Top 5 Great BMW Engines
Over the years, BMW has developed and manufactured some pretty astonishing engines. From race-spec units to your run-of-the-mill engines found in most of their road cars. Reliable, durable and powerful, they’re as gorgeous as they are tough. Although most M-sourced engines look simply stunning, they were designed to withstand abuse for thousands of miles at a time. Today, we look at five of their best engines. Bear in mind that we’re going in chronological order, ranking them based on reliability, power, desirability and tuneability. So although they might not be the most outright powerful unit BMW has ever made, they made it onto this list for a number of factors. Without further to do, let’s get right into it.
BMW M88 Engine
The M88 is a six-cylinder inline engine produced between 1978 and 1989. It’s actually based on BMW’s racing M49 engine which was used in the 3.0CSi, but they’ve modified it to make it more reliable and user-friendly. It uses a 4-valve head with a single-row timing chain design, exploiting the full potential of the Kugelfischer fuel injection which was fitted to it. Several different variations of it exist, but by far the most popular one was the M88/1. It was the first-gen engine fitted to the original BMW M1. In that guise, it developed 277 hp at 6,500 rpm and 239 lb-ft of torque at 5,500 rpm. It utilized a dry sump.
The M88/2 variation got a turbocharger which helped it develop up to 900 horsepower. It was only used for racing, specifically, in Group 5, so you can’t find it anywhere else today. The M88/3, a modified M88/1, eventually found its way into the E28 M5 as well as the M635CSi. Although the compression ratio was changed to 10.5:1, it used Bosch Motronic fuel injection as opposed to the Kugelfisher system found in the M88/1. This upped the power to 286 horsepower but torque remained the same. In South Africa the M88/3 was even used in the 745i, as the M102 unit the car originally came with had some packaging problems. Last but not least, there’s the M90. It’s a lower-performance SOHC M88/1 with a 9.3:1 compression ratio and no catalytic converter. Power output stood at 210 horsepower and you can find it in the E12 M535i, the E24 635CSi and the E23 735i.
BMW S14 Engine
From six cylinders we go back to four. The S14 is a straight-four DOHC engine which can only be found in the E30 3-Series (if we disregard engine swaps). Although it’s considered to be one of the strongest four-cylinder units to this very day, it’s not a bespoke engine in and of itself. The block is M10-based and it uses an M88 head with two of the cylinders chopped off. It also boasts two throttle bodies with individual throttle butterfly plates. There are four distinct versions, three of which can only be found in the E30 M3.
The S14B20 is, to a lot of people, not a ‘genuine’ S14. Only sold in Portugal and Italy, the 2.0-liter unit produces 192 horsepower and can be found in E30 320iS variants. The S14B23 is the M3-sourced engine everyone knows and loves. Initially, it made 200 horsepower and 230 Nm but catalytic converter-equipped models developed ‘just’ 192 horsepower. The S14B23 EVO2 received a revised intake camshaft profile, increased compression, a more efficient cylinder head intake port design and different exhaust camshaft timing. Power went up to 217 horsepower (212 hp if the car in question had a catalytic converter). Last but not least, the S14B25 EVO3 got bored to 2.5-liters and made a quoted 238 horsepower.
BWW S50 Engine
Based on the M50, the S50 is a ‘high-performance’ six-cylinder BMW used in the E36 M3. Just like the M50 it also boasts an iron block and an aluminum head. Note: U.S. M3s got the S50B30US engine which differed slightly to European-specced cars. The ‘standard’ S50B30 has Bosch Motronic M3.3 ECU engine management, a separate “VNC” Vanos control unit and variable single camshaft adjustment, helping it produce 286 horsepower. The 1995-onwards M3 GT got redesigned camshafts and a different sump and oil pump, pushing out 295 horsepower. Again, you can only find it in 1992 to 1995 E36 M3 models.
The U.S. specific S50B30US version is a tuned M50 motor with 250 horsepower. Based on the older M50B25TU it uses the exact same compression ratio but a different camshaft, pistons and connecting rods. With the facelift in 1996 BMW introduced a brand-new 3.2-liter motor dubbed the S50B32. Found in the E36 M3 and the Z3 M (except in the USA and Canada), it used Siemens MSS50 engine management, integrated Vanos control for intake and exhaust camshafts and an advanced knock control system. Power went up significantly, standing at 321 horsepower, thanks to a 11.3:1 compression ratio and the bigger 86.4 mm bore and 91 mm stroke.
BMW S54 Engine
The S54 is a high-performance M54 and a spiritual successor to the M54. Used in the updated E46 M3, the Z3 M Coupe Roadster and the subsequent E85 Z4 M Roadster/E86 M Coupe, it’s actually an evolution of the existing S50B32 unit. As similar as it is, there are quite a few differences. For starters, it gets a taller block deck (20 mm), modified camshafts, increased cylinder bore, increased compression (11.5:1), a one-piece aluminum head casting and a special scavenging oil pump for extreme cornering. The S54B32 unit, to use its full name, can be found in all M3s and Z4 Ms no matter the market (Europe, USA and Japan). Power varies depending on the application, starting from 315 horsepower and ending at 360 for the M3 CSL.
An even more advanced version of the motor dubbed the S54B32HP was used in the E46 M3 CSL. It boasts a high-flow carbon fiber air intake, a modified DME with a MAP sensor (instead of MAF) and modified valve and camshaft timing. Although power remained somewhat the same, the engine is a lot more responsive and willing to rev compared to the standard S54B32, not to mention a lot lighter.
BMW S55 Engine
Just like all BMW S-engines before it, the S55 is a high-performance N55 unit. Compared to its normal N55 sibling it boasts a different closed-deck block, strengthened pistons, twin fuel pumps, a lightweight crankshaft, different valve materials and perhaps most importantly, two turbochargers. Naturally, the intercooler has been revised to aid cooling. Just one iteration of the S55 engine exists, and it can be found in the current F80 M3 and the F82/F83 M4. The 3.0-liter twin-turbo unit makes 425 horsepower between 5,500 and 7,500 rpm and 550 Nm of torque between 1,850 and 5,500 rpm.