ENG: H-series Plenum on F22A6 runners

[wed3k]

just did this right now...

took two hours to swap and about an hour to diagnose my really high idle.

it was surging to 3k because i thought the prelude plate would do but it kept the butterfly slightly open.
swapped plates...it was jumping from 1k->1.5k

lowered idle to 900, bam...easy swap.

i had to improvise on some vac lines and coolant lines but it all works well and ive gained some torque.

[owequitit]

Good suggestion on the regrind. I don't think my engine would be at its full potential with the 272 regrind but the 260 would be a suitable addition. As far as the ECU goes, I'm worried about getting a problem with my secondaries on the installed f22a6 runners (vaccum problem) like you mentioned. Can anyone shed some light on what the deal is with that? I'm willing to get the pt6 ECU if thats what I need to run the intake but I wanna know exactly what I need before I do anything foolish.

The "black box" that everybody refers to is simply a vacuum chamber with a solenoid that mounts to the bottom of the intake manifold.

One line runs to the IM and has a check valve, one line loops around to the solenoid, and one line runs from the solenoid to the IAB diaphragm.

1)When the throttle closes, the air is drawn out of the chamber, and vacuum is stored in the tank, because there is a check valve in the line to the IM and the solenoid only allows air to travel one way.

2)That way, even when the throttle is open, and the IM has no vacuum in it, the vacuum in the tank will continue to hold the IAB diaphragm shut, keeping the IABs closed.

3) At about 4800 RPM, the ECU closes a ground contact which completes the circuit to the solenoid on the black box, causing it to open. It is only open for a very brief amount of time (probably measured in milliseconds).

4) This allows the black vacuum chamber to fill with air, thus allowing air to the IAB diaphragm, and allowing the IAB's to open.

5)As soon as the throttle is closed, the vaccum in the manifold sucks all the air out of the IAB system, and the IABs close again.

The reason the black box and the ECU are important is because without the black box, there is no way to control when the IAB's will open.

If we don't connect the vacuum line to anything, they will always be open, because there is no vacuum to keep them closed.

If we connect the line directly to the IM, it will recieve the proper vacuum when the throttle position is closed enough to create a slight vacuum (usually about -3 to -6 InHG). As soon as you go full throttle, or open the throttle abruptly, and vacuum in the manifold is lost, the secondaries will pop open. This might be fine at high RPMs, but at low RPMs where it is better to have the plate closed, we lose all of the torque advantage that this system was designed to create.

My personal opinion is this: Honda spent a lot of time and R & D on this system, to make it work best for the engine. You can't really feel them open except under very limited circumstances, so I doubt their motivation for picking 4800 RPM was based on "marketing", like most of their DOHC VTEC changeover points (they wanted people to "feel" VTEC so they would be willing to spend the $$). In my mind, this seems to be the only logical way to operate the system.

I seemed to get better gas mileage and feel that the car is more responsive with the system hooked up. I had some GTECH results that bore this out, and my ability to keep up with other moving traffic seemed to substantiate it as well. GTECH isn't the most accurate way to do things, but it is precise if you know how to use it, in that the results are repeatable.

Fizzbob disagrees with me. There was a thread on it awhile back.

MRX says that they don't seem to make much of a difference on a BOOSTED motor.

Other than the above reason, there is no reason to use the A6 ECU and black box.

[accordaffair]

Nice work posting the info. I still get asked, "Why should I bother trying to find the IAB box?" And I've explained it at least 5 times, perhaps now I can just point to this thread instead. Knowing what they are there for, and knowing their value/worth is important, whether you go with the full setup or the half-assed setup. Like Baz Luhrmann says, "Read the directions, even if you don't follow them." I won't try to press that its worthless without the IAB/ECU, to each their own.

[LinX]

Based off of the detailed response I got (and very nice write-up by the way), looks like I still gotta finish my homework on this setup. I can't afford to have the car crap out on me because of a half-ass installation and I do want the full potential of this upgrade. While some doubt the level of performance, I'm pretty sure it would help out the f22a1 by a nice degree (I'm not hoping for anything toooo big). The pt6 and the 'black box' are recommended though huh? If that's what needs to be done to keep the honda happy then that's what Ill most likely do. What is the specific name for this 'black box' though. Let's say I were to hit up a junkyard tomorrow and search for the parts I needed. What the heck would I be looking for / what parts would I be asking the guy for (everything I would need).

*note: Wed3k, did you do a full setup w/ black box and ecu?

[accordaffair]

I sincerely doubt the guy would know what it was if you asked him for it. But it is the IAB (Intake Air Bypass) box and control solenoid valve. More generically (word?) you could ask for the black box found on the bottom side of the intake manifold. Be sure to snatch up some hosing as well, unless you have extra lying around.

[crazygangsta301]

i wish i had done this when i put my h23 intake manifold on. i went ahead and swapped the whole thing and i ran into a bunch of dumb problems. woulda been a whole bunch easier just swappin the pleniums but at the time i just had to have the h23 runners too. totally not worth the trouble doing the whole swap.plenium and tb alone are good enough

[owequitit]

I sincerely doubt the guy would know what it was if you asked him for it. But it is the IAB (Intake Air Bypass) box and control solenoid valve. More generically (word?) you could ask for the black box found on the bottom side of the intake manifold. Be sure to snatch up some hosing as well, unless you have extra lying around.

If you do fab up your own vacuum line to set it up the OEM way, it is absolutely CRITICAL that you place a check valve (one way valve) in the line the runs to the nipple on the intake manifold. Otherwise, air will be allowed to flow into the vacuum box when the IM loses vacuum. You can use a check valve from the vacuum line that runs up to the vacuum box behind the headlight for the stock intake.

Make sure you can suck air through the line, but not blow it. That means the checkvalve has been installed properly. I will try to make a diagram, or take some pics.

If you don't hook the "black box" up, then it won't hurt anything, you just won't get the full benefit of the mod.

[LinX]

I understand what you mean by the mod will still work without the black box but this is a mini project that I've been thinkin about and I wanna do it 100%. Appreciate the awesome responses and level of knowledge from you guys.

Some advice for all: "Be sure to snatch up some hosing as well, unless you have extra lying around."
-accordaffair

[accordaffair]

I put a check valve in because I had one lying around from my IAC removal...don't know if it really helps but it didn't hurt. Does the stock IAB system incorporate one?

[owequitit]

I put a check valve in because I had one lying around from my IAC removal...don't know if it really helps but it didn't hurt. Does the stock IAB system incorporate one?

Yes, the stock setup has one in the line running up to the intake manifold from the black box.

A good way to double check is to rev it to about 4800 from the engine bay, while looking at the IAB pivot on the drivers side of the IM. Goose the throttle suddenly, if it pops open at very high rpm, but not before, it should be working correctly.

[wed3k]

Based off of the detailed response I got (and very nice write-up by the way), looks like I still gotta finish my homework on this setup. I can't afford to have the car crap out on me because of a half-ass installation and I do want the full potential of this upgrade. While some doubt the level of performance, I'm pretty sure it would help out the f22a1 by a nice degree (I'm not hoping for anything toooo big). The pt6 and the 'black box' are recommended though huh? If that's what needs to be done to keep the honda happy then that's what Ill most likely do. What is the specific name for this 'black box' though. Let's say I were to hit up a junkyard tomorrow and search for the parts I needed. What the heck would I be looking for / what parts would I be asking the guy for (everything I would need).

*note: Wed3k, did you do a full setup w/ black box and ecu?

nope, i just hooked the butterfly valve to the intake manifold. dont feel like getting the box hooked up, plus im going ITB's so im ditching the whole manifold anyways.

but i already installed an A6 ecu.

btw: im getting crappy gas mileage, does the computer still have to adjust?

[LinX]

ITB's huh, Haven't seen that on an accord. The crappy gas mileage is probably due to the ECU like you said. After installing my header it took half a tank for me to feel the overall effect. It could also be like mentioned before that the black box gives you that torque because of the vaccum effect and having to give the car more gas for the same amount of travel. Not 100% sure on this one though, just a thought.

[owequitit]

nope, i just hooked the butterfly valve to the intake manifold. dont feel like getting the box hooked up, plus im going ITB's so im ditching the whole manifold anyways.

but i already installed an A6 ecu.

btw: im getting crappy gas mileage, does the computer still have to adjust?

It isn't unreasonable for it to take a little while for the ECU to learn, I think mine took about 1/2-1 tank. The mileage wasn't super crappy, about 23MPG. My next tank went up to almost 28 though, and it has stayed there.

Also, not having the IABs hooked up, could explain a small portion, because in the presence of less torque, you have to accelerate longer (even if it is just a fraction of a second) to acheive the same speed. Since an accelerating throttle position is higher than a cruising position, you will burn more gas over the acceleration period (obviously), although I doubt that it would be the primary cause of you mileage issues. Maybe 1 or 2 MPG at the most.

You are probably just raping it all the time like me!

[wed3k]

yea, but i average 20mpg like all the time...hahaha

[owequitit]

yea, but i average 20mpg like all the time...hahaha

Perhaps it needs something else. I also live at higher altitude, so in the colder months I get better gas mileage than I do at low altitude and during the summer I typically get worse (density altitude issues).