RX-8 Compression
 

I've been looking at RX-8s and I noticed one from 2004 that has 87k miles, but has the following compression stats : 98 95 99. Image is attached. Is the higher mileage worth for the compression, or would the apex seals be blown too soon for it to matter?



https://cimg0.ibsrv.net/gimg/www.rx8...dcdde46b95.jpg

Those are only stats for one rotor, you need the other 3 values.

However, 98 psi at 259rom is borderline. I wouldn't spend a lot of money on this car. If it's cheap you buy it and drop in a replacement engine and start with a clean slate. These days that's a better strategy than finding a healthy original engine.

98 psi should start ok

As long as the numbers are about the same in the other rotor it should run just fine. Keep in mind, your numbers are a bit low assuming you arent high in altitude when you did the test. This engine appears to be close to needing a rebuild soon so if you can get it cheap go for it. 100 psi is minimum spec.

Somebody else just posted in another thread part of the factory service manual that says minimum spec is 98.6 psi at 250rpm.

Per the below chart...

For example...@ 250 rpm:
- Standard compression (A): ~120 psi
- Minimum compression (B): ~98.5 psi

https://cimg2.ibsrv.net/gimg/www.rx8...b34cb947c.jpeg
The swath cut threw the chart bounded by A & B demarc the STANDARD (A) and MINIMUM (B) compression range at the listed RPM along the X-axis.

Anything below 100 a good idea to start saving pennies for a rebuild. The car will run and drive fine but as the engine continues to wear over time, a rebuild is less and less likely going to be a good option due to damage being caused to rotors and housings. You may be forced to get a reman engine and swap it in.