Asynchronous design has a potential of solving many difficulties, such as clock skew and power consumption, which synchronous counterpart suffers with current and future VLSI technologies. This paper proposes a new delay model, the scalable-delay-insensitive (SDI) model, for dependable and high-performance asynchronous VLSI system design. Then, based on the SDI model, the paper presents the design, chip implementation, and evaluation results of a 32-bit asynchronous microprocessor TITAC-2 whose instruction set is based on the MIPS R2000. The measured performance of TITAC-2 is 52.3MIPS using the Dhrystone V2.1 benchmark.