ericconn

Hi, my dad used to run a shop that worked on a lot of imports and I came across some Mazda rotors that are NOS still in their original packaging. I can't find a part manual anywhere and searching online hasn't turned up anything. I'd like to eventually sell them to someone who needs them and not just scrap them. Part number for one is: 2090-23-113B. Other one is probably the same part. Thanks a lot for any help!

flacorotary

prob a race rotor. has double side seals

kinglumber

I'd guess 13B rotors from an FC from the LOC and Part NO. on the third pic. I think I'm seeing S5 as well on the other sticker under where it says parts return. If so, your looking at '89-'91.

blandry23

it says FC 13b on the side of the box. they're 13b rotors. so yea, i agree with kinglumber.

mazdaspeed7

They are race rotors of some sort. They are lightened and have double side seals. None of the production 13b or 12a engines had double side seals

ericconn

So from another forum I have this posting on, someone thinks they're from an RX-3, but didn't the RX-3 have a 12B and not a 13B? Is the FC13B on the box reliable that these are for a 13B?

mazdaspeed7

Not necessarily. The FC3 code is a chassis code for the 2nd gen. 13B is the engine code, but neither are generally linked with part numbers. Part numbers have a different code denoting year range such as N3A1 for FD, or N370 for S5 TII, N350 for S5 n/a, and so on.

The RX3 and some of the other early cars came with 13b's. It may be one of those, and I have heard of some very early engines having the double side seals. I havent had any luck finding more info online though.

Have you measured the rotors to verify their dimensions? The thickness of the rotor can help determine its origins, as well as the width of the apex seal groove.

ericconn

They're about 69-70mm thick. Could they be 12A rotors?

http://en.wikipedia.org/wiki/Mazda_Wankel_engine#12A

blandry23

12a's had 70mm wide rotors according to this website

http://www.mazdarotary.net/technical.htm

there is a chart at the bottom that has all the info.

blandry23

sorry boss, didn't see your link but yea measuring the rotor width woulda been the easiest way to figure it out. good call from mazdaspeed7 to do the basics and actually measure it. the box could have originally been for 13b rotors, they might have just switched the boxes.