Sorry about that.

It looks like the holes drilled through the stock upper plenum are quite eccentric. I baselined the internal support design from an 03 upper plenum with fairly concentric holes drilled through the top. I then added a good amount of margin to accomodate for casting variances and cases where it could be more eccentric than the baseline upper plenum model.

I will change the design of the internal supports to accomodate for even more variation.

Thank you for the feedback. This is exactly how the product design gets improved upon. I'll get right on it!
Tony

 

^so more than likely people who just bought this will have same issue..

 

I doubt it.

Thousands of the same design have gone out over the past year and a half and this is the first thread I know of to mention it. Based on this, it has well over a 1000:1 success rate.

 

hopefully mine will be a-okay !

 

Wow..I'm sorry to say this but.. hiz-n-herz got 1000:1 unlucky chance, hehe..

 

Yeah, my front center one kept falling off too. I don't like the tought of something possibly falling off into my engine! I tried all 6 on the largetst-diameter and smallest-diameter posts. They all fell off the small one and would not go onto the big ones. I thin 3 sizes of these spacer caps are needed for this install. I'd still like some retainer that held these together as one piece. It should be easy to make two pieces that hold 3 spacers apiece. or maybe just long pieces of nylon with the three holes. It could be shaped to not block so much air and hopefully have thread retainers like these little pieces do. Or of they were in a metal carrier, they could attach to the metal piece that goes down the center. Then no chance of pieces falling into the engine if someone else works on the car...

I suppose I should call Tony, but I don't want to be too much of a PITA.

 

OK... I'm off to the convienience store to buy a lottery ticket! There should be an equal and opposite 1000:1 lucky chance, eh?

 

No Prob Tony. I love to give feedback...

Regarding the holes, it's not that they are not drilled eccentrically, it's that the post itself is egg-shapped, not round (if you look at a cross-section). I could have taken better pics of the post. The cross-section looks like a cam-lobe! (street-tuned, with a short duration)


BTW, I really like my idea of a thin metal carrier that holds these guides so you don't have to worry about the snapping onto the posts. The metal carrier would have to clear the metal cover in the center of the lower collector. I can see a couple ideas in my head! these spacers could have shallow grooves around the outside and they could slide into cut-outs on the metal strip which would have a u-shape where they slide in and then bumps inside the-U to hold them in place.

Then either 1:
you screw the plenum cover bolts into them when the plenum cover is to the side and when you lower the plenum cover, they stay in place.

Or 2:
I think a better idea is to include a modified intake manifold collector cover with metal arms riveted or otherwise attached or a whole new intake manifold collector cover that that hold the spacers in place. I can see this in my head too. I prefer the solid replacement piece. There are no loose parts or parts which have the potential to come loose insode the intake plenum for a reason...

Of course all of this either adds to the cost of the unit or lowers your margins.

Let me know if you want me to sketch something up or when you have a product if I can test it out.

So does the 06 lower collector that I have look familiar? The design looks to be very different.

Lastly, can I buy additional thermal gaskets for the intake manifold<-->lower collector. I will change it back to stock if I ever have an engine-related warranty item. I don't trust Nissan will be understanding about a lower collector replacement; even though it's their own part.

Thanks,

Bill

 

As soon as you unbolt the upper plenum cover, see if these caps fit the left and right rear plenum-cover posts...

Bolts 3 and 6 on page 6 of the installation instructions pass through these posts.

 

Another interesting observation that I had...

the plenum post spacer-caps depicted in your installation manual (page 4) seem to be taller than they are wide

The ones that came with my package were wider than they are tall.


Also, the posts are more narrow where they meet the lower collector. A similar post spacer with a bit wider cup and much taller cup sides (1/2" to 3/4" cup sides) might just do the trick without a fancy (costly) intake maifold collector cover. If the cup is not wide enough, the plenum post will not go down all the way. You need one wide enough so the odd-shaped posts can reach the bottom and the sides of the cup should be tall enough to have a tight fit with the post further up the post rather than at the very end. In fact you might want a taller (deeper) cup for the narrow posts and a more shallow cup for the wider posts. Also, taller, bigger parts are less likely to fall into the intake manifold! You could do the deeper cups and the metal retainer thast hooks 3 cups together...


I don't know if I am making any sense...

Time for bed....

Any change there was a parts-spec change lately to a spacer with a more shallow cup?

 

Oh... I knew I took better pics of the posts...

Here is the post for bolt 3 which fits the spacer fine...


Now here is the pic for post 5 which would not fit in the spacer cup. Again, it's not that the hole was not drilled eccentrically, it's because the post is egg-shaped. Had the hole been drilled in the center of this post, it still would not fit the spacer cup

 

R&D at its finest...right here on my350z lol

 

Hi Bill,

Your picture above (#2) is what I meant by eccentric but to the extreme. Not that the drilling itself is eccentric, but that its position relative to the post center is eccentric.... Egg shaped.

Picture #1 is nominal. That is what Nissan intended by design.

And yes, I did expect some degree of varying eccentricity from the factory, but picture #2 is more than I would have ever expected. Nissan generally isn't a slouch on tolerances. But #2 is certaintly more than I have seen before (and i have installed many, many plenum spacers on many Z's and G's).

As far as connecting the pieces with metal or something similar, it may create more problems in practice. Small metal and plastic intermolded parts come with their own problems. Making a single large plastic molded piece for all 6 internal posts can also become another problem in post to post relative positioning. Tolerance variation over a large area becomes exponentially greater. If a single cast piece is made thin enough to be flexible at the webing then there are other potential problems that may arise in practice.

And multiple cup sizes are not needed assuming tolerance variations are properly dealt with. (This is the best angle to approach it from.)

I will increase the ID of the cup so that a far greater amount of eccentric variation can still be made to fit. And I will also design the snap mechanism to be more stout. These will be easy but effective changes.

As for the differences between the stock REVUP lower plenum and the MREV2 lower plenum, they are significant but its also exactly what it should be. You want this. It is these differences that give the MREV2 the power curve differences as seen in the dyno plots. The smaller diameter runners of the MREV2 create higher velocity... and this is the most important and crucial difference that affects the power curve.

The smaller diameter runners is what creates the very high midrange gains. The modifications I do to the lower plenum (and the 5/16" spacer itself) are used to increase the high RPM output. Put it all together and you get the best NA gains from any single bolt on.

As for the pictures shown in the installation manual, yes, they do look different from yours because they are different. The internal supports shown in that picture are from the 1/2" spacer kit. For pictoral purposes, the larger supports make for better visual illustration. And I wanted to make everything as clear as possible in the installation manual.

Thanks for the feedback. Feedback is progress.
Tony






PS - I may not be able to respond to this thread until Saturday. I'm heading off to the SEMA convention in Vegas!

I'll bring the wireless laptop with me but I don't know if a connection will be readily available.

 

Hey Tony,

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.

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. 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

I can check my wife's car (she also has an 06Z 6MT) to see if she has the same upper plenum cover. Maybe she'll let me take it off to look at the posts. Maybe not though!

Oh, and for those skeptical of the mrev2 and spacer at this point, I say go for it anyway. I would totally do it again. After a few days of it being on the car, it seems to have made a huge difference. The car feels much more fun, revs easier, and sounds better doint it.

I am trying to talk my wife into getting one for her 06Z 6MT...

I'll leave the rest to you, Tony. Thanks for the explanations. Let me know when you have a new part to try...

BTW, Your instructions were awesome! I wish other manufacturers would document things that well. I read them like 10 times before I started. Almost had them memorized!

 

i just put on mine last week , on a 06 350z, and the plastic pieces fit perfect. I did not experience the problems you illustrate.

 

hiz-n-herz,

What about the pinging? Are you just going to let it ping badly or has it calmed down? I am concerned about this mod due to the pinging.

Thanks,

Pete

 

hiz-n-herz,
thanks for the informative thread!
lots of great pics and i learned a lot!

looking forward to doing this as my next mod

 

Hmmm... Not sure what choice I have. At 62 degrees and below, the pinging is minimal. At 65-70, it's very noticeable. At 77+, it's just horrible. Sounds like I am driving an early-80's GM 4-banger with a batch of bad gas, lugging the engine up a hill

I hate to spend too much on tuning at this point because I will eventually go FI. I am not sure what to do.

Again, to be fair, I have not installed the throttle-body coolant by-pass valve yet. Not sure how much difference that will make in warm weather. I imagine if I am in slow-moving traffic, the intake plenum and collector will get heat-soaked from the heat of the engine rising up. On the highway, I would think it could sustain reduced intake temps.

It is starting to cool down here in the CA bay area, which is why I have not installed it yet. In the spring, I'll prolly install it when it starts to warm up. If it does not help the pinging, I'll take it to get tuned somewhere.

Over the next month or so, I'll prolly get it dyno'd and see what the a/f ratios look like. If it's normal, I won't worry about it too much until spring. Otherwise, I may get a tune. I may even try a reflash for now and wait on a $$$ tuning device until I know which FI route I will be going.

 

Thanks Dude... Just rub it in

 

Hey Tony,

Does this advantage hold true for FI cars? My ultimate goal is FI (probably a TT kit, maybe JWT). Just wondering which lower collector would be better for FI. Not sure what FI does to the frequency tuning effect...