I know this is a newb Q but what should the highest compression be on an s5 engine weather US or JDM?

 

Well...

S5 NA is 9.7:1, but since there were no NAs in Japan, then we are talking turbo which is 9.0:1. And it's the same for Japan and North America.

http://www.mazdatrix.com/faq/rotorwgt.htm

 

Well im S5 T2 i didnt specify sorry. Im asking because a well known shop has a jdm engine with said 40k miles and 120 compression. Im considering it to get my car driving but im worried about how the water seals are. I thought that compression is really high for a turbo but I never new what the max allowable comp is before seeing carbon build up. wich i suppose you can get rid of by blasting throught the gears. so I hear anyway.

 

then it's a 9.0:1 ratio. that is in the upper ranges so i would be skeptic that they put some oil in it during the test to skew the results. either way, the oil wouldn't affect it a huge amount so the compression figures do sound good, BUT keep in mind Jspec engines should be torn down and rebuilt anyways because the coolant seals will be dry rotted and likely won't last that long.

 

Ya thats why Im skeptical about it. Im not sure of how much longer it would last and i would spend over 1k on it.