What is the difference between an 85 13b and an 86 13b rotary engine?

The primary difference between the 85 and 86 13B rotary engines lies in their design and performance characteristics. The 1985 13B features a simpler peripheral-port design, offering decent power but limited tuning potential. In contrast, the 1986 13B introduced a more advanced engine architecture, including a bridge-port configuration that enhances airflow, resulting in improved performance and responsiveness. Additionally, changes in engine management systems and emissions controls between these years also contribute to differences in efficiency and power delivery.