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View Full Version : VVt.....wat does it do


SpoiledBoi
12-19-2001, 03:36 PM
VVt, or watever....is it really worth it for tunning...ill get a Black top wit it if its worth it....i dont hate vtec, i think its a good thing, and in a NISSAN...yea....so yes or no, and wat does it do?

HippoSleek
12-19-2001, 03:49 PM
Actually, VVT, like VTEC is bad for tuning (a turbo).  Notice that most successful Honda turbos are non-vtec motors?  Part of it is compressions, but it's also b/c variables screw up the ability to tune with lots of boost.  You will also notice that most Japanese tuners disable this feature or use s13 SR's when tuning.  I'd say, if you can find it, but a 180sx s13 black top.  Newer, but sans VVT.  Sure, you may miss the 15 hp that comes from the better turbo on the s14, but that is worth it, IMHO, b/c there is one less expensive part to break (that you can't get here) and b/c you can up the boost.

uuninja
12-19-2001, 04:26 PM
Nissan has 2 different variable valve timing systems. The earlier VTC that is on some s14 and all s15 motors basically adjusts the cam sprockets on the fly(like you would with adjustable cam gears). It is not like Vtec which uses a oil pressure solenoid to change the position of a dual lobed cam. The second newest variable valve system that Nissan has employed is VVT this is a similar system to Honda's vtec(oil pressure solonoid and dual cam). This system is found on the sr20ve and the Xtrail's sr20vet motors.

The main reason that Vtec can be bad for turbo applications is the use of a high duration cam for the second more aggressive profile. This causes what is called valve overlap (ie the intake and exhaust valves are open at the same time). On an NA motor this is not a problem, but when you introduce forced induction you see what is called blow through. Pressurized air blows right through the head and out the exhaust ports <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/tounge.gif" border="0" valign="absmiddle" alt=':p'> not good, most Honda guys live with it or swap cams to a lower duration exhaust cam.

Nissan's dose use their vtec style VVT on the xtrial's sr20vet turbo charged motor but with minimal overlap on the aggressive cam profile.

Is it worth it? Not in my opinion for the extra 2000 you will pay for an sr20det equipped with VTC. A bigger turbo other goodies that you can buy with the 2g's you save on a red top will offset the 15 hp that gain from the t28 and VTC on the s15 motor.

kitoro
12-19-2001, 08:37 PM
i was under the impression that Nissan's &quot;VVT&quot; is actually called VTL (Variable Timing and LIFT)?
cuz VVT is actually Toyota's first model of their own VTEC, it was used on the Toyota Trueno A111's engine and the awesome formula atlantic 4AG
VVTi (this is Timing and Lift as well as i recalled) is Toyota's latest incarnation that they've placed under the hood of the 2000 Celica.

Honda's VTEC was only timing... the i-VTEC has lift involved too.

(Edited by kitoro at 7:39 pm on Dec. 19, 2001)

SpoiledBoi
12-19-2001, 09:31 PM
Yes true about the VVT-i....but jst wanted to add in that it is also on the 3SGE altezza, mr2, IS300, IS200, and all the lexus's i think....not sure about any other cars..jst wanted to add that so no one makes a fool of them self...

I tell ppl to get a S13 motor and use the rest of the money for tuning, but i thought it had to make something better, i guess not. i figured all this , but wanted to make sure. B/c a black top s14 isnt much mroe than a red top. the other day i read someone sayin that if they get a red top and want it high, they can install cams(i thinK) or a system like the VCT on the red top. thanx ya all, anyone else got some input?

onebadm5
12-19-2001, 09:39 PM
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from kitoro on 7:37 pm on Dec. 19, 2001
i was under the impression that Nissan's &quot;VVT&quot; is actually called VTL (Variable Timing and LIFT)?
cuz VVT is actually Toyota's first model of their own VTEC, it was used on the Toyota Trueno A111's engine and the awesome formula atlantic 4AG
VVTi (this is Timing and Lift as well as i recalled) is Toyota's latest incarnation that they've placed under the hood of the 2000 Celica.

Honda's VTEC was only timing... the i-VTEC has lift involved too.

(Edited by kitoro at 7:39 pm on Dec. 19, 2001)
</td></tr></table><span id='postcolor'>

nissan calls their deal &quot;VVTC&quot;, variable valve timing control.

in the u.s. market, VVT-i stands for Variable valve timing - intelligent.

Archangel
12-19-2001, 10:16 PM
Just to clarify, if I'm reading the posts right, the black top comes with the vvt, and the red top does not?

crazycuban
12-19-2001, 10:19 PM
vvt-i comes on the 1ZZ-FE too (celica GT, corolla). &nbsp;vvt-i is simply variable valve timing, no lift, VVTL-i is variable timing with lift. &nbsp;both VTEC and i-VTEC use lift. &nbsp;VTEC doesnt vary the timing.
VVT simply stands for variable valve timing...i dont think whoever said it meant it as what the nissan variation is called. &nbsp;
btw, the deal with the &quot;i&quot; on VVT-i, VVTL-i, and i-VTEC is because vvt is controlled by the ecu, hence i for intelligence. &nbsp;VTEC came without variable timing, and its system was mechanical (oil pressure). &nbsp;hence, no i for intelligence.

crazycuban
12-19-2001, 10:21 PM
vvt is only found on black tops, but s13 black tops don't have it. &nbsp;basically, s14 and s15 motors have vvt, s13 motors dont. &nbsp;some1 said that most s14 motors have vvt. &nbsp;why not all?

DSC
12-19-2001, 10:47 PM
Since were on the topic, I'll add my question in here. Who can tell me about the variable timing thing on the new porshe 911 turbo? Watched a video where tiff testdrove one and he compared it to hondas vtec but described vtec as and on/off switch whereas whatever the 911 turbo has works all the way through. Anybody know anything about this?

uuninja
12-20-2001, 09:43 AM
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from crazycuban on 9:21 pm on Dec. 19, 2001
vvt is only found on black tops, but s13 black tops don't have it. basically, s14 and s15 motors have vvt, s13 motors dont. some1 said that most s14 motors have vvt. why not all?
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Cause it was introduced mid way through the s14's life span IIRC

(Edited) actually no silvias came with vvt or &quot;neo vvt&quot; as it is branded it was introduced in the Xtrail's sr20vet. The system used on the s14 and s15 is an electro-magnetic cam timing adjustment called VTC.


(Edited by uuninja at 9<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wow.gif" border="0" valign="absmiddle" alt=':0'>3 am on Dec. 20, 2001)

kitoro
12-20-2001, 10:39 AM
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from DSC on 9:47 pm on Dec. 19, 2001
Since were on the topic, I'll add my question in here. Who can tell me about the variable timing thing on the new porshe 911 turbo? Watched a video where tiff testdrove one and he compared it to hondas vtec but described vtec as and on/off switch whereas whatever the 911 turbo has works all the way through. Anybody know anything about this?
</td></tr></table><span id='postcolor'>

then it works basically like VVT-i then rite?
i was told VVT-i is fulltime...

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">I tell ppl to get a S13 motor and use the rest of the money for tuning, but i thought it had to make something better, i guess not. i figured all this , but wanted to make sure. B/c a black top s14 isnt much mroe than a red top. the other day i read someone sayin that if they get a red top and want it high, they can install cams(i thinK) or a system like the VCT on the red top. thanx ya all, anyone else got some input? </td></tr></table><span id='postcolor'>

the cams you're talking about are made by the JDM companies. i know Tomei and HKS carry cams for the SR20s.. dunno about anything else.
i'm not too sure about having VTC installed onto the SR20, altho i've been told that you can do something similar to the LS-VTEC hybrid on the redtop SR20s.
the heads from an S14, bottom from S13 SR20...?
seems possible.

uuninja
12-20-2001, 01:41 PM
I am sure that you could make a s13/s14 hybrid, but why would you want to? The LS Vtec phenomenon is a low cost alternative to buying a gsr/type-r motor with the benefit of added displacement. The catch is that all the parts needed for the swap are readily available in the USDM. I would be substantially more difficult to buy just a s14 head for a s13 block, probably more expensive than just buying the s14 motor. Most importers don't sell the motor in parts. All this to what, use a so-so system that most serious tuners in Japan disable anyway? If you want to adjust the cam gears just buy some adjustable cam gears. If you want VTC buy an s14/15 motor.

mistert
12-20-2001, 02:20 PM
heres a question...for black top s13 engines, do they have the t-25r of s14 engines, since they were manufactured in the same years? or just the same t-25 from the red top

onebadm5
12-20-2001, 02:34 PM
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from DSC on 8:47 pm on Dec. 19, 2001
Since were on the topic, I'll add my question in here. Who can tell me about the variable timing thing on the new porshe 911 turbo? Watched a video where tiff testdrove one and he compared it to hondas vtec but described vtec as and on/off switch whereas whatever the 911 turbo has works all the way through. Anybody know anything about this?
</td></tr></table><span id='postcolor'>

Porsche calls their deal Variocam

&quot;it makes seamless adjustments throughout the rev range, unlike Honda's VTEC, which is more like an on-off switch.&quot;

onebadm5
12-20-2001, 02:36 PM
bmw's setup, VANOS, which is DUAL intake/exhaust on the M3 and M5, does the same crap.

240S15DETE6K
12-20-2001, 02:39 PM
You should all read Dave Colemans article in this months Techno-Babble section of Sport Compact Car. &nbsp;It's about BMWs Valvetronic system, very interesting. &nbsp;Theres also a section on the new 350ZX and a short blurb on the next GT-R, which may be headed stateside!

uuninja
12-20-2001, 02:45 PM
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from kitoro on 7:37 pm on Dec. 19, 2001
i was under the impression that Nissan's &quot;VVT&quot; is actually called VTL (Variable Timing and LIFT)?
cuz VVT is actually Toyota's first model of their own VTEC, it was used on the Toyota Trueno A111's engine and the awesome formula atlantic 4AG
VVTi (this is Timing and Lift as well as i recalled) is Toyota's latest incarnation that they've placed under the hood of the 2000 Celica.

Honda's VTEC was only timing... the i-VTEC has lift involved too.

(Edited by kitoro at 7:39 pm on Dec. 19, 2001)
</td></tr></table><span id='postcolor'>

Hum I don't know about that. All the credible sources I have read list VVT and VTC as Nissan's name brands for their variable cam endeavors.

(Edited by uuninja at 1:48 pm on Dec. 20, 2001)