Airflow On Exhaust Side Of Turbo

[Taso84]

Need a question answered regarding pressure for my hydraulics assignment

On the exhaust side of a turbo is it better to have high pressure after the turbo (ie just before front pipe exhaust) or low pressure.

Was speaking to this guy at autobahn, he reckons that it is better to have high pressure. He was basically saying that if i on my 33gtst with stok turbo, upgrade the front pipe to 3' (got the stock 1 now) i will actually increase lag because there will be less pressure. Is this true?

My instincts say no, u would want the pressure to dissipate thus increasing air velocity and in turn making the turbo spin faster. Ie i should upgrade the front pipe.

Any1 know what the answer is?

[mad082]

a turbo is spooled up by the exhaust gases passing through it. so having less pressure means that more air can pass through the turbine in the same amount of time. if it was a natro car you want some back pressure, but that has more to do with the scavenging effect.

[discopotato03]

In a perfect world there would be no pressure south of the turbine at all . Gas only wants to know about flowing from an area of higher pressure to an area of lower pressure so you want the pressure drop across the turbine in order to drive it .

Cheers A .