minimal venturi size for 1/8

TO ALL ENGINE EXPERTS: I WOULD LIKE YOUR OPINION ON THE SMALLEST VENTURI SIZE YOU CAN RUN WITH ON 1/8 SCALE HYDRO AND NOT LOOSE TORQUE OR RPM OR OVERALL HP. THE SCALE WILL BE A PROVEN DESIGN THAT HAS ONE NATIONAL CHAMPIONSHIPS AND IS 14-15 LBS. HAS A QUALITY ENGINE IN IT LIKE MAC,CMB,K 67, RUNS...