In the world of sports cars, there’s one car that has reigned supreme over nearly everything for decades, and that’s the BMW M3. Really, it’s long been the benchmark for what a good car is and what isn’t. It combines the best of handling, power, looks, braking, and price.
Part of making an amazing car for decades and throughout multiple iterations is using a great engine. After all, the engine is the heart and soul of the car. It’s what propels it forwards.
BMW E30 M3 (S14)
To kick this off, we have to rewind the clock all the way to 1986, which is when BMW released their first-ever M3 with the E30 M3. Technically, BMW started the development of the E30 M3 back in 1984, but that’s beside the point here. What’s special about the E30 is that it was a special homologation car produced in pretty small numbers, which it’s obviously gone on to become a legendary collectors car since then.
But we’re not here to admire the E30 as a whole. We’re here to look at the 2.3L inline-four cylinder engine under the hood, known as the S14. What’s really interesting about this engine is the fact that it’s not an inline-six, which BMW had a lot of success with during that time and well after that time. Hell, BMW is still using the inline-six configuration today, but more on that later.
The reason that BMW used a four-cylinder engine for the E30 M3 as compared to an inline-six was weight. One of their big goals with the E30 was to keep it as light as possible, so using a smaller four-cylinder engine was one of the sacrifices they had to make. The block of the S14 actually came from the BMW M10, which is very closely related to the BMW M12 that was used in Formula one and produced upwards of 1500 horsepower when maxed out.
With that in mind, the block of the S14 is clearly overkill for a naturally aspirated application, but BMW already had the tooling and designs completed, so it made sense to use this specific engine block. What’s kind of interesting is that block design actually goes back to the late 1950s, as it was BMW’s first modern four-cylinder engine.
The cylinder head came from the BMW M88, which is the inline-six engine found in the BMW M1. Now you might be wondering, how did they use an inline-six engine head on a four-cylinder engine, and the answer is simple, they cut off two cylinder’s worth of the head. While that’s true for the development stage, in reality, the head on the S14 is just a shortened version of the M88 head, sharing nearly exactly the same design, but shrunken down for a smaller application.
On top of the head, you’ll find dual overhead cams, and beneath the head, you’ll find a really beefy rotating assembly with a pretty high 10.8:1 compression ratio. By today’s standards that might not be considered high, but for the 1980s, that was a pretty gnarly compressions ratio. On top of all that, the S14 was equipped with individual throttle bodies. This all equals out to 197hp.
That might not sound like a lot, but you have to remember that this was a small naturally aspirated engine from the 1980s. In all reality, what this engine was outputting for its size was nearly unheard of at the time. For reference, the 1986 Mustang with the 5.0L V8 output 200hp, which really puts in perspective how impressive the S14 was at its time.
I think it’s also worth noting that BMW didn’t stop there with the S14 because the Sport Evolution, also known as the EVO3, used an improved 2.5L version of this engine with more power and torque, to the tune of 235hp in road-legal configuration and 374hp in race configuration.
The last thing I’d like to note with the BMW S14 is that Paul Roche, one of the best engineers that have ever lived, is the mastermind behind the S14 as well as many other BMW powerplants.
BMW E36 M3 (S50)
But, enough on the S14, I think it’s time we jump forwards to the BMW E36, which itself came out in 1990 but it wasn’t until 1992 that we saw the M3 version of the E36. Unlike the E30, the E36 wasn’t a special homologation car, and as such, it was built in larger quantities than the E30.
Under the hood of the E36, BMW ditched the four-cylinder engine in favor of an inline-six, which is really the configuration that many BMW enthusiasts would’ve preferred in the E30, but that’s beside the point. This specific inline-six engine is the BMW S50. It’s at this point that I’d like to note that the North American models received a slightly detuned version of the S50, and then later received the S52.
For this particular article, we’re going to keep it simple and look at the S50B30, which was used in most countries outside the US and Canada. Unlike the S14, which was a bit of a mishmash of parts, the S50 is directly based on the BMW M50.
Interestingly enough, the biggest BMW M50 engine was the 2.5 liter, but for the S50, BMW increased the bore to 86mm and the stroke to 85.8mm, which bumped the displacement to 2990cc. Along with that, BMW increased the compression ratio to 10.8:1 and BMW M ported and polished the cylinder head. Just like the S14, the S50 received individual throttle bodies for improved throttle response and power output.
Heavy-duty valve springs were fitted along with single Vanos, a dual-mass flywheel, free-flowing intake, free-flowing exhaust system, and Bosch Motronic M3.3 engine management system to run the whole show. So, really BMW actually took a simpler approach with the E36 M3 by taking an existing engine and simply making it better, which is the approach they’ve used on every M car since.
I think it’s also worth noting that later on, BMW released the S50B32 to replace the S50B30 in countries outside the US and Canada, and this version of the S50 had its displacement increased to 3.2L, as well as using a higher compression ratio and improved double-VANOS system.
All this equals out to 240hp for the S50B30US as well as the S52, which are the two engines used in the North American E36 M3 excluding special models. 282hp for the S50B30 used in the majority of the world, and later on 316hp for the S50B32 used in 1995 and later E36 M3 cars.
BMW E46 M3 (S54)
That takes us to 2000 when BMW introduced the E46 M3, but again, the platform itself was launched in late 1997, but it wasn’t until 2000 that we saw the introduction of the M3. For many hardcore BMW enthusiasts, this is considered the pinnacle of the M3, as it’s the last naturally aspirated inline-six powered M3, but I’m getting ahead of myself.
Besides the amazing design which really hasn’t aged at all, the E46 M3 was also a fantastic handling car with tons of modern BMW features while still maintaining a relatively low weight of around 3500lbs depending on how it’s specced out. Under the hood of the E46 M3 is the BMW S54, which was touted by BMW as a performance version M54, following their new tradition of taking an existing engine and improving upon it for their M cars.
By marketing their S54 as a hopped-up version of the M54, it really makes their non-M car engines like the M54 seem really good. If they can just take that engine and modify it for their flagship performance car, then the base engine must be pretty amazing right?
Unlike the base engine, the M54, the S54, which is touted as a performance engine, uses a heavy cast-iron block which is actually based on the block from the S50 in the E36. It’s really weird because the M54 that it’s supposed to be based on uses a lightweight aluminum block, so why did BMW switch to a heavier material? Realistically, it’s because the S54 is an evolution of the S50 rather than the M54.
It features a bore and stroke of 87mm by 91 mm, bringing total displacement up to 3.2L, which was up from the S50 which was only a 3.0L unless you’re talking about the S50B32. It also features a forged and nitrated crankshaft with twelve counterweights, forged connecting rods, and high compressions forged pistons. All of this was designed to help the rotating assembly handle the stress of high RPM, with a redline around 8,000 RPM.
The aluminum, 24-valve cylinder head got a pretty major redesign as compared to the S50’s head. Not only is the S54 head lighter, but it also includes an improved continuously variable valve timing double-VANOS system, new hollow camshafts, and finger followers instead of the old bucket-style lifters. One of the more notable features is the individual throttle bodies on the intake, which offer a ton of performance.
All that fancy stuff equals an output of 338hp and 269 lb-ft of torque. Unfortunately, the variant we had here in the US had a few small changes to help with emissions compliance, so ours produces a little bit less at 333hp and 262lb-ft of torque.
BMW E90 M3 (S65)
That takes up to 2007 with the E90 Generation M3, and what makes this M3 so much different and so controversial as compared to every other M3, is the fact that it doesn’t have an inline-six engine under the hood, rather it has a V8. When you consider the fact that BMW probably wanted to keep the M3 naturally aspirated and they hadn’t dropped their first-ever mass-production turbocharged engine until that year, then switching to a V8 starts to make sense.
With other popular sports cars producing significantly more power than what the E46 M3 offered, they really needed to step it up with the E90, and if they weren’t going to add a turbocharger to it, then they needed to add displacement, which is exactly what they did. Could they have technically given the E90 M3 a massive inline-six engine? Sure, but they didn’t.
This specific V8 is the S65 which came in a few different variants, but the main version used is the S64B40, which is a 4.0L engine, but BMW also had the S65B44 for some special edition models and that engine was a more powerful 4.4L.
Interestingly enough, the S65 isn’t actually based on a regular BMW production engine, rather it’s derived from the S85 V10 engine used in the M5, but simply shrunken down to a V8. The S65 shares the same cylinder dimensions of a 92mm bore and 75.2mm stroke, as well as individual throttle bodies, double VANOS, and an insanely high 12:1 compression ratio.
While you might you BMW switching to a big 90 degree V8 with dual overhead cams would be a negative in terms of weight, you have to remember that the S54 was a cast-iron engine, whereas the S65 is cast aluminum. All in, the S65 is actually a little bit lighter than the S54, while also bumping up power quite a bit to 414hp and 295lb-ft of torque.
While the S65 is very interesting and one of the best sounding V8 engines ever, in my opinion, the fact that it was a V8 really ticked a lot of people off. But, the N54, their first mass-produced turbocharged engine was released the same year as the S65, and by the time the next M3 rolled around, BMW had really figured out how to get their new turbocharged inline-six engines to perform to their liking.
BMW F80 M3 (S55)
That takes us to the F80 M3, and as you might have guessed, by what I second a few seconds ago, the F80 ditched the V8 and returned to the inline-six engine configuration that so many BMW enthusiasts loved, but now it wasn’t naturally aspirated, instead, it was turbocharged. And again, BMW didn’t have too much of a choice on this.
With many comparable cars switching to forced induction, BMW was forced to do the same if they wanted to stay on top as the benchmark for a performance car, so that’s exactly what they did. This time around with the M3, they based the engine on the aforementioned turbocharged N series engine. More specifically, it was based on the second evolution of the N54, which was the N55, and this new M3 engine was known as the S55.
When I say the S55 is based on the N55, I really mean it. In terms of components, they have a massive amount in common, but the S55 is modified with high-performance applications and track use in mind. According to BMW, the N55 and S55 share 75% of their engine components, and 25% of the engine components are new developments.
On the side of the S55, you’ll find two mono-scroll turbochargers, each of which has cast-in exhaust manifolds. With this system, each turbo has its own bank, meaning each turbo is powered by three cylinders out of the six in the engine. With this twin-turbo system came the need for a new intake system, exhaust system, and intercooling system.
One of the cool features of the S55 is the indirect charge air cooling with two heat exchangers and a separate cooling circuit with an electric pump, rather than a typical front-mounted intercooler. BMW did this for a variety of reasons, but at the end of the day, it was done with performance in mind.
What’s really impressive about the S55’s twin-turbo system is that it actually weighs the same as the N55’s single turbo system according to BMW. It’s really weird how they went from the N54 being twin-turbo to the N55 being single turbo, back to the S55 being twin-turbo.
Looking at some basic specs and info, we can see the S55 set up pretty well for performance. It’s a 3.0L inline-6 engine with twin turbos strapped to the side of it. It uses an all-aluminum design, so aluminum head and aluminum, and more importantly, it has a closed deck block. Inside the cylinder head, we have dual-overhead cams with VANOS.
In terms of power, the S55 ranges from 359hp up to 493hp, with most of them around 425hp to 444hp. While the S55 is an amazing engine that has a ton of potential with a mild amount of aftermarket parts, it can be a little problematic. So, when the new G80 M3 came out, BMW made a very smart move to base their next M3 engine on the Supra’s B58, which as you may know, Toyota had a big hand in developing, specifically making it more reliable.
BMW G80 M3 (S58)
That takes us to 2020 when BMW launched the G80 and its hideous front end. Following the normal trend for BMW, the S58 is a 3.0L inline-six engine with twin-turbos, just like the S55, but as mentioned a moment ago, the S58 is based on the B58, which is a much more refined and reliable platform compared to the N55.
Because the S58 hasn’t been out for very long, there really aren’t many performance mods out there yet. That being said, tuning software is already available for the S58, and it’s capable of a pretty big amount of power, especially when tuned on ethanol. In totally stock form, the S58 puts down around 473hp and 442 lb-ft of torque, which is already an increase of 48hp and 36 lb-ft over the standard S55. The Competition models will push that even further, with an additional 78hp over the standard S55 and still 10hp over the beefed up S55 in the M4 GTS.
With some basic bolt-ons and ethanol fuel, we’re already seeing S58s making upward of 650whp and 650 wheel torque, and some pro-tuners are getting close to 700whp. For reference, a bolt-on S55 running on ethanol fuel will generally see a max of 600whp.
So, that’s every BMW M3 engine ever. I want to know what you guys think though, which engine is your favorite? I know for a lot of hardcore BMW enthusiasts, the S54 is the best because it’s arguably the best M3, but the new S55 and S58 engines make an insane amount of power very easily. Be sure to drop a comment down below letting me know which one you like the most.
For me, I’m probably going to go with the S55, as I’ve driven and ridden in a handful of F80 M3s and my personal car has an N55 which shares many of its components.