how much HP can i expect to gain from removing the air pump from my 88 GXL? and would the cat need to be removed along with the air pump?

 

You'll actually lose power buy taking out the air-pump on an N/A... the air-pump not only prevents your cat from destroying itself, but it also opens your 5th and 6th intake ports at higher rpms. without a functioning air pump you wont open... these ports, thus loosing a lot of top end power.



YOU COULD use and electric air pump activated at a specific rpm to open them, its been done before... But doing this isnt really worth the 2hp you might gain from taking 1 belt off the crank pulley. If you had a 4-port N/A motor, this wouldnt be a problem and you could just take the pump and cat out...not legally of course

 

wasnt the 13b in 88 a 4 port? and i live in Michigan, and theres no emissions testing here, soo anything goes

 

I'm pretty sure only 86' models had 4-port N/A 13Bs, and that everything after that was 6-port... But I could be mistaken.

I mean you could just check: Follow the hoses back and see where they go...



1) If you have two hoses (one of which runs towards the intake manifold) then you have a 6-port... in which case you NEED the air pump for auxiliary port actuation and for the cat.



2) If you have one hose running to the split-air pipe for the cat, then you have a 4-port... in which case you only need the air pump for the cat. So if you take the cat out, Theres really no need for the air pump.

 

no 86 n/a's have 6 port engines. i have a 86 sport that has a build date 09/85 and originally had 6 port 13b

 

Thanks for clarifying



Rx-7Racer... you have a 6 port, so you're gonna need to keep that air pump functioning.

 

soo whats the difference between the 86-88 6 ports and 89-91 6 ports? why are the 86-88's listed at146HP and the 89-91 listed at 160HP

 

There may be a few subtle differences that probably just gave it a few more horses...

Like the Lower Intake Manifold on the s5 is a little more responsive, s4's have mechanical OMPs while s5's have electric ones, s5's have a higher rev limit i think, minor stuff like that. There are more differences though, those are just some examples.

 

soo what kinda HP increases would i see from just adding a RB header and removing the cat and running a straight pipe to the Y-pipe?

 

Probably somewhere in the 5-10hp range