BMW M30B35/M30B34 Engine

Characteristics of the M30B35 engine

The characteristics of the M30B35 engine produced at Munich Plant between 1982 and 1992 are as follows:

This inline six-cylinder engine has a cast iron cylinder block and an injector power system. Each cylinder is equipped with two valves.

Power output is 185 horsepower at 5,400 rpm, 211 horsepower at 5,700 rpm, or 218 horsepower at 5,500 rpm, depending on the version.

Peak torque reaches 290 Nm at 4,000 rpm, 305 Nm at 4,000 rpm or 310 Nm at 4,000 rpm, depending on the version.

Fuel with an octane rating of 92 is recommended for this engine.

Average fuel consumption for the E34 535i is 17.3 liters per 100 km in the city, 8.0 liters per 100 km on the highway and 9.8 liters per 100 km in mixed mode.

Oil consumption can reach up to 1000 grams per 1000 km. For the M30B35 engine it is recommended to use oils with viscosity 5W-30, 5W-40, 10W-40 and 15W-40, and the volume of oil in the engine is 5.75 liters. It is recommended to change the oil every 7000-10000 km.

The operating temperature of the engine is approximately 90 degrees Celsius.

The resource of the M30V35 engine on the factory data is not specified, but in practice it can be estimated in more than 400 thousand kilometers. The tuning potential of this engine can reach 800 horsepower without loss of resource. The M30B35 engine was installed in BMW M535i E28, BMW 535i E34, BMW 635 CSi E24, BMW 735i E32, BMW M535i E12 and BMW 735i E23.

Reliability, problems and repairs of the BMW M30B35/M30B34 engine

Until the introduction of the M60 series in 1992, which was a V8 engine, most of the market was occupied by inline sixes known as the M30. Despite being co-produced with the M20, also an inline six, the M30 had more in common with the M10, the junior model of the four. The first M30s were introduced nearly 50 years ago and were gradually improved and modernized. One of the most advanced variants, known as the M30B35/M30B34, was launched in 1982 and was intended for BMW’s 35i cars.

The BMW M30B35/M30B34 engine was an inline six in a cast iron cylinder block similar to the M30B30, but with a crankshaft having a piston stroke of 86 mm (instead of 80 mm in the M30B30) and an increased cylinder bore from 89 mm to 92 mm. The height of the cylinder block remained the same. The connecting rod length was 135 mm and the piston compression height was 39.85 mm.

The M30B34/B35 cylinder head was single-shaft with 12 valves, without hydrocompensators, so valve adjustment was recommended every 10 thousand kilometers. The clearances (for a cold engine) on the intake and exhaust were 0.3 mm. M30B35 camshaft characteristics: phase 248, lift 8 mm.

The intake manifold was modified and 214 cc injectors were used.

The timing gear was chain driven. The fuel supply system was by means of an injector.

There were different versions of this engine: with catalytic converter and pistons with compression ratio of 8, working with Bosch Motronic 1.0, developing 185 hp at 5400 rpm; without catalytic converter and with pistons with compression ratio of 10, giving 218 hp at 5500 rpm; as well as a version with a catalytic converter, pistons with compression ratio of 9 and with Bosch Motronic 1.3, providing up to 211 hp at 5700 rpm.

In 1992, the M30B35 engine was replaced by a more modern V8 engine, the M60B40.

Problems and disadvantages of BMW M30B35 engines

Overheating

This problem is common among many BMW inline 6-cylinder engines and should not be ignored, as it can cause damage to the cylinder head. Causes of this malfunction can be related to a dirty radiator, faulty pump, thermostat or air plugs in the cooling system.

Cracks in the cylinder block

These can appear around the threads for the cylinder head bolts due to oil residue in the threaded holes after the engine has been disassembled. Signs that indicate cracks in the M30 engine include loss of antifreeze and emulsion formation in the oil. It is possible to solve this problem through repair, but a more reliable and correct option would be to purchase a used cylinder block without cracks.

Given the high age of BMW M30 engines, wear and tear is added to the above problems, which can affect everything that is possible. Most often there are problems with the timing mechanism, which leads to the inability to adjust the valves. This can be solved by replacing worn parts such as eccentrics, valves and guide bushings. It is also not uncommon for the DMR to malfunction.

To date, all BMW M30 engines have exhausted their resource, despite the fact that it can be quite high and exceed 500,000 km. Most cars with M30 are operated quite harshly, especially E34, which additionally accelerates wear and tear.

The BMW M30B35 itself was an excellent engine for its time, but time spares no one. If you’re choosing between the M30 and the M50 (and other engines in this series) when buying a BMW, it’s worth preferring the newer M50.

BMW M30B35 engine tuning

M30B35 Atmo. Stroker

There are plenty of tuning parts for the M30 on the market, and if you have the financial resources, you can achieve a small increase in horsepower, but first of all, you need to get your engine in good condition. If the engine requires a major overhaul, no amount of improvements in the form of new shafts will help. Once the M30B35 has been rebuilt, there are two development paths available:

1. The first option involves installing a 98mm stroke crankshaft, short connecting rods and boring the cylinders for 93.4mm forged pistons. This will allow to achieve a working volume of 4.0 liters, and with boring to 95 mm – 4.2 liters. However, the cost of such kits is higher than the cost of the car itself.
2. The second way involves milling the cylinder head to increase the compression ratio to ~11, modifying the channels and combustion chambers, installing a sport intake, Schrick 284/280 (or similar) camshaft, reinforced rockers, 76 mm straight-through exhaust and tuning the brains. This will produce around 240-250hp, but the old and heavy piston assembly tends to be reluctant to spin, so replacing it with a lightweight forging and installing a throttle from an S38 is recommended. Ultimately, a cheaper option may be to purchase a BMW S38 with 340 hp and do a swap.

Turbo M30B35

The factory BMW M30 engines have a very low compression ratio, so there is no need to decompress them for supercharging, making turbocharging much easier than the atmospheric version. You can buy an inexpensive turbo kit for the BMW M30 on eBay and install it on a standard engine. Or you can buy a Chinese Garrett GT35 turbocharger separately, along with manifold, 3-inch diameter pipes, intercooler, westgate, block-off valve, 630 cc injectors, and Megasquirt control unit. By raising the pressure to 0.8-1 bar, power close to 400 hp can be achieved.
Chinese turbines have a short service life, after a few thousand kilometers, replacement is required. Original Garrett GT35 turbochargers are much more reliable and efficient, but their price is several times higher.

Similar results can be achieved with a compressor, but the turbocharger is usually more efficient.

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