Best E30 Engine Swap

If you’re an E30 lover, you’ve probably noticed the herds of people asking what the best E30 engine swap is online.

There’s quite a good reason for this, as the E30 is a well-loved chassis and we’ve got to the point in its lifecycle where those special examples are being kept original and tucked away by collectors, and the scruffier, lower specced examples are starting to be modified.

I read somewhere online that E30’s never die, they just get faster. 

Having been a long serving BMW nut and E30 lover, I’ve been conducting a fair amount of research into what the best E30 engine swap options are in the hope to convert my own E30 project car in the near future.

My car is a lowly 316i so I don’t need to say anything to explain why I’d be interested in E30 engine conversions, but the truth is, even BMW’s top-specced E30’s have a limited engine line-up, especially when compared to more modern metal.

As there is nothing that looks and feels quite like an E30, it’s well worth giving one a new lease of life and treating it to an engine swap.

What follows is the result of much research and consideration. Read on to hear my thoughts on the best E30 engine swaps and ultimately make my own decision on which direction to take my E30 in.

Period Correct E30 Engine Conversions

If you want to keep your E30 as close to BMW’s vision of the ultimate driving machine as possible, or just want to maintain the old-school feel of these 80’s icons, a period correct E30 engine swap might be just the thing for you.

The E30 was available in a variety of engines, and being a 3 series they sold a whole lot of cars equipped with them too making them relatively easy to come by.

Being engines that were originally fitted in these cars, you will be on track for an easy life by selecting one of these motors, and quite often the conversion can be done very easily and cheaply.

If you have a lowly 316i or 318i BMW E30, you can source yourself some OE parts and get a lot more performance than the smaller 4-pot engines without doing anything radically custom in any way, shape, or form.

It’s worth bearing in mind however, that these engines have generally been out of commission for many years at this point, so any engines or parts you do find for a period correct conversion will be very old indeed and likely need some TLC to ensure reliability.

M20

The M20 engine was the flagship motor for the BMW E30, available in 2.5 and 2.0 variations found in the 325i and 320i respectively. These days it only makes sense to swap in the 2.5 engine in my opinion, but many find the 2 litre to be more free-revving and fun to drive hard.

At the time of publication, M20B25 engines are still readily available and can be bought for not much more than £300 in “previously running” condition.

The 2.5 M20 engine makes 170bhp and a decent chunk of torque compared to its smaller siblings with 167 lb-ft. The M20’s cams are driven by a belt that makes this a smooth straight six motor and a pleasure to sit behind. The down side to that is the timing belt needs replacing every 50k miles (or as a precaution if its been stood for a long time). Luckily it’s a breeze to swap on these engines, even in situ!

If you’ve got desires for tuning and future power gains though, the M20 probably isn’t for you.

Many have tuned their M20 engines and even swapped the crankshafts out for later M50 variants that allow for more stroke and a larger 2.7 or 2.8 cc capacity. However, the power gains are hard-won with these and you’ll certainly be in for a lot more cost by the time you’ve added any real worthwhile performance.

We will set a benchmark here of 175kg which is the weight of the M20 motor. The heaviest engine BMW ever put in an E30.

Pros:

• Very easy to swap in being OE for the E30
• Cost effective
• Period correct

Cons:

• Not that powerful or exciting by today’s standards
• No scope for future power gains

M42

This 1.8 four pot engine is the latest and probably the most technologically advanced engine fitted to an E30 from factory.

The M42 4 cylinder motor was equipped in the 318is BMW E30 variant which came late in the production run. This car featured the full 325i suspension and brake setup but that smaller and revvier 1.8 engine up front with chain driven cam.

The M42B18 produced around 150bhp and 129 lb-ft torque, this engine is also considerably lighter than the M20 making the BMW 318is light on its feet enthusiasts dubbed it the “baby M3” of the time given the more keen and sporty feel of this car compared to the heavier 6 pots.

With healthy power numbers and a lighter weight, the 318is could more or less keep up with the 325i anywhere, all while doing nearly double the miles per gallon. It’s no wonder they were so popular.

Swapping an M42B18 into an E30 is again quite easy, however being a limited run car, genuine E30 M42 engines are becoming a bit harder to come by. Luckily the E36 318is came equipped with the same engine bar a few minor changes such as the intake manifold.

The vast majority of the parts are interchangeable between these and they made a considerable number of E36’s with this engine so you won’t be short of cheap parts if you decide to undertake this swap.

There’s even more good news. These engines are solidly reliable and tuners can find a lot of purpose-designed aftermarket support for them which can make them very punchy. There’s even a race series in which you can run an E30 with this engine.

The M42 engine swap is extremely common in smaller BMW classic cars such as the 2002, often swapped in, in favour of the M10.

It’s a great BMW E30 engine swap, but is throwing in a humble 4-cyl non-M motor into your E30 worth all that hassle? That’s up for debate.

Pros:

• Very easy to swap in being OE for the E30
• Cost effective
• Period correct
• Plenty of scope for tuning

Cons:

• Not that powerful or exciting by today’s standards
• It’s a lowly 4-pot

S14

The E30 M3 engine of the time, and with famed notoriety as a special unit indeed. The S14 features individual throttle bodies (ITBs), and roars up to high revs with a wonderful linear power delivery.

This is the engine the M42 we previously talked about wishes it was, but could never be.

The majority of BMW S14 engines came in 2.3 format but later engines such as those found in the BMW E30 M3 Sport Evolution (one of the latest versions) come equipped with sought after 2.5 litre versions which had been bored and stroked up by the technicians at BMW M division for a last hoorah. 

Earlier European and UK E30 M3s came without any pollution controls allowing the S14 motor to sing unimpeded, US versions came with a catalytic converter which only slightly took the raw edge off proceedings.

The final 2.5L form of the S14 came about in 1990 and produced a solid 238 hp, but its the way this engine feels that draws its supporters.

Sadly, the days of cheap S14 engines or E30 M3 donor cars are long gone now. In the past these cars were exceptionally good value, due to this you can often find BMW 2002’s with the S14 swapped in which was a great match up.

However, most owners of those 2002’s have now pulled these engines and sold them on. in recent years they have had a renaissance and become incredibly expensive collectors items.

Not only this, but parts, new and used for the S14 are scarce and command serious money. As they are all 30 year old engines, you can expect to need to replace and rebuild them too.

Due to this, it’s very uncommon to find someone trying to swap an S14 into a normal bodied E30. Although it’s a match made in heaven, it’s hard to justify.

Leave the S14’s for the genuine M3’s I say.

On an interesting side note, the ultra rare Italian exclusive 320is E30’s also came equipped with the S14 engine, reduced in capacity to 2.0 to comply with local emissions laws. They couldn’t get the full fat E30 M3 there, so they made the best of it with a regular bodied E30 and a reduced capacity S14.

Pros:

• Very easy to swap in being OE for the E30
• Exciting M-engine power delivery
• Period correct

Cons:

• Hideously expensive to buy
• Hideously expensive to maintain
• Hard to find

M30

Affectionately known as the “big six”, the M30 engine is a BMW legend. With an epic lifespan from the late 60s right up to the mid 90s, this was one of those “don’t fix what ain’t broken” situations for BMW.

You could get M30 six cylinder engines in all manner of bodies from 3 to 6 series, and all types of capacity to match, the largest and most revered being the M30B35 3.5L motor.

While not as rip-roaringly powerful as its 3.5 capacity may fool you into believing, the M30 was no slouch. Where it really won hearts and minds are with its huge flexibility and low down grunt in any gear. It’s a big old cruising engine really and doing so is effortless for it with its 208 bhp and 225 lb-ft of torque.

The M30 is a simple old engine from back in the days where things we’re over-engineered and truly built to last.

Thanks to this impressive durability of the M30 engines, it was quickly recognised that there was plenty of headroom to add more power. They made a remarkable number of them over the years too so spare parts were plenty if you pushed it a little too far.

As these engines are quite low compression SOHC units from the factory, turbo charging these engines is the most popular route to thrills. It doesn’t cost the earth, is very well documented and you can easily tune it to over 500 bhp on stock internals.

They are still reasonably good value, especially in the US where they were a lot more popular. In Europe and the UK they are a bit rarer due to people being more conscious about fuel consumption at the time.

If you’d be planning on a turbo, it’s very hard to look past the M30’s potential. If you’re more into NA engines then the drawback of the M30 is its sheer weight.

They are a heavy old lump and can easily upset the balance of an E30. But the M30 engine swap is a solid option.

Pros:

• Extremely durable with plenty of scope for big power
• Readily available and cost effective
• Period Correct retro vibes

Cons:

• Very old engines now which will need extra care
• Very heavy
• No great shakes without the turbo

E30 24V Engine Swap

Here’s where we get to the most popular and most common engine swaps you will find under the hood of a BMW E30.

If you’re a BMW lover, chances are you are all about their 6-cyl engines, and if that’s the case you’re probably all ears when it comes to newer and more refined versions of them.

The M50B25 and M52B28 straight six engines found post-E30 production in the E36, E39, E39 variants are the weapon of choice for most E30 nuts, and with good reason!

These engines on paper don’t look like a huge step up from their M20 predecessors until you get behind the wheel and drive one. The charms of the E30’s M20 motor quickly pale into insignificance when you experience the urgency of BMW’s newer DOHC 24 valve 6-pot engines.

The power delivery is much more playful, and these engines are on song for a lot more of the rev range than previous, and the torque curve is much more progressive meaning you can more easily get the most out of them.

They also rev a bit higher, unlocking more of that linear power. This is in part due to modern technologies such as BMW’s VANOS systems which can advance or retard cam timings to utilise more of the rev range.

To make the proposition of the M5X swap even more alluring, these engines fit under the bonnet of the E30 very easily indeed, and the weight is simply on par with the M20 meaning you won’t pollute the handling characteristics.

There are a variety of sizes to select from and like the M30, many cars came equipped with these making them very easy and cheap to source. There are two specific variations of the M5X era engines that you’ll be looking for though the earlier M50B25 2.5L or the later M52B28 2.8L, there are many other interesting variants such as a more unusual Alpina tuned 3.2L version.

The E30 M50 M52 swap is exceptionally well documented online, and with considerable aftermarket support. All the information to do these swaps is available to piece together online.

M50

Let’s start with the M50B25. For many this is the better option, potentially the peak of the BMW naturally aspirated (non-M) 6 cylinder motor. Sophisticated and technologically advanced from an engineering standpoint, but simple from an electronics standpoint.

These are exceptionally easy engines to swap into an E30 because you wont have lots of external auxiliary to deal with, nor will you need to battle with BMW’s pesky EWS immobiliser  technology when it comes to the ECU.

The early non-VANOS iron block variants of the M50 engine are especially popular for those wanting to turbo charge their engines. Like the M30 predecessor this is nice and easy to do with an M50 and there’s plenty of aftermarket kits available to make this a simple bolt-on job.

For those looking to get into the drift scene with BMW E30’s and perform an engine swap which will be solid, easy to maintain and deliver enough power, a turbo M50 is the way forward.

Pros:

• Very easy to swap in
• More modern 24v power
• Solidly reliable without much to go wrong
• Cost effective and easy to source
• Extremely well documented E30 engine swap

Cons:

• Not a huge step up from the M20 in terms of performance

M52

For those who prefer their naturally aspirated thrills, the logical move is toward the M52B28.

With slightly more capacity than its predecessor and a little more sophistication with its VANOS cam timing, the M52 is the ultimate non-M BMW 6-pot motor in my humble opinion.

The M52’s trump card is its aluminium block making it lighter than the M50 or any of its predecessors. The M52 only weighs in at 163kg making it around 10kg lighter than the M20. The concept of swapping a more powerful and lighter straight six into a BMW E30 is an exciting one for any enthusiast worth their salt.

The trade-off for the M52 versus the M50 however is the additional sophistication and the advent of additional electronic complication. The vast majority of M52 ECU’s have BMW’s EWS security measures in place, and to remove this adds an additional cost and headache into any M52 swap.

Other than this, both the M50 and M52 engines are solidly reliable and happy to be thrashed time after time. They’re also one of the younger options so you should be able to pick up a very cheap engine or donor car with bags of life left in it before you’ll need to worry about a rebuild.

Of course, it always pays to do you due diligence and over-maintain engines, but from a reliability standpoint, BMW knocked it out of the park with the M5X motors. We won’t be seeing any more engines like this from BMW sadly.

Pros:

• Very easy to swap in
• More modern 24v power
• Solidly reliable without much to go wrong
• Cost effective and easy to source
• Extremely well documented E30 engine swap
• Even lighter than the M20

Cons:

• Additional swap complexity with EWS

V8 E30 Engine Swap

Now we’re talking. For those who have ambitions far beyond the limitation of 6 cylinders, it’s all about the V8. Aside from the obvious hike in power, a larger displacement and two extra cylinders can deliver, there’s no noise like a V8 engine.

The BMW E30 V8 engine swap is a top choice for drifters, these engines deliver effortless torque capable of sending the E30’s rear tyres up in a cloud of smoke very easily.

There are much more unorthodox V8 engine swaps to explore for an E30 build, but for now, let’s hang on to what morals we have left and talk exclusively about the BMW made V8 options available to us.

Many have completed V8 engine conversions using the following engines, and they are particularly popular in the states where they have an affinity to V8s and there’s an abundance of them kicking around in scrap cards waiting to be pulled.

As they are relatively popular there is decent aftermarket support, even if it does mean importing parts from the US and praying it works with right-hand drive cars.

One particular sticking point was engine mounts, but now custom fabricated mounts are readily available off the shelf. Another issue is getting the exhaust manifold to fit the E30’s engine bay, but again this has been solved and the modification has been well documented.

There are two key motors you would be looking for if you wanted to V8 swap your E30, and that’s the earlier M60B40 found in the E34 and the later M62B44 found in various cars including the E39 5 series and the X5.

M60

The M60 is considered the thinking man’s choice when it comes to E30 V8 swaps and you will have to spend a fair amount of time thinking about doing the swap before you’ll track down an M60B40 engine at a sensible price.

The M60B40 engine is a 4 litre V8 and at the time it was launched in the early 90s, one of the most sophisticated V8 engines on the market. Boasting an aluminium block, quad overhead camshafts rather than a crude SOHC configuration, and a coil-on-plug ignition system.

The M60 motor was a real treat for petrol heads, and potentially one of the best E30 engine swaps you can do.

BMW made great efforts with the launch of this V8, and it was their first proper foray into 8 cylinders having produced only a small run of not very successful primitive V8s over 25 years prior.

They came in 2 displacements but the only one worth the swap in my opinion is the 4 litre. The 3 litre alternative is famous for having straight 6 power but v8 thirst, so the only thing you’ll be gaining with that is the glorious sound.

The M60 came at that ideal time in BMWs history where the engineering had come on leaps and bounds but the sophisticated electronics we’re still absent. This makes the M60 a nice engine to swap into an E30 from a complexity standpoint with very few electrical headaches to endure.

The 4 litre V8 produced a reasonable 215 horsepower and an impressive 214 ft-lb of torque to match.

There is however one key consideration to avoid glossing over with the M60, and that’s the Nikasil electroplated bore linings. Sadly, instead of striking a home run with this new and fancy V8 motor, BMW struck out.

The petrol used at the time of this engine had larger amounts of sulphur than modern fuels do, and this reacted badly with the bore linings and over time caused damage that can not be repaired without a full engine rebuild.

The good news is, as gasoline no longer has this additive thanks to emission laws that came into force, M60 engines are no longer vulnerable, and any that have survived up to this point running most likely will continue without bore issues.

But it’s a risk you take as you often won’t know what condition the bores are in until you’ve exchanged cold hard cash for an engine.

Pros:

• Great V8 torque
• Off the shelf swap parts becoming available

Cons:

• Nikasil bore lining concerns
• Becoming very difficult to source at a reasonable price

M62

The M62 is a further advancement on the M60 engine that appeared in the latter half of the 1990s, and you’ll be glad to know it didn’t feature that Nikasil liner any more.

Given multiple technical updates throughout its lifespan, and available in many displacements in many cars, the M62 is quite a common and readily available engine.

The M62 you’ll be looking for would be the M62B44, to buck a trend, this isn’t actually the largest displacement the M62 came in. There were in fact 4.6 and 4.8 litre variants of this engine later in its lifecycle, but these are much more uncommon and much more sophisticated to boot, putting them safely in the “not worth the hassle” zone as far as E30 engine swaps go.

The M62B44 was just right with single vanos and similar complexity to the M52 straight six I talked about in detail earlier. Perfectly achievable to those modifiers with persistence and patience.

A drawback worth mentioning is that these engines are considered somewhat problematic and owners often have trouble with things like timing chain guides and hydraulic lifters.

This M62 is only marginally more powerful than the earlier M60, and with the added complexity, you’d wonder why you’d consider it over one. The truth is, it’s more how readily available these engines are compared that make them so attractive. Although I suppose every additional horsepower is worth having.

It’s worth mentioning that the M62B44 can also be found in Land Rover applications, although there’s a fair amount of conflicting information as to whether the bolt-on parts match up and can be used in an E30 engine swap.

There are later non-M V8 engines available, but there seems to be little to no documented E30 engine conversions utilising them. Probably because they became far too sophisticated and large to fit under the bonnet of an E30.

Having had the pleasure of borrowing an E60 550i which came equipped with a whopping 4.8 litre N62 V8 engine, I can see the attraction. 

The additional horsepower, and especially torque from that engine really took me by surprise when compared to my E46 M3’s S54 motor, and that’s despite the additional weight of the luxurious 5 series.

Before anyone gets upset however, the S54 is still vastly superior in its power delivery.

Pros:

• Additional swap complexity
• Great V8 power and sound

Cons:

• Known to be a problematic engine
• Tight fit in an E30 engine bay

BMW M-Power E30 Engine Swaps

Serious about making not just a bit more power, but the ultimate driving machine out of an E30? Then it’s for what we’ve all been waiting for, it’s time to talk about M-power engine swaps for an E30.

As a self confessed BMW M fan boy, this is a topic which I will happily linger on for some time imagining what could be. We’ve already talked about S14 engine swaps which is the rightful M engine for the E30. But the potential for other combinations is captivating to say the least.

Besides, the S14, although charming and with plenty of pedigree, is a bit of a lightweight when it comes to BMW’s motorsport derived engines anyway.

The thing I love about the below options is the fact that they are each spectacular powerplants straight from the factory. All of these options are soulful engines with revered power deliveries. You won’t be looking at turbo charging these to get the power you seek unless you’re a truly twisted individual.

Saying that, there are many supercharger options available for some of these motors that retain the linear power delivery while dialling up horsepower and torque to almost unmanageable levels. I’m sure you would want to retain that iconic induction roar through ITBs instead though..

S50

The S50B30 and S50B32 engines found in the E36 M3 is an exceptional place to start. The E30 M3 was the first ever M3 and a true homologation special. It’s successor the E36 M3 was more of a road car and it was both criticised and praised for it.

What enthusiasts longed for was the delicacy of the lighter and more nimble E30, but with the proper straight 6 grunt all proper BMW’s should be blessed with.

Well thanks to the miracle of modern science, you can now create this perfect combination at home in your own garage!

Both the S50 engine variants are truly solid engines, the earlier 3 litre version is known to be a bit more reliable, but both are as durable as motorsports engines come and sing through glorious ITBs and proper 6 branch exhaust manifolds.

If you liked my description of the M50 and M52 engines earlier, then this E30 S50 swap will be an enticing prospect as these engines drop in just as easily as those.

The only down sides with the S50 swap is the sheer cost of stepping up to an M engine, and the fact they are more weighty than say the M52 thanks to its iron block.

I’ll give a special mention to the S52 here for all you readers across the pond. It’s easy to look at the S52 as a real compromise with its missing ITBs and tamer power output compared to the S50.

I for one agree that it’s not a full-fat motorsports engine and more of a marketing exercise performed by BMW to support US sales of their E36 M3.

However, the more you think about it, the more you realise that its effectively a well tuned M52, bored out to 3 litres rather than 2.8. The S52 engine makes absolute sense in an E30 body and I can absolutely condone it.

In my humble opinion, an S52 in an E36 is a disappointment, an S52 in an E30 however is a sight to behold.

Pros:

• Very easy to swap in like the M5X
• Proper glorious M-power engine
• Known to be reliable

Cons:

• Expensive to buy
• Hard to find

S54

Why settle for an S50 when you could strive for BMW’s all-time ultimate straight 6 engine, the S54B32?

The S54 motor has now achieved legendary cult status to put it lightly, and with damn good reason. While it maintains the same displacement as the larger S50 option, it’s a different animal altogether.

The S54 is the S50 but turned up to 11, and you were already drooling over the S50!

I’ll try my best not to be biased here as I am the proud owner of an E46 M3 which came equipped with this engine, and it really is the star of that show. I’ve adored every opportunity to explore the capabilities of this engine and let it sing out to its 7900 rpm redline.

The S54 engine produces 343 bhp in european spec which is more than enough to enjoy, slightly less in US spec thanks to emissions equipment in the headers. The seemingly more disappointing figure is the torque which comes in at around 270 lb-ft, this means all the power is at the top end with this engine, and you have to work for it, which can be very rewarding once understood.

The S54 makes plenty of power in its E46 chassis home, putting it in a lightweight E30 chassis would certainly create something truly ballistic.

One thing to note is how many E46 M3’s were actually built by BMW, it was the most successful M3 by far, and while the cars might be starting to creep back up in value, particularly well specced and maintained manual coupes, there are much cheaper variants available such as poorly specced convertibles with the SMG gearbox.

Buying the S54 engine alone is quite often not the most cost effective route with this one, probably because there are so many people trying to do engine conversions like these.

A good route would be to buy a tired E46 M3 convertible and break it for parts keeping only the engine. I’ve even heard of people getting all their money back breaking an E46 M3, meaning their S54 engine ended up being pretty much free.

In theory the S54 might make for the best BMW E30 engine swap, and it’s becoming more and more common.

There are however a couple of downsides to be aware of with this E30 engine swap. For starters, the S54 motor is known to be a bit more highly strung than its predecessors.

The dual VANOS system which aids the power delivery so much is a weak point known to fail. It also has a tendency to burn through rod bearings leading on to potentially catastrophic engine failure.

Due to this they require more regular and careful maintenance and a recommended 100k mile rod bearing replacement.

The weight is also similar to the S50 with the iron block configuration.

Pros:

• Ultimate straight 6 BMW E30 engine swap option
• Fairly easy to swap in
• Proper glorious M-power engine
• Can be cost effective if you break an E46 for parts

Cons:

• Additional complexity with electronics
• VANOS issues
• Rod bearing issues
• Expensive to buy as an engine on its own

S62

The S62B50 is known as one of BMW’s finest M engines, and it was found in the E39 M5, known as one of the finest M cars in history.

Like the sound of the previously discussed M60 and M62 V8 swaps? This big old 5 litre V8 is the ultimate rendition of that.

These higher compression 5 litre V8 engines rev to 7000 rpm and produce 394 hp and a healthy 369 lb-ft of torque. That’s a whole 100 more than the S54 we just talked about.

Being an aluminium block and head design, the S62 isn’t heavier than the previously discussed 6 cylinder M engines making it prime for an E30 engine swap. Incidentally they are more robust motors too and are not known to be problematic if maintained properly.

The trouble with this one is its size, especially with the fancy top-mounted plenum chamber which is necessary to make those factory power numbers.

You’ll find the S62 engine quite a bit harder to find than the 6 cylinder options too.

Pros:

• Solid M-power V8 swap option
• Piggyback off M62 swap parts
• Proper glorious M-power engine

Cons:

• Additional complexity with electronics
• Challenging to fit in an E30 engine bay
• Expensive to buy

S65

Here’s where we start getting into more dangerous territory. The S65B40 is the 4 litre V8 found that the E90 E92 M3 came equipped with.

BMW’s first V8 M3 and its last swan song for naturally aspirated M cars with obnoxiously large displacements.

You might be wondering why the S65 would be better than the previously discussed S62. It’s just a smaller BMW V8 right? Probably very similar but less powerful than the other.

Well you’d be wrong…

The S65 is actually derived from an even larger engine with more cylinders which we’ll be moving on to next. Due to this it shares very little in common with the S62.

Where the S62 is a big torquey V8 setup for lazily cruising on the autobahn at ludicrous speeds, the S65 is more racey and comparable to the S54 straight 6, but with 2 more cylinders.

Like the S54, the S65 is known to be lacking in the torque department but also makes up for it with a thrillingly high red line. Interestingly it rarely gets the support that the S54 receives, despite on paper looking better in almost every way.

Maybe it will be more appreciated in the future, but as the E92 still a fairly modern car, the love for this engine hasn’t quite had enough time to mature.

The S65 V8 is high compression and uses a flat plane crank. It has a different firing order to previous BMW V8 engines giving it more of a supercar V8 feel and sound comparable to mid engined Ferraris.

The S65 engine produces 414 hp and 295 lb-ft of torque, but the 8300 rpm red line is probably the main event.

Sadly the S65 is known as an even more temperamental engine than the S54 before it was. While the S54 will generally do 100k miles before you want to be worried about the rod bearings, S65s are known to spin bearings at 60k miles.

Other issues include throttle actuators for the fly by wire throttle pedal although this issue is now well documented.

Most famously Phil from Driftworks transplanted an S65 into his E30 M3 race car which was controversial at the time, but the result is without doubt spectacular.

With the DCT gearbox brought along for the ride too, the S65 swap has been a considerable undertaking even for Phil and his team making it one of the most challenging E30 engine swap options. This indicates that its not the most DIY friendly engine conversion and you would want to consider taking it to E30 engine conversion specialists to get the job done right.

Pros:

• Thrilling M-power V8 swap option
• Amazing performance and sound

Cons:

• Huge complexity with electronics
• Challenging to fit in an E30 engine bay with plenum
• Expensive to buy
• Limited gearbox options
• Problematic engine rod bearings

S85

In my opinion this is as ludicrous as it gets, and there’s no option more ambitious than an E30 S85 swap.

The S85 is the only V10 engine BMW have ever put into a production car and is inspired by their previous F1 engine building involvement.

The S85B50 is a 5 litre supercar level engine with performance stats and engine note to match. It’s the big daddy of the previously suggested S65 V8 motor and was available in the 5 and 6 series E60 E61 and E63 of the time.

This engine was produced between 2005 and 2009 and for the EU and UK markets came exclusively paired to the SMG transmission which people grew to dislike. Only the US market got to have this engine mated up to a manual gearbox.

The S85 engine produces a whole 500 hp and 384 lb-ft of torque which is mighty to say the least. Weighing in at 240kg despite its aluminium construction, it’s a big power plant and if you’re planning to S85 swap an E30 you’ll want to be aware of that.

Such a heavy and powerful engine mounted in a light E30 is said to induce massive wheel spin and oversteer in high speed corners, and frustrating understeer in low speed corners.

So if you’re considering this swap you will need to be prepared to do some considerable suspension work to dial as much of that out of the handling as possible. Especially the understeer, nobody wants that.

It’s also worth mentioning that the weight of this V10 motor is deceptive, they are absolutely massive and it’s a wonder how anyone has ever got one of these to fit in an E30 engine bay. I suspect many of the parts usually found under the bonnet have had to find their way into the cabin for this to work.

I think you would struggle to find BMW E30 engine conversion specialists who would be willing to take such a swap on.

Like the S65, the S85 is plagued by mechanical problems and premature failure which is a real shame as it’s such a spectacular engine.

To run one of these engines long term you have to be a true enthusiast, and with either very deep pockets or considerable mechanical skill to keep on top of maintenance.

I often find myself on ebay lusting after S85 equipped M5s and M6s as their price has come down to the point where jumping out of my E46 M3 and into one would probably put money in my pocket.

At least until something went wrong anyway. I must resist the temptation of these cars as they can potentially lead to financial ruin, and it’s not just the engine which is problematic with them.

Few people have been brave enough to S85 swap an E30, but sure enough there have been people that have done it.

Pros:

• The ultimate in BMW M-power engine swaps
• Supercar performance
• Legendary V10 sound

Cons:

• Huge complexity with electronics
• Almost impossible to fit in an E30 engine bay with plenum
• Massive amount of custom fabrication required
• Expensive to buy
• Limited gearbox options
• Problematic engine with rod bearings

Non-BMW Best E30 Engine Swaps

If you’re happy to create your own Frankenstein monster and do something as unnatural as throwing a non-BMW motor into an E30 engine bay, then this section is for you.

Many would say this is sacrilegious and the devils work, but the truth is, you can often have the best of both worlds by mixing brands, or crossing the streams as some say.

There’s a whole world of opportunity when you break free of the BMW engine options in pursuit of the best E30 engine swap, but I’ll only name the most popular favourites.

They’re certainly food for thought…

Honda K20 or K24 Swap

The revered Honda 4 cylinder K20A is a real peach of an engine. Very powerful for its size and 2.0L displacement, very robust, and with a stunning power delivery enough to make a BMW M engineer proud.

This engine is most notably found in Honda Civic, Accord and Integra Type R models and while they are starting to go up in value now having achieved cult status, they are still relatively cheap and available.

Due to this, the K20 engine swap is extremely common among many circles and various marques.

The K20 engine produces 217 hp and 152 lb-ft of torque with a red line of 8400 rpm. Impressive to say the least and possibly the ultimate antidote to those intrigued by the BMW S14 and M42 4-cyl options.

Those looking to tune and go turbo power will be more interested in the lower compression K24 variant which adds a bit more displacement ideal for turbo charging. These share similar characteristics to the K20.

These engines fit under the E30’s bonnet longitudinally without a hitch too.

Pros:

• Spectacular 4-pot power
• Plenty of aftermarket support from K20 nuts
• Fits nicely into an E30 engine bay

Cons:

• Non-BMW Engine
• Still an unusual swap with custom fabrication needed

Chevy LS E30 Engine Swap

LS swap the world they say, and it’s no surprise when you look at the potential.

The Chevrolet LS V8 is the ultimate expression of the big American V8. Its remarkable how far these things have come since the days of the muscle car.

The modern LS engine is an all aluminum lightweight motor with huge displacement and torque. The tuning possibilities are almost limitless with these engines and as far as bang for buck goes, there’s nothing that can match it, especially not from BMW.

It’s absolutely remarkable how much power these can make being such an old school cross-plane pushrod design, but I suppose that’s what 70 years of constant development will do.

You can pick up a cheap LS very easily in the states, they’re found in many cars and Chevy also offer them as a “crate motor” which effectively means you can order a new one to be delivered to you on a pallet. Amazing huh?

Things are a bit more difficult in the UK with none of these engines coming over to us naturally, but due to the abundance it can still be surprisingly cost effective to simply import one.

For me, no matter how great these LS engines are, it doesn’t seem right. Maybe it’s that there are much more appropriate cars to throw LS motors in, i’m not sure. But for those who mean business when it comes to performance, this is the way.

Pros:

• Insane power potential
• Tuneful V8 noise
• Plenty of aftermarket support state-side

Cons:

• Non-BMW engine
• Would need to be imported

Which E30 Engine Swap Is For Me?

There are obviously many more engines that could potentially be swapped into an E30 than I have mentioned here, but now you know the most popular options and my personal considerations.

Bear in mind I am writing this from the standpoint of a BMW enthusiast and a long-time E30 lover. Therefore a romantic element is involved in the selection for me rather than just considering cost, difficulty and resulting power.

I personally am looking for the right balance to suit me and my wants and needs from a project car. Plus I am looking at doing the job DIY style in my home garage rather than going to an E30 engine conversion specialists in the UK.

For me, the right way forward is the M52 engine.

While not the most exciting engine on the list, it ticks the most boxes, and the resulting E30 will be an absolute delight to enjoy without any real drawbacks to taint the experience.

Now the decision is made, all that’s left to do is source myself an M52B28 and get busy. Check out our Youtube channel to follow along with the resulting E30 build.

You’ll likely see more E30 engine swap blog content to come to as I share the project and hope to inform others on how to swap an engine into an E30.