Twin-engined Lupo running pair of NOS-injected R32 motors! Hyper hatch heaven? With 12 cylinders, 6.4-litres and a nitrous-fed 800bhp, Petar Biocic’s ‘R64’ Lupo is an oldschool lunatic built with new technology. Words: Alex Grant. Photos: Tony Matthews.
800 BHP LUPO CRITICAL MASS
hen the first issues of Performance VW rolled off the printers in 1996, properly big power figures didn’t come easy in this scene. Volkswagen was pretty slow making use of forced induction, so joining the 200-plus horsepower club required hard graft until the 1.8T came along – the likes of wrung-out 16-valve race engines, boosted VR6s and notoriously fragile heavily-tuned G60s. Or, if you wanted to push your boundaries way off the map, there was always the extreme option of a second engine.
It’s become a bit of a lost art now that 300-plus horsepower four-wheel drive hot hatches are as common as the off-the-shelf parts to make them even faster, but twin-engined cars have lost none of their impact. DubSport’s pastel-painted lunatics could always pull a crowd as they howled down the GTI International strip 20 years ago, but an 800bhp Lupo with 12 cylinders on board can still stop traffic at Wörthersee today. It’s a reminder of an unhinged era, and we’re all for it. “The original idea was to build a drag car I could use every day,” Petar Biocic tells us, as he gently unloads his screw-loose creation off the back of its low-loader. “You can drive it on the road but it doesn’t really work for long journeys when you’re averaging 40l/100km (5.9mpg). So it’s become a car for fun. Lots of fun.”
If it caused a stir at the world’s biggest Volkswagen show, and a 70-plus page build thread on the Edition38 forums, then you can bet it doesn’t go unnoticed back home. Petar is based out of Funtana, a tiny fishing village in northern Croatia, and his Biox Performance workshop seems to be single-handedly upping his neighbourhood’s average cylinder count. Behind closed shutters all sorts of larger-capacity, often forced-induction, engines have been shoehorned into cars smaller and lighter than they were ever designed for. For most of them it’s a process of cutting first, then figuring out the fine tuning to make it all work.
“I’ve liked cars since I was a boy – I did my first engine swap when I was 12 years old, in a car I had for driving in the woods,” he says. “Then my Dad had a 1986 Mk2 Golf diesel, and we changed the colour, fitted a Corrado dashboard, GTI interior and big bumpers, so it was the first car I built. That led to me buying a Rallye and converting it to a 2.9 VR6 in 2003, which is where all of this really started.”
A VR6-swapped Rallye might have seemed like the ideal way to nudge Petar past that 200bhp yardstick, but it wasn’t the machine that got him there. His first owned build made way for a ground-up street and drag race car back in 2004 – a 1.3-litre Mk2 Golf with the full running gear from a Mk4 V6 4Motion. But, when a friend offered him a spare engine, new ideas started to form.
“The Mk2 wasn’t really fast enough for what I wanted,” he explains. “I had read a lot about Ian Birch and the DubSport cars in Performance VW back in the day, and started wondering about buying the Rallye back and doing something similar with it. But I was worried that it wouldn’t be fast enough, so I bought the Lupo instead. It was a risk – I didn’t know whether there would be space for the engines until I started cutting.”
Luckily for Petar, Volkswagen’s smallest ever production car is a clever bit of packaging, and even the bulkiest engines can be persuaded to fit with some help from an angle grinder. But neither transplant was straightforward, and there isn’t much of the Lupo left beneath the skin.
The front end is a hybrid of Mk3 Golf, Passat and adapted Lupo parts, with notched chassis legs for extra engine clearance and bracing around the shock towers to keep it rigid. At the back, the floorpan was cut out from the rear panel to where the front of the bench seat would have been. In its place is the front subframe and shock towers recycled from Petar’s Mk2, mounted on chassis rails strengthened with 2mm thick plating. The Golf’s steering arms are fixed in place but allow for toe angle adjustment for the rear wheels.
KW developed a bespoke Variant 3 kit to suit, with high-poundage items at the back to help stop it squatting so aggressively under heavy acceleration
Considering the bulk on board, the only visible alteration was a bonnet bulge to clear the inlet manifold, as the six-speed gearbox meant the engine couldn’t mounted any closer to the bulkhead. Both V6s have its own exhaust system – a side pipe on the left for the front engine, and one on the right for its rear-mounted partner in crime. The Lupo’s soundtrack is about as subtle as its atom bomb power delivery.
“It was a really tight fit in the front, I had to cut the chassis legs to make space and then brace them for the extra power,” he explains. “The Mk2 Golf parts were the easiest way to put an engine in the back, as it keeps the donor car’s geometry, but the track is six inches wider than a standard Lupo. So I had to widen the front and rear arches to get the wheels underneath, and the driveshafts are from a Mk4 V6 but shortened for the Mk2 subframe.”
Packaging two engines turned out to be the first of several challenges for which there was no off-the-shelf solution, and rigidity was a priority. Having cut large amounts of metal out of the shell, Peter re-introduced some stiffness with an OMP six-point roll cage then added 18 metres of extra tubing including door bars, bracing the rollover hoops and reinforcement for the shock towers. Particularly in the back, which was never really designed to support the weight and stresses of a V6 at full chat.
It’s packed in so tightly that he’s had to retrofit electric windows, not as a luxury but because the side bars meant he had to open the doors to wind the old hand cranks. Pop-out windows at the back help get the warm air out of the cabin. Air conditioning had been part of the plan, but there wasn’t enough space to make it work. The rear engine also took up the space where the factory fuel tank had been. Determined to retain the passenger seat, Petar built his own. There are two wedge-shaped tanks fitted in the rear footwells and angled to match the seat backs, each holding 15.8 litres of fuel and with their own filler neck and Bosch 044 pump. That’s enough super unleaded to take the Lupo around 50 miles between refills.
“Making the two engines work together isn’t as complicated as most people think,” he says.
“There are two drive-by-wire gas pedals in the passenger footwell, which are joined together and connected via a cable to the Lupo pedal in front of the driver. The clutch pedal has twin master cylinders and the gearboxes are cable-change – standard at the front, with a custom mechanism in the back.”
If the Golf had felt a bit soft by Petar’s standards, then the Lupo’s lag-free 408bhp, four-wheel drive and comically short wheelbase offered the sort of adrenaline rush worthy of a three-year build – especially with a 200bhp shot of nitrous on top. Despite the regular fuel stops, it spent six years touring shows, drag events and even track days, showing a surprising talent for circuits as well as straight-line acceleration.
Because it was still road legal and neither engine was heavily tuned, it could put in miles doing supermarket and lunch runs, fetching parts and terrifying his friends between events.
"Of course there are parts available to make a single engined cars faster but twin-engined cars are just cool"
The spec continued to evolve but, considering the engineering involved and the usage it was put through, the Lupo didn’t present many additional hurdles. Adding nitrous caused issues with the Golf V6 clutches slipping, solved by upgrading to heavier-duty units from a Sharan VR6. Early overheating problems were solved by switching to a pair of upgraded aluminium E36 BMW M3 radiators with powerful slimline fans, originally protected by a custom carbon fibre splitter. The coolant hoses for the rear engine are routed through the transmission tunnel.
Petar also quickly found the limits of the Mk5 R32 brakes fitted during the first phase of the build, and upgrading unravelled a few problems too. The Lupo now runs Audi RS4 two-piece discs front and rear, with six and four-piston calipers to help scrub off the speed it piles on with maniacal urgency. In turn, this meant stepping up to 8x18-inch OZ Superleggeras to find the extra space, requiring even more arch flaring to avoid scrubbing.
Wider arches didn’t cure the issue, and it wasn’t until he borrowed a friend’s coilover kit that he realised the Lupo’s suspension was the problem. KW developed a bespoke Variant 3 setup to suit, the fronts based on Mk3 VR6 coilovers, with high-poundage Mk2 items at the back to help stop its 1400kg squatting so aggressively under heavy acceleration. Rubber-on- metal contact isn’t a chance worth taking in a car with this sort of performance.
In the meantime, attention to detail and fearless engineering had put Biox Performance – and Funtana – on the map. The Lupo got its first Wörthersee outing in 2011, hauled over the border on a low-loader to avoid issues with the Austrian police, and the workshop pulled in owners from all over Europe. Pick any of the Volkswagen Group’s most potent engines and chances are Petar has put one into a Lupo or a Mk1 Golf at some point. But he had a nagging feeling that there was still potential to unlock from the W12. “I always thought it could be faster, even with the nitrous,” he says. “Then in 2016 a friend with a second hand parts shop was selling a pair of Mk5 R32 engines and offered them to me. It felt like the right way to take the build a step further, so I started dismantling the Lupo whenever I had some spare time.”
Most of the hard work had already been done. Both engines are pretty much standard, aside from the ancillaries such as the power steering pump and air conditioning compressor removed from the one in the back, but offered a 100bhp power increase out of the box. To avoid unnecessary redevelopment it still uses the Mk4 V6 4Motion gearboxes, both with the transfer box propshaft joint removed, but they’re now equipped with a race-spec Sachs clutch and single-mass flywheel.
The rebuild also gave him a chance to re-think some old details, including giving the disassembled Lupo a refreshed paint job inside and out. There’s now a combined 300bhp shot of nitrous deployed with an RPM switch, and the slimmer R32 inlet manifold meant he could do away with the bonnet bulge. It’s still tight, though. The bonnet pins are a necessity as there’s not enough slam panel left to include the factory latch, and the hybrid of Mk4 R32 and Lupo bumper parts allowed the radiators to be covered up for the first time.
But it’s started fighting with the Rallye for workshop time. Having bought back his first project car in 2007 and put it on ice since, Petar is taking advantage of a much wider choice of donor engines to give it the performance he’d been chasing back in 2004. Having stripped five paint jobs from the body, it’s mid-way through an S3 TFSI conversion complete with a dual-clutch gearbox. A fast road car, without the need to hack out half of the floorpan.
However, he’s got no plans to start interfering with the Lupo’s unnaturally oversized drivetrain: “It’s hot and loud inside, and I still think it could be faster. But TFSIs are complicated for big power, so an R32 is still the best way. A quad turbo setup would push it over 1,000bhp, and there’s space for intercoolers behind the bumper,” he says, smiling.
“Of course there are parts available to make something faster than this with a single engine - twin engined cars are heavy, and you get better traction with a four-wheel drive car. But twin-engined cars are just cool.”
ENGINE: Twin Mk5 R32 (BUB) 3.2-litre VR6 engines, 2x custom 15.8-litre aluminium fuel tanks in rear footwells, 2x Bosch 044 fuel pumps, custom side-exit exhausts with straight-through silencers, 2x modified E36 BMW M3 radiators with alloy end tanks, slimline fans, direct port NOS nitrous system with RPM switches, 2x Mk4 Golf 4motion six-speed gearboxes with transfer box propshaft joint removed, custom cable-operated gear selector, gearbox Sachs Motorsport single-mass flywheels, Sachs Motorsport race clutches, shortened Mk4 Golf V6 driveshafts, Lupo throttle pedal running twin drive-by-wire Golf pedals in passenger footwell, Lupo clutch pedal with twin master cylinders, custom wiring loom
CHASSIS: Notched front chassis legs with custom bracing, Mk3 VR6 5x100 hubs all round, Hybrid Lupo/ Passat front arms, Mk2 Golf subframe and shock towers (rear), bespoke KW V3 coilovers based on Mk3 Golf (front) and Mk2 Golf (rear) suspension, 8x18 O-Z Superleggera wheels painted orange, 215/35 Nexen N8000 tyres, Audi RS-4 360mm discs with Porsche Cayenne 6 piston Brembo Z18 calipers (front), Audi RS-4 312mm discs with Audi RS-2 4-piston Brembo calipers (rear), hydraulic handbrake
EXTERIOR: Full respray in original Candy White, Mk4 R32 front bumper, flared front and rear arches, popout side windows
INTERIOR: Carpets, headliner and centre console removed, OMP roll cage with 18m of extra tubing, Sabelt Taurus seats, Sabelt harnesses, OMP Corsica wheel, Twin RPM and water temperature gauges, twin push-button starts, black door cards with retrofit electric window conversion
SHOUTS: KW Suspension, Bodyshop Matosevic for paint, ''Katalizator'' Pula for the exhaust and many friends for big and little things. See @Bioxperformance (Instagram), Biox Performance (Facebook) for updates.