So I picked up a 91 TII long block and tranny. The motor has good compression, just came out for a V8 swap (was smoking so either turbo or oil control rings. I bought mainly for the price and thinking of using the tranny, maybe... Anyway I will have to put another motor together for my rx3 build and have 2 rew short blocks (blown) but usable parts out of both. Most likely enough to put a complete motor together and that has been my thinking until I picked up this motor. So what to do with this TII motor? Correct me if I am wrong, please...

The later TII irons were weaker around the dowel holes?
Ports are smaller?
Is the only parts I want to use are the housings and rotors?
Eshaft is the same except oil passage?


I will do a little searching around but thought someone could shed some light quicker on here for me.

Thanks..



I have torn apart many REW's but never any other rotary's.

 

91's have re-inforced upper dowel lands compared to S4's, however except for a rare handful, they are smaller/weaker than REW's. Secondary ports are significantly smaller than REW's, as well as runners, but I think the primary ports are a bit larger. Rotors are the same as REW's, housings are interchangeable, but don't have the same coating or something as the 3rd Gen's. But, it's all relative. Marko from ForceFed in BC made over 800whp on an S5 motor with just clearanced rotors and a few dowels, half-bridge and a ****-ton of boost.

 

Thanks for the info.. But I was wrong.. Its a 87
TII motor not 91. I am thinking of using a set of REW irons but the complete rotating assemble and housings from this motor??

 

The S4, S5, and FD rotor housings all have a different chroming, the newer the better. The S4 has the 8.5:1 CR as opposed to the S5/FD 9.0:1. The rotors are also about a pound heavier each. Mazda also changed the timing between the T and L plugs in the housings, but Im not exactly sure as to what. The S4 irons are thinner around the rear dowel landing, the S5 is thicker, some S5s are reinforced, and the FDs are even thicker. If you want the lower CR, then you could run the S4 assm, but if you can salvage the lighter and higher FD rotors Id go for that.
The S4, S5 and FD stat gears also have different heat treatings/windowing. Use the FDs for that too.

 

Thanks for the info. Not sure if I like the idea of the plugs being moved.

 

Yeah, don't mix and match rotor housings between S4 and S5. Either or will do just fine, as long as they're the same. The S4 rotors might be a pound heavier, but they are also more resistant to denting from detonation, and heavier rotors can actually be better for drag racing.

One big difference is the S4 rotors have cast pockets, where the S5/REW are all machined I think. Also, the front upper dowel is prone to cracking on the S4's as well, under detonation or whatever.

Personally, I'm going with a set of cosmo irons half-bridged likely, RX8 stat gears, S4 rotating assembly, and I'm gonna dowel it. I think it's a pretty good setup. The same would go for the REW irons, I would've used them but it'd be a bigger PITA to mount them in an FC than the cosmo.

 

Thanks Trots. So my plan is looking like I will use the s4 rotating assemble with rew irons. Have to do some research on the front motor mounts.