NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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-   1st Generation Specific (https://www.nopistons.com/1st-generation-specific-16/)
-   -   13b bridgeport compression test (https://www.nopistons.com/1st-generation-specific-16/13b-bridgeport-compression-test-68055/)

lanzy61 11-07-2007 01:41 AM

hey im new to the forums im looking at a s1 rx7 with a full cut 13b bridgeport thats done 5000kms since rebuild i got a compression test done and it came back 65psi per rotor that sounds very low to me but im kinda new to the game he clames they should be around 85-90 new but since its ported its lower any help would be great dont wanna lemon !

Aurosting 01-21-2008 11:10 AM

if its rebuilt it and has not compression or lower you might have a stuck seal or maybe they did th bridge wrong

1st Stop Import Performanc 02-16-2008 06:01 PM


Originally Posted by lanzy61' post='887313' date='Nov 6 2007, 11:41 PM
hey im new to the forums im looking at a s1 rx7 with a full cut 13b bridgeport thats done 5000kms since rebuild i got a compression test done and it came back 65psi per rotor that sounds very low to me but im kinda new to the game he clames they should be around 85-90 new but since its ported its lower any help would be great dont wanna lemon !



You may have an issue with compression. You first want all compression readings to be relatively equal, that is 3 compression reading from each chamber. If the bridgeport if excessive it my be effecting compression but unlikely, also if you can try to look at the apex seal either through the spark plug hole (may be difficult) or throught the exhaust port to see if the middle is blackened due to bypass, the apex seals may have warped in the middle. If this occurs you will have typically even but low compression. Also make sure the battery has good charge incase cranking speed was slow

j9fd3s 02-19-2008 11:46 AM

the bridge is open into the compression stroke, so it will compression test at a lower #. the KEY and ONLY important thing is that the numbers between all 6 chambers are equal

bigboi12A 02-24-2008 07:46 PM


Originally Posted by Aurosting' post='892661' date='Jan 21 2008, 09:10 AM
if its rebuilt it and has not compression or lower you might have a stuck seal or maybe they did th bridge wrong

were u selling your car in the autotrader a little wile back. Half bridge 13B 4 port? did u sell and who built your motor


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