Originally Posted by 91180sr

NEW UPDATE .The heads are now getting a performance 3 angle valve job done as well due to lasck of seal and concerns of motor having blown headgasket and bad seals. Not sure how much comes out of that being done?

P.S.
this is getting way to expensive !!! thankgod ffor tax money other wise i wouldnt have done it.

Originally Posted by kacz07

With aftermarket cams (or aftermarket reflash/ems), you have two options:

1. Swap in a lower revup collector and increase volume w/ a big spacer/upper plenum (SG, SexyRob)

You are trading some power under the curve for peak power, but with exhaust cam phasing, this could be massaged. Additionally, with cams, it is possible to extend the torque band and, consequently, add or maintain peak power from 6300rpm and up. Maybe to 8k and beyond, but that's cam dependent. Extending the powerband after the peak makes up for power under the curve, but you need upgraded valve springs and shims to rev higher.

Or, as mentioned/employed by Adam and reiterated by SexyRob's intake dynos, myself, and Copec:


Do you know who did this? 1cockyZ, and guess what, he made the most power on a NONREV plenum. The issue is the revups runners are too short and large, and you're losing a lot of velocity. A good port job will open up the non revs runners, and allow it to breath about as well as a revup manifold, while offering more area under the curve. I DARE you to find a Revup manifold making more power.

2. Properly ported Non-rev lower collector and spacer/big upper plenum (Z1). A properly ported Non-rev lower collector will eliminate the dip and turndown in power that most DEs see around 6300 and shift peak to 6600rpm. After that, the cams will determine how far that extends. You really don't have to sacrifice any power under the curve with this method.

References:
https://my350z.com/forum/8590473-post156.html

Look at torque, peaks, and power to redline in SG's non-rev and Jmccarty's
_______________

A side note, a regular Non-rev lower collector, as seen in SG's build will peak at 6300, dip down, and then climb back up to near peak or above (cam dependent, SG, Jmccarty). I'm guessing that the airflow, although less than what is seen at the typical Non-rev peak, is still able to allow for sufficient torque to be produced, AFTER the peak and higher in the rpm range.

I need to support these observations with dynos, but I'm busy now.

Originally Posted by kacz07

I'd get the biggest spacer you can. Motordyne has the 1/2" or Powerlabs has a 3/8th". Not sure what other options there are, but you can find a larger upper plenum like Crawford or APS. Keep us updated and let us know how it goes.

The porting of the lower collector should probably be under advice from someone like Adam at Z1auto or the like. The runners are what you'd be porting in the lower. They're much more sensitive to modifications than just making space in the upper.