This has never been answered as far as I've read. After looking at the 4th gen variable intake manifold, I notice that the intake still uses the long intake runners. I don't see any shorter intake runners anywhere on the manifold. In order to make topend power, you need shorter intake runners. The 5th gen and 2002 VQ incorporate TWO sets of runners with a butterfly switch over. The 4th gen variable intake only incorporates the long runners with some sort of box that has the intake butterflys that sits in the middle of the cylinder head valley.

Second question. Has it been determined that the switch over mechanism is vacumn operated?

I hope someone gets this installed and dynoed shortly because I'm very interested and I'm dying in anticipation. A 195-200fwhp 4th gen would own any NA Max currently in production. Like I've said before, this is the key to getting 13s NA.


Dave

 

advanced timing is the key to NA 13s - but the intake manifold won't hurt either. Not sure how well the manifold works, but if they really do work well then expect them to go up in price very fast along with demand for them.

 

Yes, I noted that too. If the manifold is set-up like the 3-gen ve manifold(which I think it is)

1) The "chamber" you see at the end of the runners(right before the ports into the lower manifold) would sorta divide the intake in two. When the it's "closed" the manifold area is reduced, promoting good air velocity at the low end. When it's "open" it, increases the intake area and allows for greater volumes of air in(like you would want in wot conditions.

2) The VE manifold uses a vacuum operated plumger. I looked at where the vacuum is sourced at and it uses an electical signal to activate a little piston that activates the vaccuum source to pull the plunger and open the flap.

Notes: If Keven97se is right, you "might" have the connector ready. But you will need the electric/vacuum switch and maybe the plunger also. These might be sourced from a VG or VE maxima. Both of these have varible volume intake chambers(but in different forms)

 

It appears to be close by the vacuum at idle and part throttle and opend when their is no manifold vacuum at WOT.

I think this is more of a "resonance" tuned intake. I noticed it also that their is no second set of runners. Perhaps it is a volume thing?

 

Timing can only do so much. It will also force the need for 94+ octance. On a 5.0, advancing the timing is good for about 5rwhp. On the VE, advancing the timing is good for a ~3 fwhp, so I've been told. Every little bit helps, but the advantage of the variable intake is that it continues to let the motor breath. Increasing breathable rpms increases hp. If you were to extend the 4th gen VQs ability to breath to 6200rpms instead of 5600rpms, you will be looking at atleast 12fwhp, according to my dyno hp increase per 100rpm.


Dave

 

You and Jeff are right. That setup looks like the one used on the VE/VG. It definately appears to be a resonance tuned intake with a "tumble" chamber to increase the intake charge at higher rpms. Seeing that the intake doesn't use a seperate set of shorter runners, the gains may not be quite what I had hoped for. The gains should still be good, but we may only be looking at a 400rpm increase in useable rpm extending power around 6000 instead of 5600. So maybe this mod is the key to low 14s, unless you're theblue


Dave

 

If I understand the euro/mideast intake manifold operation correctly, the secondary plenum that is located downstream is "disconnected" from the intake runners at lower rpms. The primary plenum (the same one that we use) is the last place the air paths are interconnected, and thereafter the air enters individual runners and runs right past the (closed) butterfly valves of the secondary plenum. At higher rpms, the butterfly valves open. At this point, ALL the runners are connected volume-wise via the secondary plenum. Now, the primary plenum (the one we use) no longer constitues the entire plenum volume. Now, the plenum is that primary plenum PLUS the volume of the runners between it and the secondary plenum PLUS the volume of the secondary plenum itself. You no have a huge plenum volumetrically that sits right above short, straight runners that ram right into the engine.

Look at the pic below:
http://www.customrides.net/tmp/Intake8.JPG
In the above pic, the primary plenum is to the right downstream of the big throttle body hole. The individual runners (that become part of the "big" plenum at higher rpms) break off to the left. They then meet up with the secondary plenum (on left, under the valve cover-looking thing with the vacuum-operated valve assembly below it). The runner section below that secondary plenum become the "only" runners at higher rpms once the butterfly valves open up. The individual butterfly valves for each runner are NOT on the flow path but are instead located above the runners, on the "roof" of each runner.

You gotta think about the way the manifold works from the air's perspective. As soon as the individual air paths (ie runners) can "talk" to each other (are connected via a common air path), they become one large, interconnected volume (ie a plenum).

Any of this making any sense?

 

Here's another view of the intake manifold from the other side. Might be a little bit easier to envision how the thing works. Imagine the butterfly valves being located on the roof of each runner above the vertical section of the runners about an inch below the roof of the secondary plenum.
http://www.customrides.net/tmp/intake5.JPG

 

I correct myself. Make that "2-3 inches below below the gasket for the secondary plenum cover."

 

Clear as day!

 

This all makes a lot of sense. Each cylinder has access to much more air volume to breath once the butterflys open up. So who is producing this intake? Is this a Nissan OEM part available in the euro market? I know Roadbeast is selling one. How is it he has access to these intakes? This is definately something I'd be interesed in adding to my 99 SE-L.

 

Road Beast can get them because he is from the middle East. I forget the country name but it starts with a B and near Saudi Arabia. They come stock on the 4th gens there so he gets them from any local dealership or Agent as I believe they are called there. The stock HP on 4th gens in his country is 222 HP.

SuDZ

 

Has anyone determined if perhaps these NZ and Bahrain maximas might be the VQ30DD. I think I saw this designation on a Nissan site from Russia. That engine makes 220 hp stock... I believe the DD as opposed to DE stands for Direct Injection or Direct Ignition... its Direct _________ I know that. If thats the case, maybe this variable intake from Bahrian or NZ isnt going to produce the gains we hope it will.

 

Well i guess road beast tried transfering noe already to a US version. He said it went fine but they dont have a DYNO over there so we might have to wait for somne here to test it out now to get an actual reading for power.

SuDZ

 

I think this would be one of the most exciting mods for the 4th gen if it worked out, but snce i don'thave that much automotive knowledge, i can't help out that much

 

Yes. If everything works right it should be great. I just hope that it does.

SuDZ