8 degrees out on both engines if you want to fly on 1 engine and not worry about rudder.

You lose 1% of forward thrust, but get 14% side thrust. I have tried lesser amounts and still seen the need for rudder. 4 degrees is definitely not enough.

Obviously, the spacing of the engines, the length of the fuselage and the size of the vertical tail all play into this equation. Right now I have 4 twins, 1 with engines straight ahead, 1 with 4-5 degrees and 2 with 7-8 degrees. I can tell the need for rudder on the first 2 when an engine quits.