2nd Generation Specific 1986-1992 Discussion

Air Pump Removal?

Old 12-03-2010, 07:54 PM
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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?
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Old 12-03-2010, 08:18 PM
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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



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Old 12-03-2010, 09:05 PM
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Originally Posted by Justen View Post
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
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Old 12-04-2010, 12:58 AM
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Originally Posted by RX-7racer View Post
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.
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Old 12-04-2010, 09:32 AM
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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
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Old 12-04-2010, 12:54 PM
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Originally Posted by RX7 13B 4 UR AZZ View Post
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.
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Old 12-04-2010, 04:37 PM
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Originally Posted by Justen View Post
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
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Old 12-04-2010, 04:53 PM
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Originally Posted by RX-7racer View Post
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.
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Old 12-04-2010, 05:06 PM
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Originally Posted by Justen View Post
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?
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Old 12-04-2010, 06:42 PM
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Originally Posted by RX-7racer View Post
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
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