That wouldn't be the ideal way to stop a car nitro engine. If you were to set it up to where you turn your idle screw down to the point where the engine stalls out, you would be hurting your braking. If you went to hit the brakes that would force the carb to close off completely and then you would be cussing that your car keeps stalling when you hit the brake. Use any of the above suggestions. If you use the pinch the tube method, watch your fingers. Its pretty close to most fly wheels. My preference is to just close off the exhaust port on the muffler. It floods the carb and stalls the motor but it also makes it start easier after a 20 min cool down period. I have yet to see it hurt any of my motors.