Exhaust pipe size

[Rockcrusher]

Just out of curiosity, is there an optimal pipe size for our little 1.4 Turbo 4s? Aftermarket systems seem to be either 2.5" or 2.25" in diameter. To be honest, 2.5" seems a little big. Is there a loss of torque with the larger pipe size or do both really perform about the same?

 

[Eric Smit]

bigger the better.

 

[firstorbit84]

4.6"

 

[sx sonic]

4.6"

dont be bashful, give him exact measurements down to the thousandth of an inch. Although this all the bolts on this car so why dont we measure to the micron?

OP since the 1.4 is turbo charged the only job of the exhuast after the turbo is to evacuate the exhuast. where as an NA engine the entire exhuast has an affect on cylinder scavenging with higher velocity exhuast favoring lowend and higher flowing exhuast favoring topend.

So to awnser your question bigger is always better on a turbo engine.

 

[teashea]

A turbocharger creates substantial back pressure so that on a turbo car, there is no need for the exhaust system to create backpressure.

 

[Rockcrusher]

Great. Thanks. BTW will adding aftermarket exhaust void any warranties (most importantly engine/powertrain), other than the exhaust system itself?

 

[turbo]

I think it's inappropriate for us to be discussing the size of our pipes on a car forum.

 

[rdss]

I think it's inappropriate for us to be discussing the size of our pipes on a car forum.

Its okay to talk and maybe even show your pipe to others as long as people aren't handling each other's pipe.

 

[laborsmith]

Great. Thanks. BTW will adding aftermarket exhaust void any warranties (most importantly engine/powertrain), other than the exhaust system itself?

To the best of my knowledge (including trading in cars with a modified/aftermarket exhaust) installing an aftermarket cat back exhaust system will not void any warranties other than that part of the system replaced.


Laborsmith

 

[ripper806]

smoke stack it!

bigger is better as far as turbo goes. The main benefit is quicker turbo spool (less lag)