Hey everyone, I have two motors, both S4 turbo. One i pulled from my car(bad coolant seals), the other is a Japanese motor I got from Brian(Japan2LA).

The "newer" motor is just about ready to go in, I swapped all the good stuff from the bad motor, the only thing left is to get the flywheel resurfaced and put the new clutch on.

Looking at both my motors, I noticed they have different flywheels and thought that was strange since they are both S4 turbo motors, and I was just looking for a little insight on this. Also, I know I probably can't swap those because of the balance issue, even though the older one looks to be in better condition.

Old motor





Newer motor

 

Well, i did a little more searching and found an old post with a link the the mazdatrix site with flywheel pictures and my S4 motor has an S5 turbo flywheel. I don't think my motor is an S5 motor with an S4 front cover, does anyone have any suggestions?

 

Just to verify the engine series, where is the knock sensor located? Also check the distance between the leading and trailing plugs as the distance is different between S4 and S5.

 

should i check the distance on center or just the space between? also, my motor did come with the twin scroll turbo. I'll check everything and post back after work, thanks.

 

If you have the S4 motor there, just check to see if the plugs are the same distance in both.

 

I did, they are the same distance apart, knock sensor location is the same, and I forgot to mention, the JDM motor came with the manual OMP. I'm hoping I don't have to tear it all down to find out what's inside.

I contacted brian but haven't heard back from him yet, hopefully he gets back to me in the next few days, i know he's a busy guy. Right now I'm hoping one of two things, I can just put my other S4 flywheel on it and be done with it, or the S5 flywheel means I have S5 rotors and counterweights. I'd be fine with switching the flywheels, but I think it would be great having the extra compression ratio of the S5 rotors.

Thanks for the help so far Turbonut

 

Dont swap the flywheels, use the one that came on the motor. It was most likely overhauled in Japan and S5 rotors swaped in. I did not change it, they way I shipped is the way it came in from Japan.

I have a shelf full of S5 TII and FD flywheels already resurfaced.. Can send one to you for cheap...

 

Yup, leave on the flywheel that came with the motor. How bad is it that it needs to be resurfaced?

 

surface rust, i think i can get it resurfaced for about 30 dollars at my local machine shop

 

what makes them different? the holes on the side? arent those just for balancing? i believe they should have the ecu code stamped on them to verify the series (N318)

 

sounds like it is an s4 with s5 internals that is if the code on the flywheel matches up with a series 5

 

S5 TII and Na rotors are lighter and need either the N370 or FD N3A1 flywheel. Fd3s flywheel will work on and is a little bit of an upgrade ( lighter by about 2 or 3 pounds)

S4 TII and Na rotor are heavier and require the N318 ( Super heavy) flywheel.

 

I already checked the codes, and my old one is N318 and the new is N370. I would have taken pictures of the stamps, but It would have been hard to get a good shot of the N370 since that motor is already back together. I'm pretty happy it has the S5 internals since it has the lighter rotational mass and also, is that why the redline is higher on S5s?

 

Not on a TII, both S4/S5 rated at 6500RPM. N/A different story.

 

Gotcha. Thanks for all the help everyone.