The E30 has a special place in the hearts of most petrolheads. It is a classic BMW with a timeless design and the proper layout — a longitudinally positioned engine, rear-wheel drive, and a manual transmission. However, in today’s world, the E30 3-Series does not feel as fast as it did forty years ago when it was first introduced to the market, replacing the first-ever generation of the 3-Series.
Because of this, engine swaps are an interesting way to make the E30 feel more enjoyable. With vast E30 engine swap options, there are loads of original builds. If you are thinking about swapping your own E30 engine, here are three of the most popular and exciting options.
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M42 — Period-Correct Engine Swap
The M42 was fitted on the 3-Series E30 from the factory, so it is one of the most viable E30 engine swap options for those owning a low-powered E30. In addition, it also makes the M42 one of the best options for a period-correct engine swap.
The engine itself is a straight-four gasoline engine with a 1.8L displacement. The power is rated at 134 hp and 127 lb.-ft of torque. These numbers make it quite a nifty engine for the light E30. The production started in 1989 and ran till 1996 when it was replaced by a newer M44. At the time, the M42 was an innovative drivetrain, as it was the first dual overhead camshaft (DOHC) engine by BMW. This made it the most technologically advanced engine BMW offered in the late 80s and early 90s.
Compared to the larger six-cylinders, which were also fitted to E30s, the M42 weighs less, and achieves better fuel economy, while making the E30 also feel sportier. An E30 with this engine is somewhat of an entry-level M3. At the first glance on paper, it might be considered a sluggish engine due to the model designation 318i, which is nowadays a label for base BMW drivetrains. In reality, this engine can keep up quite well even with the top-of-the-line 325is.
When it gets to swapping this engine into a 3-Series E30, it is quite simple given that it was a factory option. However, it can sometimes be difficult to get your hands on one, as it was a part of the E30 offering just for three years. Luckily, the successor of this 3-Series, the E36, offered almost an identical engine, which only had modifications on a few minor parts. These include the air intake, oil pan, camshaft, knock sensors, and a different bell system.
The E36 engine also has forged internals, compared to the E30s cast internals. These are the modifications that also made the later E36 318i slightly more powerful with an extra 4 hp and 2 lb.-ft of torque, which was also available from lower RPMs. The rest of the engine is identical, so even a swap from the E36 is relatively straightforward.
Why this engine is so popular for a swap, besides it being a factory option, because of its reliability and performance. Even in case, something would go wrong, parts are easily accessible, as a lot of E36s were manufactured with this drivetrain. It also has room for tuning, and it makes the E30 feel quite fast despite its low power numbers when compared to modern cars. The M42 also served as the basis for an S42B20 engine, which was used by BMW for touring car races. There, the modified engine produced between 276 and 315 hp, which shows the capabilities of this engine.
Despite its reliability, there are a few known issues. For one, the timing chain guides and sprockets are not too durable. If these fail, the repair can be quite costly. Also, the oil system is not ideal for running at high RPMs for prolonged periods, but that’s about it.
S54 — One of the Most Powerful E30 Engine Swap Options
Let’s start with the most extreme option on this list. The S54 is the engine you would typically find in an E46 M3, or the E85/E86 Z4 M. With 333 hp and 262 lb.-ft of torque, the E30 will become a proper rocket with this drivetrain. Of course, it is a straight six, which loves to get into revs, and generates immense power, but is not as heavy as some of the eight-cylinders that BMW offered. The redline goes to 7,900 RPMs!
The reasons behind the popularity of this E30 engine swap option are clear. The S54 is just a legendary drivetrain and makes the E30 stupid fast. It has an undeniable cool factor, but there are also practical reasons to choose the S54. The main one is OBD-II compliance, which makes working on your car, tuning it, and troubleshooting it much easier.
Of course, there are also downsides to going with this engine. With the E46 M3 becoming a collector piece that is highly valued by car enthusiasts, the prices are starting to creep up. There is also a huge demand for them, which increases the price even further. But then again, over 300 hp in a tiny E30 that weighs around 2500 lbs? This is truly a guarantee of fun. In comparison, the M3 Sport Evo, an ultimate sports car back in the day, produced “only” around 235 hp and 177 lb.-ft.
Back to the negatives, the S54 engine has developed a few weak spots over the years. The most common issues include weak rod bearings, which put the engine in front of potentially catastrophic damage. There is also the dual VANOS system, which helps to get a few more extra horsepower out of the engine but is known for a few issues of its own. Whether it’s the seals or the solenoids, most VANOS systems need to be rebuilt at some point. Being a much more modern engine, the electronics are also quite a bit more complicated than the typical E30 engine.
This relates to another point – the difficulty of the swap. As said, the modern E46 M3 engine is quite a lot more complicated and came around almost two decades after the E30 was first introduced. This means that there are several adjustments that need to be done to the car, starting with a custom subframe. The E30 engines all feature a front oil sump layout whereas the S54 uses a rear oil sump design. You can either modify the oil sump or the subframe. The former, although easier on paper, can lead to oil starvation issues. That’s why most people go for a different subframe.
M52 — A Refined Straight-Six That Likes to Rev
Another popular engine swap for the E30 is the M52 engine. This drivetrain is a straight-6 DOHC and was first featured in the 3-Series E36, more specifically in the 320i model, where it replaced the prior M50. Compared to the M50, this engine is a pleasant improvement. It is lighter thanks to an aluminum block, has a larger displacement, and has a bit more power thanks to an improved VANOS system. Besides the 3-Series, the M52 also found its way into the E39 5-Series and the E36 Z3. It was also featured on the E46 during the first years of production.
One of the greatest benefits of this build is the simplicity of the swap. It is not too demanding and with its huge popularity, the procedure is well-documented. It is really simple. At least as far as engine swaps go. Not only that, but the E30 runs really well with it. The car feels more responsive, the engine is much smoother, and with a wider effective RPM range. It is also more fuel efficient compared to the stock E30 engine options, which is definitely not a reason for an engine swap, but a welcome benefit, nonetheless.
In the E36 320i, from which you are most likely to swap the engine, the drivetrain was making 148 hp and 140 lb.-ft of torque. It makes this a decent upgrade in the best sense possible. Some people just do not want their E30 to make hundreds of horsepower. The M52 gives the E30 the perfect amount of power to make it feel fast, but not so much that it will try to kill you. On the other hand, if extreme power is exactly what you are looking for, BMW has used the M52 as a basis for the M-performance S52 engine. The S52 is also “E30-swappable” and makes 240 hp and 240 lb.-ft – much more than what the E30 ever made out of the factory.
Regarding the negatives of using this engine for your E30 swap, there are actually not too many. The M52 is just an overall reliable engine and at the same time, it is not as modern as, for example, the previously mentioned S54. Still, the popularity of the engine has inflated its prices over the years, so finding one for a low price is not so easy nowadays. The largest complication with this swap option is the EWS system and the cooling system, where the radiator fan needs to be adjusted for better clearance.
The Opportunities are Endless
The three presented E30 engine swap options are one of the most popular among BMW enthusiasts. However, it is only a very narrow selection from the vast number of options there are. With enough dedication, almost any engine will fit in the E30. There are numerous builds using BMW V8 engines such as the M60 and M62. Some have gone full-on crazy and even fitted an S85, the F1-inspired V10 from the E60 M5, into their E30. Of course, there is also the option of going with a non-BMW engine and swapping the E30 with something like a Honda K20/K24, or even doing an LS swap. In short, the possibilities are endless, and whichever way you decide to go, the result is certainly going to be intriguing and give your E30 a fresh breath of life.
