I've done searches on here and othe sites and have found nothing but conflicting info about the secondary butterflys in the KA24DE.
I've heard they are there for deceleration
I've heard for "swirling" the air to get better attomization.
I've heard they are there to lean the car out at highway speeds for better fuel economy.
So what are they REALLY there for?

I'm in the middle of doing a KA-T setup with a T25 and SAFC. Should I pull the butterflys out? What ups/downs are there? I drive this car every day and need drivability as much as performance.
I live somewhere where it is hot in the summer and drops below freezing in the winter.

Any imput would be great especially if someone has done this and has a good before and after compairison.

 

Hopefully this will answer your question with some simple answers.
First off SCV's are not needed for decel. So lets get that out the way right now. If you swap a 95 and above model year engine using a OBD1 ecu there will not be any complications with decel. 95+ engines do not use SCV's and are direct swappers after a few changes of bolt on parts (IAT,TB).........
OBD1 technology used swirl control valves strictly for swirl to mix under a rich mixture, also helped in lowering HC levels for smog. This would help to increase what is known as best mean torque and would increase engine VE and AE at lower RPM's (under 3000RPM) to make up for load. As far as increasing highway MPG, it will increase fuel economy while decreasing high end performance. Since butterfly's take up volumetric space within the runner it decreases optimal CFM, a basic killer for performance. To some extent it does work to lean out an ultra rich stock tune, it does help fuel economy, but over all in all reality an SAFC can be used to lean out a rich ecu tune and increase highend HP. An SAFC can also increase fuel economy just as well by leaning out at HI throttle as well as LOW throttle. Overall SCV's are not intended as a performance enhancer, really it was to increase a low end torque range that is well below 3000RPM, and that isn't the majority of the range used for racing applications.
IMO SCV's aren't needed.

 

ive been thinkin bout takin mine out but people have told me that its hard to start ur car when its cold!?

 

For the last time, S14 KAs dont have them and start up just fine. They suck, take tem out, lol.