There are two major types of intake manifold. In general, A long intake manifold produces high torque at lower engine rpm because of the increased time between the air pulses.
Intake Air Heating is made up of different methods that manufacturers do use to heat intake manifolds.
This Heating system on vehicles are often with emission controls, air cleaners use a thermostatic valve to control how much hot air enters the air cleaner.
Conclusively there are two forms of intake manifold. They are the long and short intake manifold.