fd3s_rx7

iTrader: (13)

I just got a compression test done.

It's 90lbs compression on each side of each rotor. Is that very good or not bad???

kyle@insight

consistancy is the key. If it came up to 90 each time then I'd say you're in good shape.

scratchjunkie

90 is dayam good. i scored the same compression on the motor i pulled out and have for sale.

fd3s_rx7

iTrader: (13)

Yeah its 90 consistancy for both rotors

rynberg

Actually 90 is not so good. Theoretical maximum is 125(?). I thought 90 was borderline below spec.

The consistent numbers are good though.

0110-M-P

iTrader: (10)

Well mine had 60psi on the front rotor and 68psi on the rear rotor and still running strong, well kinda. It won't hold more than 13psi on my TO4R. I am looking to get a core engine to rebuild soon that will be ported.

So in my opinion, 90 is not bad because the workshop manual says 100 is normal. But once you get down to where I am, you better plan a rebuild.

rynberg

Ok, I took the time to look it up. Mazda has a minimum compression spec of 6 kg/cm^2, which equals 85 psi. A new motor should make 8.5 kg/cm^2 = 120 psi. A motor making 90 psi all around means that, while none of the apex seals are blown, they are all worn down. Something to be expected of a high mileage motor. The engine will likely run fine for several thousand more miles, but it IS worn.

0110-M-P

iTrader: (10)

Holy crap, so your saying since I have 60 on the front and 68psi on the back, that I am only at 4.2 on the front and 4.7 on the back. A year ago I was at 6.9. Wow that sucks.

fd3s_rx7

iTrader: (13)

Are you still able to drive the car at that low of compression.?

Are there any power loss? Or did it still feel the same?