VictorC80

Hi everyone.

I'm buying a 2nd hand Mazda RX-8 from my cousin's friend.

I asked him to bring his car for compression test and this is what he gave me:

Front Rotor 7.2
Rear Rotor 7.5

Is this a safe reading. Is it recommended to buy?


And also... any other aspect I should pay attention to before I make my final decision?

Thanks guys

usnidc

What year, mileage, etc is the car?

jasonrxeight

at what rpm the pressure was taken.

neit_jnf

and you should have 3 readings per rotor

RotaryResurrection

iTrader: (3)

Mazda testers take readings in kg/cm^2, while we here in the states are more familiar with pressure readings in psi. To convert simply multiply the metric value by 14.2 to arrive at a standard value.

For the rx8:

readings above 115psi are excellent
readings between 105-115 are average
readings between 95 and 105 are weak
readings below 95 would generally fall within mazda's replacement guidelines, and such an engine would also have difficulty starting when hot, and perhaps have idle and stalling issues.

Technically the lower limit for compression on the rx8 is 96-97psi.

These values are at or near sea level and at or near 250 cranking rpm. For values measured higher than sea level, or values at lower cranking rpm, there is a correction chart to go by which tells you the lowest compression value that's acceptable because you will get lowered values at lower cranking rpm or higher altitudes.