 boost creep, boost presure drops on hi revs |
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 Apr 30, 2006 - 11:05 PM
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 Enthusiast  Joined Dec 19, '05 Currently Offline Reputation: 0 (0%)  |
what causes boost creeping? im boosting my 7afte at 8psi but when i reach around 5000rpm the boost presure drops to 5 psi. what size exhaust pipe do you use in a 7afte?
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May 1, 2006 - 7:04 PM
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 Enthusiast Joined Jan 9, '05 From green springs ohio Currently Offline Reputation: 1 (100%) |
QUOTE(akiyama @ Apr 30, 2006 - 11:05 PM) [snapback]428433[/snapback] what causes boost creeping? im boosting my 7afte at 8psi but when i reach around 5000rpm the boost presure drops to 5 psi. what size exhaust pipe do you use in a 7afte? i just got my 2 1/2 in done and it gets me to 8.5 psi at 5900 rpm 
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May 1, 2006 - 7:20 PM
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 Enthusiast Joined May 22, '03 From NOVA Currently Offline Reputation: 16 (100%) |
your not refering to the right thing here....
boost CREEP is when for example say your setting is 8psi but you keep boosting and reach 10psi...thats creep wat you are experiencing is boost DROP... this is attributed to 3 things i would say 1)your exhaust is too small... 2)your turbo is too small.....your turbo basically doesn't have the efficiency to run at that high of an RPM for the CFM moving and drops 3)your motor doesn't move enough air to keep the turbo spooling fast enough to build that amount of pressure... exhaust size on a 7afte should be 2.5" |
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May 1, 2006 - 11:28 PM
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 Enthusiast Joined Aug 31, '02 From Philadelphia, PA Currently Offline Reputation: 8 (100%) |
QUOTE(playr158 @ May 1, 2006 - 8:20 PM) [snapback]428777[/snapback] your not refering to the right thing here.... boost CREEP is when for example say your setting is 8psi but you keep boosting and reach 10psi...thats creep wat you are experiencing is boost DROP... this is attributed to 3 things i would say 1)your exhaust is too small... 2)your turbo is too small.....your turbo basically doesn't have the efficiency to run at that high of an RPM for the CFM moving and drops 3)your motor doesn't move enough air to keep the turbo spooling fast enough to build that amount of pressure... exhaust size on a 7afte should be 2.5" i just had my car on a dyno and it was at 12-13ish psi and kept droping off to 10psi in the upper rpms.... explain that! -------------------- 15PSI - 30MPG - Megasquirt Tuned
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May 2, 2006 - 12:54 AM
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Enthusiast Joined Jul 3, '04 From Yakima, WA Currently Offline Reputation: 1 (100%) |
not enough down force, lagos. need a bigger wing.
 lol im jp.
-------------------- the 1/4 doesnt have patience for a ST.... so we make them ST-T's so atleast we'll sound good going slow.
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