93+rotor housings vs 88
 

what are the exact differences? PLEASE post pics!

tia-

No pics!
But if you're speaking about the US turbo models then--
The most obvious difference would be the threaded hole for the knock sensor located directly above the trailing spark plug on the 93 rotor housings. The 89+ FC also had the same threaded hole!
On the 86 to 88 housings Mazda experimented by changing the location of the leading plugs for emission reasons. I don't exactly remember but they were either further apart or closer together on the 86 to 88 models.On the 89 to 93 housings they returned to the original position as the 85 and earlier housings.
On the 93 housings the water passage(hole) for the intake manifold were not machined(drilled) like those of the earlier models.
On the 93 housings if you looked into the water jacket next to the spark plug holes you would noticed that they were machined(thinned) for extra cooling around the spark plugs.
Also on the lower section of the housings close to where they would meet the oil pan and where you would normally apply some silicone to prevent leakage the 93 housings had a groove machined to hold the silicone in place.
All of the above apply to the turbo models as there are also some obvious differences with the non- turbo housings.

crispeed
87TII
9.20@150mph

Just to back up Crispeed on these points...

I have a 87 TII housing and a 93 housing (both of them rear housings) sitting on my kitchen table...

o The 93 has grooves cut in it on the sides of the "feet"

o The 93 has some metal machined out near the leading spark plug hole in the cooling passage

o The trailing plug holes are in the same place; however on the 87 housing, the leading plug is 5 mm higher up.

Regards,
Brian

87 TII
93 R1