Hello,

In particular, I was wondering why mazdatrix has different rotor housings for this engine. They have the Center or Rear as one part number and the Front as another. I thought that the engine mounts mounted to the rear; though, I have also heard that they are all the same.

While on this topic, does anybody know definitively the differences between noletter, A, B, C, or D with respect to the engine components. In particular, I'm interested in understanding specific differences in the rotor housings, side housing, e-shaft, and whatever else from version to version. I just acquired a series A motor and have read a few comments; though, I am still not clear. It seems that some think that the rotor or side housings are weaker do to less casting around the bolt holes. Which housings definitively have this problem? Would the oversize guru stud kit, cure these problems through clamping force.

Also, if I were to purchase new rotor housings through mazdatrix, which version would these be and what changes would still be necessary.

Lastly, I have read that the fd rotor housings are superior due to the exhaust port (I can swap these into the 20b housings). What about the location of the spark pllug? ...what impacts wrt timing...can they be overcome.

If I were to rebuild the engine, what other components should be upgraded to newer parts? ...fd bearings? ...fd thrust bearings? ...etc.

Thanks,

Gregory

 

...so this has me even more confused.

Why does Mazdatrix list different rotor housings for this engine?

 

The irons are different due to how the studs come together when the engine bolts up. You can use a FD front, mid and rear iron as replaceable irons, but you would have to machine the irons to match, which I did on the front iron. The big fat intermediate iron is a hefty $2500+.

The rotor housings are different P/N because they require specific exhaust sleeves for the Cosmo sequentials to build low end torque, also is stamped 20b on it. You can use a 13b housing, which I also did.

Someone correct me if I am wrong in any way or can add.

 

Hello,

Yes, I thought of the studs shortly after my message. I plan on guru studding things, so then I could just use the same housing for all. Is this correct? I can get a very good price on the front rotor housing for the 20b. Would this be an updated housing or would an fd housing be stronger?

Thanks,

Gregory

 

Did you mean the front ironhousing? Front rotor housings are the same as the rear rotor housings.

The 20b front iron can use the FD front iron if you are going to machine it with the GURU kit. That's exactly what I did. Your whole motor will need to be machined if your getting the oversized studs.

http://mazdatrix.com/b1.htm

http://mazdatrix.com/3rotor.htm

 

mazda makes different housings F and R (and center) because the air injection comes in thru only one side. in the FD the air injection air comes thru the center iron into the two rotor housings. they only drill one side of the rotor housings. if you care about air injection, you can drill the hole on the other side.

FD and Cosmo differ in the exhaust sleeve.

if you buy new parts you get the latest revision.

 

How can we with certitude make sure if it is a C or a D series ?

 

There is another issue you all left out about the Front rotor housing.. Think about the block bolts that go the opposite way thru the front sideplate/ front rotor housing into the thick center iron.. There is an oversized thru bolt.. front rotor housing will need the bore for this bolt enlarged.. Simple to do... on a mill....

 

Your motor should be stamped with a Letter and 3 numbers or just 3 numbers if it is a Pre A code motor.

 

Where those stamp should be on the Center, Rear and the Front Housing ?

 

yes and all of the sideplates too...

 

Sorry for the resurrection. but is there a chart, someplace, to decode housing stamps?

 

^ Are you asking about the series engine stamps? If so they are in numerical order.

000-999
A000-A999
B000-B999
C000-C999
D000-????


Yep there's only less than 5,000 20b's in existence!

You will see these numbers on each of the rotor housings (upper spark plug side) next to the MAZDA 20B. They are also on the irons a few inches up.


The F, C, R, housings isn't that important unless your running the engine in a 100% factory ecu controlled stock set up.

 

What about on 13Bs?

 

What is your question?