I asked j9fd3s and he said the 20B essentially has FC rotors is it, so the '86-'92 (N326) side springs would be fine. They're cheaper than the FD springs too.

Then as I looked around at more part numbers I noticed that a lot of the 20B-specific stuff was NF01 and most of the FC stuff was N326.

We know the 20B came out between the FC and FD production runs, and part numbers have a way of showing which engine they came out with. If the NF01 springs came out with the 20B, and were let's say 'good enough' for use in the FD, wouldn't it be a downgrade to use the FC springs in a 20B?

I'm NA for now but may want to explore boost in the future.

 

Well the same side seal spring is used in both NA and turbo II 86-91 Rx7. Don't see why it couldn't be also used in a 20b.

 

Thanks. Yeah, I'm sure it could be used with great success, and probably has been in high HP 20Bs. I was just wondering whether I should use the springs with the NF01 part number mainly because it matches the part number of practically all things 20B.

Has anyone here used the N326 (FC) springs in their boosted 20B?

 

The NF01 springs are more heat resistant, and hold up better in turbo/ high heat stress. If you were to turbo any rotary, I would use these, even if the N326 work well on a stock 200hp, mazda choose the NF01 for 255hp. Seeing as the 20b uses FD rotors, FD stationary gears, and FD oil pump, I think it would be safe to say that is also what it came with from the factory.

 

Thanks.

FD rotors? I always thought they were S5 T2. Is there a difference? I thought the rotor faces of FD rotors were thinner and less strong than S5 rotors.

I've seen what happens when the side springs don't hold up very well. My friend and I installed a cheap rebuilt '86-'88 6 port engine into his REPU and supecharged it. It lasted for around a year and then suffered massive blowby. On cold mornings, he could take the oil cap off and a ton of steam would shoot out when he'd rev it.

 

The dish in the pre S6 rotors is cast into them and it is machined into the FD rotors to be more uniform. If you look at the FC rotors the dished part is rough from the sand casting and the FD rotor has smooth machining marks.

 

i just looked in the parts fische

the 20b uses s5 t2 rotors (n3y8-11-b10), with the nf01 springs....

 

Slight correction, the Pre-S5 rotors are cast, S5 FC rotors have machined dish as well.

 

Now we know. Thank you Mike.