wassup_nuthin

I was just wondering what is a good compression number? as in is it based on a 10 point scale for the rx8? Im sure i sound like a noob but owell. I had a compression test on my 8 and its 8.0 all across the board at 250 rpm.

What is the best and how low does your compression get b4 you need to start worrying? my motor has 10k miles on it. its a rebuild so is 8.0 where it should be/?

White_Shadows

Huh...Wow I maybe lost with Rotary, but motorcycles its in psi...also ~140 numbers...

ndhoffma

Maybe the 8 is bar, not psi? That would be ~115psi

wassup_nuthin

yea its not psi its bar...well i think all i know is what my compression test paper says.#1 rotor 8.0 #2 rotor 8.0 across the screen at 250 rpms

r0tor

iTrader: (1)

8.0 is good

Sleepy-z

8.0kpa is fine, 6.9 is supposedly rebuild time. Some places do kpa some do psi. Its usually in the 9-10 range new. Problems show up in the mid 7's as in the way of starting issues and misfiring, sometimes customers convince dealers to replace them if its a starting/misfire in the mid/lower 7's. I have seen engines sent in with 5-6's which means they ran in that range well enoough for the customer to keep driving it.

claus

^^ you forgot to mention the rpm....

it's different to have 700 Kpa @ 200 rpm and another to have 700 Kpa @ 300 rpm !!!

as a rule of thumb, Normal numbers as defined by the Service Manual are:

@ 200 rpm: 750 Kpa

@ 225 rpm: 800 Kpa

@ 250 rpm: 850 Kpa

@ 275 rpm: 900 Kpa

@ 300 rpm: 950 Kpa

wassup_nuthin

so should i be worried then since min is a new rebuild w/ 10k miles on it and its that low? i did have a couple 7.9 in #1 rotor *pretty much 8* and one 7.5 in rotor #2 *the rest were 8 though* should i try to get the dealer to replace mine?? or should i be fine? mine were also at 250 rpm.

RotaryResurrection

iTrader: (3)

https://www.rx8club.com/showpost.php...6&postcount=41

wassup_nuthin

thank you rotary for that info. i searched for compresstion threads but never found that one. by what he's saying good good is between 105-125 and w/ my calculation im at 114 psi so that makes me feel better about my situation!

chromez

I am not very good at trying to compare 250 rpm to 305 rpm but my compression test was done at 305 rpm and I got the score of 9.4 and higher on all 6 readouts. Is that still good?

wcs

iTrader: (2)

Here's the stinky you need to read.

https://www.rx8club.com/new-member-f...4/#post3664045

Your answer awaits you

chromez

[QUOTE=wcs;4543670]Here's the stinky you need to read.

https://www.rx8club.com/new-member-f...4/#post3664045 when I was looking at the new member thread before I only saw the graph with red/yellow/green and the numbers. Must have been updated. Thanks for the point in the direction according to the calculator and the bar on this site I have a "stellar" engine. makes me warm and fuzzy. The twitch in my eye went away after I got the results lol

wcs

iTrader: (2)

LOLz
I said stinky

chromez

Yes you did say stinky lol. It still made sense so ur good

RIWWP

iTrader: (2)

I updated that graph chromez, the previous one was incorrect, so I took it down until I could re-do it. It's back up.

chromez

I like that chart a lot better riwwp thanks for that. My rx8 should last a long long time. I am super happy with it. I don't plan on nodding or doing anything to it. Probably will do the critical stuff for cooling and ignition but other then that I take this car around turns faster then on my cbr I just grin like a fat kid eating cake.