RX7 not boosting right :(
06-01-10, 03:43 PM
#1
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Join Date: May 2010
Location: Germany / NRW / Lüdenscheid
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RX7 not boosting right :(
Hey guys... recently bought a RX7 FD ... it had a recent rebuild when i got it with only 200 miles done! ... Anyway ive done about 2000 miles by now and have changed oil once allready... ran the engine in as i was supposed to and havent pushed it hard since... well first of all its my first RX7 and i have no idea how this cars should behave so i wanted to find out 
...as the engine is still fairly new i am still afraid to push it too hard but i wanted to see how it feels until 5000 rpm! so i drove with second gear... at about 2000 rpm and hit the throttle it was not too impressive untill 4000 rpm and thats where it kinda starts pushing you in the seat... did that in third to have a look at the boost gauge... its not showing any boost until 3400 rpm and then slowly climbs up to 0.4 bar when reaching 4500 rpm! and thats where i let go of the pedal... Havent pushed it further but thats not really the boost curve thats normal for an rx7? Boost curve should be PSI-> 10-8-10 psi So i had a look at the engine... the vacuum pipe connected to the Dump valve was kinda loose so i took it off and also had a closer look at the dumpvalve... blew in it and i could blow right through so i guess the dumpvalve was broken... so i replaced that for a Baily one my brother had lying arround... its a little bit better now but still starts boosting at 3000 rpm with 0.1 bar and reaches 0.4 when hitting 4500 ! ... Do you have any idea what could be wrong 
(btw ive got an electronic Autogauge boost gauge... so it could have some kind of delay as i dont know about the quality on those... so it also could be seeing 0.1 at 2800 or something but def. not earlier! ...)
...as the engine is still fairly new i am still afraid to push it too hard but i wanted to see how it feels until 5000 rpm! so i drove with second gear... at about 2000 rpm and hit the throttle it was not too impressive untill 4000 rpm and thats where it kinda starts pushing you in the seat... did that in third to have a look at the boost gauge... its not showing any boost until 3400 rpm and then slowly climbs up to 0.4 bar when reaching 4500 rpm! and thats where i let go of the pedal... Havent pushed it further but thats not really the boost curve thats normal for an rx7? Boost curve should be PSI-> 10-8-10 psi So i had a look at the engine... the vacuum pipe connected to the Dump valve was kinda loose so i took it off and also had a closer look at the dumpvalve... blew in it and i could blow right through so i guess the dumpvalve was broken... so i replaced that for a Baily one my brother had lying arround... its a little bit better now but still starts boosting at 3000 rpm with 0.1 bar and reaches 0.4 when hitting 4500 ! ... Do you have any idea what could be wrong (btw ive got an electronic Autogauge boost gauge... so it could have some kind of delay as i dont know about the quality on those... so it also could be seeing 0.1 at 2800 or something but def. not earlier! ...)
10-13-10, 01:28 PM
#6
Rotary Enthusiast
Wastegate pressure is 7 psi .5 bar anything below that is deffinately a boost leak. The flexible hoses to and from the stock intercooler are known to split you cannot tell until you take them off and bend them.
