RX8Club.com

RX8Club.com (https://www.rx8club.com/)
-   RX-8 Discussion (https://www.rx8club.com/rx-8-discussion-3/)
-   -   rx8 compression question (https://www.rx8club.com/rx-8-discussion-3/rx8-compression-question-274866/)

Tanner 05-02-2023 04:15 PM

closed
 
closed

Loki 05-02-2023 06:00 PM

You should have hot start issues if those numbers are accurate. What was it tested with? What rpm are those numbers at?

MincVinyl 05-02-2023 07:20 PM

I can confirm 60psi would cause hot start issues, and stalling at hot idle.

Are you sure you fully hand tightened the pressure transducer? Which order did you do your test in Front or Rear first? Was the engine at running temp during both tests, or did you take over 10mins to do the test?

MincVinyl 05-02-2023 11:39 PM

The walkaround vid on your youtube shows two comp tests, both look fine for a used engine. Unless it is an out of date vid.

MincVinyl 05-03-2023 09:53 AM

If one rotor was low enough to not make enough compression, I imagine the idle would get extremely lumpy. Which is hard to tell in your short vid, not sure what exhaust you have or what it normally sounds like. Might want to do a repeat test when just to be sure. Again try to do everything you can prepping while the car is running. Shut it off and do the test as soon as possible. The closer you are to running temp, the better the reading.

How many miles are on it?

gwilliams6 05-03-2023 05:50 PM

RX8 engine compression test chart
 
https://cimg4.ibsrv.net/gimg/www.rx8...911a23d502.jpg
RX8 engine compression test results chart. Sorry for the poor quality. Cheers


gwilliams6 05-03-2023 06:29 PM

What rpm did you do the compression test at? Look at the chart, 60's is failing at any rpm. 80-90's aren't good except if your test was at very low rpm . Your test numbers need to be normalized to 250rpm at sea level. And that is too much a gap between numbers from one rotor to another to run properly or even to start well.

Test again under controlled conditions, but it might be time for a rebuild .

Cheers and best to you.

Tanner 05-03-2023 07:55 PM


Originally Posted by gwilliams6 (Post 4982303)
What rpm did you do the compression test at? Look at the chart, 60's is failing at any rpm. 80-90's aren't good except if your test was at very low rpm . Your test numbers need to be normalized to 250rpm at sea level. And that is too much a gap between numbers from one rotor to another to run properly or even to start well.

Test again under controlled conditions, but it might be time for a rebuild .

Cheers and best to you.

Yes they were at sea lvl and 250rpm. I know that if the numbers are right they are way below spec, im just wondering how im not having any sort of issues yet if its that low. The chart doesnt even go that low LOL

gwilliams6 05-04-2023 10:00 PM


Originally Posted by Tanner (Post 4982349)
Today i did another test and this time i tried both leading and trailing. Front rotor was still 62/64/72 psi. Tested 3 times each and that was the average. Rear rotor was actually 89/91/94 psi. Car was fully warmed up oil was at 175 degrees F and coolant was 180.

Still not sure how i have 0 misfires, no smoking, and 0 starting issues. Must be lucky. Anyways time for the rebuild


Yes I think time for a rebuild.
As you know, the RX8Ckub has a list, somewhat updated, on reputable Renesis engine rebuilders across the country. Unless you are skilled on rebuilding Renesis engines, leave it to the pros.

Cheers and best to you. Keep us informed ok.

SoniaMante 01-11-2024 12:48 AM

What was the question?

BigCajun 01-11-2024 10:11 AM


Originally Posted by SoniaMante (Post 4989019)
What was the question?

The OP deleted it.


All times are GMT -5. The time now is 09:06 AM.


© 2024 MH Sub I, LLC dba Internet Brands