In 1981 the B21FT (a B21F with a turbo) was introduced with a compression ratio of 7.5:1 mated with a Garrett T3 turbocharger and a T camshaft. Additional turbo variants, not offered in the US market, were the B19ET and the B21ET, based on the B19E and B21E respectively. The turbocharger increased power output to for the B21FT, and for the B21ET. boost on the B21FT and boost on the B21ET. Also new for the 1981 model year in Canada (previously introduced in 1979 outside of North America) was the B23, with a displacement of 2.3 litres ( stroke and bore). Aside from the increased bore size, the engine is identical to the B21. Volvo used a slightly different mold for the turbo engines to cast a boss for the turbo oil return line. Because a turbocharged engine has a higher operating temperature they used sodium filled exhaust valves and a thermostat controlled oil cooler (air/oil model).