I'm trying to squeeze every bit i can up top on my 10.5 hot side turbo. I know a lot of people go with a 3" SD intake on a stock turbo. Curious to see if anybody has tried going with a 4" intake on any stock turbo and what results they got.

 

Ramses(wshihdnevo) runs a IX turbo w/S.D. on the stock stock ECU. I may be mistaken, but I think that his setup is 4" all the way from the filter outlet to a 4"-3.25" reducer coupling at the inlet of the 84mm FP anti-surge ported compressor cover. Maybe I have the facts wrong though as I have never personally seen the setup. So, your best bet would be to contact him directly via P.M. Or, maybe he'll post up on your thread if he sees it. GL.

 

You realize that when modding your stock turbo for max power on a stroker engine that you shouldn't only be thinking about the compressor side of the turbocharger. That is, S.D. and 4" intake should help, but turbocharger efficiency is directly related to the pressure differential between the compressor and the turbine.

Since your goal is to max out the stock turbo on a larger than stock displacement motor, then you should also be worried about maximizing turbine efficiency...i.e. reducing exhaust back pressure in the turbine housing. One method would be to have the turbine wheel "clipped". But, I am guessing that you probably wouldn't want to go to the trouble of sending the wheel into a shop to have it clipped and then rebalanced.

So, you are gonna need to fully port the turbine housing to minimize back pressure and maximize turbocharger efficiency. The twin chambered turbine inlet area of the housing needs to be fully hogged out. I think that it can be done while still leaving the dividing wall intact in the inlet area, although Mikey removed it altogether. Also, the turbine discharge area needs to be ported to resemble a trumpet bell. This will unshroud the turbine wheel's exducer.

Modding the turbine in this fashion will reduce power in the bottom end, but you will definitely see gains up top.

 

Hey thanks for the great info. I'lk try contacting him and I believe turbojunkie was doing something simliar with his sd stock turbo setup. I have a toxifab o2 dump collecting dust right now to help with some of that back pressure. I was debating getting the hotside ported by ppi but the car is still my daily currently and i dont want to be without for a couple days.
I didnt know ppl still clipped the wheels in the evo 16gs

 

I'd rather have a good inlet profile then the 4" tube. I went 3.5" with a velocity stack on the stock turbo. I also had it sticking out the front of the car by using a half width radiator and making a pseudo forward-facing setup.

http://www.bpi-us.com/stacks.php