How can I tell the difference between an S5 and S4 middle intake manifold for an NA car? I have two at home which are supposed to be S5 but they are not identical so I assume one is actually S4.

Both have the large, plastic rotating cylinder in the middle (VDI?) and both have identical holes and mounting patterns as best I can tell. But only one of them has the mounting spot for the cold start assist (the thing the sprays coolant into the engine in cold temps) and that one also has what look like freeze plugs on top of the runners. Other than that the two are identical. What's going on here?

The parts circled below are missing on the "s5" manifold I just got powdercoated. Sorry I don't have a picture of the black one from a different angle but you can see the missing freeze plugs at least



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Thise are both S5’s.
We don’t have much information on the european cars- these could easily be changes in the castings over the years, or one could be the more common north american spec.
Also a possibility: these cars are 30 years old. I always thought block off plates were tacky, so I would grind the bosses off and weld them and then grind flush.

 

both S5. the black manifold is California, it does not have that sub zero starting assist thing. the Federal/Canada manifold will have it.

its unusual for Mazda, but the S5 NA manifold has a couple of different castings, i have one with a freeze plug in it, and one without

 

Somewhat off topic but riddle me this. Why would they need freeze plugs in the intake manifold?

 

Theyre core plugs, used to plug the hole that was left during the sand casting process.

Also my Vert is a '91 49 states version and it was the same style intake as the black one, I suspect the casting process was changed later in production.

 

Thanks everyone, I guess I got the right one powdercoated afterall. That's one less thing I have to block off

 

oh, yeah, core plug/freeze plug.