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-   -   2011 Compression Test Results at 45K Miles (https://www.rx8club.com/rx-8-discussion-3/2011-compression-test-results-45k-miles-269403/)

Joe's Mazda 06-13-2019 10:07 PM

Yes they were. Car is all stock, could not find 1 think on it besides needing tires wrong.
https://cimg9.ibsrv.net/gimg/www.rx8...e98563b7b4.jpg

fylpa17 06-15-2019 08:36 AM

Compression results
 
Hello, I am new in the forum.
I have nearly decided to buy a 192hp 2008 challenge with the following compression at sea level. The car has 28.000miles.
The numbers are in Kpa:
Front rotor:
245RPM:
840
870
840
Back rotor:
255RPM
790
780
800.

I am really worried about the difference between rotors. Any thoughts?

Joe's Mazda 06-15-2019 09:18 AM

Those were normalized at 250 RPM and 23 feet above sea level.

Steve Dallas 06-15-2019 11:41 AM


Originally Posted by fylpa17 (Post 4890642)
Hello, I am new in the forum.
I have nearly decided to buy a 192hp 2008 challenge with the following compression at sea level. The car has 28.000miles.
The numbers are in Kpa:
Front rotor:
245RPM:
840
870
840
Back rotor:
255RPM
790
780
800.

I am really worried about the difference between rotors. Any thoughts?

That engine is technically passing. It is common for the rear rotor to have lower compression due to its proximity to the cat.


Originally Posted by Joe's Mazda (Post 4890645)
Those were normalized at 250 RPM and 23 feet above sea level.

You scored a rare good one at a great price. Congrats!

fylpa17 06-15-2019 11:45 AM


Originally Posted by Steve Dallas (Post 4890655)
That engine is technically passing. It is common for the rear rotor to have lower compression due to its proximity to the cat.

Thanks for the answer. Is it something I should worry about though?
I have read the passing limit is 1.0 (100kpa). I am at 0.9 after normalizing the results.
Is it possible that the back rotor will deteriorate so much against the front one, so that it will cause an issue? Again thank you for your time.

UnknownJinX 06-15-2019 02:19 PM


Originally Posted by Joe's Mazda (Post 4890645)
Those were normalized at 250 RPM and 23 feet above sea level.

That's very good numbers! Definitely jealous.

Steve Dallas 06-16-2019 04:21 PM


Originally Posted by fylpa17 (Post 4890656)
Thanks for the answer. Is it something I should worry about though?
I have read the passing limit is 1.0 (100kpa). I am at 0.9 after normalizing the results.
Is it possible that the back rotor will deteriorate so much against the front one, so that it will cause an issue? Again thank you for your time.

The FSM lists the spec as 150kpa. It does not specify, but I assume that is the mean front vs. the mean rear. The difference between rotors is not as important as the difference between rotor faces and overall compression of each rotor. The rear rotor will coninue to deteriorate, at least as long as the car has a restrictive cat.

Steve Dallas 06-16-2019 04:34 PM

I did a dumb thing Friday. I occasionally have to drive out west to Cisco, TX for work at my new job. From my house in the country outside of Fort Worth, that means a 90 minute drive, where 2/3 is high quality, relatively high speed, twisty back roads, and 1/3 is nicely repaved I-20. I had forgotten what a great car this is for that kind of daily driving--especially with a normal alignment. Now I'm questioning whether I can part with it. Keeping it means selling my old Tacoma and parking something else outside. RX-8 vs. Miata vs. Bimmer. The 8 is currently the only one with glycol in it. The other two are D water and MoCool at the moment. Hmmm...

UnknownJinX 06-16-2019 04:35 PM


Originally Posted by Steve Dallas (Post 4890719)
The FSM lists the spec as 150kpa. It does not specify, but I assume that is the mean front vs. the mean rear. The difference between rotors is not as important as the difference between rotor faces and overall compression of each rotor. The rear rotor will coninue to deteriorate, at least as long as the car has a restrictive cat.

He is talking about the difference between rotors, where the passing spec is <100 kPa difference.

https://cimg2.ibsrv.net/gimg/www.rx8...4fba1dee69.png

IMO this is okay, but I think the rear rotor deterioration has more to do with the coolant path versus whether or not there is a cat. Coolant loops around the rear rotor so there will be more heat there, which causes faster deterioration.

Steve Dallas 06-16-2019 04:42 PM


Originally Posted by UnknownJinX (Post 4890721)
He is talking about the difference between rotors, where the passing spec is <100 kPa difference.

https://cimg2.ibsrv.net/gimg/www.rx8...4fba1dee69.png

IMO this is okay, but I think the rear rotor deterioration has more to do with the coolant path versus whether or not there is a cat. Coolant loops around the rear rotor so there will be more heat there, which causes faster deterioration.

Oops! I misread that! Is there such a thing as verticle dyslexia?

sinkas 07-10-2019 10:20 PM

Steve,
did you have adjustment extenders on your rear Ohlins?, if so how long are they,
want to order some for my KW's,
but unsure if I can just get the short ones or need the long ones?

Steve Dallas 07-11-2019 07:59 AM

I do have the rear extenders. I think they are about a foot long and are just long enough to be convenient.

sinkas 07-11-2019 06:47 PM

cheers

Fijibluefg2 07-18-2019 07:38 PM


Originally Posted by Steve Dallas (Post 4890720)
I did a dumb thing Friday. I occasionally have to drive out west to Cisco, TX for work at my new job. From my house in the country outside of Fort Worth, that means a 90 minute drive, where 2/3 is high quality, relatively high speed, twisty back roads, and 1/3 is nicely repaved I-20. I had forgotten what a great car this is for that kind of daily driving--especially with a normal alignment. Now I'm questioning whether I can part with it. Keeping it means selling my old Tacoma and parking something else outside. RX-8 vs. Miata vs. Bimmer. The 8 is currently the only one with glycol in it. The other two are D water and MoCool at the moment. Hmmm...


LOL.

Thats the thing about the RX-8... it has amazing driving dynamics for certain driving conditions. Beyond that, it’s a tough call of a car / engine to maintain.


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