im going to be sleeving my block and getting a better turbo soon. my question is should i go 83mm to 84mm bore or stay at 81.5mm. my goal is 600hp to 650hp on my b16 with a gt35 or sc61. i see people with 81mm bore making the some Numbers im wanting and people with 84mm making the same. so looking for some in put on this.

 

All the bore sizes mentioned above are indeed capable of making the amount of power your shooting for. The bigger bore sizes have some advantages over the smaller bore sizes. An 84mm will build boost faster than the smaller 81-81.5! Also, it will take less amount of boost to reach your desired HP range. I couldn't give you an exact number though. Its really how you wanna build you motor. I will be going with 81.5 for the reason that I should have plenty of rebuilds in case of a mishap where as the 84 your limited to a few more.

 

thanks i was think about probables later on also so i mite go Little smaller at first if i can get the same numbers with just a Little slower spool i forgoer wont be all that much slower