Volvo Redblock Engine
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The Volvo B21 was a slant straight-4 engine first used in the Volvo 200 series, meant to replace the B20. The new B21 maintained Volvo's legendary reputation for designing durable motors. The B21 and all derived engines are often referred to as red block motors for the red paint applied to the block. The primary differences when compared to the B20 were the switch to a single overhead cam (SOHC) in place of the older pushrod configuration, and an aluminum crossflow cylinder head versus the iron head of the B20.
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[edit] History
Initially the overhead camshaft versions were offered as optional equipment on the 240, becoming standard in all markets by the 1976 model year. The overhead camshaft motors were available in displacements of 2.0 (B19 and B200), 2.1 (B21), and eventually 2.3 (B23 and B230) liters. The B21 featured an 80 mm stroke, and 92 mm bore. In the US, the B21's power output ranged anywhere between 98 hp and 107 hp (73 to 80 kW), based on variations in the compression ratio and was typically supplied with a B or M camshaft.
The engines are tilted approx 15 degrees to left (exhaust side) to make room for the more complicated injection systems. B19 and B21 blocks can be identified by water plugs one side of the block. The B23 blocks have them on both sides. The camshaft is driven by a toothed belt that is driven of the front of the crankshaft. The belt turns the intermediate shaft as well, which in turn drives the oil pump, distributor (on 240 engines and BXX 700 series engines) and the fuel pump of carburetor models.
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 off of the B19E and B21E respectively. The turbocharger increased power output to 127 hp (91 kW) for the B21FT, and 180hp (134 kW) for the B21ET. Also new for the 1981 model year was the B23, with a displacement of 2.3 liters (80 mm stroke and 96 mm 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).
In 1983 the B23 was introduced to the American market. Also introduced in 1983, the "intercooler boost system" (IBS) was introduced for the B21FT motors. The IBS kit consisted of an intercooler, appropriate ducting, a new fan shroud, new oil cooler lines and mounting brackets, and optionally an automatic transmission shift kit. IBS raised the output of the B21FT to 162hp, still less than the European market B21ET's 180hp.
Midway through the 1984 model year, the "intercooler boost system" became standard on American 240 Turbos. Additionally a bigger clutch and a stepped flywheel were included.
In 1985 a revised, "low friction" design was introduced, dubbed the B200 and B230 (depending on displacement).
The improvements were different, longer rods (152 mm c-c, 7 mm longer), pistons with a lower compression height, lower friction bearings (smaller in size) ,a crankshaft with 8 counterweights (instead of 4 on the older Bxx engines) and a heavy harmonic balancer in the crank pulley.
However, the robustness of the reciprocating assembly was decreased. The engine rods were sized down from 13 mm to 9 mm, the crankshaft design and fabrication were altered and main bearing placement was altered, together with smaller bearings. This low friction design was used throughout the remainder of the "red block" production.
1989 saw an upgrade to the crankshaft, with a relocated axial thrust bearing, bigger main bearings, and the use of thicker (stronger) rods . Also introduced in 1989 were 16 valve, twin-cam variants of the B200 and B230, dubbed the B204 and B234 respectively. The B204 was also available in turbo form in some markets (such as Italy) where large displacement motors were taxed heavily. The B204 turbo motor put out roughly 200 hp.
For 1993, piston cooling, oil squirting jets were added to help alleviate piston slap problems on the turbo motors. Another modification was to go from a square toothed timing belt setup to a round toothed timing belt setup which increased the service interval from 75.000 km to 150.000 km.
At the end of 1994 Volvo improved the engines again by changing to pistons with longer skirts to eliminate piston slap. These engines weren't available in the USA. All cars equipped with the updated M90 5-speed manual transmission have these better engines.
The last redblocks were made in 1998, when the 940 model was discontinued.
[edit] Special Versions
[edit] B19 Turbo
The B19ET was sold in certain markets where engines of over 2 liter displacement were heavily taxed, like Italy. The engine has the same stroke as all other redblocks, the smaller displacement is the resuslt of a smaller bore. It is a very robust engine with forged pistons (made by Kolbenschmidt).
[edit] B23 Turbo
The B23ET and B23FT motors were offered for two years only in the 1983 and 1984 760 Turbo. Both the B23ET and B23FT are somewhat unique in the 700 series as they are were only turbo motor offered in the 700 series with a block mounted distributor, forged pistons and a forged crankshaft. As these motors predate the low-friction B200 and B230 turbos and are equipped with forged pistons and crank, they are often considered one of the most robust Volvo turbo motors.
[edit] 16 Valve
The 16-valve red block motors were offered in both 2.0 liter and 2.3 liter version. The head was designed for Volvo by Cosworth. In addition to the sixteen valve head, these motors were equipped with twin counter rotating external balance shafts. The block differed from the standard B230 in that the auxialliary shaft (used to drive the oil pump and distributor on models that had block mounted distributors) was replaced with an external oil pump. The 16-valve head was, itself, a completely new design for Volvo. The head was of a multi-piece design featuring a separate cam carrier and lower section. The later "white block" motors can trace their head design back to the two-piece setup found in the B204 and B234. The 2.0 liter variant was available in turbocharged form, in some markets (B04FT/GT). Unique to the B204 turbo was an exhaust gas pyrometer which was used to detect excessively high exhaust temperatures. When excessively high exhaust temperatures were detected, the fuel injection computer would richen the mixture. It features a forged crank and forged pistons, which makes it a very strong engine.
[edit] Nomenclature
The B21, and related red block motors, were named using the following convention: B##X or B##VX. Where B stands for "bensin" (gasoline), ## stands for the displacement in deciliters, and X is an appropriate suffix. On the later low-friction motors, V denotes SOHC configuration (0) or DOHC configuration (4, for 4 valves per cylinder).
i.e. B230 (SOHC, 2.3 Liters), B234 (2.3 Liters, DOHC * 4 valves per cylnder * 4 cylinders = 16 valves)
The following suffixes were commonly used by Volvo:
- A - single constant-pressure type carburetor (such as the Pierburg 175 CDUS)
- E - high compression, no catalyst, fuel injected (usually K-Jetronic, LH2.2 Jetronic, or Motronic on the turbo motors)
- F - low compression (9.8:1), USA/Europe version (F for Federal) with catalytic converter.
Europe/APAC version, fuel injected (usually K-Jetronic or LH Jetronic)
- K - single jet type carburetor (such as the Solex-Cisac carbs)
- FB - low compression (9.3:1), fuel injected, Europe version, LH Jetronic.
- T - turbocharged, after E or F suffic (example: B21ET, B230FT)
- FK - low pressure turbo, 1995 onward, not supplied in North America. Identical to the B230FT engine of that time but lowerd boost level (4 PSI).
- FTX - Higher power output B230FT (approx 190 hp).
