My tech did one last week and he said that it cranked at 210 p.s.i., but he said the all-data said that it should crank at 270 p.s.i., but he added that that seems high enough to possibly be a typo. Which is right? 270 p.s.i. seems insane!

 

210 is great. i've seen the 270 number in text, never on an actual engine. 190-230 is common for a healthy motor

 

As I recall, 270 is the highest possible value but is never really seen. Thus, it is used so that if you have a coolant/oil leak and are getting 320psi, you will know something is wrong. Most are in that 190-230 range as previously stated....usually around 195 from my past experience. I think mine w/ JDM ITR pistons was pumping out around 230.

 

My All stock JDM B18C is right at 215-220psi per hole. Remember, consistency is the key to your engines shape, not necessarily the max number on a compression test. I think a healthy motor should all be within ~2%

 

i could like to say about 190 to 250 but it should be 10 psi apart

 

I have a JDM B18C (10.6:1) stock internals, when i did my test (all spark plugs removed for no resistance) mine read 240,250,250,240

 

is that the best way to do it? i usually leave the spark plugs in when testing the other cyclinders.

 

engine hot, distributor unhooked, throttle body open,

gauges are also all over the map. some read higher than others. i actually own one that's more of a bent valve tested than accurate. tested a newer corvette the other day with 18k miles. said 140psi in one of the cylinders lol. obviously a lil low.

 

compression numbers will also differ depending on your elevation too. Like here in Reno, Nv my b20z did 185-195 across but in sacramento it did 220-230 across