boost or no boost

[ks71z28]

I calculated my system brake torque from my old set up, 12" fronts 2.75" caliper bore, 11" rear with 2.5" bore. 1.125" master, power brakes 9" dual diaphram

New
12.75" front rotor, (2)1.69" pistons bore, rear 12" rotor, 1.75" bore, 7/8" master, manual brakes. (for better brake feel)

I cannot stop the car. Old brakes had poor feel, but would lock up and stop on a dime if needed. New system no way here is what my calculations revealed

Old total system torque- 2040 ft lbs
Pressure to calipers with booster 1080psi

New system total torque- 1077 ft lbs
pressure to calipers no booster- 938 psi

Conclusion, those big GM single piston calipers grab! If I change to a smaller bore master 13/16" i can gain 13%, and 3/4" I can gain 36%, but still off the old system.

Keep this in mind when upgrading to "big brake kits"