95RedM

So I just dropped off my VVT engine at the machine shop and the crank is most likely bad. I have an NA engine that I can grab a crank out of that I know is good, but a somewhat local miata expert says that the VVT crankshafts are different than The others due to a larger thrust bearing, and because of that I can’t put my NA crankshaft into my VVT block. Can someone give me a definite answer because literally every comment online says that they’re all interchangeable but this guy who builds and specializes in BP engines for 20 years says that’s not the case. He said you can put a VVT crank in any miata engine but an NA crank cannot go into a VVT engine.

Dr.Sep

I can't answer that for sure -- but I do know there might be something to that, because you DO need to specify which year-range when ordering the thrust bearing so I would assume there is some difference; unless its on the carrier side that the difference exists. Following just for my own knowledge

SpartanSV

The thrust bearings are different but the block is what is machined differently. I used a NA8 crank in a vvt block with vvt thrust bearings for my engine.

95RedM

You personally used an NA8 crank in a VVT block with VVT thrust bearings? And it ran just fine? Got any pics?

SpartanSV

About 20k miles. 20+ psi.

As you've found, there are plenty of threads stating they are interchangeable. I have interchanged them and had no issues.

Your miata expert isn't much of an expert.

95RedM

Yeah I guess he was wrong. Thanks for letting me know