This British Tuner Just Made The BMW E30 M3 Engine Even Better

1 month ago - 7 July 2025, Carbuzz
This British Tuner Just Made The BMW E30 M3 Engine Even Better
Improving the hallowed E30 iteration of BMW’s M3 sports sedan is a task many would consider impossible, and one most of us would suggest is done with the daintiest of kid gloves.

 British tuning company Redux has taken on this challenge though by developing something of a spiritual successor to the E30’s original S14 four-cylinder, albeit one that’s lighter and more reliable while producing 330 horsepower.

The S14, so-named as it was originally developed by Paul Roche in just two weeks, was produced between 1986 and 1991 as a race-spec engine for the Bavarian brand’s first-generation M3, itself a homologation model of BMW’s first DTM touring car. Though the S14 was a high-revving and potent force to be reckoned with – in its final EVO3 guise, the four-cylinder made up to 235 hp in road form and a hulking 374 hp in race trim – Redux’s limited-edition follow-up is said to remedy the infrequent oil leaks, cooling issues, and poor throttle response said to plague its illustrious predecessor. Just 30 examples are expected to be made.

Redux has taken the high-revving character of BMW’s original M3 (specifically the midlife S14B23 derivation), and rebuilt the engine from the block upwards with stronger, more lightweight components to produce a more reliable example for spirited road and track use while nevertheless remaining unmistakably S14 at heart.

Though Redux's rebuilt engine – dubbed S14B27 – retains a four-cylinder configuration, pretty much everything else has been overhauled, or redesigned completely. The main engine components, specifically the block itself, the liner block, the girdle insert, the dry sump pan, and both the valve and front engine covers – each of which were originally milled from cast iron – have been replaced with alternatives fashioned from aerospace-grade billet aluminum. This alone saves just over 33 pounds from the engine, and it significantly helps improve engine cooling. Similarly, a new crankshaft, connecting rods, and pistons have also been forged from a mix of aluminum, titanium and steel to achieve stronger standards.

Among Redux’s main priorities, meanwhile, was the dry sump, traditionally used on endurance racing engines but considered a known weakness under sustained heavy acceleration on the E30 M3. The original unit has been binned and a bespoke custom example fashioned with a deeper reservoir to maintain more consistent oil pressure. This in turn helps provide more consistent performance at up to 9,000 RPM.

Such a venture is not without its challenges, of course. Redux offsets the cost slightly from a tie-in with German camshaft specialist SchrickQuite, though we presume there's still a Herculean price tag involved, not to mention the time required for development. The British tuning company was also adamant the M3’s original S14 soundtrack remain as unchanged as possible. That's not as easy as it sounds (pun intended) when you start changing major engine components. However, while the S14B27 engine note is said to be sharper, the unit retains the so-called induction bark of its DTM-inspired predecessor.

Should any of you happen to be an E30 M3 owner looking for a rejuvenated four-cylinder to drop onto the chassis over the weekend, you’re out of luck. Redux will not be providing the S14B27 as a standalone crate engine. Each example will instead be built by-hand and dyno tested to order. On the plus side, once this restoration is complete, maintenance and additional tuning for North American customers will be available via the Enthusiast Auto Group, Redux's partner in the United States.