I have an a-spec s4 turbo housing and a j-spec s4 turbo housing. When I checked the locations of the spark plugs, the j-spec housing was the same as an a-spec s5 housing. WTH? I know for certain that it is an s4 housing - I pulled the engine apart myself, plus there is no knock sensor mount on the housing, while s5's have the knock sensor mounted on the rotor housing.

Is there any difference between j-spec and a-spec housings? Is there some alternate casting I have never heard of? What is going on? I'm trying to sell these (in fact I already sold one, and he was the one who alerted me to it) so I need to know whats going on.

Thanks in advance!

 

did you measure?

 

I did hear of some late model j-spec s4 engines having various bits of their castings match the s5. The rear iron coolant probe thread, the oil pedestal casting thickness, and the casting of the lump where the knock sensor screws into. I think I may remember hearing something about the plug timing too. My engine is j-spec so I should be on top of this one...

 

I measured the distances, which is how I verified it. The s4 j-spec housing I have has the same spark plug measurements as my s5 housings. That's just weird about them changing the castings.

 

ive got an s4 jspec block that is the same way

 

Good to know. Its just surprising that there's no other info on this, at least that I can find, yet it obviously exists. Well, hopefully this will help people out in the future.

The next problem is that I am now using A-spec s4 housings on my new engine, so will my front pulley be off? I'll have to look into it to make sure I'm ok. Worst case is I'll have to pull out one of my 3 or 4 s4 pulley's I have laying around.