ok, i know this is going to sound bad, but after a few days digging for info, i give up... what exactly is the difference between a S3/S4 13b? besides the year, im planning a swap for a 82 gsl in the next few months, and just want to know what im looking at ><

 

the main difference is the manifolds, ignition, ecu's and motor mounting schemes there are some minor differences internally but if you are planning on running it stock then these will make no difference to you. you will need to swap front covers between your 12a, and which ever one you buy, and you will need to slot the motor mounts back about 3/4 of an inch or so (due to extra length of 13b) now if you are thinking of turbo chargeing later on then get a trubo model to start with and save yourself the agony of trying to turbo prep an NA. you only lose about 20 HP between the NA block, and a turbo engine being run NA (due to lower compresion ratio) and that 20HP will pay for itself when you go to turbo charge the motor as you won't have to dink with the thing internally to slap a turbo on it.

kenn

 

i know the s3 have 3mm apex seals, and the s4 have 2mm

 

thanks, i was actually looking at the complete/used motors from cpracing

S4 RX7Turbo II $1500.00
S5 RX7Turbo II $1500.00
RE TT Cosmo Engines $2600.00
COSMO 20B $5900.00 (based on availability)

and trying to figure out which would be better, since the price is the same =3

and as far as mods go, i can fab up anything i need pretty easy, i have access to a full machine shop