The compression numbers given in the FSM are for when the official MAZDA tester is used.



I am not too sure about these numbers when you use a regular compression tester (witch schrader valve out) from autozone or the likes.



hugues -

it shouldnt matter what tester you use as long as you convert the units correctly



mike

over 125 psi on both in my 91 n/a



T2 tested at just over 100 on both

the t2 should be lower because its got a lower compression ratio



mike

dont make a huge deal over compression numbers. They can sometimes vary. its not a piston engine. if it starts and runs. Its fine.

you mean if it idles smoothly its fine



mike

i have 13456433 gazzillion psi, or three whooshes

was this at 8000rpm? https://www.nopistons.com/forums/pub...IR#>/smile.png

no ,,, that was at 27,430 rpm right before i was gonna shift mad quick yo!

first time I did a compression check on my 7 (6 months ago) I took out the leading plugs, grounded the leading coils, left the trailing plugs hooked up (wait, this gets better) screwed the ol compression tester into the L2 hole, had a rubberband holding the release valve on the tester, angled it in such a way that I could see it from the drivers seat, turned the key and the car started... no ****. ran like crap and sat at about 200rpms, but F%$# me man, it took a minute of disbelief before I shut her down again. had to buy a new compression tester though, wasnt sure if it'd still be good after that.