie02specv (Apr 7, 2007)

I just bought the apexi s afc neo after i got a stage 2 port and polish and the nismo cams in my car, i also but a walbro 190 lph fuel pump as well. You can use it on the controllable valve timing but it is not worth the while. it is real hard to setup on our cars as well but when u figure it out it works great. you can control a bunch of stuff and it works even better when you put a turbo on your car


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## dirtyred (Jun 24, 2007)

A Tuner's Guide Inside the QR25DE - Tech - Sport Compact Car Magazine

Here's a little article that includes information from the engineer of the motor... Clearly says 5000 rpms


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## dirtyred (Jun 24, 2007)

Theres a way to wire the AFC neo and have the secondaries kick in at 4500 and stay open until the car comes back down to 4000. I googled "qr25de wiring harness for AFC NEO" and a forum came up on b15sentra.net of a kid that had the pin layouts for all year spec V's check that shit out...


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## specvnasty (Dec 30, 2009)

I don't know why you would want to change it, It's set to 5000rpm because it's doing a job. The QR25de in it's natural state loses major power at 5000rpm, and they put the system in to increase airflow and keep power somewhat consistent. If you want more time in CVTC, order the Jim Wolf Technology Balance Shaft Removal(BSR) and valves and valvesprings, this will increase the rev limit to 7200rpm.


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## saint0421 (Sep 24, 2006)

specvnasty said:


> I don't know why you would want to change it, It's set to 5000rpm because it's doing a job. The QR25de in it's natural state loses major power at 5000rpm, and they put the system in to increase airflow and keep power somewhat consistent. If you want more time in CVTC, order the Jim Wolf Technology Balance Shaft Removal(BSR) and valves and valvesprings, this will increase the rev limit to 7200rpm.


The BSR, aftermarket valves, and aftermarket valvesprings will NOT increase your rev limit. Your rev limit is set within your ECU. The three above mentioned things simply increase the safety of raising your rev limit.


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## NorthernSE-R (Sep 2, 2010)

Heard that lowering the secondary opening point to 4700rpm would give a 3whp. It's dyno-proven look on B15U.com - Nissan Sentra Forum 

I can also hear the secondary runners open at about 5100rpm stock. I'll try soon to lower it to 4700.


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