I'm gathering parts for the rebuild of my S5 13B turbo (JDM). I'm having trouble getting a used front housing, but I can get an FD. It's my understanding that FD has no coolant port above the exhaust port and it also has grooves on the feet to help with sealing. Other than those two things they are the same? Spark plugs are identical? Still have opening for MOP fitting? What about knock sensor?



My LIM only has coolant port to match the rear housing, the front is sealed on the LIM. If all this is true then I can use the FD as my front housing, keep my FC for the rear and I'm good to go?



This just popped in my head. N/A housings aren't machined with knock sensor threads, but other than that are identical to turbo? So in theory I can also use an FC housing on the rear?

I am using FD housings in my S5 engine, they are the same except for the differences you said. As for NA housings, they will work also.

What about knock sensor threading on FD housings?

Ive had a bunch of n/a housings with the casting for the knock sensor, and I believe all of them were already tapped. It doesnt seem to be a n/a or turbo thing, it seems to be about production runs, and using whats available for the n/a motors.