I'm sorry for being a "noob," but what exactly is "pinging" in this context?

I, too, have purchased the MREV2 and 5/16th Iso-Thermal Spacer from Tony. I installed them separately as I was the first 100ish to buy the MREV2 . I, too, had to shorten the strut bar, but by more than just 2 full turns (more like 4 or 5). I also did not get the Iso-Thermal gasket that goes between the manifold and lower collector that comes with the spacer. I didn't have a problem with the plastic spacers that goes in between the collectors though.

 

Yeah, I understand the whole tuning concept when it comes to air. I used to do a lot of car stereo work and could build and tune bass-relex enclosures as well as 5th order bandpass enclosures. I think the concepts are similar. Once can adjust for the gain of the center tuning frequency and the width of the curve. (Q). No arguments here. We agree! I just can't figure out why Nissan would want peak power at redline (?) I always thought you wanted it a bit below redline so you can optimize shift points and spend more time in a greater powerband... Oh well... They were probably after that 300hp number at any cost... including less mdrange torque.

Precisely! It's 1/4 wave tuning of helmholtz resonators. And yes, its totally about the "Q". Or at least Q within the usable RPM range. Nissan targeted a ringer at redline and I completely agree that it doesn't make sense to peak it out at redline unless they were simply designing it as a marketing tool.
What looks good in advertisements and magazines doesn't make for the best track results.

Area under the curve, not peak numbers, is what gets things moving.

I find it hard to believe Nissan would have that great of a margin of error on the upper covers. I would guess that there has been a change in the upper cover.

I don't really know what their casting process is, but I believe they may be starting the mold process with some kind of silicone rubber negative image of the plenum to initiate the casting process with. I've seen how some of the various parts of the aluminum upper and lower plenum seem to move around or be slightly different from unit to unit. And I have seen a lot of uppers and lowers.

The guys doing the actual casting process have probably made somewhere around a million of these plenums. My guess is they have seen so many of them they don't want to see another for as long as they live.


One of my pics has a model number stamped onto the lip of the upper plenum cover. I imageine you've done a handful of 06's

Yep. I have both an 03 and a 06 upper plenum with the same part number.
So it doesn't look like there was a design change.

Thanks for the props!
Tony

 

I'm sure it will with even better results but there hasn't been a pre/post dyno of it on a FI REVUP engine yet.

There have been several FI NON-REVUP Z's that dynod both the REVUP and NONREVUP lower plenums on their Z and found that the REVUP plenum performed much worse. From what I recall, the REVUP lower plenum lost power everywhere. Including the peak!

I expect we will see the same results on a FI REVUP engine.

EDIT: The speed of sound inside the plenum will go up slightly due to the increased air temperature so the runner tuning frequency will go up slightly because of this.