This RamAir-sponsored tuned BMW 135i may look innocent enough on the outside, but lift the bonnet and you’ll find a mighty, 550bhp single-turbo conversion…

tuned bmw 135i E82 turbo

The sleepy town of Pewsey is one of those places that where time appears to have stood still. Nestled in the rolling Wiltshire countryside, life here runs at a more sedate pace. But don’t be fooled. Like many of the UK’s smaller towns and villages, look a bit deeper and you’ll often find a lively tuning scene.

tuned bmw 135i E82 turbo

This area is home to RamAir, one of the UK’s fastest growing air filtration specialists. With a heritage stretching back to 1981, the last five years has seen rapid growth with a new range of performance intakes. Key to this success has been a ‘can do’ attitude and willingness to help people out with unusual fitments – people like Chris Roberts.

tuned bmw 135i E82 turbo

Chris has been a mate of Dan, Chris, Mike and the rest of the RamAir crew for several years and has become their unofficial test driver. “They’ve always helped me out with products and because I’m on track a lot, everything gets a thorough testing!” he smiles. So when he needed help with his latest project, he knew where to turn. “I’m really into to track driving and after my modified Impreza went, I wanted a new toy,” he explains.

tuned bmw 135i E82 turbo

The 2009 Beemer certainly ticked all the boxes. The N54 twin-turbo straight-six produces 302bhp and sends it all to the rear wheels. It’s a fast, well-balanced car and was perfect for what Chris wanted.

tuned bmw 135i E82 turbo

Having purchased this highly-spec’d example from MCR Specialist Cars (also mates of Chris), he proceeded to drive the nuts off it at every opportunity. “I’ve lost count of the number of laps I’ve done at Castle Combe, but it must be hundreds,” laughs Chris. “I’ve also been to the Nürburgring in it and did loads of laps there – the car didn’t miss a beat.”

tuned bmw 135i E82 turbo

With so much of its time spent on track, the BM didn’t remain stock for long and the usual upgrades to the suspension and brakes were carried out to make it more capable. “It was a great handling car, but coming from a much more powerful Impreza, it felt like it needed something extra,” admits Chris. The issue was compounded by the relative girth of the 1-Series, which weighs in at around 1500kg – a fair amount for a small coupe. “I didn’t want to strip it out as it’s a nice car that I also use on the road,” says Chris. So, it was clear that more power was required.

tuned bmw 135i E82 turbo

Some research revealed that several single-turbo conversions had been carried out on the twin-turbo 3.0-litre N54 engine, mainly in the US. The logic was simple: a large single turbo would be less stressed than highly worked twins, plus it’s much easier to access. Given that this car is built to drive hard, that’s a big factor. A large single blower also comes on boost higher in the rev range than upgraded twins, which puts less strain on the N54, which can be vulnerable to high levels of low end torque. And let’s face it – opening the bonnet to be greeted by a massive ’bine is always a winner! With no off-the-shelf single-turbo kits available, Chris turned to local turbo specialists, Davefab.

tuned bmw 135i E82 turbo

These guys (both called Dave, funnily enough) have made a real name for themselves with their home-brewed turbo set-ups, most notably on their own Mazda MX-5 demo car. They couldn’t wait to get stuck into the BMW.

tuned bmw 135i E82 turbo

Clearly a large turbo wasn’t just going to bolt onto the OEM engine, but the team soon realised they could do it without incurring huge expenses.

tuned bmw 135i E82 turbo

“The plan was to retain the stock manifolds, which would make things a lot easier and cheaper,” says Chris. “We also left the engine stock, as from what we’d gathered, the internals could take over 500bhp.” The team also knew that they could get it to run via a piggyback ECU set-up. All of this meant they wouldn’t have to pay for a built engine, fancy tubular manifolds or standalone management, which would really keep a lid on costs.

tuned bmw 135i E82 turbo

Even so, a lot of thought had to go into the conversion as the 1-Series’ bay wasn’t designed for a large single turbo. Several items had to be relocated including the power steering and header tanks. A major issue was the lack of space in front of the turbo, so RamAir’s engineers developed a custom ‘short’ air filter that fits perfectly. With an in-house design and manufacturing facility, it’s something they are able to offer alongside their wide range of model specific kits and silicone hoses. The gold heat management tape is also a RamAir speciality and adds that authentic ‘racecar’ touch to the engine bay.

tuned bmw 135i E82 turbo

Once work had commenced, it quickly progressed, although a tight deadline did lead to an all night session before the car’s maiden outing. “The PAAA Industry Track Day was fast approaching and RamAir asked me to bring the car along.” Says Chris. “So we worked through the night to get the car ready. We finished it and drove straight to Castle Combe.”

tuned bmw 135i E82 turbo

With some of the biggest industry figures in attendance, the large snail under the bonnet certainly raised a few eyebrows. “We were only running on low boost at this stage, but even so, it still went really well,” he says. It was clear the big turbo set-up worked and offered huge potential once the map had been fine-tuned.

tuned bmw 135i E82 turbo

Since then a lot more development work has gone into the car and it’s now running around 550bhp and 560lb/ft. But with further mapping, Chris is certain there’s more to come.

tuned bmw 135i E82 turbo

“The highlight for me so far was at the Spring Action Day, where I was leaving a Porsche GT3 for dead,” laughs Chris. “Here was this guy in a bright yellow £170,000 car being left by a little, ten-year-old 1-Series!” The GT3 driver, along with many others on track that day, was quick to check out the BMW back in the paddock and all gave a nod of respect when they saw what was under the bonnet.

tuned bmw 135i E82 turbo

“That’s what I love about this car,” says Chris, “Most people don’t realise it’s so fast. Ok, if you know what you’re looking for you might spot the 255-profile track tyres – which stick out a fair bit and give lots of extra grip, and there’s the rear wing, but it isn’t covered in graphics or stripped out with a cage.” In fact the wheels were one of the trickiest parts to get right.

tuned bmw 135i E82 turbo

“I wanted 255s all round so that if I get a puncture, I only have to carry one spare; I haven’t got room for staggered fitments.” This meant fitting 255s on the front, which the 1-Series was never designed for. “We had to pull out the inner arches and then roll the outer arches to get the Team Dynamics Pro Race with Yokohamas to fit,” says Chris.

tuned bmw 135i E82 turbo

The arch rolling technique involved placing several magazines on the tyres, then pushing down on the wings with brute force, until the magazines slipped, allowing some movement. It’s a rather crude way of doing it, but it did the trick and is a neat little hack.

tuned bmw 135i E82 turbo

Inside, the stock interior remains, including the leather seats, which offer a surprising amount of support, even when flinging it around a track. The only giveaway is the iPhone mounted in a cradle on the dash, which shows an array of gauges. “It links to the JB4 ECU and allows me to control the boost, fuelling, check oil temps– you name it,” says Chris. The boot is home to that precious spare – from an M3 and the water/meth injection tank.

tuned bmw 135i E82 turbo

So what’s next for this ballistic BMW? “I’m going to spend the summer on track and represent RamAir at shows and events,” says Chris. “There’s more mapping to come, so it’ll make more power, but to be fair it goes pretty well as it is.” He’s not wrong.

tuned bmw 135i E82 turbo

As we wrap up the shoot, he asks if we can try a few ‘smoky shots’ and proceeds to nail the throttle and lay down some rubber. As the smoke clears, a smiling Chris gets out of the car and says, “I’ve never done that before; I’m no drifter, but that was fun.” Look out for this ballistic BM at a track near you, soon…

tuned bmw 135i E82 turbo

TECH SPEC BMW 135i (E82)

Engine
Stock 3.0-litre N54 engine, Davefab single-turbo conversion utilising the standard manifiolds, all joints V-banded for easy assembly/disassembly, Davefab custom 3in downpipe, Davefab custom water pipe, Davefab custom rocker cover/coil-injector loom heat shield, BorgWarner EFR 7670.92 internal gated turbo, Turbosmart twin-port actuator with 17psi base spring, R-spec/Mac 4-port boost solenoid, RamAir custom ‘short’ air filter, Forge uprated charge pipe with 50mm dump valve and water/methanol nozzles fitted, Goodridge fittings and braided lines throughout on the turbo, Motamec 26-row oil cooler with black braided lines, torques oil block take off and fittings, Devils own/coolingmist water/methanol injection kit with twin cm7 nozzles, water header and power steering tanks re-located due to single-turbo conversion, Wagner intercooler, Protuner Stage 2 drop in uprated fuel pump, standard exhaust cut up and gutted/straight through with quad twin-exit exhaust, Burger Motorsport JB4 ecu with Bluetooth interface connection allowing mapping/control from iPhone, BMS oil catch can, Rob Beck PCV valve, RamAir gold reflective tape for heat management, lambda sensors re-located pre-turbo in manifold runners, BMW 550i OEM clutch, NGK 1 step colder spark plugs gapped down to .20

Power
Around 550bhp and 560lb/ft @ 20psi boost (more to come when fully mapped).

Suspension
BC br coilovers with adjustable top mounts and 30-way adjustment, set up for 2.5-degrees camber all round for track, Eibach uprated 25mm front and 15mm rear anti-roll bars.

Brakes
Factory-fitted 6-pot front and 2-pot rear Brembo brakes re finished in Renault Liquid yellow, Pagid Motorsport RS29 pads all round, M-tech brakes ‘J’ hook discs all round, Hel yellow braided brake lines all round, Castrol SRF brake fluid.

Wheels and tyres
Custom made Team Dynamics Pro Race 1.3 18×8.5 et50 square set up alloys in gloss black, 15mm spacers front – 10mm spacers rear, Toyo R888r/Yokohama AD08r 255/35×18 tyres, 25mm wheel stud kits, custom gel badge black/white BMW flat centre caps.

Exterior
Factory fitted M-Sport bodywork, Itec Tuning BMW M3 GTS rear carbon spoiler with alpine white ends, BMW carbon fibre lip spoiler, BMW carbon wing mirrors, carbon aerial cover, Kerscher carbon front splitter, all arches rolled, pulled and cut to accommodate wider wheels for track, black/white BMW badges, rear bumper cut and modified to house quad twin-exit exhaust, roof wrapped in gloss black vinyl, facelift 2010 LCI dark line rear lights, fully loaded with every optional extra including xenons, parking sensors, tinted windows, headlight washers etc.

Interior
Fully loaded BMW interior including black Boston leather, iDrive, full professional Harmon Kardon stereo and sound system, E92 M3 traveller spare wheel kit, Devilsown/coolingmist water/methanol injection kit mounted in the boot.

Thanks
Dave Massey and Dave Nicholls at Davefab, Dan Mullan, Chris Yates and the gang at RamAir, Chris Beaven for all his help as without him the car would not of been possible, Paul Kang at BTN turbo, Greg Gush at Protuner, Mike Chalk and the Crew at MCR Specialist Cars, Jamie Williamson at Dick Lovett BMW Hungerford for the OEM parts, all my family for help and support, thanks also to Swindon Karting Arena for the location.

Words and photos Davy Lewis