How does adding another rotor to a 13b affect the choice of Turbo's?

I was thinking of fitting a GT40 but i'm not sure if the Turbine AR will be big enough for the Extra flow?

I am aiming for the 500Rwhp mark with a Extended port engine? will the GT40 be enough or would i be better of going for somthing more like a T78?

Thanks.

 

With an extended port motor, you can get that out of the stock twins...

If you must go single turbo, go with a T-70 or T-72. The T-78 is too small.

 

Whats the best Turbine AR for a 20B? i know the 13b is about .96-1.15ar but i would expect a 20b to alot higher than that.

 

You actually drop it down one or two "steps", especially against a divided turbine 13B.


-Ted