[mike-y]

the manifold is plastic, so its already really smooth inside. Might not be much to dremel, but hey, nothing ventured, nothing gained, right?

[allmotorh22]

Originally Posted by mike-y

the manifold is plastic, so its already really smooth inside. Might not be much to dremel, but hey, nothing ventured, nothing gained, right?

right on Mike.

hey bro, could you do me a favor and take a flash picture of the inside of your 3 stage manifold? (through the throttle body mount)

I want to see the difference that 325imax is talking about.

[335imax]

This might help. It looks just like this...

Step By Step
http://www.zpost.com/forums/showthread.php?t=455180
This picture shows the LOW speed Actuator. The High Speed one is on the other side. I would guess the Actuators probably open up a hole that is about 2 inches in diamater, allowing the left side and the right side (littery picture left to open up to connect to picture right) of the manifold to be connected on the inside. The low speed opens up the front of the manifold, and the high speed opens up the back of the manifold. You really need to get your hands on one to try to build one correctly. Sorry, mine is already mounted up... (Oh yeah, and without a tune, Im not sure this idea would even work, as the ECU won't pump enough gas into your new setup, and you might get fuel starvation because you will be introducing a TON OF AIR)

P.S. to swap the intake out is a pain in the ass. It takes 2 people, or one very determined person. It took me 10 hours to do this job by myself. Granted I could now do another one in probably 4 hours. There are just alot of little wires and plastic breather pipes your really need to document or take pictures of when you remove them, otherwise you might miss something. Some wires are near impossible to get to without groping around forever in the dark underneath the manifold.

Also please read this post about why you might not want to do this MOD without a TUNE.
http://www.e90post.com/forums/showthread.php?t=461277

[e90pilot]

Here are actuator flaps. The smaller one on the top is open.

[allmotorh22]

Sweet, thanks guys!

I would still like a close up shot of the throttle body mount.

That hole, (against the back of the runner) is that a path way for one of the stages?

how else is air being sent up to the main plenum? (other than the left and right runners?) is there another path or is everythng being being switched/actuated within the main plenum?

Yup tune, definetly... I may just run a wide band at first to see if it runs way too lean, but yes a tune will definetly be on the agenda (to take care of idling issues as well as top end power.)

[e90pilot]

No, that hole you see is for the PCV system. This manifold really doesn't change the path. The valves keep the manifold divided. One valve keeps the top devided (the one you see in the picture) and the other keeps the rear chamber divided. I forgot what the Firing order was but the valve just makes is so the resonance peaks occur near the next valve that's opening. It's kinda like mini FI from what I understand.

[allmotorh22]

so no alternate paths?

so the only way air travels from the throttle body to the main plenum is by way of those two large runners? (left/right circled yellow)


I thought their was something going on with the area circled in green (like a hole), but if not, than the runners are identical to the single stage correct?

so correct me if im' wrong, all the channels/paths are being actuated within the Main Plenum (which has identical volume as the single stage)? correct?

[e90pilot]

Let me see if I can grab a pic of the back of mine. I wish I took pics of this thing when it was still in the box. There's an "overshoot" pipe under the intake runners. There's nothing there on a single stage. Now, those two big pipes on the sides is the only way to get air up to the runners but that overshoot pipe makes changes the resonance properties of the whole thing. The actuator valve is attached to that and divides it in half front to back relative to the car. I'll go to my car right now and see if I can get my phone in ther to get a shot.

Originally Posted by allmotorh22

so no alternate paths?

so the only way air travels from the throttle body to the main plenum is by way of those two large runners? (left/right circled yellow)Attachment 472272


I thought their was something going on with the area circled in green (like a hole), but if not, than the runners are identical to the single stage correct?

so correct me if im' wrong, all the channels/paths are being actuated within the Main Plenum (which has identical volume as the single stage)? correct?

[335imax]

Here is the underside of a single intake manifold, that looks exactly like the 3 stage minus the high speed actuator. The high speed actuator would open up where indicated on this picture.

[e90pilot]

Ok so the overshoot chamber is part of the plenum. So then then the 330 plenum is larger than the 325.

[allmotorh22]

Thanks 325imax,

Ok, I think is going on...

[mike-y]

I *think* the single stage manifold is completely open on the inside, but I can check tonight or tomorrow morning when I start working on the car again.

But you are right on the 3 stage, that there aren't alternate paths for air (like on a honda). The air still goes thru the same path, but the valves open up the different chambers and use acoustical wave pulses created by engine frequencies to increase the air moving thru the manifold.

kinda like how some cool air intakes will get a big torque bump at certain rpms, when the engine reaches the pipe's resonant frequency.

I'll get my little flashlight and try to take some good pics for you to look at some more.


I'm doing the swap myself, and like 325iMax said, it's a PITA. Really, the biggest pain is disconnecting the crancase vent tubes connected to the oil separator on the back of the manifold, and the corresponding little wires that plug in back there. I bet I spent 2 hours just trying to fit my hands back there to disconnect them. I ended up breaking one, and then said F*** it and broke the other one, and everything came right out, lol.

The Z4 must have more room at the back of the motor, because I wasn't able to undo the little wiring harness clip back there, like they did in that Z4 thread.

[allmotorh22]

Originally Posted by e90pilot

Ok so the overshoot chamber is part of the plenum. So then then the 330 plenum is larger than the 325.

oh, thats interesting... I'm not exactly sure what you mean by overshoot chamber though, (the part the high speed Disa controls?). that explains "volumes" Haha...

@Mike, yeah dude let us know, and you can probably take a pic of the part e90pilot is talking about.

This manifold is kinda like an H22.

[robbiec]

Originally Posted by mike-y

But you are right on the 3 stage, that there aren't alternate paths for air (like on a honda). The air still goes thru the same path, but the valves open up the different chambers and use acoustical wave pulses created by engine frequencies to increase the air moving thru the manifold.

kinda like how some cool air intakes will get a big torque bump at certain rpms, when the engine reaches the pipe's resonant frequency.

Yes Mikey! It's all about the resonance! The single stage offers one resonance point, which I believe is about 4k RPM based on all the dyno plots I've seen on here. Now take a look at Bren's dyno on page 7 of this thread

http://www.e90post.com/forums/showthread.php?t=453274

You can clearly see the three distinct torque peaks at each of the three resonance points of the 3-stage manifold. Why would anyone want to modify this beautiful piece of engineering? Such a nice broad torque curve with great low-end response and top end power. No single stage manifold can offer such a wide torque curve. Now, I suppose if one had some big duration cams and wanted to do some serious racing, that a short runner, large diameter manifold may be preferable, but that would kill low end torque. For 99% of us, the stock 3-stage is all we need.

[mike-y]

ah, here we go. I knew I still had this pic somewhere.

and looking at this, it appears that the small valve on the underside of the manifold is the LOW speed valve, not the high one.

[mike-y]

finished the swap today, and was a success. I was pretty happy when it started right up and didn't throw any codes. Haven't really gotten a change to drive a whole lot yet, but first impressions are that low end torque is improved, and throttle response is noticeably better. Midrange seems okay, and then there is a very noticeable surge in power around 4000rpm.

I'm running it with a pbx on map 3, so it is getting more fuel than stock, but I'm still going to get a flash, just not sure who or when yet.

[335imax]

Hey Mike,

Get on on the highway and put your car in 4th or 5th at low RPMS and go wide open throttle from 2k - 3k exactly and tell me if you have any throttle surging issues. I want to know what a stock car/ECU does with the manifold swap.

Don't mess with OE Tuning! Go with AA for your tune. Its awsome!

[allmotorh22]

Originally Posted by 325imax

Hey Mike,
Don't mess with OE Tuning! Go with AA for your tune. Its awsome!

@Mike, I say go with OE since your in Los Angeles. that way if your car starts to stumble or detonate, you can take it back to him personally so he can figure it out.

@325i max, is the manifold on the way?

[mike-y]

I did stomp on it in 4th and 5th gear at around 2200rpm, and didn't notice anything unusual (other than poor acceleration, lol). I have the automatic in this car tho. I only did it once or twice, but will try again this afternoon on the way home to be sure.

I drove it 30 miles to work this morning, and I can definitely feel the difference. Pretty happy with it so far. And yeah, tuning it at OE would be nice, since they could do it on the dyno, but I just want to make sure it runs right. If I don't have the issues 325iMax has, the AA tune could work well for me also.

325imax, if you don't want to ship the manifold to allmotorH22, let me know. I can can give him mine, if he's willing to drive to Whittier (near the 60 and 605 fwy in L.A.)


I also have a spare 3 stage manifold from a 530i that I'm going to sell now. gotta take some pics first.

[335imax]

Thanks Mike
An automatic will shift before the problem will occur. This issue is only with the 6 speed MT I believe, because you can force it to stay bogged down.

Yes the intake manifold is on its way. You should have gotten tracking information.... I dropped it off at UPS on Saturday afternoon... check again tonight...

[allmotorh22]

@325imax, sweet thanks man.

@Mikey, Yeah I could use a do-over manifold in the r&d of this one. PM'ed you.

[mike-y]

325imax, I had the trans in manual mode, so I could shift it to M4 and M5, and it will hold the gear. No issues/surging with my car while doing that, other than the expected lack of acceleration.