The BMW S14 is arguably the greatest 4-cylinder engine that BMW has ever made. To bring you up to speed on its significance, you only need to know one thing — it’s the engine that powered the very first M3, the iconic BMW E30 M3.
The birth of the E30 M3, and the S14 that powered it, is quite an exciting story. In the late 1980s, BMW was looking to oust Mercedes-Benz that dominated the German racing scene, and the prestigious Deutsche Tourenwagen Masters (DTM), in particular.
The plan was to take their 3-series family sedan, make it lighter, more agile and fit it with a more powerful engine. After all, a racecar is nothing without a capable engine.
BMW S14 — A Legend Is Born
As the title of this article gives away, the S14 engine was the brainchild of German engineer Paul Rosche. Rosche built some of the most iconic performance engines ever, including the 2002TIK, a turbocharged engine that won the 1969 European Touring Car Championship, the M12 engine that powered the company’s F1 cars (also the most powerful F1 engine ever made), and the engine of the McLaren F1.
Eberhard von Kuenheim, then Chairman of the BMW Group, had put the M3 project in competent hands. Rosche got to work immediately and took the best parts from the most capable engines that BMW had previously built to put together what would become the S14.
The engine block was from the BMW M10 four-cylinder engine; this engine also formed the roots of the M12 F1 engine. Rosche and his team then took the cylinder head from the BMW M1, chopped off two cylinders, and fused that to the block. The final product was the very first S14.
The E30 M3 was designed to be an enthusiast car and proved very successful on the racetrack. It accumulated over a dozen championship titles in its time, including ones in the World Touring Championship, British Touring Car Championship, and even in rally events like the Irish Tarmac Rally Championship.
The M3 also won at the 24 Hours Nürburgring five times – 1989, 1990, 1991, 1992, and 1994. It also won the Spa 24 Hours four times – 1987, 1988, 1990, and 1992.
Available Versions
Over its 5-year lifespan, the S14 was available in 3 main iterations.
S14B23
The first E30 M3 came out in 1986 with the 2.3L S14B23 engine. Depending on the country, BMW sold the M3 either with a catalytic converter or without one. With a cat-con, peak output figures were 192hp at 6,750 rpm and 170 lb-ft of torque at 4,750rpm. These numbers were slightly higher without a cat-con: 197hp at 6,750rpm and 177lb-ft of torque at 4,750rpm.
BMW sold this engine from 1986-1989. In September 1989, they were replaced by essentially the same engine in a higher state of tune, producing 212hp at 6,750rpm 170 lb-ft of torque at 4,600rpm.
S14B23 EVO2
In 1988, BMW introduced the S14B23 EVO2 engine alongside the standard option. Displacement remained identical at 2,302cc, but power and torque were bumped up to 220hp and 181lb-ft of torque, respectively. This engine powered the M3 Evo II, of which just 505 units were made.
S14B25 EVO3
The last of the S14 was on the M3 Sport Evo that BMW produced from 1989-1990. This engine iteration displaced 2.5L — 2,467cc, to be precise — and the larger configuration also brought a modest increase in power. Peak output figures were rated at 235hp at 7,000rpm and 177 lb-ft of torque at 4,750rpm.
Only 600 examples of the M3 Sport Evo were produced.
S14B20
BMW also designed the S14B20 engine, but it plays an almost insignificant role in the engine’s history. This engine was a downsized iteration — to 1,990cc — of the standard S14 engine and was produced from 1987-1990.
It never made its way onto an M3, and its only application was in the BMW E30 320iS. BMW made this engine mainly to bypass specific tax laws in Portugal and Italy, where this engine iteration was sold.
BMW S14 — Nearly Perfect
The S14 is probably the most reliable of the E30 engines. The M10 derived engine block that it used also thrived in the grueling atmosphere that an F1 car is subject to, which should speak volumes of how reliable a piece of engineering it was.
If maintained well and taken care of, an S14 engine would sail past the 300,000-mile mark without significant problems.
That said, the most recently made S14 engine out there is at least 30 years old. And most examples out there have seen multiple owners and several thousand miles. Unsurprisingly, there are some issues they tend to throw up.
Timing Belt Tensioner
The S14 engines use a dual row timing chain design that’s exceptionally durable, and there aren’t too many reports of owners running into trouble with them. However, BMW experimented with different timing tensioners during the S14’s life, and these did cause some problems.
A faulty tensioner will cause the chain to loosen and come into contact with other internals. This typically results in a knocking sound from inside the engine.
As a result, many owners have replaced the tensioners on their S14s with ones from the newer S52 engines.
Power Loss Issues
Owners with high mileage S14 engines have reported a momentary drop in power, and, in most cases, this is usually a consequence of poor maintenance or just regular wear.
The issue stems from a faulty fuel pump or injectors, damaged O2 sensor, or worn spark plug.
These shouldn’t be too expensive to fix, but it’s something you should keep an eye out for if you want to prevent further engine problems.
BMW S14 — As Desirable as Ever
The S14 is a legendary engine, and the machine it powers is one of the most sought-after BMWs ever. With this engine, BMW showed the world that it could take a racecar and turn it into a daily driver that you could have tremendous fun in.
Today, you’ll find examples of the M3 equipped with turbos, or superchargers and these examples make some serious power. However, the engine will always remain the crown jewel in BMW’s most iconic super sedan.
