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The Toyota B engine family was a series of inline-four diesel engines.
Toyota also had a 3.4 L (3389 cc) inline-six gasoline engine from 1937 to 1947 that was also called the B engine. The earlier engine was used in early Toyota cars and trucks and in the first version of the Land Cruiser when it was known as the BJ Jeep. The later engine was used in later versions of the Land Cruiser. The two engines are unrelated and were not made at the same time.
Toyota made 5 generations of the B family engines, each one identified with a number before the B letter. Also, Toyota uses a series of letters to identify technical improvements to their engines:
- The number 1 (one) before the number of the engine model means that the engine uses direct injection, otherwise, indirect injection
- The F letter after the B letter means that the engine is multivalvular. Since the B family are inline-fours, that means that the engine uses 16 valves.
- The T letter, means that the engine is turbocharged
- The E letter, means that the engine is electronically controlled engine control unit (ECU)
For example, the 15B-FTE Engine is the fifth generation of the B engines, comes with 16 valves, is turbocharged, direct-injected and uses an ECU.
In August 1988, Toyota released re-designed B series engines (specifically the B, 3B and 11B) with a number of improvements. A mono-block design (with no cylinder liners) was adopted. An onboard, timing gear driven vacuum pump replaced a previously alternator-driven vacuum pump (Later a gear-driven power steering pump would be added to the 3B, 14B and 15B platforms). Camshafts gained larger bearing journals and roller lifters replaced earlier solid lifters. Pushrod inspection galleries disappeared to make a more solid engine block. The flywheel changed from 6 to 8 bolts and a PCV hose replaced the road draft tube. Toyota does not make a distinction in the naming of these engines, but in user communities the August 1988-on 3B is referred to as the '3B-II'.