Backpressure?

[wmerrell]

Wanted more horsepower by increasing the boost to 25 lbs. The tuner told me the car had too much backpressure. The boost ended up at 20lbs on a 49 turbo producing 348 rwhp.
Can someone explain this? What is needed in order to reduce the backpressure in order to increase the boost? different downpipe? open up the exhaust? bigger turbo? Cam? Heads?

 

[bison]

A larger turbine and larger compressor wheel is needed.

 

[kidglok]

my 49 could not keep the boost up with champion heads and a 212 roller. It would hit 22 then fall off to 17 as the rpm's came up. The engine was consuming the air faster then the turbo was able to supply it. Maybe it was backpressure, or maybe its what i think it is. But what bison said held true in my case.

 

[bison]

my 49 could not keep the boost up with champion heads and a 212 roller. It would hit 22 then fall off to 17 as the rpm's came up. The engine was consuming the air faster then the turbo was able to supply it. Maybe it was backpressure, or maybe its what i think it is. But what bison said held true in my case.

It's probably more than one thing. 53lbs/min is about it for that turbo.