Efinity

iTrader: (6)

hey everyone, im getting everything together to do electric 5th and 6th ports ( i have the compressor and need to order the rpm switch), but my question is how do people control the vdi? please keep in mind that im not an expert (i just have an idea). i suppose you could have 2 compressors and 2 rpm switches (one for the vdi and one for ports), but i was wondering if its possible to just run 2 rpm switches, and have the compressor hooked up to both the ports and vdi. by doing this id need something that blocks the psi to the vdi until the 2nd rpm switch tells it to open. is there something that can block boost until it gets the signal to open from the rpm switch? i guess thats a solenoid (like i said im not an expert)...if anyone can help me so i only haveto run 1 compressor it'd be alot of help. thanks alot
russell

NZConvertible

Congratulations, you've just described the stock 6PI and VDI system. Go look at the vac schematics in the FSM (would've been a good first move) and you'll see exactly what you've described. The air pump feeds the 6PI and VDI actuators via ECU-switched solenoids. All you're doing is replacing one air pump for another and replacing the ECU with two rpm switches.

This begs the question, why are you removing one system and replacing it with another one that's esentially the same? Your system will have no advantage over the stock one.

Efinity

iTrader: (6)

i suppose the advantage would be that i remove the air pump, drag on the motor, and weight? also i can underdrive the alt by using a RB pulley the car came with (in a box somewhere. do you have a better idea on howto remove the air pump but retain the sleeves and the VDI?

Efinity

iTrader: (6)

unless im mistaken, do i not need to even worry about the VDI? i just am wanting to remove the air pump and have everything work fine. the car came with an air horn compressor for the job, and the RB dual pulley replacment. ive heard you can use a compressor off a cadillac, as seen here
http://www.fc3s.org/how_tos/electrical/6_ports.html
but he does not cover VDI at all, so im lost on howto make the car run like stock, just without the air pump. please help!
russell

NZConvertible

Gains from removing the air pump will be partially offset by the weight and drag on the motor (via the alternator) from the new compressor. Chances are the nett gain will be tiny and not even noticable.

You want to add electrical accesories and underdrive the alternator? Do you really think that's wise? You'll gain virtually nothing and you risk charging problems. If you remove the air pump you'll need a dual-belt alternator pulley, not an underdrive one. Without a second belt, the water pump will slip under load.

If you're determined to remove the belt-driven air pump and fit an electric compressor, leave the plumbing and solenoids for the 6PI and VDI as they are and simply connect the supply from the compressor up to them. The compressor should be fed from the battery via a fuse and relay, with the relay triggered by the 6PI solenoid (it turns on first).

Why would you not do it? Leaving it non-functional will make the car slower than it would be with it working.

That's because S4's don't have it.

Sorry to be a downer, but I've yet to see anybody prove there are any performance advantages to swapping the air pump for an electric compressor. I've seen plenty of people say they're doing it to "clean up the engine bay", then do a half-assed installation with hoses and wires running everywhere. Even if it's done well, you're not going to be gaining anything except another possible point of failure.

Efinity

iTrader: (6)

nz, ill have you know that i respect you, probably the most out of anyone ive talked to on this board. the pulley kit that came with the car is the RB dual pulley, and that pulley DOES underdrive 20%, if i like it or not. if the net gain isnt much, then i wont waste my time (and risk the car being unreliable) i wish i hadnt ordered the parts tonight off ebay HAHA, oh well.
i appriciate your input, and like i said, if you say the gains will be minimal, then i wont screw around with it. the car smogs with the air pump anyways (even with headers and a streetport as well!- i just put on my aftermarket cat!) any thoughts on just running the dual alt pulley that underdrives (i already have it) with just one belt for power's sake? thanks again!
russell

Syonyk

I can't add much that hasn't been covered, other than to say that the VAST majority of the electric 6th port actuation rigs are done for people with S4 motors, because the exhaust backpressure method isn't the most reliable thing on the planet. S5 motors already have what the S4 guys want to emulate.

The only reason I can see switching things up on the S5 is if you have a lot of mods (ported motor, intake, exhaust, etc), a lot of free dyno time, and want to fine tune the actuation points for a slightly better power band. I'm not sure you'd gain enough to make it worth the time, though.

-=Russ=-