Festiva 3 spd auto swap to 4 spd auto?

[Festiva GTX]

I have EFI 1989 Festiva L with 3 spd auto.

Sometime I drive little fast like going 70's MPH but RPM always go so high 4,500 something that. Anyone have swap to 4 speed auto like from 323 Mazda or other car can fit with 1.3 L engine block?

I want make RPM little lower to make MPG better and less harsh sound from engine.

Any better suggest?

(No, I don't want change to 5 spd manual since my wife's car )

[Festiva GTX]

Well? Noone know how or never tried before?

[Damkid]

the 323's came with 4 spd auto? well i'll take your word for it
i'd imagine it would fit, it'd be the same with other tranny's, need to make mounts but if you used the 323 flywheel, torque converter, and starter, i don't think there would any problem making it work as long as there is room for it, (i'm not sure but i think it'll fit) it'd be worth trying it

[Safety Guy]

Since the auto 323s I've seen were all 3 plug ECUs, I'm betting that there is some computer control for the 323 4 speed ATX. You'd probably have to do a lot of rewiring for the 323 ATX as well as custom mounts, etc.

Just a guess, mind you.

The Festiva ATX has no computer controls, just a vacuum line to the air plenum.

Karl

[Festiva GTX]

Uhmm thanks for info and I might give a try 4 speed auto with 1.3 L block or ever better if take with 1.6 L engine together and whole wiring kit.

it is 323's 4 speed auto bigger than 3 spd auto stock? Maybe I have to measure up the wide and size at junkyard to compare it.

3 speed auto stock is somewhat awful revving high too long and i get about 30MPG if steady 60 MPH and 26 MPG if 75MPH lol. unlike 5 speed manual make easy on engine and better MPG as my 1993 Festiva GL get about 48 MPG with 5 speed manual.