Truck Repair: jake brake, jake brake, resistance

Question
I'm curious if cutting off the intake air supply would accomplish the same thing?

Answer
no it wouldnt. by cutting the air supply to the engine your just cutting power to the engine which be no different then letting off the gas pedal. Jakes on the other hand shut off power to the engine but it uses the compression in the engine to slow you down. Blocking the intake would not give you resistance to let the engine slow you down.