Engines

List of Engines

To maintain and repair your engine, you need to know what lump you have under the bonnet of your E30. Below is each engine, listed by model and year, for the E30. By clicking on the engine, you will have access to information regarding Maintenance, Cooling systems, Fuel, Intake, Exhaust and Electrical systems, as well as Common Problems and Upgrades.

Name	Engine code	Volume	Engine	Valvetrain	Fuel	Output	Torque	Years
316	M10B18 M40B16	1766cc 1596cc	4cyl	SOHC 8V	Petrol	99hp (66kW) @4500 rpm 102hp (75kW) @4500 rpm	103ft/lb (140Nm) @4250 rpm 105ft/lb (140Nm) @4250 rpm	1982–1990 1988–1995
318	M10B18 M40B18	1766cc 1796cc	4cyl	SOHC 8V	Petrol	104hp (77kW) @4500 rpm 113hp (85kW) @4500 rpm	103ft/lb (140Nm) @4250 rpm 122ft/lb (165Nm) @4250 rpm	1982–1990 1987–1995
318iS	M42B18	1766cc	4cyl	SOHC 8V	Petrol	140hp (104kW) @4500 rpm	127ft/lb (172Nm) @4250 rpm	1989–1991
320i	M20B20	1990cc	6cyl	SOHC 12V	Petrol	123hp (92kW) @5800 rpm 127hp (95kW) @6000 rpm	125ft/lb (170Nm) @4000 rpm 120ft/lb (164Nm) @4300 rpm	1982–1985 1985–1991
320iS	S14	1990cc	4cyl	DOHC 16V	Petrol	192hp (143kW) @6750 rpm	155ft/lb (210Nm) @4750 rpm	1982–1990
323i	M20B23	2316cc	6cyl	SOHC 12V	Petrol	139-150hp (104-110kW) @4500 rpm	0ft/lb (0Nm) @4000 rpm	1982–1985
325e	M20B27	2693cc	6cyl	SOHC 12V	Petrol	127hp (95kW) @4250 rpm	169ft/lb (230Nm) @3200 rpm	1982–1990
325i	M20B25	2494cc	6cyl	SOHC 12V	Petrol	169hp (125kW) @5800 rpm	163ft/lb (222Nm) @4300 rpm	1982–1990
325iX	M20B25	2494cc	6cyl	SOHC 12V	Petrol	169hp (125kW) @5800 rpm	163ft/lb (222Nm) @4300 rpm	1982–1990
M3	S14	2302cc	4cyl	DOHC 16V	Petrol	197hp (147kW) @6750 rpm 212hp (158kW) @6750 rpm	176ft/lb (0Nm) @4750 rpm 170ft/lb (0Nm) @4600 rpm	1986–1988 1989–1991
M3 Evolution	S14	2302cc	4cyl	DOHC 16V	Petrol	197hp (147kW) @6750 rpm	176ft/lb (0Nm) @4750 rpm	1987–1987
M3 Evolution II	S14	2302cc	4cyl	DOHC 16V	Petrol	217hp (162kW) @6750 rpm	181ft/lb (0Nm) @4750 rpm	1988–1988
M3 Sport Evolution	S14	2467cc	4cyl	DOHC 16V	Petrol	235hp (175kW) @6750 rpm	177ft/lb (0Nm) @4750 rpm	1990–1990
324d	M21D24	2443cc	6cyl	SOHC 12V	Diesel	84hp (63kW) @4600 rpm	112ft/lb (152Nm) @2400 rpm	1985–1993
324td	M21D24	2443cc	6cyl	SOHC 12V	Diesel	114hp (85kW) @4800 rpm	162ft/lb (220Nm) @2400 rpm	1985–1993

If you are still unsure about which engine you have in your car, you can find the number on the engine itself.

Maintenance

All engines need looking after, and while simple jobs like oil changes are standard to all E30s, some jobs are specific to either the 4-cylinder or 6-cylinder engines. Click on the engine model for your car to get specific information:

• M10
• M20
• M40

Special engines

• M42
• S14

The following topics are standard maintenance tasks to keep all engines running smoothly

• Cleaning the Injectors

Ancilliaries

The main body of the engine is surrounded by ancillary components to supply fuel, air and spark, as well as devices for lubrication and cooling. The overall engine is controlled by an engine management system.

Fuel

Main article: Fuel

All cars need motion lotion. This is stored in a tank under the rear seats. From there, the fuel is delivered via a fuel pump, through a filter and hard pipes, to the engine bay. From there the pipes are made from rubber, and enter a fuel rail. At times controlled by the ECU, injectors will squirt fuel into the relevant cylinder of the engine. From the other end of the fuel rail is a fuel pressure regulator and return fuel line, which returns fuel to the tank, making a closed loop.

On carburettor engines, the fuel rail, injectors and fuel pressure regulator are replaced by a carburettor, which connects to the inlet manifold.

Air

Main article: Intake

All engines breathe. When you press the accelerator pedal, you are not controlling the fuel (as some think) but the amount of air the engine can take in. Fuel needs oxygen to burn, so no oxygen means no burn.

On injected engines, air enters the system through a filter box at the front of the engine bay. Included into this filter box is an Air Flow Meter which measures how much air is coming in, and sends this data to the ECU. From there the air enters a large rubber distribution pipe connected to a number of ancillaries and the Throttle Body. The Throttle body is a cable-operated flap (connected to your accelerator pedal) which allows air into the engine when the pedal is pressed. Air enters the intake manifold which supplies air to all cylinders in the engine head.

On carburettor engines, the AFM and throttle body are replaced by a carburettor. Carburettors use a venturi effect (like blowing over an empty bottle to make it whistle), using air flow to suck fuel into the intake manifold.

Spark

Main article: Ignition

To make the fuel and air mixture burn, it must be ignited with a spark. This ignition system uses a standard distributor design.

The engine's electrical system charges a large capacitor, known as a coil, mounted at the front of the engine bay. This coil is directly connected to a rotating mechanical distributor, which works like a clock with one hand. For those who have seen the film Back To The Future, the moment the clock's hands strike the right point, a massive electrical charge is delivered through a cable, called an HT Lead, to a spark plug, which converts the charge into a spark. The number of points directly correlates the number of cylinders in the engine, as each cylinder requires its own HT lead and spark plug.

The firing of the distributor must be in time with the injection of air and fuel in the cylinder so that the combustion provides the maximum force. Incorrect firing can cause damage to the valves.

On injected engines, the timing is controlled by the ECU, allowing for retarding or advancement of the spark. On carburettor engines, the timing is mechanically matched to the cam shaft.

On M42 engines, the coil, distributor, HT leads and spark plugs are replaced with coil packs which generate and deliver a spark for each cylinder, controlled by the ECU.

Engine Management

The Engine Management system on injected engines is a rudimentary electrical brain called an ECU. It receives data from various sensors in the engine and drivetrain, and controls Fuel and Spark based on a set of parameters, known as a map, inside the ECU chip.

On carburettor engines, there is no Engine Management system.

Cooling

Main article: Cooling

The engine has an optimal temperature range, where the heat of the block helps the fuel to evaporate and ignite. Heat is also good for thinning the oil, allowing it to penetrate and lubricate all the small nooks and crannies of the engine. However, too hot an engine will cause the metal components to wear quickly, and can cause failure of seals and gaskets, or even cracks in the metal such as the head.

For this reason, the engine is cooled with a water circuit. The engine block is filled with water channels, which carry coolant in and out of the engine. The system is pressurised with a water pump (driven by the timing chain or belt), which delivers the water to a radiator mounted at the front of the engine.

The pressure, or flow, of the system is regulated by a thermostat. This simple valve is controlled by the ECU, which takes data from a thermometer known as the Blue Plug and uses these readings to control the heat as well as the fuelling of the engine. If the Blue Plug reads cold, more fuel is added to help the engine run in cold conditions.

Under hard load, the natural air flow over the radiator may not be enough to cool the system. For this purpose, there is a fan behind the radiator. Again, readings from the Blue Plug tell the ECU when the fan should operate.

Oil

Main article: Oil

The internals of an engine are complex moving parts, rotating thousands of times a minute with metal rubbing on metal. Without oil, these metal components would lock solid, causing irreparable engine damage in most cases. A well lubricated engine will deliver power smoothly and last for many years.

Upgrades

For many, BMWs engines were as perfect as possible, and power upgrades are not easy to come by. Considering the youngest of these engines is now 17 years old, restoring the engine to its original condition will provide better power upgrades than any aftermarket accessories, in terms of Pound per hp.

With that in mind, there are some upgrades specific to each engine. Check out the relevant page for your engine for more info.

Engine Swaps

While every E30 is a sublime driving machine, the desire for more power leads many to look at their options. Since many E30 engines are unsympathetic to "tuning" without spending serious cash, the following engines are popular choices to replace your current donk:

• M30
• M50
• M52
• S50/S52
• M60
• S62