Disconnect this sensor and gain POWER!

[Busky2k]

Yeah thats right Cecam. I cant see why running it permanantly retarded will actually gain power at all.

[51jay]

It gives you more torque in low and mid range and then cuts out to give best power at top end. However you can't change the cut off point with the stock ECU and it is programmed to suit a stock as a rock motor. Obviously the optimum changeover point will vary with the amount of mods and state of tune of your particular motor. With most aftermarket ECUs you can set the cutoff point. When you have got it tuned as you want it you do a power run with it on then one with it off ,superinpose the 2 curves and where they intersect is the optimum cutoff point fot the best top middle and low range power and torque.

As Sydneykid often points out ....it's not the peak power figure, but the best usable power range that counts. If you don't believe that next time your at the drags do a run with and without it.

[dojobi]

I had my VCT plug out and dyno'd my car. 120rwkw. The bottom part of the curve was the same for both runs up until the point where it was supposed to kick in. When plugged in, I got 177rwkw. There is no way that unplugging it gives you more power anywhere in the rev range as far as I am concerned. Are you sure it was that?

[EnricoPalazzo]

interesting...

[Steve]

Some more food for thought. I tried disconnecting the VVT after I had an initial tune with aftermarket cams, as I thought perhaps there was too much overlap with the inlet being advanced, thus causing additional lag due to reversion.

the car was sooo much worse bottom end/midrange, and the lag got worse.

I also put the cam and rough engine specs into Dyno 2003 software, and tried advancing the inlet. The resultant change in the power curve showed gains the further I increased the inlet (only went to 20 degrees), but the interesting thing was that the curve fell over and produced less power above 4500rpm. According to the Tomei stock cam spec sheet, 4500 is where NVCS switches off.

Looks like nissan got it right.

[Steve]

Perhaps, if disconnecting the NVCS reaps gains, esp with stock cams and ecu, it points to problems with the NVCS, ie its not operating correctly?

[whatsisname]

I can confirm Steve's info.

We have played with the VCT quite a few times & found the stock 4,500rpm switch off point to be pretty much spot on. The VCT is switched on @ 1500rpm & off @ 4,500rpm. Keeping VCT switched on higher in the rev range (via aftermarket ECU) loses 10-15rwkw top end, as you'd expect. Turning it off sooner loses mid range.

For a gain to be made by having VCT disabled it will mean poor bottom end torque Unless you have upgraded inlet/exhaust cams dialed in spot on.

[Bass Junky]

Steve,

What's this Dyno 2003 software....

You say you could calculate figures and adjust timing and overlap and stuff?

Could you put the figures of an R-34 GT-t into it and figure out why my engine didn't gain any power with four degrees retard on the exhaust cam??

BASS OUT

[Steve]

I would need all the cam specs, when they open and close, and what lift. I would also need to know how much lift the cams have and how much the NVCS moves the cams, as it is different for Neo AFAIK.

I think it would be worth throwing a timing light on your car too, just to make sure its setup right.

At the end of the day though, I cant see how it wouldnt make some difference, as even moving the timing 1 deg makes a difference which dyno 2003 can pick up - remeber the software is designed for a 'perfect world' scenario, and will give an indication of possible gains and losses but cannot take into account every possible variation.

I believe Warpspeed is better at me than manipulating it, I have only played with my cam timing and that is all, but yeah, I will give it a go if you can find out the specs