OK...I've searched and read through countless threads. I think I'm getting it but I do need some clarification/advice/more clarification.
History:
I've put a '91 13b into an '86. I'm down to a few things before I start it up for the first time. The 91 13b didn't have the airpump but otherwise there's no indication of it being removed by the previous owner. There's no double belt pulley on the alt. and the ACV is intact. I didn't want to transfer the 86 air pump to the 91 motor so I am leaving it off and have now removed and blocked off the acv.
From what I've read here, the airpump removal and the acv removal are separate issues. Removing the pump doesn't mean, necessarily, that you have to remove the acv.
Question(s):
1. Comments on the above?
2. Does the acv activate the aux ports?
3. I have a racing beat header and presilencer with factory behind it. (I know it will be loud, but my son is 19 so who cares...). The RB presilencer has the air injection port on it but a friend of mine says that I can just plumb that to activate the aux. port. Any comments from the experts here? If true, how?
4. What else do I have to do now that the acv is removed? (i.e. vacuum hose routing/plugging etc.)
5. Thanks!

 

Can someone answer three questions?

1. On an S5, do I absolutely have to have an air pump to activate the VDI and aux ports?
2. If so, can I use an air pump off of an S4?
3. If not, what is the easiest, cheapest, most reliable way to open the VDI and the aux. ports at the right time?

Thanks.

(I only ask because I've spent the better part of three hours searching and reading when I should have been working on my sons car)

 

??

 

OK....let's make this even easier.

Can I activate the the VDI and the aux ports by plumbing the Racing Beat presilencer port to the hoses going to each? Will the exhaust create enough pressure at the time the solenoids open?

Thanks.

 

On S5 13B the aux. port actutators are different than the S4 - they were (obviously) designed to be operated by the air pressure from the air pump, not exhaust backpressure - I don't remember the test specs from the two service manuals, but I think a slightly higher pressure was needed to operate the S5's.
Using exhaust backpressure from a RB header / exhaust is just a stab in the dark as far as I can see - you don't know whether they will open or at what rpm.
VDI requires air pressure as well, and at a higher rpm than the aux. ports.
Both these systems were designed to accentuate airflow harmonics in the intake tract. Opening either one early or late just creates boggy flat spots in the powerband.
My advice - put an airpump on, or get an electric one. S4 one should fit fine. Only difference between the S4 & S5 ACV is that there is a small nipple on the air intake pipe of the S5 one to supply pressurized air to the VDI & aux. port solenoids. I don't understand why people remove the ACV - it doesn't 'hinder' performance in any way.

https://www.rx7club.com/2nd-gen-archive-72/how-diy-rpm-switch-6th-ports-vdi-233381/

PS. You have a ECU controlled oil metering pump on that S5 - did you swap over to an S4 OMP and S4 throttle body & linkage?

 

Thanks for the reply.
It is my understanding that, on the S5, the pressure from the air pump has nothing to do with the timing of the actuation of either the VDI or the aux ports. The timing comes from the ECU and the solenoids. Kinda like the water in your house. The water pressure is always there (air pump) and you turn on the faucet (solenoids) to get flow. Am I way off base here?
Thanks for the link, not interested in that...
To answer your question...no.

Anyway...I'm inclined to re-install the ACV and mount the S4 air pump. Just want to make sure that there isn't another way, other than in your link, before I go through the trouble.

I'd have to look at the schematics again, but it sure did seem to me that, on the S5, the VDI and the aux ports are vacuum operated, not pressure operated, and through the ACV not the air pump. The reason I say that is because there is only one small connectiion to that mess of metal and rubber hose rack and it comes from the ACV. And it sure looks like a one way port going INTO the motor on the back of the ACV, which, I would think, pulls air through the ACV thus creating vacuum.
Anyway, just thinking outloud before I check it out again.

 

I have found another source for answers and information.

Thanks.

Mike