mine is reading 93.
it is spuddering and shaking at idle...i think my car is screwed

 

Normal, it's all normal.

 

Give us some history on your car. What kind of driving did it get, reg or prem gas, short trips to work mostly city or freeway, was it driven hard or never red lined, oil change interval, 5X20wt oil or what, pre-mix used, oil consumption, miles driven, what parts and service has it had, what year, has it ever been flooded, just anything you can tell us....THANKS

 

mines been spuddering and shaking at idle for the last 73K miles.

 

I would read the directions on how to take a compression test.

The RX8 engine has to be done correctly or you will get false readings.

 

i got the results back form mazda today, my compression was 85

 

If I'm not mistaken, 85 is lingering towards the rebuild number, but it will be fine for another while. I drove on 65 compression for well over a year in my 88 RX-7 Turbo II...and I didn't take it easy on the car, either...

 

alright, cool.
thanks

 

yeah if ur gettin low on compression you can always start premixing to try so slow the process or say "screw it" and get a new engine soon!

 

Compression figures on a rotary should always have cranking rpm accompanying them and should be comprised of 6 figures (3 front and 3 rear). Low cranking speed will result in low figures.

Paul.

 

lol a new motor isnt costing me anything, so im just going to do that....if they are offering, why not take it?
thanks paul, my dealer knows nothing about rotorffies, but they sent it in to mazda, mazda approved of the new engine, so im just going to take the motor

 

Hell yeah! People usually bitch and moan about it, but it's like "A BRAND new engine...why complain?"

 

For the rx8, 96 is the threshold mazda uses for determining if you get a new engine under warranty. However, the engine can continue to run fairly normally well lower than that. I drove my car for about 2 years with 90-92psi and it ran like new...possibly not as powerful as a new model, and started a bit weakly...but ran fine. In the 95 and under range you can start having idle and startup problems, varying from car to car. Rotaries *can* run normally, well into the 85psi range.

 

i was about to say, what is the definition of "safe."

the car will just slowly have less power as the compression goes down. its not like it will explode and engulf the car in a gigantic fire ball. as engines go, the renesis is pretty "safe."

 

As your Rotary gets weaker on compression you can also add pre-mix and save on reg-gas too.

 

A lot of people see things in black and white. An engine is either "good" or "bad" to most of these people...there seems to be no in between in their minds. IT is as if, at 97psi, the car must make 200rwhp and life is fine. And at 95psi, the car suddenly only makes 130rwhp and it is a piece of ****. People actually say that the rx8 has a "blown" engine when the dealer replaces one under warranty for weak sealing compression...that **** didnt blow up, it is just not sealing especially well.

In reality most people could be given a 95psi engine and a 110psi engine to drive back to back and feel no significant difference, other than perhaps a slightly faster startup for the stronger engine.

To me there are 3 types of engines. Strong compression tight engines that run well, weak compression engines that still run okay with a bit of a rougher idle, and BLOWN engines that are not streetable because of broken apex seals (zero compression), bad coolant seals (overheats and burns coolant) or bad oil seals (smokes and burns a lot of oil).