Perfectly-modded 290bhp S50 3.0-litre engined BMW 330i Coupe E30

With its clean styling and super-subtle exterior additions, there’s no way you’d know this perfectly-modded E30 is hiding an S50 under its bonnet, and it’s transformed this classic Three into a serious driver’s car.

Words: Elizabeth de Latour

Photos: Jason Dodd

S50 E30 – CLASSIC THREE GETS M POWER

S-tier - Everybody loves the E30, but there are plenty of ways to improve it. Sticking an S50 under the bonnet is certainly one of them, and this M-powered beauty is simply superb.

The E30 loves an engine swap, there can be no denying this fact. While swapping out the S14 from an M3 takes a certain degree of bravery, pretty much anything else is fair game if you’re not talking about any of the rare, hard-to-find E30s. Of course, we can totally appreciate the appeal of originality, but if you’re looking for some serious performance from your E30, it’s going to be far better to swap in something more substantial than it will be to attempt to fettle even something like the venerable M20B25.

And if the opportunity to pop something like, say, an S50 under the bonnet of your E30 appeared, we doubt anyone could turn it down. Kieran McCabe (@k_gtr_e30) certainly couldn’t, and his E30 has seriously cranked up the spice levels, not that you’d ever suspect that this super-clean classic Three was pushing out almost 300hp by looking at it. Naturally, our first question to Kieran is to establish just how big of a BMW fan he is, and that’s when we find it’s time for a surprising fact from the man himself. “I have to confess that my car history has been predominantly JDM,” chuckles Kieran nervously before quickly adding: “but I have always liked BMWs! And aside from my first car, a Peugeot 106 with a subwoofer in the back that weighed almost as much as the car, BMW is the only make of car I’ve owned that isn’t Japanese, and that wasn’t until I was 30!” he exclaims, so we’ll let him off there.

My favourite mod has to be the engine swap! It feels and looks like it’s the engine that should always have been put in this car

“My first BMW was a Z4 M Coupé. I’ve always loved the shape of this car and the S54 straight-six engine,” Kieran enthuses. “It was really different to anything I’d owned in the past. The car I had just before it was a V6 350Z, which I really enjoyed but always felt was lacking something. I didn’t know just how much it was lacking until I test-drove the Z4 M,” he grins. “When I first saw the Z4 M come up for sale online, it was at a dealer four hours away. I called up, and they said I would have to put a deposit of £1000 down to secure it if I wanted it, as they expected it to be gone within 24 hours. I took a gamble, which ultimately paid off, as I completely fell in love with the car after a short test drive,” he smiles. “In the time I owned it, I fitted 19” graphite Ispiri alloys, a Remus full stainless exhaust, and carbon rear lip spoiler and wrapped it in 3M Satin Perfect Blue. Eventually, I sold it to buy an R35 GT-R Black Edition which I still own,” he says, but that long-distance love of BMs was now bubbling to the surface, and, it wasn’t long before Kieran was on the hunt for another Bavarian offering.

“I’ve always loved E30s and also loved the idea of owning a retro car that I would keep for a long time,” he begins. “I’d started looking online just at the time when prices started to rise quite rapidly. I knew that if I was going to go for it, I needed to find one fairly quickly before prices became unrealistic for my budget, which at the time was a pretty healthy £10k… Not so healthy by today’s standards!” he laughs.

“The moment that really tipped me over the edge from just ‘looking’ to ‘I want one immediately’, was when I was in London and saw a blacked-out E30 Coupé at some traffic lights. It was absolutely gleaming, sitting on 16” BBS RS polished rims, low to the ground, and I just stopped and stared. I called my friend Mark Dady and said: ‘You need to help me find an E30’,” he laughs, and the hunt was on. “Mark had previously tried to talk me out of buying an E30 because he had owned a couple in the past and figured that I wouldn’t like the way they drove or handled compared to other cars I’d owned just because of their age,” explains Kieran. “Once I’d convinced him that I was adamant I was going to buy one, he offered his help to prevent me from just purchasing the first one I saw on impulse. Mark made some calls, and within a couple of days, he called me to say that he found a 325i Sport for sale in Essex that was high mileage but well looked after. I arranged to view the car straight away, along with a 318i Coupé I’d seen, which was a low-mileage example only a few miles away. As soon as I arrived to view the 325i and saw it there, in its stock form, gleaming in the sun, I knew I was going to buy it. It was exactly what I imagined and exactly what I wanted, despite the high mileage (196k miles),” Kieran enthuses, and the deal was done.

Kieran has modified a lot of his previous JDM purchases, so it was inevitable that the E30 would receive some upgrades, but things didn’t go in quite the direction he’d originally intended. “My original plan for the car was ‘Low & Slow’,” Kieran explains. “I wanted to make a couple of very subtle mods, like wheels and suspension, and then just keep the car standard. It was also quite a rare car, being a Sport and completely original, except for being converted from an auto to a manual, so it had the potential to appreciate in value. But that’s not why I bought it, and it wasn’t long before the mods went past the ones that were originally planned,” he chuckles.

Things started slowly, with the usual sort of mods we all begin with. An H&R Cup suspension kit went on to get the E30 sitting nicely and to tighten up the handling, but it was still a little lacking for Kieran’s tastes. “The steering response still felt like an old car and just needed sharpening up a little. I bought a purple tag steering rack from a Z3, which I still think is one of the best mods I’ve done on the E30.

It made a massive difference,” he enthuses. “I then purchased a set of 16” BBS RS replica alloys, which looked the part, but I knew deep down that they weren’t the real deal and I was just pretending,” he says. “They were also adding unnecessary weight to the car, so I knew I would eventually change them for the real thing when the bank balance allowed it. I then temporarily fitted a Scorpion exhaust back box just to tidy up the slightly rusty original rear box. Then I fitted black eyelids, tinted the headlights and fog lights, fitted retro black number plates, clear lenses and tinted indicators,” and this is the extent of the exterior mods. Regular readers will know we’re big fans of E30s when they aren’t fitted with an abundance of extra styling elements, so we definitely approve of Kieran’s approach here.

Of course, what we’re really interested in, is what’s going on under the bonnet because it’s transformed this E30 into a serious sleeper. “An opportunity came up when a friend of mine, Matt Oliver of Steeralign, contacted me to say that he’d just been on a job where he’d weighed an E30 chassis for a customer that was looking to carry out an engine conversion from a previously swapped E36 S50B30 to an E46 S54B32,” Kieran tells us. “I asked for the guy’s number to ask for a price for the S50 if he was looking to sell. Luckily for me, he was an absolute legend and sold me the engine, radiator, gearbox, BTB manifold with full custom stainless exhaust and ECU, all for a fair price, so it was almost a straight swap,” he grins.

“Also very lucky for me, Matt is an absolute wizard with engine conversions, and he was able to carry out the conversion within a couple of weeks, working around his other regular work. The only additional parts I needed to buy were an E28 M5 engine mount, some new E36 radiator brackets, new gearbox mounts, and an S50 wiring adaptor from Hack Engineering to convert the 25-pin S50 engine plug to the E30’s 20-pin body plug. I also had a Chase Bays power steering kit fitted and replaced all the engine bottles with new ones from BMW,” he says. Kieran was incredibly fortunate to get his hands on essentially a ready-to-go engine swap package and even luckier to have a friend who could do the work for him. And while the M20 is a fine engine, it can’t hold a candle to the S50. This E30 now gets to enjoy 290hp, which is a very healthy amount in such a light car, and it’s no surprise that Kieran loves the S50. “My favourite mod has to be the engine swap! It feels and looks like it’s the engine that should always have been put in this car,” he smiles.

Of course, you can’t just add another 120hp to an E30 and leave things at that, so Kieran set about ensuring the rest of the car was able to cope. “With the additional power from the S50 engine, I knew it was going to need something a bit more substantial than the original brakes, so I turned to Wilwood for its DynaPro four-pot front calipers and its 280mm drilled discs with some Ferodo DS2500 pads,” and that combo has given this E30 some serious stopping power.

The chassis, naturally, also needed some attention, because as good as the H&R Cup kit was, Kieran wanted something that would take the car’s handling to the next level. “BC coilovers seemed to have a good reputation for E30s, and once they were fitted, in addition to a Whiteline front strut brace, they completely transformed the appearance and sharpened the handling even further, making the car feel even more like a go-kart!” he grins. “Dropping the car even lower did have its consequences, however,” adds Kieran. “We needed to fit a rallyspec skid plate under the S50’s sump, which sat lower than the original M20’s sump. The uneven country roads where I live have certainly put the skid plate to the test! Not to mention the E30 M3 front splitter!” While we can’t appreciate the handling, we can appreciate the looks, and the drop served up by those coilovers has got this E30 sitting so well.

The perfect drop deserves the perfect wheels, and we all know what Kieran was gunning for here. “Ever since seeing that E30 in London, I knew it had to be a set of BBS RS that I’d have to go for! I did buy a set of ultra-rare Centra Mesh alloys that were simply stunning, but, unfortunately, the offsets were too low for the car, and without fitting a wide-arch kit, they wouldn’t have been on the car long. The replica RSs I had did their job for a time, but as soon as I saw my current set of BBS RS 033 split rims, I knew I had to buy them. Originally 15” but stepped up to 16”, they fitted beneath the arches perfectly and gave the car the quality finish it deserved,” gushes Kieran, and we’re equally in love. The combo of silver centres and polished lips is a classic one, while the red and gold centre caps add a splash of contrasting colour, and these wheels were the perfect choice.

And then, all that was left was to add a couple of finishing touches. “I decided to add some very subtle matt black stripes down each side of the car with a little ‘S50’ decal towards the rear. This is the only external giveaway of the engine work that’s been done on the car (unless it’s running, then it’s obvious it’s not stock!),” says Kieran, and, honestly, we really like them. They add that little bit of a personal touch to the car but are so super-subtle you’d miss them if you weren’t paying attention. And on the inside, he’s fitted a Blaupunkt Bremen retro-style head unit that suits the cabin aesthetic perfectly but adds DAB and Bluetooth for those welcome mod cons. It’s taken three years of work to get the E30 to this stage, and it was all worth it. The subtle exterior mods have enhanced that iconic classic styling, the wheels are pure perfection, and the S50 swap makes this something special. We’re all for originality, but you can’t knock having some serious M power under the bonnet of your E30, and it’s given this classic Three some proper pace. No wonder Kieran is planning to hang onto it. “I won’t be parting from the E30 for some time, and I plan on enjoying it as much as possible!” he exclaims, and that’s something that comes very easily with a build like this.

TECHNICAL DATA S50 E30

ENGINE AND TRANSMISSION: 3.0-litre straight-six S50B30 from an E36 M3, BTB tubular manifold with full custom stainless exhaust, E36 M3 radiator, ECU and oil cooler, E28 M5 engine mounts, Hack Engineer S50 wiring adaptor, Chase Bays power steering kit, rally-spec skid plate. ZF Type C five-speed manual gearbox from an E36 M3, custom-built 3.25 Type 188 limited-slip differentialMAX POWER: 290bhpCHASSIS: 16” BBS RS 033 three-piece split rims with silver centres, polished lips and red and gold centre caps, Nankang tyres, BC Racing coilovers (51mm strut) 6/6kg springs, Whiteline front strut brace with quick-release clips, BMW Z3 purple tag steering rack, Wilwood DynaPro four-piston front calipers and Wilwood 280mm drilled discsEXTERIOR: Tinted headlights and fog lights, clear indicators, eyelids, de-chromed grille, E30 M3 front splitter, matt black stripes with S50 decalsINTERIOR: Blaupunkt Bremen retro-style head unitTHANKS A massive thank-you to one of my oldest friends, Matt Oliver from Steeralign; the project wouldn’t have happened without him. Also a huge thank-you to Mark Dady for helping me find the car in the first place and stopping me from buying some absolute shockers just out of impulse!

The 3.0-litre S50 serves up 290hp and has transformed the driving experience.

The engine swap has made sure this E30 is a keeper for owner Kieran, and he loves it. Gorgeous BBS RSs started out life as 15s, but have been stepped up to 16s.

The interior has been left stock, with just a retrostyled modern Blaupunkt head unit added