I've been doing some researching on secondary butterflies and i've come to find out that what causes them to open is the engine creating enough vacuum and WOT which pushes on a diaphram which opens the secondaries.
Now, here is my question/theory.


If you are running boost and (for arguments sake) a GE vacuum manifold, would it be possible to run one nipple from the VM to the diaphram? Then, if you are running say 15psi, put a boost solenoid (i think that's what you'd use) inline between the vacuum manifold and the IAB diaphram that would open it at a specified psi? In turn, wouldn't that give you more air above that set psi?
Thanks in advance for any help clarifying this.

 

The ECU controls a solenoid valve to open/close the secondaries, they're not simply driven by manifold vacuum.

There's a vacuum reservoir bottle under the IM (at least in my '95 GSR). That bottle stores vacuum so the ECU can operate the IAB butterflies even when the manifold doesn't have vacuum.

 

would there be any way to make work what i was tryin to say?

maybe w/ a custom tune?

 

You are putting way too much thought into something that doesn't really deserve it.

IF you had a boosted setup, you would make more power with a manifold that has a larger plenum and shorter, thicker runners than you ever would with a stock manifold with the IAB's rigged up like you are thinking.

 

That manifold really isn't worth your time or effort.

 

The butterfly valve is crap for anything but a stock, or I/H/E only cars...modification beyond this point doesn't really benefit from 'switching between short/long intake runners'

It's an innovative idea, but it's used with much more practicality / performance benefit in the newer K series engines...

 

The b18c1 intake manifold has a dual runner/ dual chamber system.
The butterflies block big fat air until needed. Then both air streams meet in a small deep chamber particular to each runner. This air meeting occurs before the air is drawn down the tube towards the injectors.
I am speculating that the long runner air flow sits on top of the fat short air flow as they meet in the 2nd small chamber and proceed to the injectors. Now, I have reason to believe the big fat air is squeezed toward the injector by the pressure of the "long" air stream joining and traveling on top. Remember the long runners are always open. I see a venturi effect amplifying the fat runner air delivery.
The small channell chambers will also effect reversion waves within the runners. It will absorb the wave prior to going back up to the main intake chamber. Like capacitors absorbing certain electronic frequencies. When the bounce wave hits the small chamber the air slows quickly. This makes it easier for the incoming wave to proceed toward the valves.
Of course....I have no idea what I am saying, that is why I am free to speculate.

 

While the stock manifold will find its limits in a boosted application, tuning the IAB for maximum performance has its advantages. Honda was on to something when they designed it. While larger runners would help a high horspepower application, one could have their IAB machined for larger butterflies to be installed. I do think, however, they are much more suited to NA builds.

 

Not to mention all the other things the K series engines have going for them-programable cam timing---me wantee-

The IAB is a good idea, and I'm not saying that it's TOTALY useless, but when put together with i-vtec, cam timing, and the few other particulars that come in a K series, the IAB is able to realize it's full potential as a practical invention-

It helps the GSR b-series, don't get me wrong, but doing anything other than a mild N/A build, it just gets in the way...

or, you could have the GSR manifold totaly re-worked, re-sized for larger butterflies, and built for high IM pressure ( boost )

www.attituderacing.com

go to customer cars

1st listing-
Alexs' turbo 92 civic

He has a reworked GSR manifold...you DON'T want to know how much it costs to have this done...

more than the cost of a Full-Race IM--If you know what Full-Race is, you know what kind of $$$ we're talking here...

lets just say it's enough to justify NOT doing it...