I am just wondering what others are getting for numbers on their engines.
PSI on front and rear rotors, or whatever the numbers mean on the mazda compression tester.

Read my sig for mine.
I was told it was the highest seen on the mazda tester at the Ottawa meet this summer.

 

Surprisingly no, not yet, I don't wanna know right now haha.

 

I'm buying one tomorrow to tell me what i think i already know...... chipped apex seal

 

I think that tester needs to be calibrated...


-Ted

 

please do tell.

 

no not yet, it's on my "to do" list, just below "rebuild engine"

 

Had somebody do a piston engine checker on it, and got 60-70 on both faces. Somethings wrong, I'd think, because that was almost a year ago. I figured my car would have blown up by now :P

 

10.5 what? PSI? I hope not. Last time I checked mine was 90-92 psi.

 

In general I don't bother checking compression unless there is a reason to. If the engine runs fine, starts easily and makes decent power, compression is fine.

 

^^what he said...

I compare it to STD tests. You want to get the test done, but you really don't want to see the results, you know, just in case. lol

 

No it was tested using the genuine Mazda electronic compression tester.
It's a rotary specific tester that displays readings for each rotor face.

Looks like this:


I don't remember what the measurement units were.... I think it might have been in kg/cm2 or something like it.

 

ive heard that 100psi is optimum..

 

Uh oh. I need to do this on all of mine. [still]

 

You realize 10.5 kg/cm2 equates to over 150psi right? That hardly seems possible on a motor with over 100,000 miles on it, NA or not... Is there a possibility there's something wrong with the adapter/pressure sensor on your tester?

 

+1

 

no, I don't want to jinx it...she just needs to stay strong for another month and a half!!

 

All testers read differently--so you've got to keep that in mind. I've been using my current "piston" tester with the check-valve removed for about three years now. I hope for numbers of 100PSI or more. The highest PSI I've seen yet has been a Series 5 13BT with 120k miles on it. On my tester it was seeing 115PSI front and rear (cold). It was beautiful watching that needle bounce.

Most of my FC's have had engine's with numbers hovering between 95-105PSI--although some have ran and drove excellent with numbers closer to 90-95PSI.

 

I read 80-85 PSI on my rotors. No wonder I have trouble starting.

 

Get your fuel-injectors cleaned if you haven't yet. Even if the engine is on it's way out--you *might* be able to reduce flooding issues for at least a while...

 

Not an expert on the subject, but wouldn’t you expect the best compression on high mile engines (at least ones that have been rebuilt). I have herd racers like to use well warn parts to build their engines

 

Already have that in mind. But I've just purchased some high dollar items which has pushed the cleaning back a couple weeks at least.

 

My engine- with 176k showing- reads 80-85psi front and back with healthy bounces.
Starts fine, no smoking or unusual oil consumption (although oil pressure reads kinda low) and gets decent mileage (16 city/25 highway).

Decided not to worry about it till something actually went wrong.

 

I think the "worn" part has to do with the break in period, for example if you use new apex seals with older housings the compression won't be as good(in the beginning) because the seals haven't worn down enough to make the best seal if that makes any sense...someone jump in if this info is a bit off. The real difference I would say is racers like engines that have been properly broken in rather than well worn.

 

I was going to say properly broken in but I went with well worn to separate a 20k engine housing from a 200k-engine housing

 

Couldn't carbon build-up cause higher compression?