I brought this up once before but seemed to have opposition. But I thought I'd share some recent experiences when running under boost.

As the weather has gotten warmer an interesting point has developed. I was watching the boost gauge and it would jump 0.5 - 1.0 PSI when the IMRC opened (right around 4k revs). Normally I would consider less boost to be better because it means the engine is using the supplied air well. But if I am not mistaken, it pulls harder when the boost goes up. This is the opposite of what I would think as the amount of air flow has not (and cannot) changed through the blower and higher boost would indicate less air being used.

Might disconnecting the IMRC or removing the plates make more overall power? I suspect that an engine designed for good NA duty might not be the best for boosted duty. It might need some additional tuning. I think I might drive for a day with the IMRC disconnected and then for a day with the plates removed. Of course all will be verified on the rollers but we have to start somewhere.

 

Um... yeah...

I wish i knew as much about this stuff as you. I say give it a try, but i know nothing.

 

Heck, this one is easy to test. I might just pull the plates tomorrow and drive for the rest of the week like this.

 

i was thinking the hemholtz effect at work...it's creating the small super charging effect 1 p.s.i. in your system, so the two combined are making more boost more power...i would think by removing the plate s/c'd you'd e doing the same thing as tried N/A lose low end

 

But without vacuum the air/spring effect changes. Under boost all things which might work NA become moot in many cases. Eric brought up an article which covered this before and made sense.

Regardless, it does hurt to test....

 

very curious scalbert let me know.also im getting the lightweight flywheel put in tuesday am how much would it help in the 1/4 mile?scalbert

 

All of that neato gee whiz stuff about the IMRC etc in the intake is more or less useless in a car that uses forced induction .All of that stuff was designed to maximize airflow in a NA engine and increase power output at all possible ranges .The blower more or less makes the IMRC and associated equipment useless .ANother thing to remember is that the vtec gear is also negated to some degree .Since the boost comes on at a lower point than the VTEC engages you could in theory lower the engagement point for VTEC richen the mixture to the same point where the blower kicks in and expect more power since all VTEC really does is increase the lift on the valves .This way with a larger lift you have more airflow possible hence more power .this is one of those times when the APEX,i VTEC controller might actually be worth more than the pretty light show it puts on .Jens

 

so what your saying yens is your going to install the apex on my car? lol

 

ummmmmmmmmmmmmmmmmmm no

 

I agree, under boost the intended effects of the IMRC are lost as the blower is doing more than what the resonance could ever hope to achieve. I'm just curious why boost increases by about 1 PSI when it opens. My assumption is that the actual charge effect the IMRC is supposed to have has a slight impact even under boost. As previously mentioned, you would normally expect a slight drop in power if boost went up for no reason but that is not the case here.

The problem with using the VAFC on this application is the lack of fuel control. The VAFC adjusts the MAP signal to give more or less fuel. But in this case we are already clamping the MAP output voltage to a certain high limit. I guess the ECT signal could be altered to give more fuel too.

Jackson Racing has a less expensive unit to control the VTEC control:

http://www.jacksonracing.com/pages/hondapps/vpac.html

But in the end an RPM switch and two relays are all that is needed to control this. In my experience with our cars the VTEC solenoid control signal is not as complicated as Honda and others make it out to be. Even without throttle (during coast down) the solenoid is still open above 4800 revs.

Hrmm, I already have the cold start valve in there, maybe a RPM switch and another relay might be put in place...