I couldn't find anything specific to my combo when searching, so I'll put the question out there. What size wastegates for a 650-750 fwhp 355 with twin 57's? Right now my guess would be around 14- 16 lbs of boost to make the above power numbers.

 

You could put the internal WG's on those compressors they are the hybrid T3/T4 deals I believe but if your wanting to go external 35-38mm would be fine for it.

 

They are an external wastegate type with an exhaust ratio of .84 and a twin scroll, but otherwise similar to the ones you said. Thanks.

 

No reason to complicate things internal gates will work fine.

 

There is no place for internal wastegates, only a v-band for the exhaust side.

 

He is referring to the exhaust side. The V-band part you have, is part of a 5 bolt flange on back that would come off and the Internal gates would replace it. You'd just have to clock it to the bracket on the Turbo housing, and it becomes part of the new clamp/bolts that hold the housing face on. Then the back of the internal gate has your V-band location to put the exhaust too. But by clocking the actuator and arm, its allowing for free movement and not binding.

 

The v-band is one piece with the turbine housing, no bolts or anything. Wish I could post pictures, but it really is only a external type setup. Thanks for the help, that is why I joined this group.

 

Ah gotcha, 2 38mm gates will be fine.

 

38's it is. Thanks.