Originally Posted by Lee_R21Turbo
Ryan.....correct - hence why I was wondering if I increased the exhaust housing it might help??
Done a bit of reading on the net the reason for getting surge at lower rpms is due to too small a exhaust housing or too large compressor housing.
Increasing the exhaust turbine housing size will help prevent surge as it will delay the increase of boost with rpm so that the WOT boost curve on the compressor map misses the surge zone.
Look at the europacup turbos, they ran a 0.63 a/r T3 exhaust housing with a "stage 3" aka 76 trim turbine wheel and a T04e compressor housing witha 46 trim compressor wheel, the larger exhaust housing prevents the surge,however it also means more lag and you will have to wait longer for full boost.
Don't shoot me down if this is wrong I'm still learning....