Vk50ve

[thehelix112]

Its late 2008, does anyone know if the Infinit FX50 is in showrooms yet? I wanna go have a look under one to see how the 4wd system works. If its the same as the RB26 then it should be possible to convert this engine to RWD.

 

This engine looks to be a nice little unit stock, 290kw @ 6800, 500Nm. Does anyone have any experience with the VVEL system? How difficult is it to upgrade the cams and push the powerband a little higher in the rev-range?

 

Comments?

 

Dave

[thehelix112]

http://www.nissan-global.com/EN/DOCUMENT/PDF/IREVENT/PRESEN/2007/070713VVEL-e.pdf

 

Page 10 has a diagram showing how it works. I'm not sure if this means it will be necessary to extend the limits of how far the system can alter the timing in order to get any more power up high?

 

*Goes back to trying to decipher diagram*

 

Dave

[KillerBjt]

just from reading that pdf i can tell its gonna require alot of money and work to change the cam for that, since there isnt a conventional cam. it uses eccentric shafts with rockers to adjust the valve lift and duration.

[thehelix112]

I'm sure someone will do some work for them. I think I understand how the lift is varied, but I definitely don't understand the duration. A simple video would go a long ways towards explaining this.

 

Dave

[thehelix112]

 

Like that, but for this system.

 

This video has a real video that the last 2 seconds is close, but not good enough for me to get it.

 

Dave

[thehelix112]

 

There we go. But I still don't get how it changes the duration. It can't move back and forth every valve actuation.. Maybe the drive shaft (from page 10 in the above pdf) is connected to a VTC type system that changes the timing.. but that still doesn't get you the duration..

 

Anyone have any ideas?

 

Dave

[WizardBlack]

If you look at the end of section 3-3, I will explain it if you are still scratching your head a tad.

 

Basic operation:

First of all, the upper grey shaft is stationary and only turns back and forth over a limited range of motion with an eccentric lobe to change the pivot point. When the VVEL isn't changing anything, this just sits there doing nothing.

Second, the lower grey shaft is the actual "camshaft" as we know it. Look at the big eccentric lobes on it that are inside the big black linkage. As it spins, it tugs the black linkage up and down like the drive system on a train. As it spins, the black link goes up and down.

Third, since the green link is connected to the big black link, it is swinging back and forth like a see-saw. It is pounding the little black link up and down as well. The little black link is connected to the blue link that is hitting the buckets on top of the valve. The blue links are NOT fixed on the lower grey shaft, they just spin freely on it.

 

Now, to change the lift, you simply turn the upper grey shaft. This changes the pivot location for the three linkages (black-green-black). This can be further improved by adding your typical valve timing control with a system at the cam gear with oil pressure, etc. I kinda like the design Subaru has with AVCS; which is just a variable version of Nissan's NVCS. The video the previous poster showed clearly indicated this was the case.

 

The awesome thing about this setup is it mitigates the need for new cams assuming you don't need ridiculous amounts of lift beyond the range VVEL is capable of. You don't have the option of assymetric lobes, however. The blue lobe shoves the bucket down, then it stops and goes back up the way it came. Once you do need new cams, aftermarket shops would need to give you new lower grey shafts, larger diameter black links and new blue lobes to affect lift and ramp rate.

 

The downside of this system is you have more pieces and the pieces are moving and stopping, moving and stopping instead of just spinning. Likewise, when you change lift, you also change duration since with less lift you are moving the blue lobes away from the buckets. Imagine simply raising the centerline of your existing cams up and down and you get the idea. Come to think of it, this system might be a tad loud with it not maintaining lobe to bucket contact all the time.