why a 94 bottom end over everything else?
 

oooook so I bought a 94' miata with the intentions of building the motor (m-tuned rods, 8.6:1 supertech's, etc.) I thought "cool I have the motor with the awesome bottom end". Well I pulled the motor this last weekend, and noticed that the VIN on the motor didn't match the VIN on the car. Turns out the engine is out of a 99'. So cool I have the motor with the awesome head haha.

I searched around and couldn't find the exact answer to my question.

Is the 94' bottom end THAT much better than the 99's? Or is it just lower compression, and the oil port on the side of the block?

Should I go out of my way to go find a 94 bottom end?

This. It's a moot point if you're replacing rods/pistons, any 1.8 will work for you.

Don't forget about the water port on the side of the block too.

derrr.... trying to delete post - now see OP knows about oil port.

Alright, I can work around the oil and water ports. I thought Mazda might have sprinkled magic fairy dust on the block/bottom end to make it stronger or something.

Sounds like good news to me, you got a nice upgrade assuming it came with the '99 head.

For a while, people thought the stock NB rods were weaker than NA rods, but that theory seems to have been discredited. Obviously this wouldn't matter anyway, since you're replacing them too.

--Ian

The pictures on google look like the head on my motor. Is there a way to tell if it's a 99' head for sure?

It will have BP4W cast into the back of the head.
https://www.miataturbo.net/attachmen...ine=1317780923

Awesome. I'll have to check when I get home in the morning! :D

Edit: looks like it is. Now who wants to sell me a bp4w exhaust cam? :)