I'm building a VVT 6.2L equipped swap car now and have been researching this like crazy. The big issue in making great power isnt the VVT, in fact if its tuned properly theoretically it should make the same top end power as an LS3 with more low end because of the ability to adjust cam phasing. Basically VVT means the cam retards as the engine RPM goes up. Lots of retard = screaming top end. When RPM lowers the cam \ advances respectively. These parameters are controlled by the PCM and fully tunable too which is great and theres lots of power potential there even stock as the cam timing is set by the factory mainly for fuel mileage not tuned for peak power.
In short; Lots of advance = tons of torque, Lots of retard = tons of top end. Being able to have BOTH?
Get the idea?
Not all is currently roses however as theres two HUGE issues at hand right now that seems to have everyone baffled. This is all stuff i've read on many many message boards and pieced together what makes sense at this point based on reputable board members/sponsors opinions so if this info isnt 100% dont scream at me Im only trying to help spread some info thats current as of now.
1. AFM. Active fuel management and VVT are two completely separate systems do not confuse the two. AFM lifters are less than ideal for big lift cams it seems. They just dont seem to be able to handle the big load of high valve springs that are required when running big cams. This is the biggest issue with stock L99 cam swaps PERIOD. Furthermore GM apparently has some kind of patent on the AFM lifter design preventing the aftermarket from building a hi-perf set to swap out with. So for the time it appears that the only safe option on any decent sized cam swap is going to require AFM delete and removing the 4 AFM lifters and replacing them with 4 new stock non AFM units. Keeping the stick VVT system is fine however and should make the engine outperform a comparably cam'd non VVT equipped engine so good news there. That said VVT cam research is really just getting off the ground so as noted above a little patience is probably your best friend here while the aftermarket figures out exactly how to extract the most out of these VVT phasers and what lift/lobes/duration works best.
2. VVT phaser. The stock VVT phaser looks to be the weak link in the VVT system thus far. They just dont seem to last with big dual valve springs and big cams. So selecting a cam that doesnt require monstrous dual valve springs is also important. For the time being that is... Im smelling a completely new aftermarket phaser on the horizon or at least an upgraded version that will not suffer these ills and then we're good to go. In the meantime if you NEED a cam then I'd shy away from going too big for the time being and select a cam that can get by with single coil beehives. Besides theres lots of threads recently coming up with smaller cams making bigger power through LS3 heads so this isnt all that bad. Search Justin Timberlake cam over at tech. A quote from a tech member "The JT cam is so named because although its small like JT is, They can both still go around ****ing anything they want to"
Thats about all thats different between a regular LS3 and an L99 so there are some hurdles that need to be crossed before everyones on board with this. In the meantime New Era has done a good job R&D'ing cams for the L99 and can hook you up today if your ready to go.
If your a handy owner and want to go at this yourself? I'd steer clear of the current cam offerings off the shelf and get a custom grind done. Contact PatrickG or Geoff at EPS and they'll take care of you.
I'm still hunting down info so if anyone has more to add I'd like to hear it.
