Differences between 20B models?
 

As I understand, there were two 20B engines made - an early model and a later model.

Am I correct that the early model can be identified by the normal (silver) colored intake manifold, and the later model can be identified by the charcoal colored intake manifold?

Besides the eccentric shaft being stronger in the later model engine, what other improvements were made?

What year did the change take place?

Good question! I honestly can't remember any of the differences.
Evil Aviator probably knows a few of them.

now has a thread on this

mike

The 20B in the Series I JC Cosmo (90-92) had a silver manifold, while the 20B in the Series II JC Cosmo (93-95) had a black manifold.

I'm not aware of any significant changes in the two series of engines, and both had the same published performance numbers. Also, Mazda lists all 20B parts as "20B" or "20B-REW", and makes no reference to year or series number. Apparently, some of the first-run engines were not made as well, but they should have all been destroyed or modified by now.

Here is the thread previously mentioned:
https://www.rx7club.com/forum/showth...5&pagenumber=1

Thanks! I was just sitting here checking the thread every few hours for the past couple days waiting for your reply ;)

Oh geez, there's an easier way to do that. Whenever you reply to a message, there is an "Options:" menu below your reply screen where you type your message. Just click the box next to "Email Notification: emails sent to you whenever someone replies. Only registered users are eligible.", and you will get an email message so you don't need to waste your time checking the thread all the time.

what mazda usually does when they update something is to change the part number, and then the old number get superceded by the new. since our parts info is from the 97 catalog (but mazdacomp has a 90-91 book) they may or may not be updated.

mike