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Boosting Problem

Old Sep 24, 2005 | 03:21 PM
  #1  
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nice_head
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From: Essex
Default Boosting Problem

Had a T3 on my cossie which woz running around 21psi and now ive just bolted on a T34..

The thing is the T34 doesnt boost up to the same psi as the T3 did and I havent touch the acuator so it should be running 21psi..

Any ideas on why its not running the same boost?
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Old Sep 28, 2005 | 11:29 PM
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From: Exeter
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Hi

I had the same problem only the other way - mine had way too much boost. Mine was related to the good ol' amal valve (the crappy plastic thing on the front of the intercooler).

Lets assume that you are not running the standard chip - which is important. If not, then you will probably need to modify the amal valve input pipe diameter to restrict/ release pressure to achieve your target boost.

It is possible to completely bypass the amal valve (which I have done) and replace with a variable pressure valve. This is not without risks, and if not properly set up will lead to major problems, and I mean major problems.

Suggest that you speak to local tuner to help you resolve the problem.

hope this helps

JJ
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Old Sep 29, 2005 | 08:57 AM
  #3  
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unless your actuator is connected directly to the compressor housing, the actuator will normally 'see' less pressure than the compressor housing (or inlet manifold or wherever you are measuring boost).

it's not a case of the actuator does nothing until you hit x psi and then it opens the wategate to maintain that boost pressure - it's always seeing some boost pressure on it's diaphragm that is pushing against the spring inside it. as soon as that pressure starts to overcome the spring force, the wastegate will start to open slightly.

as your t34 has a larger turbine housing than your t3, it is easier for the exhaust gas to escape, and this will affect the boost level that you get.
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Old Sep 29, 2005 | 06:31 PM
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Ive just booked it in at engine advantages for a set up..
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Old Sep 29, 2005 | 11:16 PM
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Originally Posted by foreigneRS
unless your actuator is connected directly to the compressor housing, the actuator will normally 'see' less pressure than the compressor housing (or inlet manifold or wherever you are measuring boost).

it's not a case of the actuator does nothing until you hit x psi and then it opens the wategate to maintain that boost pressure - it's always seeing some boost pressure on it's diaphragm that is pushing against the spring inside it. as soon as that pressure starts to overcome the spring force, the wastegate will start to open slightly.

as your t34 has a larger turbine housing than your t3, it is easier for the exhaust gas to escape, and this will affect the boost level that you get.
but hwen it escapes, the wastegate will close again...so it should still keep the same pressure if set the same.

my question is, how did you keep the actuator set the same when you swapped turbos?????
surely you moved it from one turbo to another, and so one wastegate to another.....that would alter the tension on the wastgate in itself wouldnt it?
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