I was told that the b18a tb will fit on the d16y8 intake. I just want to make sure, is this correct?

 

yes

 

all the studs?

 

bolt pattern is the same

 

Is the transition still smooth? no porting or anything needed?

 

No, the bore on the b18 tb is larger, so you will have to port match the opening of the intake manifold. I want to say that the b18 is 60mm and the d16 opening is 56mm, but I may be wrong. I just put an h22 tb (62mm) on my z6 IM, and it took probably an hour, maybe a little less, with a dremel. It would go a lot faster with a grinder or a dremel with a bit that was made for aluminum (mine was not)

 

h22=60mm
b18a=58
b18b=60

 

thanks chris. are those diameters at the plate or at the opening? Cuz i swear the tb i just put on had a 62mm opening

 

plate sir