air pump ?
 

ok so iv been checking out the forums a lil more and reading and in a few threads iv seen ppl say keeping the air pump hooked in will increase power ? i thought i was the other way around?

fyi i have a 88 gxl with no cat.

This is a complicated issue.

On an S4, you have aux intake ports controlled by exhaust backpressure. Upgrading the exhaust (removing cats, for example) often means there is no longer enough backpressure to actuate them. Thus another method is needed, so often the air pump is removed. So if you pull the air pump off of an S4 with an upgraded exhaust, you will have to figure out some exotic way of actuating the ports. Without the aux ports working, you have about a 20HP loss above 4K.

On an S5, the aux ports as well as VDI is opened by the air pump. Removing the pump disables these systems and results in about a 40 HP loss above 4K.

Go to www.rotaryressurection.com there is a method on this webiste using a tach activated air compressor to open the ports, allowing you to make your exhaust as free flowing as you want and delete the air pump. I havent done this yet, I am still trying to learn more about it myself and locate the necessary parts.

Honestly, in most cases it is easier to just use the air pump. The power lost by turning the airpump is about 1HP.

ya i hooked my air pump back up and i can tell the difference.

Ah, no you can't. The butt dyno isn't sensitive enough to measure 1 HP.

On S4s you can take your air pump off it doesn't do anything other than make your car smell worse and give you about 1 HP. Which for some, is :awesome: