What effect does leaving the carburetor heat on during takeoff have?

Leaving the carburetor heat on during takeoff increases ground roll because carburetor heat introduces warm air into the engine's intake, which can reduce air density entering the carburetor. This decrease in air density leads to a reduction in engine power since the engine is not receiving the optimal amount of cool, dense air needed for combustion. As a result, the aircraft may require a longer distance on the runway to achieve the necessary speed for takeoff.

In a standard takeoff procedure, using carburetor heat is not advisable unless specifically required for icing conditions, as it affects engine performance negatively. During takeoff, maximizing engine power is critical for ensuring a short and safe ground roll, which is compromised when carburetor heat is applied.