I just hit 2000 miles after rebuild with all new seals and did a compression test and am not happy with the results. The front housing with schraeder out has three even bounces of 65 and rear 3 75 bounces. With the schraeder in to get total compression it is still the same numbers. Its a large street port in a 6p 13b with a 45dcoe {i know its too small now but at the time was told by a reputable company it was suffeciant} I used s4 turbo housings and s4 na irons.
My main question is since its winter and have time is it worth the 200 dollar gasket kit to open her up to see if something is wrong like side seal clearance or let it go to see if it builds more. With a little oil it hits 100psi

 

was the test done with engine warm? I dont mean to insult you but I have to ask the basic questions to get an idea what you are up against and rule out the obvious.

 

I've seen a number of members who've had low readings from piston compression testers. I think it's often the tester or the testee that's at fault, not the engine. Standard test is with the engie warm, as mentioned, cranking rpm at 250 and the accelerator pedal to the floor. The FSM has a chart if the cranking rpm is off. Since oil brings the pressure up that much, I'm not sure if I'd worry. What was the condition of the housings?

 

The irons were in specifications and the housings had minor flaking but nowhere near as bad as ive seen others use. The engine was warm and pedal to the floor. The test was done on my parts store tester and my co-workers matco tester. And no tach signal the way i have it all wired up unless i disable it at another point in the circuit but i did try with a 40 amp charge on battery with no change

 

i also seem to be flooding often and have a rough idle and cruise miss, but accell is great

 

Did you set the side seal clearance to specification when you rebuilt the motor? Were the apex seals stock Mazda or aftermarket?

RXDad

 

Should be at 120. Could you feel the motor make more power as it was being broken in? Used apex seals? Any Used springs?

 

The only used parts were housings. Yes i clearanced the side seals. and yes i semms to be making better power but i also recently added 4.78 rear gears. The reults are the same as they were from day one.