Circle D Specialties Torque Converters are the best upgrade for cars N/A, nitrous or forced induction cars. Available in billet single disc and multi disc high performance and pro performance torque converters. Choose the Stall Speed with standard Dual Disc or 5 Star Penta Disc for extreme heavy duty applications such as drag racing or weekend grudge racing. Beefcake Racing runs Circle-D Converters in all their automatic equipped race cars. Beefcake Racing is an Authorized Dealer for Circle-D Torque Converters, call 1-855-827-7223, 9am-10pm EST.