The 2.1-liter Honda B21A belongs to the B20A family and was installed only in the third-generation Prelude in 1990-1991: as the B21A in the Japanese Si States version and as the B21A1 in the North American Si and Canadian SR.
It is a bored-out B20A5 with the bore increased to 83 mm. To keep the outer block dimensions, Honda used thin fiber-reinforced metal (FRM) cylinder liners. The engine has 16 valves, two camshafts driven by a belt and PGM-FI injection.
The B20A family also includes: B20A.
Specifications
| Production years | 1990-1991 |
| Displacement, cc | 2056 |
| Fuel system | injector |
| Power output, hp | 140 – 145 |
| Torque output, Nm | 183 – 186 |
| Cylinder block | aluminum R4 |
| Block head | aluminum 16v |
| Cylinder bore, mm | 83 |
| Piston stroke, mm | 95 |
| Compression ratio | 9.4 |
| Features | DOHC |
| Timing drive | belt |
| Turbocharging | no |
| Fuel type | petrol |
The engine was installed on:
- Honda Prelude 3 (BA) in 1990 – 1991.
Disadvantages of the Honda B21A engine
- FRM cylinder liners cannot be bored to repair size, so a worn block is difficult to restore;
- The timing belt must be replaced on schedule;
- Being a rare engine, spare parts are scarce.
