VQ V-TEC Specifics ANyone??
03-13-2003, 06:55 AM
#1
VQ V-TEC Specifics ANyone??
Ok - this could be one for Newman....
I was driving into work today (enjoying a nice 2nd to 3rd gear 5krpm rev!) and wondering about just HOW exactly the VARIABLE VALVE TIMING in the VQ works????
Is it simply an Emissions control situation (like that damnable muffler) or do we have TRUE variable geometry Cams and Valve Actuators???
I know ALOT about OTHER manufacturers' V-TEC systems, but strangely I HAVE NEVER read or seen much data on how the VQ is designed or operates -- in theory OR principle.
Can any of you more educated VQ'ers out there help me out??
I bought this car secure with the knowledge that VARIABLE VALVE TIMING was including in the new VQ's technology, but I need some reassurance!
Help me out guys!!
g.r.
I was driving into work today (enjoying a nice 2nd to 3rd gear 5krpm rev!) and wondering about just HOW exactly the VARIABLE VALVE TIMING in the VQ works????
Is it simply an Emissions control situation (like that damnable muffler) or do we have TRUE variable geometry Cams and Valve Actuators???
I know ALOT about OTHER manufacturers' V-TEC systems, but strangely I HAVE NEVER read or seen much data on how the VQ is designed or operates -- in theory OR principle.
Can any of you more educated VQ'ers out there help me out??
I bought this car secure with the knowledge that VARIABLE VALVE TIMING was including in the new VQ's technology, but I need some reassurance!
Help me out guys!!
g.r.
03-13-2003, 07:43 AM
#2
now I could be wrong.. but I think the 3rd gen is the only one with variable valve timing.
of course that's what I read from the 3.0 motor comparison here:
https://maxima.org/shoptalk/sub_read...ns/index.shtml
so maybe the vq35de may be different, but I doubt it.
of course that's what I read from the 3.0 motor comparison here:
https://maxima.org/shoptalk/sub_read...ns/index.shtml
so maybe the vq35de may be different, but I doubt it.
03-13-2003, 08:10 AM
#3
Not DAVEB the parts guy
Join Date: Aug 2000
Posts: 8,555
The 3.5 VQ does not have "VTEC". It has variable cam timing. "VTEC" systems incorporate cams that have two completely different lift profiles. At a certain rpm, the cam is adjusted so that the "big" cam profiles are engaged and the motor is able to rev higher and longer while producing significant power gains. That deep wail at ~5000rpms you hear on VTEC Hondas is the cam profile changing or what the riceboys call "hitting VTEC, YO!!!".
The system on the Maxima doesn't use different cam profiles. All the system does is advance or retard cam timing based on the running rpm of the motor. This is done to increase performance and to reduce emissions. The VE 3rd gen and the current 3.5VQ are the only Maxima motors to use this.
The VE, 3.5VQ, 00-01 VQ, and 3.0s equipped with MEVI use variable tract intake manifolds that engage anywhere from 4500-5000rpms. The change in intake pitch is much like that of a VTEC Honda's because the amount of airflow is increased. The sound you hear is the change in intake resonance. Instead of big cams allowing more air in, the variable intake manifold incorporates a shorter intake path which increase air velocity in the upper rpms.
Dave
The system on the Maxima doesn't use different cam profiles. All the system does is advance or retard cam timing based on the running rpm of the motor. This is done to increase performance and to reduce emissions. The VE 3rd gen and the current 3.5VQ are the only Maxima motors to use this.
The VE, 3.5VQ, 00-01 VQ, and 3.0s equipped with MEVI use variable tract intake manifolds that engage anywhere from 4500-5000rpms. The change in intake pitch is much like that of a VTEC Honda's because the amount of airflow is increased. The sound you hear is the change in intake resonance. Instead of big cams allowing more air in, the variable intake manifold incorporates a shorter intake path which increase air velocity in the upper rpms.
Dave
03-13-2003, 08:20 AM
#4
Originally posted by Dave B
The 3.5 VQ does not have "VTEC". It has variable cam timing. "VTEC" systems incorporate cams that have two completely different lift profiles. At a certain rpm, the cam is adjusted so that the "big" cam profiles are engaged and the motor is able to rev higher and longer while producing significant power gains. That deep wail at ~5000rpms you hear on VTEC Hondas is the cam profile changing or what the riceboys call "hitting VTEC, YO!!!".
The system on the Maxima doesn't use different cam profiles. All the system does is advance or retard cam timing based on the running rpm of the motor. This is done to increase performance and to reduce emissions. The VE 3rd gen and the current 3.5VQ are the only Maxima motors to use this.
The VE, 3.5VQ, 00-01 VQ, and 3.0s equipped with MEVI use variable tract intake manifolds that engage anywhere from 4500-5000rpms. The change in intake pitch is much like that of a VTEC Honda's because the amount of airflow is increased. The sound you hear is the change in intake resonance. Instead of big cams allowing more air in, the variable intake manifold incorporates a shorter intake path which increase air velocity in the upper rpms.
Dave
The 3.5 VQ does not have "VTEC". It has variable cam timing. "VTEC" systems incorporate cams that have two completely different lift profiles. At a certain rpm, the cam is adjusted so that the "big" cam profiles are engaged and the motor is able to rev higher and longer while producing significant power gains. That deep wail at ~5000rpms you hear on VTEC Hondas is the cam profile changing or what the riceboys call "hitting VTEC, YO!!!".
The system on the Maxima doesn't use different cam profiles. All the system does is advance or retard cam timing based on the running rpm of the motor. This is done to increase performance and to reduce emissions. The VE 3rd gen and the current 3.5VQ are the only Maxima motors to use this.
The VE, 3.5VQ, 00-01 VQ, and 3.0s equipped with MEVI use variable tract intake manifolds that engage anywhere from 4500-5000rpms. The change in intake pitch is much like that of a VTEC Honda's because the amount of airflow is increased. The sound you hear is the change in intake resonance. Instead of big cams allowing more air in, the variable intake manifold incorporates a shorter intake path which increase air velocity in the upper rpms.
Dave
YOU THE MAN!!!
03-13-2003, 09:02 AM
#5
Dyno plot says I have the most area under the Administrator curve
Join Date: Jul 2001
Posts: 7,060
Dave covered all the bases already 
, but...
Nissan's "CVTCS" is functionally equivalent to Toyota's VVT-i. These systems just vary the phase of cams to optimize performance/emissions depending on load and RPM. Valve lift and duration is not adjusted, only timing. In the Maxima's case, only the intake cam is phase shifted. But if I'm not mistaken, both intake *and* exhaust cams are variable on the higher end VQ35's like in the 350Z.
, but...Nissan's "CVTCS" is functionally equivalent to Toyota's VVT-i. These systems just vary the phase of cams to optimize performance/emissions depending on load and RPM. Valve lift and duration is not adjusted, only timing. In the Maxima's case, only the intake cam is phase shifted. But if I'm not mistaken, both intake *and* exhaust cams are variable on the higher end VQ35's like in the 350Z.
03-13-2003, 11:10 AM
#6
Originally posted by Dave B
[BThe system on the Maxima doesn't use different cam profiles. All the system does is advance or retard cam timing based on the running rpm of the motor. This is done to increase performance and to reduce emissions. The VE 3rd gen and the current 3.5VQ are the only Maxima motors to use this.
Dave [/B]
[BThe system on the Maxima doesn't use different cam profiles. All the system does is advance or retard cam timing based on the running rpm of the motor. This is done to increase performance and to reduce emissions. The VE 3rd gen and the current 3.5VQ are the only Maxima motors to use this.
Dave [/B]
03-13-2003, 11:30 AM
#7
Originally posted by hombre
So are you saying the timing advance mod some people have done is overwritten whenever it needs to be...and doesn't really increase hp?
So are you saying the timing advance mod some people have done is overwritten whenever it needs to be...and doesn't really increase hp?
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