kanuk93gt

i swapped my s4 intake to an s5 vdi and im getting a rb true dual system, should i get the s4 exhaust system and hook the s5 aux ports to the header or will this not work cause it won't make the proper pressure to open s5 ports and just get the s5 system so i don't have a leak where the auxport tube is?

thanks
Dennis

NZConvertible

You should operate the both the 6PI and VDI systems from air pump pressure switched by solenoid valves with rpm switches. Anything else is a waste of time.

Jaguarx7

Or if you're keeping the ACV and air pump you could run them off the air dump hose at the bottom of the ACV. I'm using this setup, and it's proven entirely reliable and quite easy to do.

kanuk93gt

i guess what ill do is either run the air pump or get an electric pump and run the rpm switches, but one question still remains. do i order an s5 exhaust or an s4?

wmelon137

you could always do something like this.
http://howto.globalvicinity.com/gv_w...i=46&co=1&vi=1

lupin

iTrader: (3)

so that uses a electronic solenoid?

the boost circuit doesn't actually create boost?

kanuk93gt

interesting, i might try that, good thing my dad is an electrical engineer, he may be able to help

NZConvertible

If you're using this crude method for the VDI then you're opening it way too early and missing out on a big chunck of mid-range. IIRC the ACV dumps at ~3500rpm; the VDI valve shouldn't be opened until ~5200rpm.

If you don't use exhaust backpressure to actuate the 6PI system, you don't need the pressure pick-up fitted to the S4 header, so get the cheaper S5 one.

Did you actually read it?

rwdburnout

could you just use a S5 harness and S5 ECU on the S4 motor when you do the intake manifold swap.....correct me if im worng but the signal to run the VDI comes from the S5 ECU am i right ....... im asking cause in another thread someone is useing the S4 ECU on a S5 motor

(In the stock S5, the VDI port is turned by a linear air actuator. The electrical system applies pressure to the actuator via a switched air solenoid. This system is not in the stock S4,)

Jaguarx7

NZ, my VDI isn't opening untill about 5000 rpm. As you'll recall, the VDI actuator takes more pressure to open than the 6PI actuator.

kanuk93gt

so there are no issues with putting an s5 exhaust on an s4 correct?