I know I can use a N326 ECU to control spark with a carb for fuel., But what is the spark limit of the N326 ECU? I've heard 7800 rpm. Is that spark or fuel cut? Thanks guys...

 

Well since you have a Carb now..it wouldn't be fuel cut..
The ECU would no longer control the Pressure to the Carb or the actual amount of fuel now to the engine.

 

I'm getting ready to go carb. I am trying to find out if a S4 N/A N326 ecu has a limiter? If so, would it be a fuel or spark cut? Can I use this ECU for 9-9500 rpm?

 

I don't believe any fc ecu has a RPM cutoff

 

They do have a rev limiter in the form of a fuel cut. OEMs always cut fuel because this is catalyst friendly. (Nowadays they also cut the throttle plates shut, which sounds very odd, like a rev limiter bounce being played in reverse)

I don't know what the ignition would do if it runs "off the map" though.

 

An S5 ecu can rev to 9 without issues.
S4 I doubt you can. I think it fuel cuts at 8 and wont rev past that.

 

The majority of car makers cut injector cycle, but ignition stays sparking.

My guess is you will be fine.