BMW M30B35 engine

BMW M30B35 is one of the most popular powertrains from the German manufacturer, which was produced in various modifications. This is a six-cylinder engine equipped with 8 valves (2 for each cylinder). It was installed on cars of the concern from 1968 to 1992. To date, this motor is considered obsolete, despite the fact that a huge number of cars still drive on it. Unpretentiousness in maintenance, long service life and lack of serious problems and technical flaws allowed the engine to become one of the most popular and reliable. Until the moment, when in 1992 there was a series of motors M60, having eight cylinders, in its place was a line of M30, providing a large volume and in-line arrangement of 6 cylinders. At the same time with this motor produced and in-line six-cylinder M20, but it had more in common with its little brother M10.

The first engine of the M30 range saw the light of day more than 50 years ago. During its existence, the motors have been constantly modernized and improved. M30B35 is one of the most popular variants, which was produced since 1982 and installed on cars of the German concern with the index 35i. This is an inline six-cylinder engine, which had a cast-iron block, just like the M30B30. A distinctive feature was the increased stroke of the piston on the crankshaft – instead of 80 millimeters it was 86. The cylinder diameter was also increased to 92 millimeters, up from 89. There were no changes to the height of the cylinder block. The connecting rod was 135 millimeters long, with a piston compression height of 39.8 millimeters.

The cylinder head was equipped with one shaft with twelve valves. There were no hydrocompensators on this engine, so the valves had to be adjusted after every 10 thousand kilometers of mileage. The intake manifold of this power unit also received changes. The injectors were replaced by units with a capacity of 214 cc. The timing was driven by a chain, and an injector was used for fuel supply.

Several modifications of this power unit were presented. The choice of buyers was offered an engine without a catalyst, which was able to develop up to 185 horsepower. The version of the motor without a catalytic converter allowed to get about 218 horses at the output. There was also a third version of the engine with a catalyst, which was equipped with pistons under compression ratio 9, allowing to provide a power of 211 horsepower.

1992 was the last year for production of these engines. They were replaced by the improved and modern M60B40 engines with eight cylinders.

M30B35 engine specifications

Disadvantages

A classic problem for all German six-cylinder engines is overheating of the power unit, which should not be ignored, otherwise the risk of cylinder head failure increases. Thermostat failure, pump failure, radiator contamination or air plugs in the cooling system are all causes of overheating in six-cylinder engines.

Crack formation in the cylinder block. When engines are disassembled, oil is not removed from the thread wells, which can cause cracks to form around the threads for the head bolts. Oil emulsion and antifreeze leaving are the main symptoms that indicate cracks in the engine block. Some owners of cars with this engine try to solve the problem with repairs, but the safest option is to buy a used but whole block. Given that cars with such an engine have not been produced for a long time, then to the above problems can be added to the wear and tear of parts. The timing mechanism often succumbs to wear, which makes it impossible to adjust the valves. Replacing the eccentrics solves the problem along with worn valves and guide bushes.

The resource of such power units exceeds 500 thousand, but despite this, almost all cars have already rolled it out. Also, an additional imprint on the performance of the motor is its hard operation, which is frequent for such cars.

The motor is very well made for its time, but years of use do not go away. Therefore, at the time of purchase it is better to lean towards cars with newer M50 engines.

Chip Tuning

The availability of a large number of parts for tuning M30B35 motors allow you to get extra power if you have a certain amount of cash. But first you need to do a proper overhaul. After the repair, there are two ways of tuning – stroker or atmospheric engine on shafts. For the first option will have to install a crankshaft with a piston stroke of 98 millimeters, shortened connecting rods and bore the cylinders for forged pistons with a diameter of 93.4 millimeters. This will give an opportunity to get 4 liters of engine displacement. Boring to 95 millimeters will give 4.2 liters. It will not be possible to achieve a larger volume.

The second option is milling of the cylinder head to achieve a compression ratio of up to 11. The ducts and combustion chambers can also be modified. A sports intake, reinforced rockers and a re-flashed engine control unit are installed. Also will not do without replacing the camshaft with a Schrick 284/280. This will make it possible to get about 250 horsepower. But the heavy old piston spins reluctantly, so it is better to replace it with forged pistons. Motors with factory settings are characterized by a low compression ratio, so it is not necessary to unclench under the supercharger installation. This entails one conclusion – it is many times easier and cheaper to supercharge such a motor than to make it atmospheric. There is a huge number of inexpensive turbo kits for M30B35, which allow you to remove under 400 horsepower with a supercharger up to 1 bar.

The set of tuning is also present for the compressor engine, but the installation of a turbine gives a greater effect and is cheaper. This is the best option, despite the fact that Chinese turbines have a very short life span.

This engine is installed on the following models:

BMW 5-Series (E34)