Old Grey

I have noticed slight changes here and there, but I've been out of the rotary game for a while



Mazda cleaned out a lot of their old housings a while ago and it got dumped on the Sydney market by the pallet load and there was some odd ball ones in there eg no exhaust ports, RX8 before the car was released, I knew about them because there is a SAE paper on them. 3 spark plug ones from the motor sport division



Back in the 70s there was a 12A New Zealand housing that had no sleeves and it wasn't machined for a sleeve so it had a smaller port than a 12A with the sleeve taken out. The pros said it was special and sought after





Its' slowly coming back, I remember the 318 number, I had a bunch of housings(20) on the bench for storage and looked down the centre one day and noticed not all the spark plug holes lined up but I can't remember which ones and I think some exhausts were different

bumpstart

a bit late on the reply,, but this may be the aussie / jap info you are after

--- our s4 NA housing has the MFR spark locations

















s4 has just the spark plug holes with collars , nothing more

( these are all s4 housings in pic )

turbo ones, have a conventional exhaust baffle , conventional spark location , and are cast with "n318" onto the top

the 2nd housing in from left is an NA one

note the housing leg differences

and that the leading spark hole is actually different to others, and is in same location as factory PP housing :!:

- and the factory inserts the mezzanine exhaust baffle

( this NA housing also has a full sized font boss and doesn't have "N318" cast onto the top )



however i have yet to see an N318 with the full sized boss casting







s5 turbo and not have a threaded hole above the trailing plugs for revised knock sensor location

- and same spark plug locations , these are N370, s5 turbo

- and more usually, full sized font casting, evident in pics ( there is exceptions )









most visible on the red s4 housing, and not on those s5 ones next to it is the differences in casting on top of the housing

- here the s4 turbo housings have " N318 " bossed onto them









the leading spark hole on the N326/7 is actually different to others, and is in same location as factory PP housing :!:

( this NA housing also has a full sized font boss and doesn't have "N318" cast onto the top )