Drag machine 1400hp RB26-engined 4WD BMW Z4 E85

1400HP 4WD Z4 insane 900kg drag machine


Over the years – almost 21 of them – we’ve featured an awful lot of cars in PBMW and within that massive selection of modded motors there have been some truly insane builds, so you might think that we’ve really seen it all and there’s nothing left that can surprise us. But, every now and again, something makes an appearance that really blows us away, and what you’re looking at now is exactly one such car. On the face of it, it appears to be some sort of weird-looking Z4, but there is more to this outrageous machine than you could ever imagine – we’re about to find out just how deep the rabbit hole goes…

Let us introduce to you Henrik Karlsson; Henrik hails from Sweden and he doesn’t just come from a motoring family, he comes from a motorsport family; “My dad was very interested in motorcycling and drove rally at elite level here in Sweden,” he tells us. “When I was born he had to stop because it cost too much and there was too little time to continue when my parents bought houses, renovated and built garages. The house they bought is located 1km away from a motocross track so when I was three-years-old, dad took me to the track and I got stuck in right away. I trained a lot and when I was 11, I started to compete,” and there followed a truly incredible adventure, with the young Henrik competing in countless championships across the world, with his dad by his side as his private coach and mechanic and they made an awesome pair, with Henrik collecting a whole host of silverware throughout his teens and into his 20s. Sadly, when he was 21, Henrik lost his dad in an accident, leaving Henrik to become his own manager, with a friend taking over mechanic duties, and nowadays he mainly competes in motocross time trials. But the love of motocross has been passed onto his eight-year-old son, who has been riding in motocross since he was two-and-a-half and, just like Henrik and his father did, he and his son work as a team with Henrik handling the coaching and mechanic duties, just like his dad before him.

So we know that Henrik loves his bikes, but that love of speed and engines also carries over to his love of cars, and he’s big on power and performance. “I have always been interested in cars!” he says with a grin. “Since I was 18 years old and got a driver’s licence, I have always had a 4WD car alongside my truck. My first was an Audi 200 4×4, followed by an Audi S2 4×4 and then I got a Mitsubishi Evo 3; I still have it today, it’s got 650hp. With the cars, I have driven a lot on the ice and on gravel roads with rally tyres. I like 4×4!” he beams. “I like to drag race and often when you see cars built for this they have big supercharged or turbo V8s but I didn’t want to build the same sort of car as everyone else – I wanted to do something completely new!” he grins. “Anyone can build a fast V8, you just buy an engine and build a frame around it but my car is unique, no one has built anything like this. My thoughts before I started to build the car were that I wanted something small, with little air resistance, low, a long engine bonnet to fit everything that needs to be accommodated in the engine bay, a lot of horsepower, sequential gearbox to save time when changing gears, 4WD of course, and the car should blend in with other traffic and not stand out as a large V8-powered car does. You, as the driver, should sit far behind, just in front of the rear wheels, the car should have wide tyres for optimal grip and traction, it must have a lot of horsepower and have a proper roll-cage.” Now, that’s an awfully long lost of requirements but the Z4 you see before you, built over 12 months, is exactly the car he wanted to create and it ticks all of those boxes – all of them…

So, how does one even go about creating something like this? Well Henrik, a man with both the vision and skill, makes it all sound rather easy, but this was nothing short of an absolute monster build. “I bought a broken Nissan Skyline GT-R to get the six-cylinder RB26 engine as it is easy to get a lot of power out of, and I also got the front and rear diffs and all axles, hubs and brakes, they are all that was needed from that car. I then bought a crashed BMW Z4 that I repaired to make it drivable – I used the car to get the shapes that I needed to mould the body, which I made from carbon and fibreglass. I then started to build a frame in my garage using iron beams, which I could use to measure everything I needed to build the car. I located the axles and hubs and then I made the brackets for the engine to mount to and then the rear diff, and this all took me two week to ensure that everything would end up in exactly the right place and was measured with military precision. I then hung the body over the frame so I could check the fitment and would be able to make adjustments later if I needed to. “When I was happy that everything was going to fit together perfectly, I started building the chassis out of chromoly tubing, making sure that I knew where my seat, the pedal box, firewall, harness, roll-cage and everything else would need to go. I then started to build the roll-cage around the cockpit, which is Funny Carspec and rated for a 7.5-second quarter mile car, which is what I was aiming for with this build. I built a firewall from thin sheet metal and afterwards I was ready to attach the body to the frame, make the hinges and fit the doors. I then added the suspension, which uses Öhlins remote reservoir coilovers mounted on custom chromoly carrying arms.”

Obviously a machine like this needs something serious at the business end and Henrik didn’t choose the RB26 to power his Z4 because it’s got a pretty face… The 2.6-litre straight-six has received some serious upgrades and they, in turn, have resulted in a incredible power figure.

The RB26 has been fitted with forged CP-Carrillo pistons and rods, there’s an uprated head gasket, the head has been ported and fitted with Supertech valves, guides and valve springs, custom camshafts designed and ground from the stock cams by Matte Bolin, and there’s ARE Stage 4 dry sump lubrication, which lets you know that this is a serious engine for a serious car. As you can see from the photos, the turbo configuration is rather unique, with the Precision 7675 Gen 2 turbo mounted at the back of the engine on a Pure Performance Factory custom manifold, with the exhaust and Precision 66mm wastegate having both been designed to be as short – and therefore as light – as possible and they exit just behind the left front wheel. Intake air is kept cool with a monster custom front-mount intercooler from PPF, and in the boot you will find the fuel setup. There’s a custom PPF 30-litre alloy fuel cell with internal Deatschwerks DW400 pumps, designed to be neat without loads of external hoses, and the tank was built high and narrow so that Henrik wouldn’t require a separate swirl pot.


“I like to drag race and often when you see cars built for this they have big supercharged or turbo V8s but I didn’t want to build the same sort of car as everyone else – I wanted to do something completely new!”



This array of components ensures that the RB26 can gulp down as much E85 as it wants through that Nuke fuel rail and we get the feeling that 30-litres really doesn’t last very long at all. Overseeing all this engine-based madness is a FuelTech FT600 ECU and all the components combine to make an absolutely astonishing 1400hp, which makes this tubular-framed, lightweight 4WD Z4 an absolutely insane machine. Of course, just making the power isn’t enough, you have to actually be able to get it to the road and Henrik has cut no corners here. First of all, we’ve got the transmission, and it’s a monster gearbox; “The gearbox is a five-speed sequential Rallycross box from Sellholm with a pneumatic paddle shift system; this sends a signal to an electric controller that then opens an air valve, which sends air to a cylinder that sits on the gearbox and changes gear for you; at the rear of the car, behind the fuel cell, there is a small compressor and a small air tank that activates the shifts,” he explains. The gearbox uses a Tilton twin-plate clutch, there’s Magnus Motorsports launch control, and power is sent to all four wheels via a pair of spools, which lock both left and right axles together at each end of the car for ultimate traction when launching. The Z4 uses custom-made Rallycross driveshafts and the original Skyline propshafts, shortened to fit the more compact body dimensions, while the steering rack is from a Mitsubishi Evo 3 and Henrik’s chosen gearing gives him just one turn from lock-to-lock. The brake discs are custom-made from thin steel with aluminium hats so they’re as light as possible and fit under the custom-made wheels that Henrik runs; these measure 8.5×15” up front and 10×15” at the rear and are wrapped in ultra-sticky Mickey Thompson ET Drag slicks.

But there’s still more on this amazing build, as Henrik is keen to tell us; “The car is completely smooth underneath, which a racing car should be, where I have fitted a thin floor of carbon fibre. All the windows are made from Lexan, which is almost like Plexiglass and much lighter than regular glass. Behind the lamps is the completely standard Z4; I have only taken the Z4 glass and mounted it to a thin aluminium plate on the inside and attached two lamps in order to bring down the weight even more and I built brackets for the dry sump pump and tank. After that, I disassembled the car, which was just spot-welded, and I completely welded the chromoly tubes with a tight weld, which one has to do for the car to be classified for the 7.5-second chassis class, and the welding must be done a little at each place all the time so that the frame does not move away from the heat when welding,” he explains. The end result of all that weight reduction is a car that weighs just 900kg which, combined with the 1400hp, results in a power-to-weight ratio of over 1555hp per tonne, which is frankly terrifying and higher than any hypercar ever made and is even more than almost any superbike, which is just insane.

“When I was happy that everything was going to fit together perfectly, I started building the chassis out of chromoly tubing”

It goes without saying that building the car was not a quick or easy process and throughout it all Henrik had to race against tight deadlines. “When I picked the car up from painting there was still a lot of work left. I had three weeks before it would be on show at Sweden’s largest car show, Elmia. I had to work day and night to catch up with everything and while the car was not drivable it looked ready, and that was fine for the show. After Elmia I had 11 weeks to complete the car before my first competition, which was Street Week. There was still a lot of work left, like the wiring, all the hoses for fuel and oil, brake lines, water and cooling hoses, The car also needed to be started up, tested and mapped. It was but not perfectly; there were 200 participants in the competition on the day and I finished eighth. After that competition I knew that everything worked but had to be adjusted to make it even faster. I ran a 5.8-second 1/8th mile at best, which was okay for the car’s first outing and I will continue to fine-tune everything this spring so I’ll be ready for this year’s competitive season,” smiles Henrik, but the question is will everyone else be ready for him? And it’s not just drag racing that his monster Z4 has been designed for, oh no, this is a car of many talents. “When I built the car I thought that maybe I would want to go to other events such as on track, time attack or maybe drifting with 4WD, they would be cool! All this I can do with some changes to the car’s setup as the cage and the entire car are approved to compete in these other events, so it’s ready to go,” he grins.

“The end result of all that weight reduction is a car that weighs just 900kg which, combined with the 1400hp, results in a power-to-weight ratio of over 1555hp per tonne, which is frankly terrifying”

Henrik’s Z4 is a truly astonishing machine, an absolutely unhinged creation that defies the laws of nature but it’s been built with a purpose, and that purpose is to be as fast as physically possible without causing Henrik’s brain to melt and pour out of his ears, but there’s still a chance that might happen anyway… There are so many amazing numbers that make up this Z4, so many incredible motorsport components, but perhaps most impressive of all is the concept itself, and the fact that Henrik made it happen. Engine swaps are one thing, but drivetrain swaps and custom, lightweight bodies over tubular frames are something else entirely and this whole car was one man’s vision, and it’s been made so very real. “Thanks to my competitive motocross past, I have got a will without equal and a desire for perfection that one must have if you are to perform at a high level in all sports. I applied that when ordering all the parts for my car and that’s why I have built my car as I have done, as I do not want to leave anything to chance!” and we don’t blame him – you can’t take chances when you’re sitting on 1400hp and running seven-second quarters.

Henrik’s insane Z4 is without doubt one of the craziest machines we’ve ever featured in PBMW, and it’s also one of the most impressive and that’s just reading about it. Watch some videos of this machine online and you immediately have a new-found respect for both it and the slightly unhinged Swede behind the wheel. Performance BMWs don’t come much faster – or wilder – than this.

DATA FILE 4WD RB26 drag Z4

ENGINE 2.6-litre straight-six RB26, ported head, Supertech valves, guides and valve springs, custom camshafts, CP-Carrillo pistons and rods, ARE Stage 4 dry sump system, Precision 7675 Gen 2 ball bearing turbo, Precision 66mm wastegate, PPF custom intake and exhaust manifolds, PPF custom intercooler and piping, Nuke fuel rail, FRAM Racing oil filter, FuelTech FT600 engine management with FuelTech CAN EGT and FuelTech Nano wideband lambda

TRANSMISSION Sellholm MPG five-speed sequential gearbox with pneumatic paddle shift system, Tilton twinplate clutch, shortened Skyline propshafts, front and rear spools, custom Rallycross driveshafts, Magnus Motorsports launch control

POWER 1400hp

CHASSIS 8.5×15” (front) and 10×15” (rear) custom wheels with 26.0/8.5-15 (front) and 26.0/10-15 (rear) Mickey Thompson ET Drag slicks, chromoly tubular frame chassis, Öhlins remote-reservoir coilovers, Mitsubishi Evo 3 steering rack with one turn lock-to- lock, Nissan Skyline GT-R four-piston calipers (front) and Brembo two-piston calipers (rear) with custom lightweight brake discs (front and rear)

EXTERIOR Custom carbon fibre and fibreglass wide-body, custom lightweight headlights, side-exit exhaust and wastegate, Lexan windows, flat carbon fibre floor, rear diffuser

INTERIOR Sparco Circuit GRP driver’s seat, Sparco Evo II passenger seat, TRS four-point harnesses, Grant Racing steering wheel, carbon shift paddles, FuelTech FT600 race display, custom Funny Car-spec roll-cage, PPF custom 30-litre alloy fuel cell with twin Deatschwerks DW400 in-tank fuel pumps, Nuke fuel filter, compressor and air tank for pneumatic paddle shift system


Massive Precision 7675 Gen 2 turbo.

RB26 has received a huge number of mods.

Dry sump oil pump.

Hose for one of the remote reservoir shocks.

Sellholm five-speed sequential Rallycross gearbox.

ARE dry sump system. FuelTech FT600 display. Sparco seats and TRS harnesses .

Fuel cell with twin in-tank pumps, and tank and compressor for pneumatic gearshift system.

Custom-mounted Öhlins remote reservoir coilovers.

Fat Mickey Thompson drag slicks all-round.

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Jean-Claude Landry
Jean-Claude is the Senior Editor at eManualOnline.com, Drive-My.com and Garagespot.com, and webmaster of TheMechanicDoctor.com. He has been a certified auto mechanic for the last 15 years, working for various car dealers and specialized repair shops. He turned towards blogging about cars and EVs in the hope of helping and inspiring the next generation of automotive technicians. He also loves cats, Johnny Cash and Subarus.