Volvo Redblock Engine

Volvo Redblock Engine

The Volvo B21 was a slant straight-4 engine first used in the Volvo 200 series, meant to replace the B20. 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.


Initially the overhead camshaft versions were offered as optional equipment on the 240, becoming standard in all markets by the 1977 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 on one side of the block. The B23 blocks have them on both sides. The camshaft is driven by a toothed belt that is driven off 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 700/900 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 on 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 thinned to 9 mm, the crankshaft design and fabrication were altered and thrust bearing placement was moved from number 5 journal (B21/23) to the number 3, 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 back to the number 5 journal , bigger main bearings, rods were enlarged to 13mm from 9mm in 1990. 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. It came in two versions: the B204GT turbo motor operates with a lead resistant lambda probe and puts out roughly 200 hp. The B204FT has a catalytic converter and puts out appr. 185 hp. Both were the first redblocks standard equipped with oil squirters for piston cooling. Crankshaft, conrods and pistons all forged. Exhaust valves were sodium filled for cooler operation. It has smaller valves and stiffer valve springs than n/a 16V. Crank torque is 290 Nm at 2950 rpm for the GT, and 280 Nm for the FT.

For the B230 engines 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 made for quieter belt running. "(For this engine the volvo belt service interval shows no change from every 75k KM (47k miles)though this article previously stated it was to increase belt life to 150k (94k miles))"

At the end of 1994 Volvo improved the engines again by changing the pistons. What is better about the new pistons is unknown. 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.

pecial Versions


special version for Europe with shorter stroke then the B19, 88.9mm bore and 71.85mm stroke

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 result of a smaller bore. It is a very robust engine with forged pistons (made by Kolbenschmidt).

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. The B23ET was the only redblock known to be equiped with a small coolant passage verion of the higher flowing 405 cyl head, the FT had to make do with normal 398 head. 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.

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 auxiliary 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, forged connection rods and forged pistons, which makes it a very strong engine.

Volvo Penta

Volvo Penta sold the OHC redblocks as marine engines as well, just like the older OHV engines. Depending on the model the displacement was 2127 (as B21), 2316 cc (same as B23/B230 automotive) or 2490 cc. The engines with the bigger displacement got a longer stroke crankshaft (86 mm stroke) together with pistons with a 3 mm lower compression height. Penta used both the 8 valve and 16 valve cylinder heads.


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 cylinder * 4 cylinders = 16 valves)

The following suffixes were commonly used by Volvo:

* A - single constant-pressure type carburetor (such as the Pierburg 175 CDUS), typically with manual choke
* B - high compresion, with twin carburetor's, either twin zenith-strombergs or twin SU's.
* 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 on B230F, 9.5:1 on B280F, 10.0:1 on B234F and 10.7:1 on B6304F), 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), typically with automatic choke
* G - LH2.4 Jetronic but without cat. converter, CO adjustment on the AMM (similar to LH2.2 Jetronic). Some models without O2 sensor, others with O2 sensor which requires regular replacement at intervals due to lead fouling. For markets which unleaded fuel was rare in the early 90's, eg. Eastern Europe
* FB - low compression version of B230F (9.3:1) with the "531" cylinder head and VX3 camshaft, power output 11kW and 2Nm more than B230F. LH2.4 Jetronic fuel injection, for European markets.
* FD - essentially a B230F fitted with Exhaust Gas Recirculation (EGR) and Pulse air system for cleaner emissions
* T - turbocharged, after E or F suffix (example: B21ET, B230FT)
* FK - low pressure turbo, 1995 onward, not supplied in North America. Identical to the B230FT engine of that time but lowered boost level (4 PSI)
* FTX - Higher power output B230FT (approx 190 hp)

ee also

* List of Volvo engines
* [ Volvo Cars of N.A. Online Bookstore]

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