i got a 01 gsr swapped civic and someone took the butterflies out before i got the engine what are the advantages of them?

 

the what...

 

the IABs. more commonly known as variable length runners, or variable geometry intake.

i found this link from a short search on google for "IAB honda." the guy did a few dyno runs with different intake and IAB combos.

my guess is that you'd be better off sourcing a "type-R" style intake than trying to reinstall the IABs. just a guess though..

 

The GSR IM is a dual runner design, at low rpms the secondary butterflies will be closed and air will take the longer track to reach the valves (this helps with low/mid range torque).
IIRC the GSR secondary butterflies will open @ 5700 rpm. This will provide air to the cylinders via the shorter runners. High rpm applications prefer shorter but larger diameter runners (ie type r, blox, skunk2 style IMs).

Without the secondary butterflies, you will notice a loss in torque on the low/mid range rpms. Do you notice a lag during the low/mid rpms & during the vtec engagment at 4400 rpm? You may have to up the vtec engagement point and tune the car for the higher rpms.

 

Well said Slay

using the IAB function or not is completely dependent on your setup and goals.

 

Few people will sell the IABs separate. Fortunately, the manifolds are fairly cheap. They go for about $50. I have an extra if you're interested.