3" prodrive system or 2.5" , which is better
27 June 2006, 02:00 PM
#1
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3" prodrive system or 2.5" , which is better
just put a new 2.5" b/b and centre on the 02 sti ppp, didnt realise the prodrive centre and b/b was 3"
will there be any issues going from 3" to 2.5", i just wanted it a bit louder
the new b/b is a ti-phoon/firestorm from tsl, looks and sounds great
will there be any issues going from 3" to 2.5", i just wanted it a bit louder
the new b/b is a ti-phoon/firestorm from tsl, looks and sounds great
27 June 2006, 02:25 PM
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In theory you'd lose some performance in dropping to 2.5" from 3", especially if the PPP is mapped for 3".
The 2.5" exhaust will have a lot less surface area over the 3" meaning less exhaust gas can be expelled which in turn inhibits the turbo.
The 2.5" exhaust will have a lot less surface area over the 3" meaning less exhaust gas can be expelled which in turn inhibits the turbo.
27 June 2006, 02:32 PM
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i thought that might be the case, but the car still feels exactly the same
i thought prodrive fitted 2.5" systems not 3"
is it ok to leave the new system on without worrying or do i go back to the "noiseless" prodrive system
i thought prodrive fitted 2.5" systems not 3"
is it ok to leave the new system on without worrying or do i go back to the "noiseless" prodrive system
27 June 2006, 03:04 PM
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From what i've been told and read; a 2.5" system does not become restrictive until around the 350bhp mark.
That probably explains why you felt no difference.
That probably explains why you felt no difference.
27 June 2006, 03:39 PM
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Originally Posted by GazTheHat
From what i've been told and read; a 2.5" system does not become restrictive until around the 350bhp mark.
That probably explains why you felt no difference.
That probably explains why you felt no difference.
Look at it in terms of the turbo being a fan where you want as little restrictions as possible for the air being sucked in and the air being blown out. Fewer restrictions means better efficiency but at some point you'll reach a position where the size of the fan is the restricting factor, not the airflow in or out so you jsut get a bigger fan. With your car, a bigger turbo and then you start over. Obviously there are other factors involved like fueling but it gives you a basic idea.
27 June 2006, 04:06 PM
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ive just found out that the system that i have taken off is NOT the prodrive system they didnt do a 3" system, so its obviously an aftermarket one of some sort, so i should be ok after all
thanks for the replys though
they didnt do a 3" system, so its obviously an aftermarket one of some sort, so i should be ok after all thanks for the replys though
27 June 2006, 05:01 PM
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Originally Posted by AlexT
It's nothing to do with bhp as such, more to do with how much you're pushing the turbo. If you're applying more boost then that means more air and fuel and thus more waste gases to expell. Although the bhp figure is around the same for the cut off point of a 2.5" system for STI's it's the dynamics of air in vs air out thats more the limiting factor, not the actual bhp figure.
Look at it in terms of the turbo being a fan where you want as little restrictions as possible for the air being sucked in and the air being blown out. Fewer restrictions means better efficiency but at some point you'll reach a position where the size of the fan is the restricting factor, not the airflow in or out so you jsut get a bigger fan. With your car, a bigger turbo and then you start over. Obviously there are other factors involved like fueling but it gives you a basic idea.
Look at it in terms of the turbo being a fan where you want as little restrictions as possible for the air being sucked in and the air being blown out. Fewer restrictions means better efficiency but at some point you'll reach a position where the size of the fan is the restricting factor, not the airflow in or out so you jsut get a bigger fan. With your car, a bigger turbo and then you start over. Obviously there are other factors involved like fueling but it gives you a basic idea.
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