Redux S14 2.5L Turbo
Lurking behind all those pipes and wires is Redux #1’s fully restored, significantly upgraded and beautifully re-engineered 4-cylinder, 2.5l S14 turbo. If you’re not familiar with BMW engine codes, the S14 is unique to the E30 M3 and one of Paul Rosche’s creations: Rosche was BMW Motorsport’s most gifted and well respected engine builder who developed the S14 from the M10 block and the M88 head, which makes it the love child of two other iconic BMW engines.
Rosche also used the M10 block in his seminal M12/13 4-cylinder, 1.5l turbocharged F1 engine, which powered Nelson Picquet’s Brabham to the World Championship in 1983; the first drivers’ title to be won using a turbocharged engine. Amazingly, given the significant advances in automotive technology over the last 30 years, the M12/13 is still the most powerful engine ever to have raced in F1; in qualifying trim – i.e. everything turned up to maximum – it was estimated to have produced a staggering 1,400hp. However, when Rosche was asked to verify the figure he casually stated: “It must have been around 1,400 horsepower; we don’t know for sure because the dyno didn’t go beyond 1,280hp.”
The 6-cylinder M88 featured in three other Motorsport classics: the E26 M1 road and race cars, and the E24 M635 CSi and E28 M5 road cars. In naturally aspirated M1 road car trim (M88/1) it delivered an impressive 277hp, however when turbocharged for the M1 Group 5 race cars (M88/2), power was increased by over 300% to 900hp.
In the late 1980s and early 1990s, the E30 M3 dominated “The Golden Years” of the DTM (German Touring Car Championship). Steve Soper, Roberto Ravaglia and Johnny Cecotto became household names and the E30 M3 remains the most successful road race car in history in terms of outright wins; never mind class wins or even championships. With such strong racing pedigree, there was never any consideration given to suggestions of replacing the original 2.3l 4-cylinder S14 with a more modern 6-cylinder, 8-cylinder or even 10-cylinder engine (amazingly, the E60 M5 5.0l V10 fits in the E30’s engine bay). The addition of a turbo did raise a few eyebrows amongst the purists, however the S14’s M12/13 and M88 turbocharged lineage proved too tempting to resist exploring.
Once the Redux S14 turbo’s initial specifications were drawn up, the development and build was entrusted to Terry Wilson and Ric Wood. With decades of combined experience delivering high performance BMW road and race engines, they were confident the power-to-weight ratio target of 365hp/tonne would be achieved. All Redux M3s are designed to be capable of delivering exceptional track performance combined with impeccable road manners. Therefore every aspect of Redux #1’s original 29-year old 2.3l engine was reviewed resulting in the majority of components being upgraded to higher specification parts. The result: an engine which redefines the S14’s already legendary status.
On the dyno, with revs limited to only 4,000rpm, running very low boost (0.6 bar/8.7 PSI) and without any mapping, the Redux 2.5l turbo comfortably surpassed the E30 M3 Sport Evo’s 2.5l naturally aspirated engine’s maximum output figures. Therefore, Redux’s new engine can be run well within its maximum performance parameters and still deliver enough torque and power to satisfy any level of driver.