I need to know how to tell the difference between s4 and s5 turbo and nonturbo rotors like fatory stamps in the rotors. markings anything. I know the tubs are different but a local guy has a 89-91 s5 nonturbo car and when he pulled the motor out it has what I'm pretty sure are turbo rotors and housings. So I does anyone have a way to tell by the letters and # stamps on the rotor? any help would be great.

 

To my knowledge the only stamps on the rotor is the weight stamp, which won't tell you if its turbo or non-turbo. I don't actually know of a way to tell if its turbo or non-turbo, just s4 or s5.

 

s4 rotors the compression pocket is rough and cast? ( or something like that) and then on s5 rotors its smooth and machined

then within each series

the s4 turbo rotor has a pretty deep pocket, and the s4 na one isnt as deep

then in s5 turbo has a semi deep pocket, and the na rotors have a shallow pocket

with out a pic u might not know what im talkin about but if u have a couple rotors to look at u can tell which series it is or which is the deeper...

 

i just realised weight has nothing to do with it. lol. shizer. lol. hm...

 

Didn't want to start a new thread so i decided to post here. Are there really no markings on the rotors to tell the difference between turbo and n/a rotors.? thanks for the help
Dom

 

well correct me if I am wrong but weight does have a little to do with it. at least between the turbo and non-turbo, because if the pocket is deeper on one than the other I would assume more metal is missing on the deeper ones. I thought I read that the s5's were lighter than the s4 which is why when rebuilding people perfer the s5.

 

same series turbo and n/a rotors are the same weight, i just am not sure how to tell the difference between turbo and n/a