This B18 was a straight-4 automobile engine produced by Volvo Cars from 1961 through 1968. The five-bearing, cam-in-block engine, had OHV overhead valves operated by pushrods. The B18 is quite different in design from its predecessor, the three-bearing B16.

These engines are reputed to be very durable. The world's highest mileage car, a 1966 Volvo P1800, has run all its more than 4,000,000 km (2,500,000 mi) on its original B18 engine.

B18

The B18 displaced 1.8 L (1778 cc/108 in³) OHV engine and was used in the Volvo PV544, P210 Duett, 120 (Amazon), P1800 and 140 series. The B18 could also be found in the L-3314 and the Bandvagn 202 military vehicles. It was fitted to many Volvo Penta sterndrive marine propulsion systems.It was fitted too in the FACEL-VEGA Facel III.

There are actually four variations of this engine:

• B18C: single carburetor version - 40 HP SAE with a lower compression ratio and 2500 RPM mechanical regulator, fitted in the gasoline powered versions of the Volvo BM 320 tractor,
• B18A: single carburetor version - 75 HP SAE,
• B18D: dual SU carburetor version - 90 and 95 HP SAE and
• B18B: dual carburetor version - 100 and 115 HP SAE with a higher compression ratio, fitted variously with dual SU or Zenith/Stromberg sidedraft carburetors.

B20

The B20 displaced 2.0 L (1986 cc/121 in³) and was produced from 1969 to 1981. It was used from 1969 to 1981 in the Volvo 120, 1800, 140, C202 and 240 series, and also in the Haubits 77 Bofors howitzer. The design is quite similar to the predecessor B18 and many parts are interchangeable.

The later B20E and B20F versions featured Bosch fuel injection (both electronic D-Jetronic and later with mechanical K-Jetronic), larger valves, and intake/exhaust ports. Output was raised to 124 hp (DIN) (92 kW) in B20E, slightly lower in B20F because of stricter emission control and lower compression. All B20 engines displace 1986 cc from 88.9 mm bore and 80 mm stroke.

Some 240 models and the C202 were offered with the "metric", eight bolt, 2.0 liter pushrod B20 motor as standard equipment.

Despite their OHV pushrod design, the engines can rev to 6,500 rpm.