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apex stage 1 low boost

blown apex

VIP Member
Joined
Jan 29, 2006
Messages
227
Location
ALTON ILL.
Website
ristermotorsports.com
supercharged apex
I noticed the boost is only 8.5 psi now it used to go to 12
I have a racepak dash and recorded a few runs
it takes off with 12 on launch then I can feel engine pull down a little and
this is were I have 8.5 psi ( that's why I recorded it)
the boots look good and on tight
the afr is richer than it used to be (recorded also)
I took the blow off valve off to test it but maybe ill block it and try it again
I have about 5000 trouble free miles on it now after the 1st engine burnt at 1000 miles
do these superchargers start loosing performance if so should I turn it harder with a pully change
it still runs smooth and fast with no problems but I shouldn't feel it pull down
it revs to 10200 wot groomed trail used to go 10700= 11000
thanks for any recommendations to start with snow is 10 hrs from me
 
Last edited:

Duane,
Check your exhaust donuts and pipes for a leak, crack, etc. You might not be developing sufficient back pressure to drive the turbo enough to build 12 lbs boost...
 
No they won't be reduced that much in performance in 5k miles. Check the s/c belt- could be getting worn. Check all intake connections and boost gauge line connections, could be something simple. Have you changed your s/c oil? Would recommend doing so if you haven't
 
Better check the belts and pullies, you may have a pulley with a stripped key way or something that is allowing it to slip and not build boost. It is possible the unit could be bad if a bearing or something let loose. Just need to get in there and starting checking that drive system.
 
Ah crap, sorry I missed that you put right at the top it was a supercharged apex, duh.
I know FPP was troubleshooting a MPI stage1 SC that would only produce boost up to a threashold on the dyno, ended up diagnosing it was slipping real bad internally. Just something to check, not sure what boost level it was slipping at but wouldn't build any more boost past it.
 


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