I remember reading an article way back in the days by i think Ed Sassler and explaining that you can reduce lag by minimizing the length of the charge pipes. This way you have less space to fill up when the turbo starts to fill the pipes with air.

I guess thats why the wrx has the intercooler, turbo, and intake so close together...

 

thats highly true... but probably in the sub seconds... Narrower pipes would also move air more rapidly into the engine, but suck for higher CFM rates.

 

i read yesterday in sport compact car mag that if u re-direcct the air from the BOV back into the intake tubing it will help reduce lag.


re-circulation tube from BOV
//=================\\
<|=======||========[][]=======^=====<====>
Filter re-circ turbo BOV TB

 

that makes sense, i wonder if any one here has tried it?

 

but it wont sound as good

 

Hrm, I think the logic behind Subaru redirecting the air back in front of the turbo was actually because its kinda not governmentally accepted to have air just blowing out into the open space

 

i know the reason dsm's recirculate the air is because they use a mass airflow meter instead of a MAP sensor. the air that the BOV would be venting to atmosphere has already been accounted for by the MAF and ECU. venting it to atmosphere would make the car run pig rich. so they recirculate it post MAF/pre turbo. i dunno whether WRX's are MAF or MAP. i think they're MAF as well, as it seems to better suit turbo cars from the factory..

one thing that helps is porting out the turbine housing. smooth the surfaces inside the housing (that are normally like 60grit sandpaper) and the airflow will improve through the housing because there is less surface area for the air to "catch" on and lose energy. same with the compressor housing. make the inside as smooth as possible.

use a pressure relief valve between the pressure source and wastegate to prevent the wastegate from seeing any boost until it reaches the level you want to open it (or maybe a psi or 2 before that to minimize spiking). the valve blows, opens the wastegate and you hit the limit, but spool time is much faster because the wastegate isn't creeping open as the boost rises. the grainger valve/dawesdevices/gus mahon boost controllers do this.

 

you will still hear the BOV sound. Not quite as loud, but with a open filter on the intake tube you will still hear it. The same way when u put an intake on your stock motor you get a growl from the open filter.