Well, I got my plenum and installed it. The instructions were pretty dead on, except there are some things you guys need to know. Don't forget to transfer that nipple from the old plenum to the new plenum. I forgot, and I wondering why the car was idling rough. Also, watch out for the rubber part where you pour in the oil. It's very easy to get in stuck under the plenum. Oh, and I did the coolant leak fix too. I did notice a faint coolant smell, so I re-did the three connections. I was able to do this without taking the plenum off. The smell is gone now.

As far as power. It's defintely noticeabe, especially on the top end. The car just screams toward redline. The sound is slightly more aggressive. I have the Z-tube and K&N for now. Anyway, after install, I noticed that my idle is kinda high. I did a ECU reset, but it's still hovering around 950 rpm without A/C and 1050 with. Anyone encountered a high idle? Even though the directions say don't unplug the throttle body, I did anyway. I had to. It was filthy. I took it off and cleaned it. You think maybe that has something to do with it?

 

I don't know which Plenum Brand you purchased but my Kinetix says take off the throttle body. I guess each brand is diffrent

 

When I installed the MREV, I took the upper collector off . . . And by doing so had to disconnect the TB harness. My idles at 600 rpm and 800 rpm with the AC running. Could you have inadvertently bumped the butterfly in the TB assembly?

 

Don't think it's the Butterfly (trottle plate), they're in there really good. The only reason I know is that I bought one for an experiment I'm going to try! There is locktite on the brass screws and I had to really crank hard on them to get them off.

 

I am about to get the Motordyne Plenum but I need to know if I get the 1/2 inch, will my engine cover go back on?

 

The 1/2" spacer is a mixed bag. Some people say that their engine covers fit, while others say that theirs did not.

 

I heard that the cover fits back on but the stock strut bar doesn't.

What is the difference with the 5/16 and 1/2" plenum spacer in terms of power gains? I thought it was pretty neglible.

Les

 

The said strut bar applies only to the 350Z . . . And the power difference is 1 to 2 hp at peak, I believe.

 

i have the 3/8 and the cover fits but the bumps rub on the underside of the hood. so i can only imaging 1/2" would be worse

 

Does the 1/2" spacer give more circulation clearance than an aftermarket plenum: ie Crawford or Kinetix?

 

the plenum install was pretty easy, but always have the tq wrench handy and dont over torque it cuzzz bad stuff happens. trust me made a really really big hassle

 

The aftermarket plenums will give you more room because they increase the overall area of the front part of the stock plenum and overall as well. By eliminating that downward forward angle, some plenums, like kinetix, will give you as much as a 33% increase so the air can flow better into those chambers towards the front of the plenum. Spacers will only increase the mass of the upper collector as a whole by the size indicated (either 3/8, 5/16 or 1/2 inch). Only Dynos will give you the gains you may be looking for. Some people prefer the spacers because it still gives you that stock look whereas the plenums give you the other look. It all depends on what gains you are looking for and I guess the look as well.