With perfect 50/50 weight distribution, this rally-inspired, 180bhp bike-engined Fiesta is the perfect track-day tool.
Dropping a big engine into a small car has always been a great way to increase performance. From fitting the 1.6 CVH turbo into an XR2i to a Cosworth YB into a Mk1 Escort, countless conversions have taken place over the past 40-odd years. Which makes perfect sense: if you start with something larger and more powerful, then, generally speaking, it’s easier to make the car faster – especially if it’s turbo’d and you hit it with the tuning stick.
So, if someone suggested fitting a smaller engine to increase performance, you’d question their sanity, especially if it came from something two-wheeled… And Japanese.
But there’s more than one way to get your performance thrills, as Will Cairncross’s fizzing bike-engined Fiesta demonstrates.
How the bike-engined Fiesta plan came about
Will admits, “As with all my projects this was completely unplanned. Two years ago, my dad decided to build a Dutton Reef amphibious kit car, which uses a Mk7 Fiesta Zetec S as a donor and uses pretty much all of the Fiesta: interior, engine, suspension, the lot.
“There was a stripped shell in my workshop on a dolly. I’d been eyeing it up for weeks; my mind was ticking away every time I saw it.”
The motivation to go for it came when Will’s mate popped in: “Robin is a dab hand when it comes to building bikes, trikes, cars and pretty much anything else. He casually remarked we should build a bike-engined track car, and that was all the persuasion I needed.”
By the end of that week, Will had already ordered the S2000 bodykit from a company in Poland. It was on.
Will says, “The brains behind the build was Robin; he’s built so many things, it simply couldn’t have happened without him. While I can do most things relating to the build, I just simply wouldn’t have had the confidence and trust in myself to do it.”
Why use a bike engine on a Mk7 Fiesta?
But why a motorbike engine? “The main reason was to keep the weight down. The whole engine and gearbox setup we used only weighs 68kg. This build is all about the power-to-weight ratio,” Will explains.
He continues, “The price helps too. We were able to buy the complete engine, gearbox, and everything needed to run it for just a couple of grand.”
With the 180bhp Suzuki GSXR 1000cc engine being so small, physically dropping it into the Fiesta’s engine bay was a piece of cake – there’s plenty of room. The Suzuki engine is tiny compared with the typical Zetec or EcoBoost you’re expecting to find, so you get a great view of everything else, including the Gaz Gold suspension setup.
Will explains, “It sits in a fabricated cradle that bolts to the one-off subframe. It wasn’t particularly difficult to get it all to fit, but it’s all custom fabrication so was time-consuming to get right.”
“The cradle proved to be a Godsend not long ago when the engine blew up: we were able to swap the engine in just four hours.”
Tuning the bike-engined Fiesta
The engine has been treated to a few upgrades to maximise performance, including a Dyno Dynamics Power Commander 5 and Auto Tune. Hardware upgrades include OBP header tank and oil catch can, a Facet Red Top Works fuel pump and a high-flow alloy radiator. But there’s more to come, as Will has already got his eye on a TTS Performance supercharger kit too.
Putting that power to the ground, Will made use of the GSXR’s gearbox, which is integral to the engine. This means the Fiesta already has a six-speed sequential gearbox built-in, and it sends power to an Elite Racing Transmissions MX200 rear end via a custom propshaft. All very clever stuff.
But it gets even cleverer. “The MX200 diff unit not only has a limited-slip differential, it also has a reverse gear too. That means the car has a little party trick: it has six forward gears, plus six reverse speeds too.”
Will’s not finished there. “I’m going to fit a new Healtech gear indicator to mount to the dash, as it’s the first sequential-gearbox car I’ve had, and I quickly lost track of what gear I was in at Pembrey the other week.”
Exterior modifications on the bike-engined Fiesta
When it came to the exterior, Will wanted something that would suit the aggressive track focus of the Fiesta: “It was always going to take on the look of a rally car; in my view there are no better-looking cars than those from the WRC, from almost any era. Initially I was hoping for an R5 kit but the cost difference between that and the S2000 seemed too much to justify, so that was that.
“On the upside I do actually prefer the look of the front end of the S2000 cars.”
It certainly looks the part, finished in Frozen White, but that wasn’t the original plan.
Will says, “It was always going to have a full livery wrap, either a nod to a real car or something bespoke to promote my business.
“But once the car was painted and the matt black details started going on I swayed right around to leave it in the clean Frozen White.” With carbon headlight blanks and a set of tasty OZ WRC wheels, it looks ready to attack a special stage – or in this case, Castle Combe race circuit.
Interior modifications
Inside, there are no concessions to comfort or style. Everything has been fitted to save weight and make it as safe as possible. An OMP multi-point roll cage has been welded into place and provides ample protection, as well as adding rigidity to the shell.
It took some work, though, as Will explains, “I never want to get involved in painting the inside of a fully-caged car again. I’m not sure my back has fully recovered, even now.”
Having started off with a bare shell there was no need to remove anything, so Robin and Will could get on with the job in hand, adding only the bits they needed – including carbon fibre seats, TRS Magnum harnesses, and OMP Targa 330mm steering wheel.
Behind the wheel sits an AIM Solo 2 GPS speedometer and lap timer, fitted into a custom carbon housing. Beneath the wheel there’s an OBP pedal box – a work of art in itself. Open the tailgate and there’s a neat box, which contains the fuel cell – again, all really well thought-out and perfectly executed.
Bike-engined Fiesta Mk7 verdict
So what’s it like to drive this 790kg, 180bhp Fiesta in anger? Well, with a power-to-weight ratio of around 230bhp-per-tonne, it’s about the same as the S2000 rally car this car shares its bodykit with.
Will says, “The driving sensation is massively heightened by the rawness of the car. The lack of driver aids, the noise, the heat in the cabin, the rattles and bangs make it feel super exciting. Certainly, the closest thing to a race or rally car I’ll ever be behind the wheel of.
“It won’t be the fastest top-speed car at the track, but it gets there quick and can carry it through the corners, which makes for fun.”
But that’s not the end of the story. As we mentioned earlier, Will has plans to fit a supercharger kit to the GSXR motor, which will give this Fiesta something like 350bhp-per-tonne – and that’s like a full-blown WRC Fiesta. We can’t wait to see (and hear) when the ‘charger is finally fitted.
“Anyway, I get to pay Robin back now by fitting the bodykit and painting his build – yep, there is another one of these on the go.”
Words and photos: Davy Lewis
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