So I assume the coolant hoses on the BAC have a purpose... Does it regulate how much the idle is adjusted by the computer between cold and warm engine temperature? That being said, if one were to remove the coolant hoses from the BAC and say, loop them together... would the duty cycle increase when the engine is warmed up? Meaning loads from AC, lights, steering input etc would demand more air from the valve?

 

On the NA engine (and I assume, the turbo, but can't say for sure), the coolant flow through (actually over the BAC simply stabilizes the valve from extremes of ambient temp- it has nothing whatsoever to do with the operational parameters of the valve itself.
That setup is very reminiscent of the earliest, and cheesiest, PC heatsinks and is basically useless.
It can easily be bypassed or discarded altogether with no ill effects. My NA has had that entire coolant loop- including the thermowax- completely removed for several years now.

 

I was just curious if it had any mechanical purpose, or if it was about as useful as the AWS and sub-zero systems... My SA has the BAC removed, but just purely for simplification due to no AC and no PS. I like the fast idle on a cold engine though so have never worried about removing the thermowax or fast idle cam on any 13b EGI I have ever owned. However, I do always remove the secondary butterfly plates and vacuum parts associated with them to simplify things.

I have just noticed that with loads on, particularly AC, with FCs the BAC seems less effective after the engine is fully warmed. It could mean that the idle stop screw needs to be turned 1/2 - 1 turn inwards to increase primary throttle clearance. Or it could just be because mine all have Racing Beat flywheels...

 

i think the coolant mostly goes through the BAC valve to keep the hose routing tidy. the BAC freezing/running hot is a thing, but its pretty insignificant.

 

If the coolant actually went through the valve body, it might (emphasis on "might") have an effect...but it goes over the top exterior of the valve and cannot do much of anything.
If one wanted to keep the stock setup and give it a snowball's chance of achieving any effect at all, you'd have to remove the valve and the aluminum passthrough tube and lap them together.
Reassemble with thermal paste (recall that I compared this to a very early PC CPU/heatsink arrangement) and check the contact patch.

I still think it'd be useless but that would be as good as it's going to get.