It Took Five Engine Swaps To Get Here

At Gatebil Rudskogen, things are rarely what they first seem.

When I spotted this little orange Opel Kadett on display in the paddock, something told me I should take a closer look. Why? Well for a start, Kadetts of this era are pretty cool little things, and you don’t see them around very often. And secondly, there’s no way that a standard or even lightly modified 1.6 S Kadett would be shown with its bonnet up at this event.

Opel Kadett V6 Honda by Jordan Butters Speedhunters-1

It turned out to be a good call, and I managed to persuade owner Kristoffer Paule Bråthen to let me shoot it once the track closed on the Saturday evening.

Opel Kadett V6 Honda by Jordan Butters Speedhunters-22

The 1.6-litre Kadett spent a deal of its life in Kristoffer’s hands with a lowly 75hp to play with. Eventually, when he felt the need for more oomph in 2011, he built up a 2.5-litre Opel CIH motor, over doubling the horsepower he had before. Sadly, this motor gave way just months later at Rudskogen, so he built another the same. That one lasted until the following spring before going the same way whilst on the dyno.

Opel Kadett V6 Honda by Jordan Butters Speedhunters-6

“When I was tired of blowing up Opel engines, I decided to do what many Scandinavians would do,” Kristoffer explains. “I threw in a Volvo B230FK. A friend sold me a fully ported cylinder head with larger valves and a huge camshaft, along with forged pistons, rods and crankshaft. This engine made 512whp and 606wNm. I drove the car a couple of summers with the Volvo engine, before I decided to change it out for something bigger.”

At least it didn’t blow up, right?

Opel Kadett V6 Honda by Jordan Butters Speedhunters-18

Kristoffer’s fifth engine choice, and the one the car sports now, is something truly unexpected. Wanting to up the capacity, but mindful of the lack of space he had to play with and needing to keep the budget under control, he opted for a 3.5-litre Honda J35 V6, as normally found in the Honda Odyssey people carrier.

Kristoffer imported the engine from the US. However when he attempted to test fit it into the engine bay, the sump blocked its path into position. “I thought about making a rear sump, but figured out that I had to have the starter motor under the oil pan, so moving the sump was not an alternative,” he told me. “I had to find the big angle grinder and start cutting to move the engine further back. The first cut we did was not enough, so the engine got stuck when we test fitted it. When we finally got the engine loose again, we cut out an even bigger bit.”

Opel Kadett V6 Honda by Jordan Butters Speedhunters-13

Solving one problem often creates another, and with the engine where it needed to be, Kristoffer couldn’t sit in the driver’s seat as the repositioned firewall didn’t offer much in the way of legroom. The answer was to move the seats back, which then meant that Kristoffer had to build a new roll cage to accommodate the new driving position. As it sits now, the seats are almost touching the mounting points for the rear axle.

Opel Kadett V6 Honda by Jordan Butters Speedhunters-17

Not wanting to settle for stock Odyssey power, a BorgWarner S369SX-E turbocharger was mated up. The engine was then rebuilt with Wiseco forged pistons and H-beam conrods.

Opel Kadett V6 Honda by Jordan Butters Speedhunters-20

The heads were ported as was the intake manifold before being fitted with a 70mm throttle body. Engine management is by MaxxECU V1 and fuelling is thanks to 1,000cc injectors and an Aeromotive A1000 pump and adjustable fuel pressure regulator.

Opel Kadett V6 Honda by Jordan Butters Speedhunters-25

A BMW 530D 5-speed gearbox and 7.25-inch Quarter Master clutch carry around 591whp and 707Nm torque rearwards via a custom strengthened prop to a modified Volvo 240 rear axle, complete with limited slip diff. The results are a very lively little Kadett that surprises a lot of people.

“It’s quite nervous to drive,” Kristoffer says. “This much power in a car that is this short is a bit challenging. It is unforgiving. If you make a mistake, it will come back and bite you in the ass.”

Opel Kadett V6 Honda by Jordan Butters Speedhunters-23

To help balance the weight in the front, the cooling system was moved to the car’s boot area and features two Nissan 200SX radiators and a Volvo 850 electric fan. Air is drawn in from underneath the car. One clever little trick is an electric actuator linked to the boot catch; once the fan kicks in, the boot lid lifts 10cm automatically to allow the warm air a passage out. It shuts again once things have cooled down.

Opel Kadett V6 Honda by Jordan Butters Speedhunters-4

One of my favourite features, and Kristoffer’s too, is that the exterior is modified in a very subtle manner, even down to retaining the original 1.6 S badges on the bootlid. A set of 15-inch BBS wheels wrapped in Toyo Proxes R888R rubber, a couple of speed holes in the rear, and the aforementioned roll cage the only immediately visible clues that all is not as it seems.

Opel Kadett V6 Honda by Jordan Butters Speedhunters-9

The front wings and front panel have also been replaced with lighter fibreglass items, not that you can tell.

Opel Kadett V6 Honda by Jordan Butters Speedhunters-2

Of course the Opel has been fettled in the suspension department too. Two-way AVO front dampers and Koni rears are up to the task, while custom arms keep the alignment in check.

Opel Kadett V6 Honda by Jordan Butters Speedhunters-11

Inside, a pair of Sparco Prodrive seats and a Sabelt steering wheel are to hand, while Kristoffer had to custom make the pedal box and shifter to suit the new driving position.

Opel Kadett V6 Honda by Jordan Butters Speedhunters-12

A utilitarian dash complete with the essential gauges keep things simple. You can see from here just how far the engine and box enter into the Kadett’s tiny cabin.

Opel Kadett V6 Honda by Jordan Butters Speedhunters-26

Sadly Kristoffer’s track time at Gatebil was cut short by an engine issue, but a huge thanks to him and his team for pushing the car into place for us to shoot.

Hopefully this doesn’t mean engine swap number six is on the way, although I’m not sure if there’s anything bigger than would even fit at this stage.

Jordan Butters
Instagram: jordanbutters

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I always wondered about odd swaps and combinations like this. Do they need to have a custom adapter plate made? Would a specific combination of bell-housing work? Honda engine and BMW gearbox definitely sounds Scandinavian, hahaha, but I would love to know more about how these combinations are put together.


It is an adapter plate between the engine and gearbox, and a custom flywheel with a spacer, so that the clutch can reach the splines on the input shaft of the gearbox. If you want to see more, visit Oakheart Racing on Facebook and Instagram :)


Ooooo, thanks so much! Gonna do some research on them as well.


LS swaps are common enough for these cars that you can buy engine mount kits!


Even though this kind of high HP monsters are not my style, I'll gladly take a classic Opel feature any day!


I was wonder why the engine choice & turbo placement looks familiar... I've seen the work-in-progress photo(s) of this Opel back in May 2017 on facebook.


Great execution in this build. I love the non-traditional engine swap. I appreciate the extra fabrication and money it costs to do something different. But if it broke at Gatebil, I'd hate to say it - LS swap it and be done. Unless you prefer working on it to driving it.

I'm in the same boat right now working on a non-traditional car with a non-traditional swap. I've burned through two motors and tons of time doing CAD and fab work. Fortunately for me, I have more time to fab than to drive right now, so I don't mind it. But this build and execution is so nice, I want to see this one driven.


Still prefer the "simple" Volvo engine swap, but can't deny the work done here.
Are the wheels not sitting properly in the arches or it's just the photo angle?


They do look quite far back in the fenders.


Wow, crazy build! I love the creativity!
I really love watching these cars screaming on those Bergrennen St. Ursanne Race videos.


Very unexpected, but absolutely awesome. Since I own both an Opel and a Honda, I like this build very much :)


I love the originality of this. So much better than a LS and unexpected.