rx_86

i was wondering if anyone knows if the air pump is needed and what it does?

Boosted11

iTrader: (11)

Not needed, nobody seems to have them anymore. Mine came without air pump when I bought it. The purpose of the air pump, is a good question I dont even know. I think it has something to do with emissions.

AGreen

iTrader: (11)

it actuates your auxiliary ports, but there are better ways of doing that. Use an rpm switch from summit racing and a vacuum solenoid valve.

shadoe

all it does ius pump air into your cat to make your emssions a cleaner mix after inspections it doesnt need to be there

YaNi

iTrader: (2)

If you run the cat w/o air injection you will kill it very quickly.

rx_86

so will the car run fine without it or do i need to do something with my cat?

texFCturboII

iTrader: (17)

wow, some bad info here!!! First off, is your car N/A or turbo? Is it a series 4 or series 5? It will run jsut fine without the air pump, yes. However, if your's is a series 4 N/A then you need the air pump, or some kind of air pump to activate your 5th and 6th ports. You don't need to do anything with the cat per say, but without the air pump it will eat that cat up pretty quick. maybe you could relocate it if you wanted to fab up some stuff, but otherwise just do like everyone else and get rid of it. lol.

Aaron Cake

iTrader: (1)

The answers to this thread hurt my brain...

If your car is:

S4 NA: Then you only need the air pump if you still have cats installed. Additionally if the exhaust has been modified on this car it's likely that your aux ports are not opening since they rely on exhaust backpressure.

S5 NA: You need to keep the pump to actuate the aux ports and VDI

S4 TII: Only if you have a cat.

S5 TII: Only if you have a cat.

7fold

well, i have a s4 N/A. I am getting my LIM and UIM ported, also, i am getting the 5th and 6th ports removed so they will always be open. So, i may as well get rid of it right? i will be running no cats as well.

classicauto

iTrader: (3)

Sure.

Provided you don't need to e-test the car also.

Aaron Cake

iTrader: (1)

Useless.

Fix them so they work properly and the car will be faster.

Saavedro88

iTrader: (1)

I knew A.C. would be in here eventually!!

And A.C., not to call you out or anything, but I think you meant to put S5 up there where you put the second "S4 NA"...

Any chance you could elaborate for us what LIM, UIM, VDI, and Aux ports are for? Just so it's all clear in this thread, as there seems to be a lot of questions about the functions of the air pump...

7fold

i dont see why porting all of those would not lead to more power?

SpeedOfLife

iTrader: (16)

Because the UIM and LIM are not particularly inefficient. The actual ports in the motor and the throttle body are where it's at.

Dr-Zine

iTrader: (1)

Just to be clear about the OP's question.

If you plan to keep a working cat you NEED the air pump. Without the air pump the cat will burn up, clog up, crack up, and finaly rust away into nothing. The air pump does exactly what it is called it pumps fresh air into the exhaust to make the cat work correctly. Running with a clogged/dead cat will kill off alot of your engine power.

Your posting name is rx 86. So I asume you have a '86.... If its a NA or Turbo and you dont run a cat you dont need the air pump.

If it is a NA without a cat, you need to find a way to run your AUX ports. The air pump can be used to run them, or you can rig up an electric pump/rpm switch.

7fold

having said that, whats the best way to do that? what would be the ideal rmp to open the aux ports?

Aaron Cake

iTrader: (1)

This is all covered in the training manual (see links in FAQ) and the FSM (links in FAQ).

LIM = Lower intake manifold
UIM = Upper intake manifold

Aux ports are sort of like "Vtek". A secondary set of intake ports sit above the secondary intake ports on the end housings (got it? ). At about 3800 RPM under load these open up giving the intake ports much more duration. Air velocity is high at this point and keeps filling the chamber (even a little bit into compression).

VDI is a secondary set of intake runners that S5s use. Long runners are used below 5K or so (I forget the exact number) and then a shorter set of runners is switched in above that RPM.

Because the bottleneck is not the intake manifolds. You may gain a tiny amount, but it will be within the margin of error on any dyno so it's not worth the trouble unless you already have everything apart.

You will find writeups in the FAQ and Archives. Ideal point on a stock car is 3800 RPM.