So I currently have true dual exhaust, Stillen intake/heat shield, ZTube and Megan straight pipes I haven�t installed. I plan on doing hfc for Noise instead of the straight pipes (California) so I�m holding off for now. My question is does anyone know if the lower plenum from a non revup ACTUALLY makes gains. I read a few times it�s the same as the MREV and that the revup engine makes no gains from the spacer without MREV or MREV2 lower plenums.

anyone have an answer? Pic of my G

 

The non-rev lower plenum is the foundation on which the MREV2 was built, but the MREV2 receives additional machining to increase volume over the rear-most runners/cylinders. I can't say if the spacer makes power without the non-rev lower, but I can tell you that my hack-job DIY MREV2 plus a full Motordyne spacer + isothermal kit absolutely made more torque in the lower RPMs via butt-dyno. YMMV.

 

Really happy to hear someone having experience with this. So I have a few questions since you�ve taken this route.

1. Did you use the lower plenum and collector or just lower?
2. What exactly did you do to change it from non-rev to �MREV�?
3. Did you get a tune after all of this?

Sorry to be so to the point, this is a mod that I really want to get done so I can go get my tune already lol.
From all the research I�ve done this should give you roughly 10-15whp throughout the entire rev range and yield the most power more towards 5500-6k range vs pure top end.

 

Think I found my answer. Any input?

 

1. Did you use the lower plenum and collector or just lower?
non-rev upper and modified non-rev lower
2. What exactly did you do to change it from non-rev to “MREV”?
filed down the two rear-most runners based on pictures of the mrev2, as well as removed flashing and excess metal wherever reasonable.
3. Did you get a tune after all of this?
not immediately, but eventually yes after I sorted out my exhaust... like a year and change later.

 

I had my suspicions but wanted to find someone who actually dyno'd the combination before I posted.

https://g35driver.com/forums/g-spot/...-manifold.html

Basically you pick up the mid range torque but the engine falls flat on it's face after 6k. Even a mild do-it-yourself port job to clean up the top of the rear runner and smooth off all the rough corners would pick the upper back up again though. Too much turbulence in the stock plenum and you NEED to smooth everything off to keep it flowing smoothly at high velocity.

Basically if you hit all these circled spots (non-rev plenum on the left, revup on the right) and smoothed/rounded them off REALLY WELL then you'll pick up bigger top end gains on the non-rev plenum. When the air hits a sharp edge it creates turbulence so you want everything rounded off as well as you can.

 

Thank you very much for the info and pics I really appreciate it. Tbh I don�t really like revving my engine pst 6.5k anyways so that sounds perfect, I came from 9k Honda�s but it still makes me hesitant on my G lol.

Alright so looks like I will be picking up this as a mod because for my driving style this is perfect. I�ll letcha know what happens when I finally get everything on and tuned!

 

The best thing to keep in mind when porting, imagine you are quickly pouring WATER into the plenum, you want the water to roll smoothly off every edge, if it creates a little "waterfall" on the edges then it's going to create turbulence.

 

If you want to remove even more material the front two runners can have a little more than 3/16" material removed from the top. You can use some play dough and a calipers to measure the gap with your spacer and upper plenum in place. Make little ***** of play-dough, stick it to the top of the intake runner, put the spacer and upper plenum on, remove, measure the height of the play-dough ball. You want them to all be the same and there is less clearance on the front two runners, the slope of the upper plenum causes less clearance in the front so basically you just even it out.

 

It took me a min to visualize what you were saying but now that I can see it that�s a great idea. Just to clarify the runners being the red circled portion that the air �runs� over, right? Or the opening where the air goes down into the collector? I�m sure I got it because it makes total sense. So just to clarify all I have to really do is smooth out those edges and that makes it MREV basically?

Did you increase the diameter of the lower plenum and the collector at the bottom at all or just the upper and lower plenum material reduction and polished?

Im close to going ahead and doing this on my own so would like as much info as possible lol.

 

So the runner is the 6 holes that air travels down to go into the manifold below it. The top of the front two runners have less clearance to the top of the UPPER plenum because of the slope of the upper.

Circled the area on the top of the runner where material needs to be removed. Strongly suggest using the play-dough and calipers trick so you don't remove more than necessary.

This guy went a little overboard removing material from the top of those runners, looks more like 1/2" removed, it's all about balancing the airflow so you want the gap between that point and the upper plenum lid the same (or close) across all runners so you have even airflow.

 

Here's some pictures that I found on MY350Z of an intake that Tony (Motordyne) confirmed was an actual MREV2

 

hey thank you so much for all the info! I�m picking up my non revup upper and lower plenum this weekend to start the work!

 

Keep in mind that particular intake was a FULL POLISH that the customer paid extra for, typically there's not that much work done to it, just the reshaping of various areas and the lowing of the front two runners.

 

def notes, gonna try and do the best I can though haha