Consider 1/2-HP models for standard doors. For most garage doors, a good quality, highly rated 1/2 HP model is adequate. The price difference is usually only $50 to $100, depending on the brand. Return to Garage … Depending on the type of drive you pair it with, the 1/2-HP motor can lift most garage door … The reliable 1/2 HP … For very heavy or tall garage doors, look at a 3/4 HP or even a 1 HP model. This Contractor Series 1/2 HP AC Chain Drive is the perfect choice for the reliability and value to your money. 1/2-HP is the standard for most garage doors, and it is also the most popular motor speed. For most single-car garage doors, a 1/3-hp unit will suffice, but for a two-car garage door, you will want at least a 1/2-hp unit. It comes with replacement operator for the old 3255 1/2 HP AC chain drive garage door opener. Balance your garage door and take care of periodic maintenance.