Hi everyone, I have an 05 G35 coupe with a 6mt. Note that my car has the Rev up motor making around 300hp stock. I have a question, I looked around and I don't think it has been answered yet.

I was wondering if it would be worth it to buy a non rev up lower plenum and port that (like the mrev2) or to just port the stock revup lower plenum?

Note that I would be porting and polishing the upper plenum and lower runners on each setup. I will also be getting a plenum spacer on each set up.

Thanks in advance guys

 

Don't use the stock rev-up lower plenum, it's too restrictive in the midrange, use the non-rev lower with a 5/16 plenum spacer.

Match porting is definitely beneficial, but (smoothing out) the rough casting has been proven many times over to be a waste of time with no power gains. There are sections of the lower plenum that can have material removed in some of the pinch points/corners that will improve performance.

Imagine what water would do if it rolled off the edges, look at the path the air flows, if there are any places where it can create a "waterfall" instead of just smoothly rolling over a corner or edge then that will create turbulence which kills power, you want the air to flow smoothly without creating any turbulence. You can eyeball where those problem areas will be with a little practice. Keep in mind that air is not affected by gravity like water so you need to take that into consideration.

The biggest difference between the actual MREV2 plenum and the stock is the front two runners, the casting over the top of the runners is too high and iirc it needs 5mm of material removed from it. This is because of the slope on the upper plenum creating less volume in the front and thus slightly starving the front two runners. Some manufacturers have made a wedge-shaped plenum spacer to compensate for this. Z1 Motorsports for example, their plenum spacer is 5mm taller in the front.

 

Thank you very much for this information I really appreciate it and will definitely keep this in mind when its time to port my intake.

Most people run the non revup setup to help out the midrange as you have noted.

But I will be tuning my g with the up-rev software so do you think I will loose a lot of top end power with this set up? Or does porting the non revup plenum solve this issue

Currently on the car I have a invidia Gemini cat back with isr test pipes, a 3" true cai and a 75mm tb

Thanks again for your input I appreciate it

 

A ported rev-up will net you 2whp at the top end.

A ported non-rev will net you 23whp in the mid range.

This is why people use the non-rev, much better gains in the part of the powerband you actually use on a daily basis.

 

Ok sounds good, I'll look into finding a used lower plenum then.

Thanks so much man for your time and knowledge I appreciate it.

Cheers

 

Check your local pick-n-pull wrecking yards. I grabbed one for $15.

 

If I can find one for under $50 I would be ecstatic.

Cheers