The guy I'm buying from says I should use a msd rmp activated switch with rpm selector switch (instead of changing the plugs). I'm a newbie and I would like to know what this does.

 

WTF are you talking about??????????????

Using the RPM switch to operate the VDI??? or the 6-ports???????? what????

 

The RPM switch is used to activate the VDI when the engine speed has reached the appropriate RPM (and I always forget what RPM this is...it's in the Factory Service Manual).

 

OK... Now i see where we're going here...

you may need TWO RPM switches.. Here's why

1) VDI is RPM based.. need one for that because your s4 ECU doesn't have that capability..


2) 6-ports s-5 6-ports are RPM controlled VACUUM actuated... (s4 are non-controlled and exhaust backpressure activated) SO... if you got the COMPLETE s5 LIM with the 6-port actuators and the vac lines between them, all you have to do is tap into a vac source with a "T" fitting, run that line to a spare Vac solenoid (boneyard in the pocket part!!!) and then to the 6-ports nipple. you use the RPM switch to activate the Vac solenoid

***NOTE*** dependin on what vac solenoid you get, you may need to put a one way valve on it (green and white bubble thingy you'll see on some of the vac lines, has an arrow on it) so that it doesn't suck air when the switch is not engaged.

If you are opening the VDI and the 6-ports at the same time.. you can just use one RPM switch to run both, If you have to open them at different times, you'll need two switches

 

I have a question about that when would I need to have them open at different times?


p.s. You guys pwn

 

what if u were converting to s5 uim. only . and wanted to run the vdi off the air pump? whats a good way to do this.. also i want to run the 5 & 6 ports off the air pump alos, can both these be ran of the pump?


ps..
alot of people (knowledgable people) say that using the s5 lim will amke u loose power. port matching the s5 uim to your s4 lim will get the best results and make about a 12hp gain

 

I May have miss-spoken up there....

s5 6 ports are NOT vac actuated.. they are operated off the air pump... my mistake... Been dicking with FD's too much lately...

I don't know what the hell I was thinking about..

ANYWAY..... the principle is just the same.. the PROBLEM is a bit more complicated...

IF you want to open the VDI AND the 6-ports at the SAME time, you'll need two things.. you'll need the 6-port actuator solenoid from a s5 NA and a summit RPM switch. (you could use one of the other solenoids as well, but, you need one of the ones with an input, and output and the little plunger looking vent thing)

TEE the outlet of the Solenoid off and run it to the 6-ports and the VDI... Set the RPM switch to open at 3850.

NOW.. the pressure... If you've removed the ACV and the Air pump.. you COULD use an electric air pump from a late model camaro to supply your pressure to the solenoid. Some guys are doing this to operate s4 actuators when you have a free flow exhaust...

If you still have the air pump hooked up in stock form, you can stick a barb fitting into the outlet hose that goes to the ACV and use that to supply the pressure to the soleniod.

 

If you still have the ACV and air pump you can just stick a barb in the air dump hose at the bottom of the ACV, run hose to the VDI and 6PI, and not even need an RPM switch. The air dump hose has the right amount of pressure to open the ports at the right time, so there's really no need for all the extra stuff.

 

Im the guy he is lookign to buy them from. I was going to use the rpm switch with a small airpump to open the vdi and then use the s4 aux actuators to open the aux ports off the exhaust backpressure just like stock.

Incase anyone is interested (the poster) the msd part numbers are 8670 and 8950.

 

I can't pm you BklynRX7. I wanted to let you know that I'll be sending the money orders out monday. You might want to delete a few pms.