Newbie question... is the crank pully and underdrive pulley the same?

 

Crank pulley is attached to your crankshaft (and the thigh bone is connected to the leg bone )

Underdrive pulley is your Alternator or Power Steering.

 

The crank pulley is the pulley at the end of the crankshaft providing power to the accessories pulley via the belts.

The accessory pulleys are the pulleys attached to tha AC compressor, PS pump, and alternator.

Both types of pulleys (crank and accessories) can be "underdriven". Underdrive pulleys are smaller diameter in the case of the crank pulley, in order to provide less drive to the accessories than stock, meaning the accessory pulleys will rotate slower. Accessory pulleys are larger in diameter, so that there has to be more belt travel to complete one rotation compared to a stock pulley. In both cases, the goal that is achieved is underdriving the accessories, or making them rotate slower by changing their diameter.

For more details on pros and cons with underdrive pulleys, check these links out:
https://honda-tech.com/zerothread?id=416889
https://honda-tech.com/zerothread?id=319189

Hope it answers your question.
Jeff

 

thanks for the info!