BMW M88

BMW M1 engine

The BMW M88/3 is an inline 6-cylinder (I6) piston engine. It was based on the M88/1 that was used in the BMW M1's street version, with double overhead cam and four valves per cylinder. The M88/1 was in turn based on the M49 engine which was used in the BMW 3.0CSi. The M88/3 was used in the early BMW M635CSi and BMW M5 (E28) and produced 286 PS (210 kW/282 hp).

BMW engineers used a 4-valve head and a single-row chain. The cylinder head was made in two parts. The lower part formed the combustion chambers and water jackets, and the upper half contained the camshaft bearings and the bores for the tappets.

Kugelfischer fuel injection was used with individual throttle valves and the distinctive six inlet pipes. The M88 produced 277 bhp in the version built from 1978 to 1981 for the BMW M1.

For the Procar M1's, the M88 was tuned to 470 to 490 bhp. The resulting M88/1 engine had new camshafts, bigger valves, reshaped ports, forged pistons, use of throttle slides (instead of butterfly valves), and improved exhaust.

For Group 5 racing, the engine was pushed to between 850 and 900 bhp by the addition of two turbochargers. This was the M88/2 powerplant.

From 1985 to 1987 the M88 was used in the European-market 5 Series M5 (E28) and from 1983 to 1989 in the 6 Series M635CSi Coupe (E24). The engine was designated M88/3 and produced 286 bhp. It was also fitted to the South African 745i as substitute for the turbocharged motor due to the proximity of turbocharger in the right-hand side of engine bay where the steering column and box would be.

S38

The S38 was an updated M88/3 and produced in three versions :

S38 B35 - US-spec BMW M5 (E28) and E24 BMW M6 and late-production catalyst-equipped European market M635CSi (260 DIN HP).

S38 B36 - all US-spec and '89-'92 European-spec BMW M5 (E34)

S38 B38 - '92-'96 European-spec BMW M5 (E34)

The S38 B35 was a revision of M88/3 with dual-row timing chain, reduced compression, catalyst-equipped and fitted with tubular exhaust manifolds rather than equal length "bundle of snakes" headers.

For the S38 B36 displacement was enlarged from 3453 to 3535 cc. Thanks to the use of a Bosch Motronic 1.2 engine management, power grew to 315 PS (232 kW/310 SAE hp) at 6900 rpm. A dual-stage intake plenum helped to improve flexibility over the rev range. All versions were catalyst-equipped. With respect to the B35 unit, the B36 revision had increased compression and used longer duration camshafts, larger throttles and larger valves. European and US versions both used equal-length exhaust headers.

In 1992, with the introduction of Euro I emission legislation, BMW opted to enlarge the engine once more, to 3795 cc, with power climbing to 340 PS (250 kW/335 SAE hp) and torque going up to 400 Nm (295 lb·ft). Coil-on-plug ignition replaced the traditional distributor from the B35 & B36. The B38 engine also received a Motronic 3.3 engine management. This engine was used in the M5 until the E34 finished production in 1996.

Production Models

Engine	Displacement	Power	Torque	Bore	Stroke	Year	Application
M88/1	3.5 L (3,453 cc (211 cu in))	203 kW (272 hp) @ 6500 rpm	330 N·m (243 lb·ft) @ 5000 rpm	93.4 mm (3.7 in)	84 mm (3.3 in)	1978–1981	BMW M1
M88/3		210 kW (282 hp) @ 6500 rpm	340 N·m (251 lb·ft) @ 4500 rpm			1983–1989	BMW E28 M5, BMW M635CSi
S38 B35		188 kW (252 hp) @ 6500 rpm	330 N·m (243 lb·ft) @ 4500 rpm			1986–1988	BMW E28 M5 (NA spec), BMW M6 (NA spec), BMW M635CSi with catalytic converter
S38 B36	3.6 L (3,535 cc (216 cu in))	231 kW (310 hp) @ 6900 rpm	360 N·m (266 lb·ft) @ 4750 rpm	93.4 mm (3.7 in)	86 mm (3.4 in)	1989–1993	BMW E34 M5 (NA spec) and Euro spec 1989–1992
S38 B38	3.8 L (3,795 cc (232 cu in))	250 kW (335 hp) @ 6900 rpm	400 N·m (295 lb·ft) @ 4750 rpm	94.6 mm (3.7 in)	90 mm (3.5 in)	1992–1996	BMW E34 M5

See also

BMW S14 - Engine fitted to the E30 M3