Anybody know the highest amount of hp and tq that a stock s5 n/a auto can handle? I'm not asking abot the motor just the transmission, axle, diff, etc.

 

thats a good question. some t2's in japan had autos. i dont know if the tranny was any different than ours, but i dont know.

 

i don't know of anyone even seriously attempting to make power on an automatic Rx-7. It's funny though... autos are much better for drag racing, but I guess they are just not suited for high revving rotary engines.

 

I've seen it reported on this forum that the part number for the auto tranny in a USpec N/A is the same as for a JSpec TII.

 

I have aways thought that it would be the coolest to do a turbo conversion on an automatic vert - I had planned to source a jspec auto transmission.

 

Yea well, im not shooting for crazy numbers, i just want to have a reliable yet fun daily driver, and im starting to look for more power in addition to my current mods on my 91 n/a auto and want to make sure that my transmission can safely support the added power. Also since you mentioned drag racing, does anybody know the best way to launch an auto? Just curious- not really planning on racing it though.

 

auto keeps the turbo spooled per shift....

 

i am also interested in power capabilites of the NA auto, if built right, and if the Jspec and 20b Cosmo Autos are the same, and capabilities of each

I drag race quite abit now and an auto would be awsome... I can pull 1.60 60fts with my 5speed on slicks... but

Just think about leaving the line on 15-20psi of boost, that would be incredible, with out a harsh 2step to build boost, and ill bet the drive train takes half the abuse of a 5 speed launching and will still give a better time


I just dont think there is much or any aftermarket for the autos in question... in order to beef it up with billet shafts, 5-6 pinion planetaries, ect. I spose by just rasing the line pressure and adding more disks to the clutches you would have a stout piece of equipment

 

PM Rotaryshack.

He built (or has experience) with the NA auto.

 

The main thing for the transmission is the torque increase. Are you planning on being n/a or turbo or using N2O? If you're going to be n/a, you probably don't have to worry about it too much. Most of the n/a power mods will cause a relatively modest increase in torque. Take a look here at a pretty extreme n/a example:
190rwhp, 128ftlbs https://www.rx7club.com/time-slips-dyno-128/90-n-dyno-sheet-580049/

That's a huge percent increase in power, but a fairly small increase in torque.

 

I think a better solution would be to find a different auto from a different car that fits into the RX-7... or to make one fit... Because the FC auto tranny is teh suck.

The Toyota AW4 transmission would be an excellent choice as it is nearly indestructible (jeep cherokee), and supports higher-revving engines (supra). Its also used in some tacomas...

Just an idea.

 

The FC auto and the FD/cosmo auto are nowhere near the same trans. The FC auto struggles to hold the stock power levels, and usually after 75k+ miles they are in pretty sad shape, shifting poorly and sometimes slipping or missing gears altogether. Part of the issue with the auto trans in the rx-7 is the gearing and shift control that mazda put in place...totally unsuited to the rotary's lack of low end. The gears are spaced too far apart and geared too tall, in an attempt to make up fuel economy. As a result the low end and midrange totally suck and the car is a slug.

IF a man had the ability to go in and change the gear ratios and make the trans shift much more firmly it would not be so bad. The auto cars had a 3.90 rearend behind them, and even if you put a 4.33 back there it is not what it should be but it is much better.

 

It's my understanding that the FD auto trans is the same auto trans that's in the Mazda MPV minivan.

 

Isn't the mazda mpv minivan FWD? I can't imagine its exactly the same.

 

why not? it'd just be a chage in bellhousing, tail ends and linkage . . .

 

The older MPV's (early 90's style) were RWD. They were also available with 4 wheel drive. I can't say anything about the tranny, though, cause ours had a manual tranny.
But seriously, though, how hard would it be to put the cosmo/fd auto in an FC? I would think you could fab up a mount and possibly a custom driveshaft. I guess you would need the wiring/electronics as well, but it shouldn't too hard if you have some fab skills.

 

Yeah, that'd be a pretty sweet mod. I'm sure somebody has done it.

 

Just put a GM transmission behind it like the supra guys and everyone else does.

Adapting an auto transmission isn't that hard.. just need the bellhousing and converter to fit the engine correctly.

 

Except for the fact that the mazda transmissions are electronically controlled, which is why you dont see anybody transplanting them into anything. IT's the same reason nobody does cosmo RE/20B swaps with the stock ecu...because they were all auto, all electronic controlled, and one without the other is hard to get to work.