S5 but has tube from cat ???
 

89 GXL. this looks like it has the air pump running my 5th and 6th actuators like an s5 should, but seeing my car on the lift today i noticed a tube from cat before y-pipe connecting to smog pump.

can somebody clear this up, am i just not understanding this right? air pump/smog pump confusion? can i remove this tubing when i install my rb street headers with presilencer?

really appreciate it! thanks

the pipe is there to supply fresh air to the cat or something like that.

ok, can i remove the pump, or will this disable my 5th and 6th ports?

If you still have a cat then no you can't remove the air pump or the line. With those items removed you will burn up the cat.

Also the 5th 6th ports will not work with out the air pump UNLESS you add another air pump (such as a fish aquarium one[1]) OR you connect the port actuators s4 style via a host from the exhaust[2].

Sources:
[1] http://www.rotaryresurrection.com/2n...actuation.html
[2] http://racingbeat.com/resultset.asp?PartNumber=16405 I remember the curly line being on the header before but if it works then it works.

i will be installing the rb header and presilencer, but the presilencer i ordered doesn't have the tube attached, i ordered the s5 one.

thanks for the suggestion, i might try the fish tank pump idea, but can i just cut the split air pipe going to the cat and just leave it venting to atmosphere if i don't want to reconnect it, but still want my ports to work?

connecting the ports via exhaust doesn't sound reliable, i hope to have very little back pressure with my new exhaust setup, so doesn't sound good

It's an S5, so the split air pipe has zip to do with the aux. ports. You can unplug it from the back of the LIM and leave everything else alone (no need to cut anything). There will only be the a small amount of air directed out of it from the air pump.

I wouldn't suggest removing the air pump, but if you do, you'll need to have a way to trigger an electric pump. If you leave it running all the time, it will burn up. The pump will also need to be set up to feed the VDI solenoid/actuator, as well as the 6PI system.

in other words, leave the pump alone and just remove the split air pipe?

I may have misunderstood your post. While I don't know exactly how much air is needed. I do know that leaving an aquarium air pump running constantly will not burn it up. The air pump my dad has is probably near 8 years old. The only time it's off is during power outages or tank cleaning. But I don't know if one or two little aquarium pump would work for the entire system.

Pumping a continuous flow against a few feet of water is much different than holding pressure in a pneumatic system. I think the system needs about 5PSI (not 100% on S5 though) so I would recommend a pressure relief valve to vent over 5PSI so that you don't deadhead the pump (that's what will burn it up). I have a system using an air horn compressor and RPM switch right now. Way too much air. Hadn't thought of fish tank pumps though.

what's the advantage of a fish pump over just leaving the stock air pump to work? i mean, it really can't be taking that much power...?

The stock air pump uses very little power, so the only real advantage of an electric pump is cleaning up the engine bay a little. And as pointed out Yeti, supplying continuous pressure in the hot environment of an engine bay is a great way to overheat a little fish tank pump.

Also, both the S4 and S5 actuators require about 2 psi to open the ports. The VDI valve requires about the same amount. Exact pressures are listed in the FSMs. The stock S5 setup uses the relief valve in the ACV to prevent excessive pressure build up, so a triggered relief or a permanent small vent would be the way to duplicate that. In reality you're talking about a lot of work for basically no gain over the stock S5 NA setup.

thanks for the detailed explanation. so i'll just remove the split air pipe and leave the 6PI system as is