Bajazda

I got the banzai block off plate kit and put them both on. I just had questions on the coolant lines that run into the BAC. Can I just plug those? Or do I need to route them somehow. Also for the ACV, the 2 air hoses that are still in the bag should I just plug as well. I can take pictures if needed. I already plugged the tiny air hose from the ACV I’m talking about the 2 bigger hoses.

WondrousBread

For the BAC valve, the coolant line starts from a nipple on the rear iron, goes through the thermowax (for the cold start fast-idle function), through the BAC, and then to a nipple on the water pump housing.

If you want to retain the thermowax for the fast-idle function, keep the tube that runs from the rear iron nipple to the thermowax intact. Then run the tube that ran from the thermowax to the BAC straight to the nipple on the water pump housing. If you don't want to retain this function, you can remove all the hoses (get a container to catch the coolant first) and then just put a cap on the nipples on the iron and housing. Make sure to use a hose clamp on the cap to prevent leakage.

For the ACV, the hose comes from the air pump on the front to the ACV, then through the ACV it comes out going to the catalytic converter. The function of the ACV was to divert this air into the exhaust ports depending on engine speed.

If you still have the air pump and catalytic converter and wish to keep them functional, connect the tube from the air pump straight to the tube that goes to the catalytic converter. I haven't tested this myself, but can't see why it wouldn't work. If you want to remove them, you can remove the air pump and the catalytic converter and not worry about it (depending on local emissions laws). I ran with my catalytic converter installed but not receiving any air for awhile, and I didn't notice anything too unusual, but Mazda designed the system that way for a reason so I'll defer to their judgement and advise that you either keep them together or get rid of both (again, depending on local emissions laws).

This is where it becomes a bit of a rabbit-hole: Removing the air pump also requires a dual-pulley for the alternator with two belts. This is because the same belt that drove the air pump was also one of two belts that ran the water pump, the other belt being the alternator belt. Running with just one belt is inadvisable, since (again) Mazda designed that pulley to have two belts for a reason. Slippage could cause the water pump to not pump enough, causing overheating. Also, removing the catalytic converter means that the split-air tube doesn't run up to the car anymore. If you have a Series 4 car, the split-air tube provided the pressure to open the auxiliary ports, meaning you'll need to wire them open or find an alternative way of providing the pressure to open them. If you have a Series 5 car, the air pump provided the pressure to open the auxiliary ports, meaning you'll (again) need to wire them open or find an alternative way of providing the pressure to open them. If you have a Racing Beat exhaust, the new tube is provided for you on the header. If you wire the ports open, you'll lose low end torque below 4000 rpm.

lzy.boy

Sorry for highjacking, but i haven't been able to find the answer I've been looking for. the Auxiliary ports operated by the air pump and exhaust back pressure are only on the N/A motors right? both S4/S5 T2 motors don't have auxiliary ports? Are there any issues with deleting the air pump and cat? I've read something about afterburn?, Possible boost creep with less exhaust back pressure?

WondrousBread

Correct, S4/S5 T2 models don't have the auxiliary ports.

My understanding (and I'm going to provide the disclaimer that I don't own a T2) is that the stock wastegate opening isn't suitable for controlling boost once you unrestrict the exhaust. The S4 one I've seen is comically small, and the S5 one (with two openings) is slightly less comically small. The stock wastegate opening is only adequate given that the exhaust is doing some of the work restricting flow.

Once you install a free-er flowing exhaust, the extra flow that the turbo is generating will overcome the wastegate and begin to boost creep and eventually hit fuel cut. The cheap solution (bad, do not recommend) is to install a device that defeats the fuel cut. This is dangerous. The better solution is to port the wastegate. I can't say from experience whether that on it's own is enough, but I'll say that there is quite a bit of material you can remove from the wastegate runners to get more flow. Again, you'll need to do research beyond what I can tell you before proceeding with exhaust modifications. Someone else with more hands-on turbo experience may chime in.

As for afterburn, I'd say based on the loud popping noise and flames that come out of catless rotaries, there is definitely afterburn. Whether this is a problem depends on your personal opinion and local emissions laws.

EDIT: Oh, and the dual-pulley setup I mentioned above still applies for the T2. Removing the air pump means you should run a dual alternator pulley and two belts.

lzy.boy

Thanks for the info, appreciate it!