SR20DEN

iTrader: (7)

I finally got to remove and disassemble a VTC on my VQ35 the other day and I have confirmed that my previous assessment was wrong. The VTC on the Maxima VQ35 does only vary the timing of the intake cam. Although the exhaust cams are slaved from the intake cam gear the exhaust cam timing is NOT affected by the VTC.
Upon learning this I decided to do some more investigation into the 350Z VTC. If it's VTC was different I was going to use two of them instead of the ones my motor came with. But I learned that the Maxima,Altima and 350Z VTCs all have the exact same part number. This concludes that the 350Z does NOT control the timing of the exhaust cam. So either the published magazine data is all a crock or the Nissan parts records are wrong. I was advised that there are plenty of mistakes in the monthly updates the dealer gets for their parts records but those mistakes usually do not last very long. So I believe the parts data is correct. The 350Z has the same cam, VTC and cylinder head part numbers.
However the 2004 (A34) Maxima has different cylinder head part numbers from the other cars. But that doesn't really mean that they're better, there may just be a few new bolt holes or something. But the 2004 Maxima does use the same cam part numbers as the other vehicles.
The 2004.5 350Z IIRC does use some different part numbers on either the cams or cylinder heads. Perhaps DAVEB could re-check this data for us. I didn't get any of that data printed out when I was looking this stuff up.

And all of you people who still think you want to do cam swaps in your VQ Maximas . As I have said form day#1 you have to remove the engine to do this.

92 SE-R 02 SE

good info. How is the car running with the new motor?

SR20DEN

iTrader: (7)

It makes good power but I think it has other issues.

SR20DEN

iTrader: (7)

Here is an old picture I have of a VTC thats still in the car.

http://www.poweredbynissan.com/image...ce_nodisc2.JPG

BigDogJonx

iTrader: (7)

Ive been thinking the same thing about how you are going to have to pull the engine to do the cam change, this doesnt look like a bolt on job in the engine.

Dixit

SR20DEN

iTrader: (7)

If you look at the VTC in that picture you will notice a little green button that is located near the cover disc bolt on the right. That part contains the spring that holds in the lock pin. If you change that spring rate you can effectivly change the RPMs in which the VTC advances.

dmontzsta

VTC's are great, when they advance at 4k you can really feel a little kick. Also, make sure you keep your oil clean and changed, or tick tick tick...

Donkey®

iTrader: (3)

SR20DEN

iTrader: (7)

Hater .

dwapenyi

iTrader: (3)

I don't know if you guys saw this somewhat related thread. Nissan keeps tweaking the VQ35. Now to find which car has the 3rd gen VQ35;

http://forums.maxima.org/showthread.php?t=246246

DW

Jeff92se

iTrader: (82)

Hmm who told you that there were VTCs on the intake and exahust? odd. You can tell that there is only intake side varible timing because there is only one assembly per bank. It would be extremely difficult to use two per bank. It would require alot of custom machining and new valve cover/timing cover casting etc.. One one thing that's nice about the new VTCs(over the old VE30DE style) is that they are a truely varible? (ie instead of off/on preset cam advance/retard VE30DE version)

Very nice pics! Thanks.

SR20DEN

iTrader: (7)

No one told me that Jeff. I knew all along thet the VTC was only located on the Intake cam. The exhuast cam is slaved off the intake cams VTC so it can be designed to function either way.

Jeff92se

iTrader: (82)

I don't get this. You mean Nissan could easily run the VTC on the exhaust cam also?? Yeah, they probably will run varible intake/exhaust cams at some point. ala BMW. But as a DIY, it would be next to impossible because of the timing cover/valve cover/ecu/hydraulics issues... Nissan could do it of course by casting new pieces etc... That was my point.

SR20DEN

iTrader: (7)

The slave drive sprocket is bolted to the outer part of the VTC unit. A machinist with the right tools and skills could easily set this up so that it bolts to the center VTC or intake cam itself. Thereby changing the exhaust cam timing along with the intake cam timing.

Jeff92se

iTrader: (82)

How do you control it? How do you feed it oil? If the hydraulics are solenoid driven, where you machine that in? How do you cast new timing covers to accomodate the assemblies? How much would it cost to weld in buldges in the cam covers? How do you make sure the valves won't touch each other now that they are both adjustable?? IMHO, alot of stuff needs to be done other than just fitting another VTC assembly onto the exhaust cam. Expensive I would say.

SR20DEN

iTrader: (7)

You're missing my point Jeff. You do not add another VTC. The one CVTC can be setup to control both cams instead of just one. There are no more hydraulics. There are no more solenoids. You do not have to add anything. All you have to do is disconnect the slave drive sprocket from the outer part of the CVTC and fasten it to the inner drive part of the CVTC.

The crank sprocket only drives the Intake cam sprockets. The intake cam sprokets have slave sprokets right behind them to drive the exhaust cam. There are three timing chains and three tensioners in the VQ.

I will have to get you a detailed picture so you can see what I am talking about. The concept is very simple.

Jeff92se

iTrader: (82)

No. I know what you mean now! I see. Clever. But now the question is. You must be limited to the range of adjustability right? So whatever the intake cam is ajusted to, the exhaust cam would be adjust the same amount? I don't know if that would do anything.

SR20DEN

iTrader: (7)

Yes the range would be identical but the lobe separation and overlap would never change. Advancing the timing on the exhaust cam has pretty much the same effect on an engine as advancing the intake cam. Now the question remains why did Nissan not already do this? And is the hydraulic force of one CVTC sufficient to adjust two cams instead of just one. These VTC units are quite large and heavy, I think it will work.

Jeff92se

iTrader: (82)

I would suggest having someone cnc a new adjustable exahust cam gear(manual type) and tune it that way. Advance it the same amount and dyno it. If it shows the same high rpm gains, take it to the next level. If not, not need.

IceY2K1

iTrader: (3)

There HAS to be a reason. I'm betting it's emissions related.

Any chance you'll attempt this SR20DEN?

I bet some of the 350Z guys would be interested in "testing" your theory.

SR20DEN

iTrader: (7)

The main drawback to that is that you cant access the exhaust cam gears with the front cover on. Only the CVTCs have the access panels. But there are 52 teeth on the main VTC sprocket so going forward or backward by one tooth will yeild a 7º change for both cams at once.

SR20DEN

iTrader: (7)

I'll probably try at least one crazy and or stupid thing before I get this other motor running again.

Jeff92se

iTrader: (82)

Oh that sucks. The VE's timing cover can come off to expose both cams

Jeff92se

iTrader: (82)

SR20DEN

iTrader: (7)

I wish we had it that easy. At least you dont have to pull your entire motor and dissasemble half of it to change cams.

IceY2K1

iTrader: (3)

McDisneySoft

I don't really understand the dynamics of these cylinder heads, or VTC heads of any kind, but, I was wondering if it would be possible to fit VQ30DE heads onto a VQ35. The reason being that I heard that the VQ30 heads have a larger volume, so this would lower compression. If we ever get a turbo or supercharger for the VQ35 max's, lower compression could help a bit. Or, would it be possible to fit VQ35 heads onto the VQ30 (so as to raise compression for a N/A buildup.)

On a separate note, have you concitered porting and polishing the heads while they're off the car?

And if you want to try something crazy, maybe try to fit a 350Z intake manifold under your hood (well from what I've gathered, you'de need a new hood.) This has been tried before, but the project stalled for reasons i have not yet been able to find out-it is something I am looking into though.

MrGone

iTrader: (30)

Sweet!

I still like my idea of lifting the rocker's fulcrum in order to provide more duration/advancement

Do all VQ's drive the exhaust cam off the intake cam? I guess I could just look at an FSM.

SR20DEN

iTrader: (7)

Too late, BMW already does that with Valvetronic.

IceY2K1

iTrader: (3)

So...looks like these 350Z NISMO cams are another option to the SGP cams:

$1,375.00 - 262 degree duration / .426" lift Cold lash = .010" to .013"
http://www.hpautoworks.com/ni35peca.html

SR20DEN

iTrader: (7)

Yeah these are more aggressive than the Tomei cams but perhaps too much for the street. I still think the set is overpriced.

IceY2K1

iTrader: (3)

Agree, but this is NISMO we're talking about here.

I know TOP SECRET has a set of cams too, but don't know the specs.. However, I guarantee the price will make NISMO/TOMEI stuff look like childs play.

McDisneySoft

this may be a cheap way around it, bt if some company has already done the R&D to make cams, then that much is done. But we'de be fools to pay for that R&D,right? So, we get the specs from one of those companies, and have a custom cam manufacturer produce them for us, thus saving the R&D costs that are built into the cams now available.

HitManSE

iTrader: (1)

Very nice, and useful as always Cant wait to see what you come up with man.

Triple8Sol

iTrader: (29)

Very interesting discussion here...can't wait to see this idea taken further...

McDisneySoft

I tlked to a colt cams developer a while back who said VQ35 cams were unfeasable because of the cost of R&D, but now that we have that taken care of, I contacted them again. We'll see what pricing looks like. BUT, do we have, or can we get the specs on the cams other than these NISMO cams? And why do you think the cams ae too aggressive? I don't know a whole lot about cam design, so just how extreem do those numbers look?

And finally for the idiot question: what's the worst that could happen if cams like these were installed (being that they were designed for the 350Z)