Are there any core out there
 

Are there any 20B core out there. Any 4 rotor cores?

Are there?

4 Rotor cores are the 26B. I highly doubt you'll find a 26B core anywhere, and if you do it's going to be extremely expensive. I've seen 20B's on Ebay around the 4k range though, not sure if that's a working engine or just a good core.

In that range, most are JDM engines. There are some built 20Bs in the 20B sub-forum (way more than $4000). You can save yourself a lot of expense and work by buying my car.

http://www.cris.com/~Asam/20B.html